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Journal articles on the topic 'Hydrothermal time'

Author: Grafiati
Published: 4 June 2021
Last updated: 5 February 2022

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1

Arruda, Maria Cecília de, Angelo Pedro Jacomino, Ana Luíza Pinheiro, Rafael Vasconcelos Ribeiro, Michelle Antonio Lochoski, and Raquel Capistrano Moreira. "Hydrothermal treatment favors peeling of 'Pera' sweet orange fruit and does not alter quality." Scientia Agricola 65, no. 2 (April 2008): 151–56. http://dx.doi.org/10.1590/s0103-90162008000200007.

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Consumer demand for ready-to-eat-products has stimulated the development of new processing techniques to prepare fresh-cut fruit and vegetables. The aim of this study was to propose a peeling method for 'Pera' oranges (Citrus sinensis [L.] Osb.) by using a hydrothermal treatment and to determine its influence on the respiratory activity, physicochemical and sensorial characteristics, as well as on the peeling time. Cooled oranges (6ºC) were immersed in heated water (50ºC) for eight minutes and then, peeled and stored at 6ºC. The internal fruit temperatures taken at 1 and 3 cm depths (from fruit surface) were 15ºC and 10ºC, respectively, at the end of the hydrothermal treatment. Non-hydrothermally-treated peeled oranges were used as control. The peeling time for treated oranges was 3.2 times as short as the time used for the control. The yield of marketable oranges was 95% for hydrothermally-treated oranges versus 60% for control. The respiratory activity of hydrothermally-treated oranges was greater than that of control oranges only during the first hour after peeling. The hydrothermal treatment influenced neither the physicochemical quality (given by soluble solids, titratable acidity and ascorbic acid content) nor fruit flavor. Oranges peeled with the aid of the hydrothermal treatment had better appearance. The hydrothermal treatment makes the peeling of oranges easier and does not affect their respiratory activity or their physicochemical and sensorial qualities.
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2

Sutarno, Sutarno, and Yateman Arryanto. "PHASE TRANSFORMATION IN THE FORMATION OF FAUJASITE FROM FLY ASH." Indonesian Journal of Chemistry 5, no. 3 (June 15, 2010): 278–82. http://dx.doi.org/10.22146/ijc.21804.

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Faujasite was hydrothermally synthesized from fly ash at 100oC in alkaline solution by reflux with 5M HCl and fusion with NaOH pretreatments. Phase transformation in the formation of faujasite was performed by variation of NaOH/fly ash weight ratios and hydrothermal times. The solid products were characterized by X-ray diffraction method. Results showed that faujasite was formed through dissolution of fly ash components such as quartz, mullite and amorphous aluminosilicates followed by crystallization to form faujasite. Arranging the NaOH/fly ash weight ratio as well as hydrothermal time can selectively form faujasite. Faujasite with crystallinity of 97.06%, Si/Al ratio of 2.68, and specific surface area of 452.93 m2/g was successfully formed using NaOH/fly ash weight ratio of 1.2 for hydrothermal time of 72 hours. In more concentrated alkaline solution as well as for longer hydrothermal time, faujasite was completely transformed into hydroxysodalite as the final product. Keywords: fly ash, faujasite, and phase transformation.
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3

Kamitani, Masataka, Toru Tagami, Takashi Fukaya, Mitsunori Kondo, Tomonori Hiki, and Atsushi Nakahira. "Synthesis of A-Type Zeolite from Flat Glass Recycle by Hydrothermal Treatments and its Evaluation." Key Engineering Materials 616 (June 2014): 183–87. http://dx.doi.org/10.4028/www.scientific.net/kem.616.183.

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Synthesis of monolithic A-type zeolite (LTA) was attempted by hydrothermal processing from recycling flat glass. Crashed flat glass were pretreated and subsequently hydrothermally treated at 95°C for 24 h. As a result, monolithic A-type zeolite without another phase was successfully synthesized by the hydrothermal treatments. The synthetic condition was clarified during the pretreatment and hydrothermal treatments. The development of hydrothermal process for recycle of flat glass was carried out since the monolithic A-type zeolite was obtained under the optimum synthetic conditions (reaction temperatures, reaction time and pretreatment conditions etc).
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4

Yun, Hong, Zhi Guo Zhang, Qun Jie Xu, and Chen Ying Tan. "Enhanced Anticorrosion Properties of SnO2 Coatings in Simulated PEMFC Environments by Hydrothermal Treatment." Advanced Materials Research 860-863 (December 2013): 793–96. http://dx.doi.org/10.4028/www.scientific.net/amr.860-863.793.

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SnO2 coatings were supplied on the surface of 304 stainless steel (304SS) by a sol-gel process followed by hydrothermal treatments at different reaction temperature and time, respectively. The effects of hydrothermal temperature and time in pure water on the anticorrosion performances of the SnO2 films in simulated proton exchange membrane fuel cells (PEMFC) environments were investigated by potentiodynamic polarization curves, open circuit potential-time curves and electrochemical impedance spectroscopy (EIS). It was found that the SnO2 coated 304SS via the hydrothermal treatment showed a better corrosion resistance than the sample without hydrothermal treatment and bare 304SS. The SnO2 coated 304SS hydrothermally treated at 160°C for 3h showed the highest corrosion resistance among the samples. The results have been discussed in terms of surface structure of SnO2 film and its anticorrosion performance in simulated PEMFC environments.
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5

Choi, Chan Yang, and Jai Won Byeon. "Nondestructive Reliability Monitoring of Zirconia Degraded under Hydrothermal Condition." Applied Mechanics and Materials 249-250 (December 2012): 968–71. http://dx.doi.org/10.4028/www.scientific.net/amm.249-250.968.

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3%yttria-stabilized tetragonal zirconia polycrystal (3mol% Y2O3-ZrO2, 3Y-TZP) ceramic suffers from low temperature degradation (LTD) during long time use under hydrothermal condition. In this research, an attempt was made for monitoring hydrothermal degradation of the ceramic by using semi-nondestructive X-ray diffraction (XRD) method. In order to simulate accelerated hydrothermal degradation, the specimen was placed under water vapor atmosphere at 134°C, 150°C, and 200°C in an autoclave for various exposure time up to 40 hours. From the X-ray diffraction peak, two feature parameters including intensity ratio and full width at half maximum were determined and observed to increase with hydrothermal exposure time and temperature. The consistent changes in XRD parameters were correlated with the tetragonal-to-monoclinic microstructural change. Based on the established linear correlations with hardness reduction, potentials of the two XRD parameters were suggested for health-monitoring of the hydrothermally exposed 3Y-TZP ceramic.
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6

Lin, Wen-Hao, Shiuh-Ke Jang Jean, and Chii-Shyang Hwang. "Phase formation and composition of Mn–Zn ferrite powders prepared by hydrothermal method." Journal of Materials Research 14, no. 1 (January 1999): 204–8. http://dx.doi.org/10.1557/jmr.1999.0030.

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Mn–Zn ferrite powders were prepared by hydrothermally aging the coprecipitates of compositional metal ions using ammonium hydroxide as a precipitant. R value (alkalinity) = (moles of added OH−)/[(moles of added Zn2+) × 2 + (moles of added Mn2+) × 2 + (moles of added Fe3+) × 3] was introduced to adjust the amount of added ammonia. The results show that the R value of starting suspension and hydrothermal time have similar and dominant effects on the composition, spinel ratio, and crystallite size of synthesized powders. From the analyses of x-ray diffraction (XRD) and inductively-coupled plasma (ICP), it notes that no α–Fe2O3 peak in the XRD patterns of powders synthesized at R = 2–3, 150 °C × 2 h, may be due to lower degree of crystallinity and less amount of α–Fe2O3 existing in these powders. Both the increase of hydrothermal time and of R value can promote the crystallinity of powders and also cause a significant loss of zinc, hinting that in the hydrothermal process, the loss of zinc may play a crucial role in the crystallinity of hydrothermally synthesized powders.
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7

Yeh, William W. ‐G, Leonard Becker, Shi‐Qian Hua, De‐Pu Wen, and Jian‐Min Liu. "Optimization of Real‐Time Hydrothermal System Operation." Journal of Water Resources Planning and Management 118, no. 6 (November 1992): 636–53. http://dx.doi.org/10.1061/(asce)0733-9496(1992)118:6(636).

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8

Naversen, Christian Øyn, Arild Helseth, Bosong Li, Masood Parvania, Hossein Farahmand, and João P. S. Catalão. "Hydrothermal scheduling in the continuous-time framework." Electric Power Systems Research 189 (December 2020): 106787. http://dx.doi.org/10.1016/j.epsr.2020.106787.

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9

Srilai, Suphada, Worapak Tanwongwal, Kobchai Onpecth, Thanapat Wongkitikun, Gasidit Panomsuwan, Masayoshi Fuji, and Apiluck Eiad-Ua. "Influence of Crystallization Time for Synthesis of Zeolite A and Zeolite X from Natural Kaolin." Key Engineering Materials 824 (October 2019): 231–35. http://dx.doi.org/10.4028/www.scientific.net/kem.824.231.

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Zeolite A and zeolite X was successfully synthesized from natural kaolin from Lampang province using calcination and two-step method of hydrothermal under the optimum conditions. Firstly, metakaolin was achieved by calcining the kaolin at 700 °C for 2 h. Secondly, hydrothermal experiments can be separated into two steps, the high temperature and short time of hydrothermal, metakaolin was mixed with NaOH to form hydrous sodium aluminosilicate, which was dissolved in dilute HCl. After the filtration, adjusted with deionized water to pH = 7 to form an amorphous aluminosilicate gel. Low temperature and longtime of hydrothermal, aluminosilicate gel was mixed with NaOH to form zeolite A and zeolite X. The optimum conditions for synthesis zeolite A is the high temperature and short time of hydrothermal with NaOH 8 M at 200 °C for 3 h and low temperature and longtime of hydrothermal with NaOH 1 M at 90 °C for 72 h. The optimum conditions for synthesis zeolite X is the high temperature and short time of hydrothermal with NaOH 8 M at 200 °C for 3 h and low temperature and longtime hydrothermal was NaOH 1 M at 90 °C for 120 h. The characterization of zeolite A and zeolite X were examined by x-ray diffraction (XRD), scanning electron microscopy (SEM), and infrared spectroscopy (FT-IR). Keywords: Zeolite A, zeolite X, Kaolin, Hydrothermal, Kaolin
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10

Wang, Jing, Shi Jun, and Xu Bing. "The Effects of Hydrothermal Time on the Microstructure of Hollow Sphere Boehmite." Advanced Materials Research 295-297 (July 2011): 440–45. http://dx.doi.org/10.4028/www.scientific.net/amr.295-297.440.

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Using aluminum sulfate as precursor and urea as precipitator, hollow sphere boehmite was synthesized by hydrothermal treatment on 140°C for 24h. The time effect of as-synthesized product was studied by XRD, SEM and TG, et al. The results show that with the hydrothermal time increasing the product’s phase transformed from sodium sulfate aluminum to amorphous form to mixture phases of sodium sulfate aluminum and boehmite to boehmite. After 24h hydrothermal treatment, the product can completely change to boehmite. With the hydrothermal time increasing, the micromorphology of hydrolysis product experienced the evolution of smooth dense globe to core-shell sphere to hollow sphere.
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11

Belviso, Claudia, Antonio Lettino, and Francesco Cavalcante. "Influence of Synthesis Method on LTA Time-Dependent Stability." Molecules 23, no. 9 (August 23, 2018): 2122. http://dx.doi.org/10.3390/molecules23092122.

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Time-stability of LTA zeolite formed by hydrothermal method with or without the action of ultrasonic irradiation was investigated by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). The results show that 6 months after the synthesis by hydrothermal process with continuous sonication, LTA evolves into a more stable sodalite, whereas no differences are detected 12 months after LTA synthesis by conventional pre-fused hydrothermal process. These data confirm that using the two approaches, different mechanisms control both zeolite crystallization and time-stability of the newly-formed mineral at solid state. The results are particularly important in the light of the synthetic zeolite application.
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12

Wang, Yi, Fang Cai, Pengran Guo, Yongqian Lei, Qiaoyue Xi, and Fuxian Wang. "Short-Time Hydrothermal Synthesis of CuBi2O4 Nanocolumn Arrays for Efficient Visible-Light Photocatalysis." Nanomaterials 9, no. 9 (September 5, 2019): 1257. http://dx.doi.org/10.3390/nano9091257.

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In this article, a short-time hydrothermal method is developed to prepare CuBi2O4 nanocolumn arrays. By using Bi(NO3)3·5H2O in acetic acid and Cu(NO3)2·3H2O in ethanol as precursor solutions, tetragonal CuBi2O4 with good visible light absorption can be fabricated within 0.5 h at 120 °C. Tetragonal structured CuBi2O4 can be formed after 15 min hydrothermal treatment, however it possesses poor visible light absorption and low photocatalytic activity. Extending the hydrothermal treatment duration to 0.5 h results in a significant improvement invisible light absorption of the tetragonal CuBi2O4. The CuBi2O4 obtained through 0.5 h hydrothermal synthesis shows a band gap of 1.75 eV and exhibits the highest photocatalytic performance among the CuBi2O4 prepared with various hydrothermal time. The removal rate of methylene blue by the 0.5 h CuBi2O4 reaches 91% under visible light irradiation for 0.5 h. This study proposes a novel strategy to prepare photoactive CuBi2O4 nanocolumn arrays within 0.5 h at a moderate temperature of 120 °C. The hydrothermal method provides a facile strategy for the fast synthesis of metal-oxide-based photocatalysts at mild reaction conditions.
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13

Liu, Yu Qin, Hong Tu Xia, and Hong Wen Ma. "Kinetics of Hydrothermal Decomposition of Potassium Feldspar with Calcium Hydroxide." Advanced Materials Research 549 (July 2012): 65–69. http://dx.doi.org/10.4028/www.scientific.net/amr.549.65.

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The aegirine-augite syenite potash ore, taken from Changling, Luonan in Shannxi province, were hydrothermally decomposed over the temperature ranges of 533 K to 563 K using calcium hydroxide as additive. The dissolution ratio of the K2O at different reaction temperature and time was determined. Analysis of the experimental results revealed that the dissolution rate of potash ore satisfies the chemical reaction controlled kinetic equation. The rate constant of hydrothermal reaction at different temperatures was obtained. The activation energy was calculated using the Arrhenius equation. The hydrothermal decomposition mechanism of microcline was proposed.
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14

Milawati, Sri, Intan Syahbanu, and Risya Sasri. "Synthesis TiO2 -SiO2 Composites Using The Method Sol-Gel-Hydrothermal." Jurnal ILMU DASAR 22, no. 1 (January 14, 2021): 51. http://dx.doi.org/10.19184/jid.v22i1.14492.

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Titanium dioxide (TiO2) is a transition metal oxide material which has been researched extensively and can be used for various applications. In this research, synthesis of TiO2 -SiO2 using TTIP and TEOS precursor. Research aims to determine the characteristics of composite materials generated based on the influence of hydrothermal time and precursor composition. Synthesis is done by variation of hydrothermal time (4 hours, 8 hours, 18 hours, 24 hours and without hydrothermal) and TEOS precursor composition variation (1:1, 1:2 and 2:1). Synthesis is made by dissolving the two precursors through the sol-gel-hydrothermal method and continued with the calcination process. Characterization using FT-IR showed a bonding Ti-O-Si at a wavelength of 950 cm-1 . This bond is formed from the interaction between TiO2 and SiO2 which indicates the success of the synthesis. The XRD characterization results show formed of a peak at 2θ° the range 25° for all composites. The results of the dr-uv characterization on the TiO2 -SiO2 composite comparison of 2:1 showed absorption at 387 nm and obtained band gap energy of 3,20 eV. Based on the data obtained it can be concluded that synthesis of TiO2-SiO2 hydrothermally obtained the optimum time 24 hours and the best comparison is contained in the composition 2:1, which produces an anatase structure with a crystal size of 15,899 nm, so that the resulting composite can be used as a photocatalyst. Keywords: Hydrothermal, Sol-gel, TiO2 -SiO2.
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15

Wang, Yi Fei. "Transformation of Natural Clinoptilolite to High Purity of Synthetic Zeolits." Advanced Materials Research 466-467 (February 2012): 42–46. http://dx.doi.org/10.4028/www.scientific.net/amr.466-467.42.

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In this paper, the Chinese natural clinoptilolite was treated hydrothermally, with fusion with NaOH powder as pretreatment. High purity of zeolite Na-Y, Na-P and Na-A were identified as the reacted products, depending on the reaction conditions such as hydrothermal time and the Si/Al molar ratio in the gels. And their cation exchange capacity (CEC) are 257, 355 and 335meq/100g respectively, which are greatly higher than that of the natural zeolite (97 meq/100g). In the hydrothermal reaction, an interesting phenomenon of crystal transformation has also been found
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16

Zhou, Long, R. Yu, K. Zhu, J. Yao, X. Xing, D. Wang, and X. Wu. "Preparation of Plank-Like BaTiO3 by Hydrothermal Soft Chemical Process from Layered Titanate Precursors." Key Engineering Materials 336-338 (April 2007): 66–68. http://dx.doi.org/10.4028/www.scientific.net/kem.336-338.66.

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The influence of processing parameters on the morphology of hydrothermally derived BaTiO3 powders was investigated. Layered H2Ti3O7 with plank-like morphology were used as the Ti-precursor materials. The BaTiO3 powders were characterized by XRD and SEM. Lower Ba/Ti ratio is benefit for preparation of BaTiO3 particles which retains the morphology of the precursor. The BaTiO3 particles obtained at 200°C for 24h were large, uniform, and plank-like particles. Extending the hydrothermal temperature or the hydrothermal time does not help to synthesize BaTiO3 powders of large size and uniform morphology.
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17

Bloomberg, M., J. R. Sedcole, E. G. Mason, and G. Buchan. "Hydrothermal time germination models for radiata pine (Pinus radiataD. Don)." Seed Science Research 19, no. 3 (September 2009): 171–82. http://dx.doi.org/10.1017/s0960258509990031.

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AbstractThe objective of this study was to fit a hydrothermal germination model to germination data for a seedlot of radiata pine (Pinus radiataD. Don). Seeds were incubated for 50 d at constant temperatures and water potentials (T = 12.5–32.5°C, Ψ = 0 to − 1.2 MPa). Most seeds completed germination within 50 d, but for low Ψ and/or non-optimal temperatures (T < 17.5°C,T>25°C) many seeds did not complete germination. In general, germination data conformed to the hydrothermal model. Departures from the model were encountered for slow-germinating seeds at suboptimal temperatures (T ≤ 20°C). To account for these departures, two alternative hydrothermal models were fitted with an additional term for an upwards shift in seed base water potential with increasing time to germination. The alternative models more correctly predicted germination time than the original model. Similarly, reduced percentage germination at supra-optimal temperatures (T>20°C) was explained by including a term in the hydrothermal model which shifted the base water potential of seeds upwards towards zero, which in turn reduced the predicted rate that hydrothermal time would be accumulated by seeds. The rate of this upwards shift in base water potential was dependent on time to complete germination and ambient water potential as well as supra-optimal temperature.
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18

Onofri, Andrea, Paolo Benincasa, Mohsen B. Mesgaran, and Christian Ritz. "Hydrothermal-time-to-event models for seed germination." European Journal of Agronomy 101 (November 2018): 129–39. http://dx.doi.org/10.1016/j.eja.2018.08.011.

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19

Ng, Soo Ai, Abdul Razak Khairunisak, Kuan Yew Cheong, Poh Choon Ooi, and Kean Chin Aw. "The Effect of Hydrothermal Reaction Time on Formation of AuNPs by Sacrificial Templated Growth Hydrothermal Approach." Advanced Materials Research 1024 (August 2014): 71–74. http://dx.doi.org/10.4028/www.scientific.net/amr.1024.71.

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This work describes the formation of gold nanoparticles (AuNPs) by using the sacrificial template growth hydrothermal method. AuNPs was grown on Aluminum/ polymethylsilsesquioxanes (PMSSQ) /Silicon substrates. Sputtered Al was used as a sacrificial template. The effect of hydrothermal reaction time on AuNPs properties was investigated for 1, 2, 3 and 4 hours. Properties of AuNPs were studied by using Field-Emission Scanning Electron Microscope (FESEM), X-ray Diffraction (XRD) and Semiconductor Characterization System (SCS). This approach allows the formation of AuNPs directly on the substrates. XRD analysis proved that Al template was removed during hydrothermal reaction. This approach allows the formation of AuNPs directly on the substrates. The number of AuNPs increased with increasing hydrothermal reaction time. However, longer than 1 hour reaction time, AuNPs tend to grow in clusters that could be due to unintended aggregation and agglomeration caused by self-association of the AuNPs. I-V characteristics showed hysteresis properties that indicated charge storage capability of AuNPs embedded in PMSSQ. AuNPs grown in 1 hour hydrothermal reaction produced the best memory properties due to well distribution of isolated AuNPs as observed in SEM image with the lowest abrupt current of 2.4 V.
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20

Li, Xiao Hua, Xiao Ling Cheng, Fu Yuan Xie, Xiao Qun Wu, and Yu Zi Yu. "Hydrothermal Time Effecting on the Morphology of Hydroxyapatite Templated by L-DOPA." Advanced Materials Research 881-883 (January 2014): 211–14. http://dx.doi.org/10.4028/www.scientific.net/amr.881-883.211.

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Using Ca(NO3)2·4H2O, (NH4)2HPO4 and ammonia water as the starting raw materials and L-DOAP as template, hydroxyapatite (HAP) crystals were successfully prepared at 180 °C by changing the hydrothermal time. The HAP crystals were characterized by X-ray diffractometry (XRD), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscope (FESEM). The XRD patterns indicate that increasing hydrothermal time is helpful to improve the purity of the product and enhance crystallinity of HAP crystal. The FTIR analysis shows that the carbonate ions enter into the HAP crystal lattice and the final products are carbonate-containing hydroxyapatite. The FESEM images illustrate that HAP crystal morphology changed to flower-like hierarchical structures and grass blanket-like hierarchical structures when increasing the hydrothermal time to 1 h and 24 h. Therefore, hydrothermal time has a great influence on the morphology of HAP and the possible formation mechanism of HAP samples has been discussed.
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21

Будагаева (Budagaeva), Валентина (Valentina) Григорьевна (Grigor'evna), Арюна (Ariuna) Арсалановна (Arsalanovna) Раднагуруева (Radnagurueva), Елена (Elena) Владимировна (Vladimirovna) Лаврентьева (Lavrent'eva), Дарима (Darima) Дондоковна (Dondokovna) Бархутова (Barkhutova), and Даниил (Daniil) Николаевич (Nikolaevich) Оленников (Olennikov). "CARBOHYDRATES OF MICROBIAL MATHS OF ALKALINE HYDROTHERMS OF BAIKAL REGION." chemistry of plant raw material, no. 1 (October 17, 2017): 45–51. http://dx.doi.org/10.14258/jcprm.2018012168.

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Alkaline hydrotherms of the Baikal region are extreme aquatic ecosystems characterized by the presence of the specific microbial communities, mats. A study of the carbohydrate composition of the biomass of microbial maths from four hydrothermal waters of the Baikal region (Alla, Garga, Seya, Umkhei) showed the presence of mannitol (1,93–7,25 mg/g, from the dry weight), uronic acids (1,15–15,85 mg/g) and neutral monosaccharides. The latter were galactose (2,02–56,56 mg/g), glucose (2,00–45,96 mg/g), mannose (4,83–78,86 mg/g), xylose (1,18–10,53 mg/g), fucose (0,23–2,40 mg/g), and arabinose and rhamnose as a trace. It is shown that the mats from the studied hydrothermal waters of the Baikal region characterized by the different ratio of carbohydrate groups and a specific monosaccharide composition. A fraction of water-soluble polysaccharides was isolated from the biomass of the microbial mat of Seya hydrotherm. It was a mixture of seven components with molecular masses from 122 to 1700 kDa. The dominant polymer Se-WSPS-07 with a molecular weight 122 kDa was isolated and preliminarily characterized as a heteropolysaccharide containing galactose, glucose, mannose as dominant monosaccharides, and protein (5,92%). It was found that Se-WSPS-07 possesses biological activity demonstrating its perspectiveness for the further study as a therapeutic agent. The chemical characteristics of the carbohydrate components of microbial maths from the alkaline hydrotherms of the Baikal region were realized for the first time.
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22

Ebnalwaled, A. A., Mohamed H. Essai, B. M. Hasaneen, and Hossam E. Mansour. "Facile and surfactant-free hydrothermal synthesis of PbS nanoparticles: the role of hydrothermal reaction time." Journal of Materials Science: Materials in Electronics 28, no. 2 (November 11, 2016): 1958–65. http://dx.doi.org/10.1007/s10854-016-5749-x.

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23

Moon, Jooho, Jeffrey A. Kerchner, Henrik Krarup, and James H. Adair. "Hydrothermal synthesis of ferroelectric perovskites from chemically modified titanium isopropoxide and acetate salts." Journal of Materials Research 14, no. 2 (February 1999): 425–35. http://dx.doi.org/10.1557/jmr.1999.0061.

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The feasibility of the acetylacetonate-Ti isopropoxide complex as a new precursor for synthesis of Ti-based perovskite particles under hydrothermal conditions has been demonstrated. Perovskite powders including BaTiO3, PbTiO3, PZT, PLZT, and SrTiO3 were prepared by reacting the acetylacetonate-modified Ti precursor in metal acetate aqueous salt solution under hydrothermal conditions. Synthesis parameters including reaction time and temperature, feedstock concentration, nd reaction medium significantly influence particle characteristics of the hydrothermally derived erovskite powders. It is proposed that use of the acetylacetonate-modified Ti precursor promotes ntimate mixing among multicomponent reacting species at the molecular level and promotes article formation through a dissolution/recrystallization mechanism.
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Patil, Sandeep K., Nipun Shah, Frank D. Blum, and Mohamed N. Rahaman. "Fourier transform infrared analysis of hydroxyl content of hydrothermally processed heteroepitaxial barium titanate films." Journal of Materials Research 20, no. 12 (December 1, 2005): 3312–19. http://dx.doi.org/10.1557/jmr.2005.0406.

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The concentration of hydroxyl (–OH) groups in epitaxial barium titanate (BaTiO3) films (thickness ∼ 200 nm), deposited on single-crystal strontium titanate (SrTiO3) at 150 °C by a hydrothermal technique, was investigated using x-ray photoelectron spectroscopy and Fourier transform infrared (FTIR) spectroscopy. After hydrothermal treatment, a broad FTIR resonance for the hydroxyl groups indicated a significant concentration of surface –OH groups in the films. The as-deposited films were subsequently treated hydrothermally with D2O, and the kinetics of the exchange reaction between –OH incorporated into the film and –OD from the D2O were studied using FTIR. For reactions carried out intermittently, the kinetics of the exchange reaction between –OH by –OD depended not only on the total reaction time, but also on the duration of each treatment. The broad FTIR hydroxyl resonance in the as-deposited hydrothermal film was significantly reduced only after heating for 1 h at 600–800 °C.
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Rejas, J. G., C. Pothier, C. Rigotti, N. Méger, I. Vásquez, O. C. Rotunno, J. Bonatti, and H. Barbosa. "STUDYING EVOLUTION OF HYDROTHERMAL ALTERATION MATERIALS IN THE TURRIALBA VOLCANO TROUGH MULTISPECTRAL AND HYPERSPECTRAL IMAGES." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLIII-B2-2020 (August 14, 2020): 1259–64. http://dx.doi.org/10.5194/isprs-archives-xliii-b2-2020-1259-2020.

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Abstract. The aim of this work is to develop a geospatial methodology for the analysis of the time evolution of The Turrialba volcano using different automatic imaging techniques compared to expert-based remote sensing techniques. Change detection of hydrothermal alteration materials in relation with time series from multisensor data acquired in spectral ranges of the visible (VIS) and short wave infrared (SWIR) have been calculated. We used for this purpose multispectral and hyperspectral scenes of the Sentinel 2, ALI and Hyperion sensors, respectively, on four dates from 2013 and 2018. This work adopts a multi-source approach, applied to the analysis of the correlations between hydrothermal materials and spectral anomalies in The Turrialba volcano complex, located in The Central Volcanic Range (Costa Rica).An expert-based technique called Crosta’s technique for detecting hydrothermal materials have been applied. We have chosen four variables for generating a different Principal Component Analysis (PCA) for groups of channels, two highly reflective and two highly absorptive for each mineral. We have tested another technique to detect hydrothermal materials based on a discrete spectral profile analysis and an unsupervised data mining approach. In other sense, we have applied an automatic technique called anomaly detection to compare with the hydrothermal materials results. Results are presented as an approach based on a comparison of two different strategies whose main future interest lies in the automated identification of patterns of hydrothermally altered materials without prior knowledge or poor information about the area, which has relevant implications in image-based prospecting.
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You, Qi, and Yang Chen. "Ultrabright, highly heat-stable gold nanoclusters through functional ligands and hydrothermally-induced luminescence enhancement." Journal of Materials Chemistry C 6, no. 36 (2018): 9703–12. http://dx.doi.org/10.1039/c8tc02119h.

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Strongly luminescent, highly heat-stable gold nanoclusters with a quantum yield of up to 59.6% were prepared by a simple hydrothermal reaction. Hydrothermally-induced fluorescence enhancement of gold nanoclusters is observed for the first time. Heat-stable gold nanoclusters can be applied as a luminescent label in polymerase chain reaction (PCR) thermal cycles of DNA amplification.
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27

Bozbag, Selmi Erim, Deniz Şanlı, Barkın Özener, Gökhan Hisar, and Can Erkey. "An Aging Model of NH3 Storage Sites for Predicting Kinetics of NH3 Adsorption, Desorption and Oxidation over Hydrothermally Aged Cu-Chabazite." Catalysts 10, no. 4 (April 8, 2020): 411. http://dx.doi.org/10.3390/catal10040411.

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A unified transient kinetic model which can predict the adsorption, desorption and oxidation kinetics of NH3 over hydrothermally aged Cu-chabazite was developed. The model takes into account the variation of fractional coverages of NH3 storage sites due to hydrothermal aging. In order to determine the fractional coverage of these sites, the catalyst was aged for various times at a certain temperature followed by NH3 adsorption, desorption and temperature-programmed desorption (TPD) experiments. TPD profiles were deconvoluted mainly into three peaks with centres at 317, 456 and 526 °C, respectively. Hydrothermal aging resulted in the progressive increase in the intensity of the peak at 317 °C and decrease in the intensity of the peaks at 456 and 526 °C, along with decreased NH3 oxidation at high temperatures. A model for hydrothermal aging kinetics of the fractional coverage of storage sites was developed using three reactions with appropriate rate expressions with parameters regressed from experimental data. The model was then incorporated into a multi-site kinetic model for the degreened Cu-Chabazite by the addition of aging reactions on each storage site. The effects of both aging time and temperature on the kinetics NH3 adsorption, desorption and oxidation were successfully predicted in the 155-540 °C range. This study is the first step towards the development of a hydrothermal aging-unified kinetic model of NH3-Selective Catalytic Reduction over Cu-chabazite.
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Sulardjaka, Deni Fajar Fitriyana, and Agus Purnomo Adi. "Synthesis of Zeolite from Geothermal Waste." Applied Mechanics and Materials 660 (October 2014): 157–61. http://dx.doi.org/10.4028/www.scientific.net/amm.660.157.

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The high content of silica in geothermal waste can be used as a alternative source of amorphous silica for the production of silicon based materials. In this research, geothermal waste was used as silica sources in hydrothermal reaction of zeolite synthesis. Zeolite was synthesized by unstirred hydrothermal process. Hydrothermal process was conducted at variation temperature 100, 110 and 120 °C for 5 hours. To study the effect of holding time on hydrothermal product, hydrothermal process also done in variation of: 1, 3 and 5 hours holding time at temperature 120 °C. All of hydrothermal products were characterized by XRD. The results show hydrothermal process successfully converts geothermal waste into zeolite A and sodalite.
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Arnelli, Arnelli, Noor Afifah, Narita Rizki, Tri Windarti, and Yayuk Astuti. "Synthesis of Zeolite from Sugar Cane as Detergent Builder: Variation of Si/Al Ratio and Hydrothermal TimeSynthesis of Zeolite from Sugar Cane as Detergent Builder: Variation of Si/Al Ratio and Hydrothermal Time." Jurnal Kimia Sains dan Aplikasi 21, no. 1 (January 31, 2018): 24–28. http://dx.doi.org/10.14710/jksa.21.1.24-28.

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Synthesis of zeolite from bagasse with variation of Si / Al ratio (1,2,1,4,1,6 and 1,8) with ZS1-ZS5 code and hydrothermal time (160, 190, 250, 340, and 460 minutes) with sample code ZSa - ZSe has been conducted. The synthesized zeolite was then applied to the detergent builder. The detergent builder of synthetic zeolite was used as a substitute for sodium tripolyphosphate, which is not environmentally friendly as it can lead to eutrophication. One of the detergent builder functions is to improve the washing efficiency of the surfactant by inactivating water-absorbing minerals (Ca2+ and Mg2+ ions) which may further deter the detergency process. Zeolites were synthesized using a sol-gel method followed by a hydrothermal process. The material used in this synthesis is Na2SiO3 (aq) (derived from bagasse) mixed with NaAl(OH)4 (aq), then stirred to form a white gel and continued by heating using autoclave at 100°C. The results obtained are zeolite-A and zeolt-X for variation of Si/Al ratio and hydrothermal time variation, with CEC value and detergency proportional to Si/Al ratio and hydrothermal time.
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30

Yoshito, Walter Kenji, Valter Ussui, Dolores Ribeiro Ricci Lazar, and José Octavio Armani Paschoal. "Synthesis of Nickel Oxide - Zirconia Composites by Coprecipitation Route Followed by Hydrothermal Treatment." Materials Science Forum 660-661 (October 2010): 977–82. http://dx.doi.org/10.4028/www.scientific.net/msf.660-661.977.

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Nickel oxide-yttria stabilized zirconia (NiO-YSZ) for use as solid oxide fuel cell anode were synthesized by coprecipitation to obtain amorphous zirconia and crystallized β-nickel gels of the corresponding metal hydroxides. Hydrothermal treatment at 200°C and 220 psi from 2 up to 16 hours, under stirring, was performed to produce nanocrystalline powder. The as-synthesized powders were uniaxially pressed and sintered in air. Powders were characterized by X-ray diffraction, laser scattering, scanning and transmission electron microscopy (SEM/TEM), gas adsorption technique (BET) and TG-DTA thermal analysis. Ceramic samples were characterized by dilatometric analysis and density measurements by Archimedes method. The characteristics of hydrothermally synthesized powders and compacts were compared to those produced without temperature and pressure application. Crystalline powders were obtained after hydrothermal process, excluding the calcination step from this route. The specific surface area of powders decreases with increasing time of hydrothermal treatment while the agglomerate mean size is not affected by this parameter.
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31

Kartini, Indriana, Ira Nur Arba’atul Jannah, Fitri Rizki Amalia, Salim Mustofa, Eko Sri Kunarti, and Respati Tri Swasono. "Short Time Synthesis of Titania Nanotubes: Effect of Pre-Mixing Prior Hydrothermal." Indonesian Journal of Chemistry 19, no. 1 (January 29, 2019): 58. http://dx.doi.org/10.22146/ijc.26777.

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The effect of pre-mixing by mechanical stirring before hydrothermal and hydrothermal time on the crystalline phases and morphology of titania has been studied. It was shown that nanotubes titania can be obtained after 5 h hydrothermal at 150 °C. The XRD patterns and Raman spectra of the produced powders showed the existence of anatase and titanate crystalline phases. At the longest stirring, TiO2 (B) was observed. High textural coefficient for [200] plane of anatase (TC200) confirmed oriented growth of one-dimensional anatase along [200]. All powders resulted at various stirring time were nanotubes, as confirmed by Transmission Electron Microscope (TEM). It was found that the longer the stirring, the higher the surface area of the nanotubes. All powders showed type-IV isotherm for nitrogen gas adsorption/desorption, indicating the existence of mesoporous materials. However, long hydrothermal induced the nanospheres formation, hence reducing the surface area. The band-gap of the resulted titania nanotubes were ranging from 3.11–3.16 eV. The photocatalytic performance toward the degradation of methylene blue of the titania nanotubes was higher (~50%) compared to the bulk TiO2 (~5%) under visible-light and was comparable under UV-light (~60%). These results pave a way of producing visible-sensitive TiO2 photocatalyst by altering the morphology.
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32

Xu, Zhenjia, Jun Zhou, Yongdi Liu, Lifeng Gu, Xujun Wu, and Xueying Zhang. "Effect of hydrothermal carbonization on dewatering performance of dyeing sludge." RSC Advances 8, no. 67 (2018): 38574–81. http://dx.doi.org/10.1039/c8ra05350b.

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33

Duangkaew, Pattasuda, Shuhei Inoue, Tsunehiro Aki, Yutaka Nakashimada, Yoshiko Okamura, Takahisa Tajima, and Yukihiko Matsumura. "Real-Time Mass Spectrometric Analysis of Hydrothermal Reaction Products." Industrial & Engineering Chemistry Research 56, no. 36 (August 29, 2017): 9993–98. http://dx.doi.org/10.1021/acs.iecr.7b02663.

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34

Liu, Fei, Ting Li, Xiao Dan Wang, and Jian Xin Cao. "Influence of Hydrothermal Conditions on Ultra-Light Calcium Silicate Material In Situ Strengthened with Xonotlite Whiskers." Advanced Materials Research 648 (January 2013): 139–42. http://dx.doi.org/10.4028/www.scientific.net/amr.648.139.

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The ultra-light calcium silicate material was reinforced with the method of xonotlite whisker in-situ growth via hydrothermal synthesis. Effects of different hydrothermal temperatures and reaction times on the microstructure and physical properties of the reinforcement were studied in this paper. The results indicated that the hydrothermal temperatures and times posed great impacts on microstructure of the reinforcement. The increase of hydrothermal temperature and time was beneficial to the growth of xonotlite crystal. The effect of buffer and transfer action of the xonotlite whiskers was the key to reinforcing the ultra-light calcium silicate material.
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35

Germ, Mateja, Alena Vollmannova, Július Árvay, Tomáš Tóth, and Aleksandra Golob. "The disappearance of vitexin from Tartary buckwheat flour-water mixtures after the hydrothermal treatment." Fagopyrum 38, no. 2 (July 6, 2021): 31–34. http://dx.doi.org/10.3986//fag0020.

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Vitexin is an apigenin flavone glucoside with known biological functions. This research reported the effects of initial temperature treatments of Tartary buckwheat flour mixture with water and time of methanol extraction from the cooked doughs on the amount of extractable vitexin. The mixtures of flour and water were initially hydrothermally treated at temperatures from 25 °C to 95 °C. Afterward the mixtures were cooked at 95 °C for 20 min, and vitexin extracted at room temperature with 80% aqueous methanol for 20 min, 2 h and 8 h. The extractable vitexin was extracted during the same extraction times for the control in the nonhydrothermally treated Tartary buckwheat flour-water mixture samples. For the cooked dough samples, the hydrothermal treatments were important in terms of the extractability of vitexin. The extractable vitexin persisted in the control samples during the extraction time up to 8 hours, while in the hydrothermally treated and cooked dough samples, there remained none detectable vitexin. The high-temperature initial treatments during dough preparation appeared not to prevent the degradation of vitexin in Tartary buckwheat flour.
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36

Goulart, Francisco A. P., Renan R. Zandoná, Maicon F. Schmitz, André R. Ulguim, André Andres, and Dirceu Agostinetto. "Modeling the Emergence of Echinochloa sp. in Flooded Rice Systems." Agronomy 10, no. 11 (November 12, 2020): 1756. http://dx.doi.org/10.3390/agronomy10111756.

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Barnyard grass (Echinochloa sp.) is one of the main rice weeds. Knowledge of its emergence can support management measures. The present study models barnyard grass emergence at different flooded rice sowing periods. Furthermore, the effectiveness of the hydrothermal time model in estimating barnyard grass emergence is analyzed. Field emergence was monitored three times a week during two sowing times (October and November) and two growing seasons (2017/18 and 2018/19), in rice sown and unsown areas. Data were converted to cumulative emergence based on total seedlings. Soil temperature and moisture data were used to determine hydrothermal time. The sowing in October led to a continuous emergence of barnyard grass, while the sowing in late November led to different emergence rates. The highest emergence rates of barnyard grass occur in the first sowing time. The hydrothermal time model is adequate to estimate barnyard grass emergence in both sowing times.
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37

Kansara, Saurabh, Shivani Patel, Yong X. Gan, Gabriela Jaimes, and Jeremy B. Gan. "Dye Adsorption and Electrical Property of Oxide-Loaded Carbon Fiber Made by Electrospinning and Hydrothermal Treatment." Fibers 7, no. 8 (August 18, 2019): 74. http://dx.doi.org/10.3390/fib7080074.

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Our current study deals with the dye adsorption and electrical property of a partially carbonized composite fiber containing transition metal oxides including, iron oxide, nickel oxide, and titanium oxide. The fiber was made by electrospinning, carbonization, and hydrothermal treatment. During the electrospinning, titanium oxide particles were dispersed in polyacrylonitrile (PAN) polymer-dimethylformamide (DMF) solution. Nickel chloride and iron nitrate were added into the solution to generate nickel oxide and iron oxide in the subsequent heat treatment processes. The polymer fiber was oxidized first at an elevated temperature of 250 °C to stabilize the structure of PAN. Then, we performed higher temperature heat treatment at 500 °C in a furnace with hydrogen gas protection to partially carbonize the polymer fiber. After that, the oxide-containing fiber was coated with activated carbon in a diluted sugar solution via hydrothermal carbonization at 200 °C for 8 h. The pressure reached 1.45 MPa in the reaction chamber. The obtained product was tested in view of the dye, Rhodamine B, adsorption using a Vis-UV spectrometer. Electrical property characterization was performed using an electrochemical work station. It was found that the hydrothermally treated oxide-containing fiber demonstrated obvious dye adsorption behavior. The visible light absorption intensity of the Rhodamine B dye decreased with the increase in the soaking time of the fiber in the dye solution. The impedance of the fiber was increased due to the hydrothermal carbonization treatment. We also found that charge build-up was faster at the surface of the specimen without the hydrothermally treated carbon layer. Electricity generation under visible light excitation is more intensive at the hydrothermally treated fiber than at the one without the hydrothermal treatment. This result is consistent with that obtained from the dye adsorption/decomposition test because the charge generation is more efficient at the surface of the hydrothermally treated fiber, which allows the dye to be decomposed faster by the treated fibers with activated carbon.
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38

Zhang, Xia, Yan Li, Danqing Li, Yujun Zhang, and Yuandong Xu. "Effect of synthetic condition on the electrochemical behavior of MoO3 microplates used as anode in lithium-ion batteries." Canadian Journal of Chemistry 96, no. 3 (March 2018): 340–44. http://dx.doi.org/10.1139/cjc-2017-0549.

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Molybdenum trioxide (MoO3) microplates are synthesized via the hydrothermal method and a simple heat treatment process without adding surfactant. Different hydrothermal reaction times and acidities are employed to explore the influence of preparation condition on the electrochemical performance for MoO3 microplates. These studies reveal that the hydrothermal time and acidity have a great impact on the morphology of MoO3 microplates. As anode materials for lithium-ion batteries (LIBs), the sheets-assembled MoO3 microplates with longer hydrothermal reaction time and proper acidity possess a superior morphology, which show better cycling performance and rate capability stability. The prepared MoO3 microplates display that the coulombic efficiency is around 100% during 50 cycles, demonstrating much better lithium storage properties. Considering the excellent electrochemical performance, the MoO3 microplates are considered to be a potential candidate in high-performance LIBs.
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39

Abbasian, Saeid, and Majid Taghizadeh. "Effects of Microwave and Ultrasonic-Assisted Aging on the Synthesis of H-ZSM-5 Nanozeolite and Its Catalytic Performance in Methanol Dehydration." International Journal of Chemical Reactor Engineering 12, no. 1 (January 1, 2014): 355–62. http://dx.doi.org/10.1515/ijcre-2014-0021.

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Abstract H-ZSM-5 nanozeolite was hydrothermally synthesized under static conditions. Evaluation of hydrothermal synthesis of ZSM-5 was performed by treating the synthesis mixture using different aging processes, consist of ultrasonic, stirring, and microwave-assisted aging, prior to the conventional hydrothermal treatment. The catalytic performances of selected catalysts were studied for the dehydration of methanol to dimethyl ether (DME) in a fixed-bed reactor under the same operating conditions (T = 300°C, P = 1 atm, and WHSV = 26 h−1). The prepared samples were characterized by XRD, SEM, BET, NH3-TPD and FT-IR techniques. The results showed that ultrasonic and microwave-assisted aging shortened the crystallization time and reduced crystal size of the obtained products without having any considerable effects on their catalytic activities.
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40

Hawkins, K. K., P. S. Allen, and S. E. Meyer. "Secondary dormancy induction and release inBromus tectorumseeds: the role of temperature, water potential and hydrothermal time." Seed Science Research 27, no. 1 (January 10, 2017): 12–25. http://dx.doi.org/10.1017/s0960258516000258.

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AbstractSeeds of the winter annualBromus tectorumlose primary dormancy in summer and are poised to germinate rapidly in the autumn. If rainfall is inadequate, seeds remain ungerminated and may enter secondary dormancy under winter conditions. We quantified conditions under which seeds enter secondary dormancy in the laboratory and field and also examined whether contrastingB. tectorumgenotypes responded differently to dormancy induction cues. The study also extends previous hydrothermal time models for primary dormancy loss and germination timing inB. tectorumby using similar models to account for induction and loss of secondary dormancy. Maximum secondary dormancy was achieved in the laboratory after 4 weeks at –1.0 MPa and 5°C. Seeds in the field became increasingly dormant through exposure to temperatures and water potentials in this range, confirming laboratory results. They were released from dormancy through secondary after-ripening the following summer. Different genotypes showed contrasting responses to dormancy induction cues in both laboratory and field. To examine secondary dormancy induction and release in the field in terms of hydrothermal time parameters, we first created a model that allowed mean base water potential (Ψb(50)) to vary while holding other hydrothermal time parameters constant, as in models for primary dormancy loss under dry conditions. The second model allowed all three model parameters to vary through time, to account for changes (e.g. hydrothermal time accumulation) that could occur simultaneously with dormancy induction in imbibed seeds. Shifts in Ψb(50) could explain most changes in dormancy status for seeds retrieved from the field, except during the short period prior to dormancy induction, when hydrothermal time was accumulating. This study illustrates that hydrothermal modelling, and specifically changes in Ψb(50), can be used to characterize secondary dormancy induction and loss inB. tectorum.
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41

Sutarno, Sutarno, and Arief Budyantoro. "SINTESIS DAN KARAKTERISASI FAUJASIT DARI ABU LAYANG : Kajian Pengaruh Waktu Sintesis Terhadap Stabilitas Termal Struktur Faujasit (Kinetics of Faujasite Formation from Fly Ash)." Sains & Teknologi 2, no. 2 (October 17, 2019): 10. http://dx.doi.org/10.24123/jst.v2i2.2249.

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Faujasite was hydrothermally synthesized from fly ash at 100oC in alkaline solution by reflux with 5M HCl and fusion with NaOH (weight ratio of NaOH/fly ash = 1.2) pretreatments. Kinetics of faujasite formation was performed by variation of hydrothermal time (0-120 hours). Thermal stability of faujasite from fly ash was tested at 400-900oC and was compared with commercial zeolite Y. The solid products were characterized by X-ray diffraction method. Results showed that faujasite was formed through dissolution of fly ash components such as quartz, mullite and amorphous aluminosilicates (0-3 hours) followed by crystallization to form faujasite (6-48 hours). In longer hydrothermal time (48-72 hours), faujasite transformed into zeolite P and completely formed hydroxysodalite after 120 hours. X-ray diffraction pattern showed that thermal stability of faujasite from fly ash was relatively lower than that of commercial zeolite Y. Faujasite from fly ash transformed into amorphous phase at 800oC whereas commercial zeolite Y transformed into amorphous phase at 900oC.
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42

Wang, Shi Ping, Hong Yan Miao, and Guo Qiang Tan. "Hydrothermal Synthesis of Sodium-Potassium Niobate Nanopowders." Key Engineering Materials 368-372 (February 2008): 579–81. http://dx.doi.org/10.4028/www.scientific.net/kem.368-372.579.

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Sodium-potassium Niobate (K0.4Na0.6NbO3, KNN) nanopowders were prepared by hydrothermal synthesis at the temperature range of 140-180°C for 12-48h using Nb2O5, NaOH and KOH as source materials. By means of XRD and SEM techniques, the effects of composition and hydrothermal treatment process, such as the rate of [R]/[Nb], the concentration of the alkali, the hydrothermal treatment temperature and the hydrothermal treatment time, on the microstructures and the crystallinity of alkali metals niobate were investigated in details. Results show that K0.4Na0.6NbO3 powders could be achieved by hydrothermal synthesis at the temperature range of 140-180°C with the alkalinity concentration of 2-8M. With the increase of hydrothermal reaction temperature and time, the crystallinity of KNN particles was improved. The obtained K0.4Na0.6NbO3 polycrystalline particles have rhombic structure.
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43

Zhu, Jie, Lan Ying Zhou, and Yu Liang Yang. "Study of Hydrothermal Synthesis of Analcime." Applied Mechanics and Materials 367 (August 2013): 22–25. http://dx.doi.org/10.4028/www.scientific.net/amm.367.22.

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Na2SiO3·9H2O and NaAlO2are used as raw materials to synthesize analcime molecular sieve with hydrothermal synthesis. Theinfluence of SiO2/Al2O3 ratio, mixing time,aging time, crystallize temperature， crystalize time are also discussed to determine theparameters of synthesis.
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44

Velebil, J., J. Malaťák, and J. Bradna. "Mass yield of biochar from hydrothermal carbonization of sucrose." Research in Agricultural Engineering 62, No. 4 (November 28, 2016): 179–84. http://dx.doi.org/10.17221/73/2015-rae.

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In this article, the effect of increasing dry matter content and reaction time of hydrothermal carbonization on mass yield of biochar was studied. Carbonization took place in batch experiments in a pressure vessel. Results have confirmed the assumption that the mass yield of biochar would increase with growing dry matter content in the initial solution and also with reaction time at reaction temperature of 200°C. It was found that components of the liquid product that remain in the biochar have a measurable impact on its mass yield. Mixing of the reactor proved to have a considerable effect on the mass yield as well. Biochar produced in absence of mixing had higher pore volume and higher yield. This was evident even after subtracting the equivalent liquid phase dry matter in the biochar after drying.
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45

Wu, Dien-Shi, and Nae-Lih Wu. "Hydrothermal Synthesis of Submicron SnO Crystallites." Journal of Materials Research 15, no. 7 (July 2000): 1445–48. http://dx.doi.org/10.1557/jmr.2000.0210.

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SnO crystallites having a size ranging 0.1–0.2 μm were synthesized by a hydrothermal process, which consisted of prolonged solution aging under pH = 1.0, followed by hydrothermal treatment under pH = 9 to 10 at 75–95 °C. Oxidation of Sn+2 to Sn+4 during the hydrothermal stage was effectively inhibited by increasing the solution-aging time. This was attributed to the formation, upon aging, of polymeric hydrous SnO colloids, which are more oxidation resistant than aquo-hydroxo tin complex monomers. For solutions with a sufficiently long (≥240 h) aging time, the SnO yield increased with increasing pH and temperature during the hydrothermal treatment.
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46

Moloney, Timothy, Kenneth Sims, and John Kaszuba. "Uranium and Thorium Decay Series Isotopic Contraints on the Source and Residence Time of Solutes in the Yellowstone Hydrothermal System." UW National Parks Service Research Station Annual Reports 33 (January 1, 2011): 187–207. http://dx.doi.org/10.13001/uwnpsrc.2011.3821.

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Hydrothermal fluids in Yellowstone National Park have widely varying chemical composition. Heat and volatile flux from the hydrothermal system can be estimated by monitoring the composition and volume of emitted hydrothermal fluid, but the source of solutes in hydrothermal fluid is often nebulous and the geochemical processes that affect the nuclides are poorly understood. Measurements of 220Rn and 222Rn activity in hydrothermal fluids and of CO2 flux from fumaroles and hot springs were carried out in Yellowstone National Park during the summer of 2010. We observed a weak relationship between (220Rn/222Rn) and CO2 flux, which indicates that CO2 acts as a carrier gas to bring radon to the surface, but the radon is sourced from aquifer rocks rather than magma. If radon reaching the surface were sourced from magma below Yellowstone, there would be a stronger correlation between (220Rn/222Rn) and CO2 flux. Measurements of 223Ra, 224Ra, 226Ra, 228Ra, and major solute chemistry in hot spring waters support the hypothesis that the time scale of solute transport from the deep hydrothermal reservoir is long compared to the half lives of 220Rn and 222Rn, which are useful for processes operating on the time scale of 5 minutes to 20 days. Radium isotope activities in hot springs indicate that the solute transport time varies significantly from region to region, indicating that circulation in some areas operates on the time scale of 224Ra/223Ra (20-55 days) and circulation in other areas operates on the time scale of 228Ra/226Ra (25-1600 years). The radium isotope composition of hot spring water is also influenced by differences in regional aquifer rocks and geochemical processes such as sorption and mineral precipitation. In summary, geochemical and hydrothermal processes in Yellowstone operate on many different time scales and in diverse geologic conditions, but radionuclide activities possess excellent potential to study these complex phenomena.
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47

Liu, Fei, Ling Ke Zeng, Jian Xin Cao, Qian Lin, and Jing Li. "Preparation of Xonotlite Whiskers from Carbide Slag." Key Engineering Materials 434-435 (March 2010): 787–89. http://dx.doi.org/10.4028/www.scientific.net/kem.434-435.787.

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Carbide slag was used as raw materials for the first time to prepare xonontlite whiskers via a hydrothermal route without special instruments and synthesis conditions. And the effect of pH value of emulsion of carbide slag and hydrothermal conditions on removal rate of impurities, morphology and crystallinity of synthesized xonotlite whiskers were explored using ICP, SEM and XRD techniques. The results indicated that the carbide slag after purification could be used to prepare xonotlite whiskers, and different pH values of emulsion of carbide slag had great impact on the removal rate of impurities and morphology of xonotlite whiskers. Xonotlite whiskers with 20-40 μm in length and 100-500 nm in diameter were hydrothermally synthesized at 230 °C for 15 h with using silicic acid as kiesel material.
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48

Bradford, Kent J., and Anthony M. Haigh. "Relationship between accumulated hydrothermal time during seed priming and subsequent seed germination rates." Seed Science Research 4, no. 2 (June 1994): 63–69. http://dx.doi.org/10.1017/s0960258500002038.

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AbstractSeed germination rates are sensitive to both temperature (T) and water potential (ψ). The times to germination of seeds imbibed at suboptimal T and/or reduced ψ are inversely proportional to the amounts by which T exceeds a base temperature (Tb) and ψ exceeds a base water potential (ψb). Germination rates across a range of suboptimal T and ψ can be normalized on the basis of the hydrothermal time accumulated in excess of these thresholds. However, seeds can also progress metabolically toward germination even at T or ψ too low to allow radicle emergence to occur. Seeds preimbibed at low ψ and dried back, or primed, germinate more rapidly upon subsequent reimbibition. We show here that the increase in germination rates of tomato (Lycopersicon esculentum Mill.) seeds resulting from seed priming is linearly related to the hydrothermal time accumulated during the priming treatment. The threshold temperature (Tmin = 7.05°C) and water potential (ψmin = −2.50 MPa) for metabolic advancement were considerably lower than the corresponding thresholds for radicle emergence of the same seed lot (Tb = 11°C; ψb = −0.71 MPa), allowing the accumulation of hydrothermal priming time that is subsequently expressed as more rapid germination when T or ψ increase. The hydrothermal time model can now be applied to quantify and analyse germination rates of seeds across the entire range of suboptimal T and ψ at which metabolic progress toward radicle emergence is possible.
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49

Bacsa, R., P. Ravindranathan, and J. P. Dougherty. "Electrochemical, hydrothermal, and electrochemical-hydrothermal synthesis of barium titanate thin films on titanium substrates." Journal of Materials Research 7, no. 2 (February 1992): 423–28. http://dx.doi.org/10.1557/jmr.1992.0423.

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Well-crystallized polycrystalline films of cubic BaTiO3 have been synthesized on Ti metal substrates by electrochemical, hydrothermal, and electrochemical-hydrothermal reaction of a Ti metal with a saturated solution of Ba(OH)2 in the temperature range 80 °C−200 °C. The films can be produced in the electrochemical process by the anodization of a Ti substrate in Ba(OH)2 solution at pH = 13 and current densities of the order of 10–50 mA/cm2. The films can also be synthesized by the hydrothermal reaction of Ba(OH)2 and a Ti substrate without electrical bias. A combination of these two techniques reduces the reaction time to 30–45 min. The films were found to have good adherence on the substrate and films of thickness up to 2 μm could be formed within a reaction time of 45 min. Capacitance measurements have yielded a dielectric constant of 300. The films prepared by the three different techniques have been compared for crystallinity and microstructure. The thickness of the films increased with temperature and time of reaction. The crystallinity decreased with extended time of reaction for a given temperature. It is likely that a reactive intermediate such as Ti(OH)4 (aq.) is formed in all the three cases which leads to the formation of crystalline BaTiO3.
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Liu, Yang Si, Xiao Li Xi, Zuo Ren Nie, Lin Yan Zhao, and You Shu Fan. "Effect of Hydrothermal Conditions on Crystal Structure, Morphology and Visible-Light Driven Photocatalysis of WO3 Nanostructures." Materials Science Forum 993 (May 2020): 893–98. http://dx.doi.org/10.4028/www.scientific.net/msf.993.893.

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Tungsten trioxide (WO3) nanostructures were synthesized by a hydrothermal method, and the influence of essential hydrothermal conditions, temperature and time, on their crystal structure, morphology and visible-light driven photocatalysis was studied. The hydrothermal temperature was varied from 120 °C to 200 °C, and the hydrothermal time changed from 12 h to 32 h. The crystal structure, morphology and photocatalytic performance of WO3 nanostructures were characterized by XRD, SEM and UV-Vis. The crystal structure of WO3 nanostructure was triclinic phase and their morphology was mainly one dimensional nanorods. Methylene blue was used as the target to evaluate their photocatalytic performance under visible light (λ>420 nm). The photocatalytic results suggest the suitable hydrothermal conditions to synthesize WO3 nanostructures for the wastewater treatment application.
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