Journal articles: 'Aqua Regia'

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Dari Jaafar, Ayad. "Extraction of Platinum From Spent Catalyst as pt/Al2O3 in aqua regia." DJES 12, no. 3 (2019): 8–14. http://dx.doi.org/10.24237/djes.2019.12302.

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Spent catalyst from Biji Refining contained valuable metals such as platin. This study focus on platinum extraction in aqua regia solution. Three factors effecting on the process were study including dissolution temperature, normality of aqua regia and agitation speed. The ideal conditions for process give 0.22 gm platinum extraction in dissolution temperature 80 C0, normality for aqua regia was 6 and 120 rpm mixing speed for solution

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Gao, Bingyu, Wenjun Li, Lianchang Zhang, and Jun Gao. "The Implications of HClO4 for Dissolving Large Masses of Low Level Os in Metal Sulfides and Factors that Influence Re-Os Dating." Applied Sciences 10, no. 18 (2020): 6218. http://dx.doi.org/10.3390/app10186218.

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In general, no more than 1 g of metal sulfide can be completely digested in 20 mL of inverse aqua regia using the Carius tube technique. In this study, the sample weight increased after adding HClO4 to inverse aqua regia while the volume of acid concurrently decreased significantly. Three grams of metal sulfide were digested in 12 mL of acid (3 mL of HClO4 and 9 mL of inverse aqua regia) via the HClO4-inverse aqua regia method. The results using molybdenite reference materials JDC and HLP mixed with 3 g of pyrite were consistent with certified values. Compared to the traditional method, the HClO4-inverse aqua regia method could dissolve a larger sample mass (3 g) with a smaller volume of acids (12 mL). We simultaneously found that the oxidation of digestion acids greatly affected the Os signal but had no influence on the equilibrium of isotope exchange between 185Re and 190Os spikes in Re and Os samples. Remarkably, the heating temperature was the most significant factor influencing the equilibrium of isotope exchange, and the Os in a sample was not equilibrated with the spike until the heating temperature reached 190 °C.

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Alassali, Ayah, Caterina Picuno, Hanin Samara, Sascha Diedler, Silvia Fiore, and Kerstin Kuchta. "Antimony Mining from PET Bottles and E-Waste Plastic Fractions." Sustainability 11, no. 15 (2019): 4021. http://dx.doi.org/10.3390/su11154021.

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In this study antimony concentration was analyzed in 30 plastic items (from polyethylene terephthalate (PET) bottles and e-waste) directly by X-ray fluorescence spectroscopy (XRF) spectroscopy. PET samples were digested in a microwave oven with aqua regia. The plastic components deriving from e-waste followed three parallel routes: 1. microwave digestion using different acids (aqua regia, 18 M H2SO4, 12 M HCl and 6 M HCl); 2. conversion into ash (at 600 °C) and then microwave digestion with aqua regia, and 3. extraction with 12 M HCl at room temperature for different durations (2 h and 24 h). Results showed that antimony extraction yields from PET were between 57% and 92%. Antimony extraction from e-waste plastics was more challenging: aqua regia was inefficient for poly (acrylonitrile butadiene styrene) (ABS) samples (extraction yield was about 20% only), while on a mixture of ABS and polycarbonate (PC), aqua regia, H2SO4 and HCl exhibited equivalent performances (~21%). Ashed samples returned yields ranging from 20% to over 50%. Room temperature extraction on e-waste plastics obtained lower extraction efficiencies, yet longer incubation durations lead to higher yields. In conclusion, the main challenge associated with antimony mining from plastic waste could be its heterogeneous composition; therefore, the development of reference analytical procedures is highly needed.

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Yoshimura, Akihiro, Shunta Tochigi, and Yasunari Matsuno. "Fundamental Study of Palladium Recycling Using “Dry Aqua Regia” Considering the Recovery from Spent Auto-catalyst." Journal of Sustainable Metallurgy 7, no. 1 (2021): 266–76. http://dx.doi.org/10.1007/s40831-020-00335-x.

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AbstractIn this research, a recycling process for palladium using “dry aqua regia,” which consists of iron(III) chloride–potassium chloride, was proposed. Palladium was dissolved in “dry aqua regia,” and the dissolved palladium was recovered by leaching with potassium chloride solution with added ammonium chloride and nitric acid. Palladium was almost completely dissolved in 3 h at 600 K, and the recovery ratio of dissolved palladium was up to 80%. In addition, the dissolution of palladium in coexistence with platinum and the dissolution of platinum-palladium alloy by “dry aqua regia” were also tested. The dissolved palladium and platinum were separated and recovered by solid–liquid separation technique using the difference in solubility of their compounds in potassium chloride and sodium chloride solutions. As a result, pure compounds of each element were recovered. This result suggested the possibility of using “dry aqua regia” for the separation of platinum-group metals. Graphical Abstract

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Putri, Raden Rara Dewi Artanti, Dimas Pangestu, and Diva Candra Khairunnisa. "Pengaruh Variabel Solvent dan Waktu Leaching terhadap Konsentrasi Emas Terlarut pada PCB Handphone." Fluida 15, no. 1 (2022): 30–37. http://dx.doi.org/10.35313/fluida.v15i1.3458.

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ABSTRAK Perkembangan industri elektronik di Indonesia meningkat, maka begitu juga dengan limbah elektronik yang dihasilkannya. Salah satu bentuk limbah elektronik adalah lempengan PCB (Printed Circuit Board). Logam seperti Au, Ag, dan Cu dapat ditemukan pada PCB, dan logam-logam tersebut dapat dilakukan pemisahan dengan metode leaching. Penelitian ini bertujuan untuk mengetahui pengaruh volume larutan HNO3 sebagai tahapan pre-leaching, perbandingan HCl:HNO3 (aqua regia) dan waktu leaching terhadap konsentrasi emas terlarut. Variasi volume larutan HNO3 (20, 40, 45, 60) mL, variasi perbandingan HCl:HNO3 (3:1, 1:3, 10:1, 1:10) (v/v) dan variasi waktu leaching dengan aqua regia (30, 60, 90, 120) menit. Proses leaching dilakukan pada suhu 70℃. Filtrat hasil leaching dengan aqua regia kemudian dianalisis menggunakan AAS. Hasil penelitian ini memperoleh kondisi optimum leaching logam Au pada volume HNO3 60 mL dengan konsentrasi hasil pelarutan sebesar 26,11 mg/L, perbandingan HCl:HNO3 1:3 (v/v) dengan konsentrasi emas terlarut sebesar 23,77 mg/L dan waktu leaching dengan aqua regia 90 menit dengan konsentrasi logam Au sebesar 26,38 mg/L.  ABSTRACT The development of the electronics industry in Indonesia is increasing, and so is the electronic waste it produces. One form of electronic waste is PCB (Printed Circuit Board) slabs. Metals such as Au, Ag, and Cu can be found on PCBs, and these metals can be separated by the leaching method.. This study aims to determine the effect of the volume of HNO3 solution as a pre-leaching step, the ratio of HCl: HNO3 (aqua regia), and the leaching time to the dissolved gold concentration. Variations in the volume of HNO3 solution (20, 40, 45, 60) mL, variations in the ratio of HCl:HNO3 (3:1, 1:3, 10:1, 1:10) (v/v) and variations in leaching time with aqua regia ( 30, 60, 90, 120) minutes. The leaching process is carried out at a temperature of 70℃. The filtrate from leaching with aqua regia was then analyzed using AAS. The results of this study obtained the optimum conditions for leaching Au metal at a volume of 60 mL HNO3 with a concentration of 26.11 mg/L, a ratio of HCl: HNO3 1:3 (v/v) with a dissolved gold concentration of 23.77 mg/L and Leaching time with aqua regia was 90 minutes with a concentration of Au metal of 26.38 mg/L.

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Emmanuel, U. Dan, and J. Inam Edu. "Effect of Acid Digestion Methods on Total Metals Recovery from Sludge from Water Treatment Plants (WTPS) in Nigeria." Chemistry Research Journal 2, no. 2 (2017): 13–18. https://doi.org/10.5281/zenodo.13956193.

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Effect of acid digestion methods on total metal recovery from sludge from water treatment plants in Nigeria was conducted. Sludge samples from four (4) different water treatment plants namely Lower Usuma Dam Water Treatment Plant, Bwari (LUDWTP), Le-Meridien Ibom Hotel and Golf Resort Water Treatment Plant, Uyo (LMWTP), Akwa Ibom State Water Company Water Treatment Plant (AKWTP) and Champion Brewery Water Treatment Plant (CBWTP) were collected and analysed for total metal recovery using Atomic Absorption Spectrophotometer after digestion using two different acid combinations (aqua regia and HNO3/ HClO4  2:1). The results reveal that HNO3/HClO4 extract recorded the highest mean total 16.58 mgkg-1 Zn, 0.40 mgkg-1 Cu and 0.47 mgkg-1 Cd than aqua regia extract in all the fifteen metals analysed. Aqua regia extracts had the highest mean total  61.99 mgkg-1 Ca, 3.60 mgkg-1 K, 29.57 mgkg-1 Mg, 52.19 mgkg-1 Fe, while Co, Cr, Pb, Mn and Na were 0.07, 0.27, 1.47, 19.37 and 12.69  respectively. Aluminium and arsenic levels were not detected in all the four samples extracted with aqua regia and HNO3/HClO4. From the results of this work, aqua regia digestion method is very effective for use in routine monitoring of metals in sludge from water treatment plants in Nigeria.

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RITTER, STEVE. "A NEW TWIST ON AQUA REGIA." Chemical & Engineering News Archive 89, no. 14 (2011): 11. http://dx.doi.org/10.1021/cen-v089n014.p011.

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Tsai, L. J., S. T. Ho, and K. C. Yu. "Correlations of extractable heavy metals with organic matters in contaminated river sediments." Water Science and Technology 47, no. 9 (2003): 101–7. http://dx.doi.org/10.2166/wst.2003.0502.

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In southern Taiwan, almost all the main rivers have been contaminated by anthropogenic heavy metals and organic matters. The main pollution sources include agricultural, industrial, and domestic activities. River sediments potentially have large capacities to accumulate heavy metals and organic matters when the river water flows through it. The sediments sampled from high contaminated river (the Yenshui River) and moderately contaminated rivers (the Tsengwen, Chishui, Potzu, and Peikang Rivers) were used to realize correlations between each kind of aqua regia extractable heavy metals (Co, Cr, Cu, Zn, Ni, Pb, Mn, and Fe) and organic matters in vertical sediment cores. Organic matters and aqua regia extractable heavy metal concentrations, analyzed by strong acid-digested extraction, were determined in vertical profile segments from downstream sediments of the five rivers. Sum of six aqua regia extractable heavy metals (Co, Cr, Cu, Zn, Ni, and Pb) were below 3,000 mg/kg in sediments of the Yenshui River, and below 500 mg/kg in the other four rivers' sediments. Strongly positive correlations (r = 0.83-0.95) between each kind of aqua regia extractable heavy metals and organic matters (concentration range between 0.6 to 3.8%) were observed in sediments of the Yenshui River. The slopes of the linear regressive lines approximated the average metal complexation ratios with organic matters in the sediments. In sediments of the other four rivers, smaller positive correlation coefficients between aqua regia extractable heavy metals and organic matters (below 2.6%) were observed. The complexation ratios derived from the four moderately polluted river sediments were smaller than those derived from the highly contaminated river sediments, indicating that the importance of organic matters in the accumulation of heavy metals in river sediments.

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Arifiyana, Djamilah, and Ermayulis . "Analisis Kandungan Logam Timbal pada Sediaan Kosmetik Bedak yang Beredar di Pasar Pengampon Surabaya." Journal of Pharmacy and Science 4, no. 2 (2019): 111–14. http://dx.doi.org/10.53342/pharmasci.v4i2.149.

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ABSTRAKBedak merupakan salah satu sediaan kosmetik yang banyak dimiliki masyarakat dan merupakan kosmetik dasaratau lumrah dimiliki oleh wanita. Penelitian ini bertujuan untuk menganalisis kandungan logam berat timbal dalam produk kosmetik bedak yang beredar di pasar Pengampon Surabaya. Sampel yang digunakan dipreparasi dengan destruksi basah menggunakan aqua regia. Dari kelima sampel bedak, secara keseluruhan sampel mengandung logam timbal, dan tiga diantara melebihi batas yang telah ditetapkan oleh BPOM RI (20 mg/kg). Sampel dengan kode BD1, BD2 dan BD5 dengan nilai cemaran timbal masing-masing sebesar 27,2746 mg/kg; 21,0297 mg/kg; dan 24,2015 mg/kg.Kata kunci: Logam berat, Timbal, Bedak, Aqua Regia, Spektrofotometer Serapan Atom (SSA)ABSTRACTPowder is one of the many cosmetic preparations and cosmetic standard or commonly owned by women. This study aims to analyze the content of lead heavy metals in powder cosmetic products circulating in Pengampon market Surabaya. The sample used was prepared by wet destruction using aqua regia. From five powder samples, the overall sample contained lead metal, of which three outweighed the limits set by the BPOM RI (20 mg/kg). Samples coded BD1, BD2 and BD5 had lead contamination values of 27,2746 mg/kg; 21,0297 mg/kg; and 24,2015 mg/kg, respectively.Key Words: Trace metal, Lead, Powder, Aqua Regia, Atomic Absorption Spectrophotometer (AAS)

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Okabe, Toru H., Sachiko Yamamoto, Yoshihiro Kayanuma, and Masafumi Maedaaff. "Recovery of platinum using magnesium vapor." Journal of Materials Research 18, no. 8 (2003): 1960–67. http://dx.doi.org/10.1557/jmr.2003.0272.

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To develop an effective process for the recovery of precious metals from scrap, we investigated a new platinum extraction process using alloy formation by magnesium vapor and successive leaching with an aqueous solution. Pure platinum plates were reacted with magnesium vapor at constant temperatures ranging between 873 and 1173 K for 3 h, and Mg–Pt alloy samples were synthesized. The obtained Mg–Pt alloy was then dissolved in aqua regia or in an aqueous HCl solution at room temperature. Platinum was recovered from the leaching solution by conventional precipitation technique, and the platinum obtained by each process was analyzed chemically. It was found that 94% of the platinum was recovered by this process. After Mg vapor treatment, 100% of the platinum was dissolved when kept in aqua regia for 1 h, whereas only 25% of untreated pure platinum was dissolved when kept in aqua regia for 4 h.

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Innocent, Joseph, M. Maina H., Amos Isah Pigweh, and E. Eneche J. "Comparative Analysis of Some Digestion Methods Used in the Determination of Metals in Soil and Sediments." Chemical Science International Journal 19, no. 4 (2017): 1–4. https://doi.org/10.9734/CSJI/2017/34652.

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Analytical study was carried in order to compare the accuracy of three (3) frequently used digestion methods, in the determination of metals in soil and sediments. Samples of soil and sediments were taken from three different locations namely; Bakalchi, Batare, and Anguwan Honna in Girei Local Government Area in Adamawa State Nigeria. Sample matrix was formed from the three samples and the three digestion methods was carried out on each of the sample matrix formed, the methods are, Method I: Roast before digestion using aqua regia as used by Ehi-Eromosele and coworkers [1], Method II: Air dried and digest using Aqua-regia similar to the work of Saxena [2], and Method III; Roast using ammonium chloride before digestion with aqua regia similar to the work of Voica et al [3]. The metal elements Calcium and Iron were chosen because of their relative abundance in natural soil and sediments. Results obtained shows that the soil and sediment samples contain the metal element calcium and Iron which were used to examine the frequently used digestion methods. Based on the result obtained from the analysis, method III (Roast with NH4Cl and digest with aqua regia) appears to be the most promising, given the higher concentration of the elements in all the matrix samples examined.

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López-Núñez, Rafael, Fátima Ajmal-Poley, José A. González-Pérez, Miguel Angel Bello-López, and Pilar Burgos-Doménech. "Quick Analysis of Organic Amendments via Portable X-ray Fluorescence Spectrometry." International Journal of Environmental Research and Public Health 16, no. 22 (2019): 4317. http://dx.doi.org/10.3390/ijerph16224317.

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The determination of heavy metals in soils and organic amendments, such as compost, manure, biofertilizer, and sludge, generally involves the digestion of samples with aqua regia, and the determination of those in the solution using various techniques. Portable X-ray fluorescence (PXRF) has many advantages in relation to traditional analytical techniques. However, PXRF determines the total elemental content and, until now, its use for the analysis of organic amendments has been limited. The objective of this work is the calibration of a PXRF instrument to determine the aqua regia-soluble elemental contents directly in solid samples of organic amendments. Our proposal will avoid the digestion step and the use of other laboratory techniques. Using a training set of samples, calibration functions were obtained that allow the determination of the aqua regia-soluble contents from the PXRF readings of total contents. The calibration functions (obtained by multiple linear regression) allowed the quantitative determination of the aqua regia-soluble contents of Fe, K, P, S, Zn, Cu, Pb, Sr, Cr, and Mn, as well as the organic matter content and a semi-quantitative assessment of Al, Ca, V, Ba, Ni, and As contents. The readings of Si, Fe, Al, Ca, K, or S were used as correction factors, indicating that the calibrations functions found are truly based on the chemical composition of the sample matrix. This study will allow a fast, cheap, and reliable field analysis of organic amendments and of other biomass-based materials.

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Xiong, Zhenfeng, Ying Huang, Kemei Zhou, Dong Zhang, Juan Bao, and Zifei Sun. "Metal Leaching Efficiency from Waste Printed Circuit Boards by Inorganic Acid." Journal of Solid Waste Technology and Management 45, no. 3 (2019): 355–62. http://dx.doi.org/10.5276/jswtm/2019.355.

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Waste printed circuit boards (WPCBs) from personal computers were ground and subjected to a two-step leaching process using two inorganic acids (nitric acid and aqua regia) to leach metals. Three kinds of samples were used: the whole WPCB, the golden finger part, and the WPCB excluding the golden finger. Leaching efficiencies of metals from these samples for different nitric acid concentrations (followed by aqua regia) were evaluated to identify the best concentration of nitric acid. The extracted Au concentration from the golden finger was 5.5 times of that from the whole WPCB board. Metals that compete with Au, such as Ni and Fe, have lower mass fractions in the whole WPCB board compared to those in the golden finger. However, Cu comprises a higher proportion in the golden finger. Au can be effectively separated from most other metals by initially leaching the ground WPCB with 5M nitric acid, followed by leaching with aqua regia. Considering the high leaching proportion of Au, it is advantageous to leach Au and base metals separately from the golden finger and from WPCB excluding the golden finger.

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Saini, Meenaxi, Yogeshwar Masirkar, Ritu Varshney, Partha Roy, and Kalyan K. Sadhu. "Fluorogen-free aggregation induced NIR emission from gold nanoparticles." Chemical Communications 53, no. 46 (2017): 6199–202. http://dx.doi.org/10.1039/c7cc00641a.

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Snyman, H. G. "Characterisation of sewage sludge metals for classification purposes using the potentially leachable metal fraction." Water Science and Technology 44, no. 10 (2001): 107–14. http://dx.doi.org/10.2166/wst.2001.0594.

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The South African sludge guidelines were revised in 1997 with considerable amendments to the heavy metal loading and usage restrictions. The industry continued using the aqua regia extraction method to characterise and classify sewage sludge. This meant that a Class D sludge (most stable class and sellable product) could not be generated at any South African plant. This caused the industry to seek alternative non-beneficial disposal methods. It was then realised that the metal limits were in fact the TCLP (Toxicity Characteristic Leaching Procedure) extractable limit. This method was developed to determine the potential of a waste to contaminate ground and/or surface water. The agriculturists, however, use the NH4EDTA extractable fraction to establish metal concentration in soils. This paper specifically aims to establish the feasibility of using the available metals extraction methods such as NH4EDTA and TCLP to determine the fate and therefore the risk of sludge-borne metals (Cd, Pb, Zn, Cu). The results show that the TCLP extraction method could potentially underestimate the impact of sewage sludge-borne metals when amended to agricultural soils. The extraction efficiency of the NH4EDTA and TCLP methods relative to the aqua regia extraction method was presented for Cd, Pb, Zn and Cu. The NH4EDTA extraction method seems to be an alternative to the aqua regia method, especially since the NH4EDTA measures the fraction of the metal that may become available in the environment. It is recommended that the aqua regia and NH4EDTA be used to classify and characterise the metal content of South African sludges.

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Muhammad, Irpan, Agus Triantoro, and Yuniar Siska Novianti. "Optimasi Kondisi Pelarutan Logam Au Dalam Endapan Placer Dengan Proses Hidrometalurgi." Jurnal Geomine 7, no. 3 (2020): 162. http://dx.doi.org/10.33536/jg.v7i3.465.

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Emas diperoleh dengan cara mengisolasinya dari batuan bijih emas. Proses hidrometalurgi dengan Aqua Regia sebagai pereaksi digunakan untuk mengisolasi emas dari endapan alluvialnya. Penelitian ini dilakukan untuk mengetahui hasil ekstraksi Au menggunakan Aqua Regia dan waktu optimum dari proses hidrometalurgi serta seberapa besar massa logam Au yang terlarut. Dalam penelitian ini sampel diambil di tiga titik berbeda yang berada Sungai Katingan Kalimantan Tengah dengan masing-masing kedalaman sampel 3 meter dari permukaan air, kemudian sampel dilindi menggunakan Aqua Regia dengan rentang waktu 5, 10, 20, 60, 100 dan 120 menit. Data yang digunakan berupa data konsentrasi logam Au yang didapatkan dari sampel yang telah dilindi sebelumnya dan dianalisis dengan menggunakan instrument AAS (Atomic Absorption Spectrometry) kemudian diolah dengan menggunakan kurva x dan y untuk mendapatkan waktu optimum serta massa logam Au terlarut didapatkan dengan menggunakan persamaan. Data hasil penelitian menghasilkan konsentrasi Au pada waktu pelindian dengan rentang waktu 5, 10, 20, 60, 100 dan 120 menit pada masing-masing sampel disetiap lokasi secara berurutan pada lokasi 1 adalah 11,07Mg/L, 10,68Mg/L, 11,02Mg/L, 11,23Mg/L, 2,21Mg/L, 0,51Mg/L dengan massa Au terlarut 1,27x10-3gr, 1,22x10-3gr, 1,26x10-3gr, 1,12x10-3gr, 2,54x10-4gr dan 5,87x10-5gr. Lokasi 2 adalah 656Mg/L, 587Mg/L, 584Mg/L, 625Mg/L, 645Mg/L, 210Mg/L dengan massa Au terlarut 7,54x10-2gr, 6,75x10-2gr, 6,71x10-2gr, 7,18x10-2gr, 7,41x10-2gr dan 2,41x10-2gr. Lokasi 3 adalah 261Mg/L, 931Mg/L, 625Mg/L, 631Mg/L, 639Mg/L, 915Mg/L dengan massa Au terlarut 3x10-2gr, 1,07x10-1gr, 7,18x10-2gr, 7,25x10-2gr, 7,34x10-2gr dan 1,05x10-1gr. Dari hasil tersebut memperlihatkan waktu yang paling optimal untuk proses hidrometalurgi pada endapan alluvial berada pada waktu 5 menit karena menghasilkan konsentrasi logam dan massa Au yang paling optimal dalam kondisi Aqua Regia yang masih stabil.

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Johnson, Karin, and Jonathan W. Steed. "Oxonium-ion crown ether complexes from aqua regia." Chemical Communications, no. 14 (1998): 1479–80. http://dx.doi.org/10.1039/a802537a.

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Mousavi, Aliyar. "How aqua regia overcomes the chemical inertness of cinnabar: a thermodynamic analysis in light of long-term knowledge about a reaction that has been of interest for centuries." Reviews in Inorganic Chemistry 39, no. 4 (2019): 223–31. http://dx.doi.org/10.1515/revic-2019-0014.

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AbstractWith the rise of the Swiss-born alchemist Paracelsus in the 16th century, the dissolution of cinnabar (red HgS) in aqua regia has repeatedly appeared in the chemical literature. This article reviews the relevant history and takes a thermodynamic approach to shed new light on the dissolution. The conclusions reveal that the reaction in which the sulfide ion is oxidized by nitric acid is the most thermodynamically favorable step in the dissolution. The importance of the role of hydrochloric acid in the dissolution, when it provides complexation, was also observed. Further, it was found that the overall effect of nitric acid is much greater than that of the aqua regia by-product elemental chlorine.

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Levchenko, Volodymyr, Cristiano Glessi, Sigurd Øien-Ødegaard, and Mats Tilset. "Organometallic chemistry in aqua regia: metal and ligand based oxidations of (NHC)AuCl complexes." Dalton Transactions 49, no. 11 (2020): 3473–79. http://dx.doi.org/10.1039/c9dt04472h.

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Szymczycha-Madeja, Anna, Maja Welna, Monika Zabłocka-Malicka, Pawel Pohl, and Włodzimierz Szczepaniak. "Development and Validation of an Analytical Method for Determination of Al, Ca, Cd, Fe, Mg and P in Calcium-Rich Materials by ICP OES." Molecules 26, no. 20 (2021): 6269. http://dx.doi.org/10.3390/molecules26206269.

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Four procedures based on closed-vessel microwave-assisted wet digestion with different oxidative reagents, including HNO3 (P1), HNO3 + H2O2 (P2), aqua regia (P3) and Lefort aqua regia (P4), for preparation of calcium (Ca)-rich materials prior to determination of total concentrations of Al, Ca, Cd, Fe, Mg and P by inductively coupled optical emission spectrometry (ICP OES) were compared. It was found that digestion with Lefort aqua regia (P4) provided the best results for all examined elements, i.e., precision of 0.30–4.4%, trueness better than 2%, recoveries of added elements between 99.5–101.9%, and limits of detection within 0.08–1.8 ng g−1. Reliability of this procedure was verified by analysis of relevant certified reference materials (CRMs), i.e., Natural Moroccan Phosphate Rock—Phosphorite (BCR-O32). Additionally, selection of appropriate analytical lines for measurements of element concentrations, linear dynamic ranges of calibration curves and matrix effects on the analyte response were extensively investigated. Finally, the selected procedure was successfully applied for routine analysis of other Ca-rich materials, i.e., CRMs such as NIST 1400 (Bone Ash), CTA-AC-1 (Apatite Concentrate Kola Peninsula) and NCS DC70308 (Carbonate Rock), and six natural samples, such as a dolomite, a phosphate rock, an enriched superphosphate fertilizer, pork bones, pork bones after incineration, and after steam gasification.

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Cayme, Jan-Michael C., and Aniano, Jr N. Asor. "Extraction Methods for Quantifying Iron, Calcium and Magnesium in a Historic Brickwork Produced During the Spanish Colonial Period in the Philippines." KIMIKA 26, no. 1 (2015): 27–37. http://dx.doi.org/10.26534/kimika.v26i1.27-37.

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This study demonstrates the feasibility of performing chemical analyses on heritage materials in the Philippines. Four extraction methods were evaluated based on the percentage of iron, calcium and magnesium in a clay brick sample obtained from an old Spanish colonial period church at Ilocos Norte. Aqua regia (1:3 HNO3:HCl, v/v) solvent was used to extract these elements by conventional hot plate digestion. The extraction methods are: digesting the sample directly with aqua regia (M1), sample pre-digested with NH4Cl and ethyl alcohol prior to the actual digestion (M2) and soaking the sample with aqua regia for 24 hours (M3) and 48 hours (M4) before digestion. Atomic absorption spectroscopy (AAS) was employed to quantify the concentration of the intended elements. The percentage composition of iron ranges from 4.193 to 4.418%, calcium from 0.123 to 0.203%, and magnesium from 2.346 to 2.458%, respectively. Energy-dispersive X-ray spectroscopy (EDX) analysis was done to support the data obtained from AAS. M1 was more effective in extracting calcium from the brick sample, while M2, M3 and M4 were useful for extracting iron and magnesium. Infrared spectroscopy (IR) provided a basic mineralogical composition of the sample, with peaks that were attributed to quartz, kaolinite, calcite, silicates and hematite.

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Lu, Li Hong, Jing Wu Zhang, and De Jiu Shen. "Characterization of Anatase Coatings on NiTi Shape Memory Alloy by Plasma Electrolytic Oxidation Method." Applied Mechanics and Materials 121-126 (October 2011): 3837–41. http://dx.doi.org/10.4028/www.scientific.net/amm.121-126.3837.

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The anatase coatings was obtained by aqua regia dealloying and plasma electrolytic oxidation (PEO) method on NiTi shape memory alloy (SMA) substrate. The PEO manufacturability of NiTi SMA before and after dealloying was researched. The PEO surface morphologies of the aqua regia treated and untreated specimens were investigated with scanning electron microscopy (SEM). The composition of the PEO coatings was investigated with X-ray diffraction (XRD). The element concentration of the surface of the PEO-treated NiTi SMA was measured by an energy dispersive X-ray spectrometer (EDS). The results indicate that the pre-treatment technology by aqua regia dealloying can greatly improve the PEO manufacturability and the PEO morphologies of the NiTi SMA. The optimum dealloying parameters are at room temperature for 10 min. At this circumstance, the PEO manufacturability of the treated samples is most close to that of the industrial pure titanium. There are many honeycomb-like micro-pores in the surface of the PEO coatings, which act as discharging channels. The cracks are invisible in the SEM images of the PEO coatings. The PEO coatings formed on the NiTi is composed of Ti, Ni, Al, O, Au and P. The composition of the PEO coatings is mainly composed of NiTi phase and anatase phase.

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Fang, Jinyang, Qingke Zhang, Xinli Zhang, et al. "Influence of Etchants on Etched Surfaces of High-Strength and High-Conductivity Cu Alloy of Different Processing States." Materials 17, no. 9 (2024): 1966. http://dx.doi.org/10.3390/ma17091966.

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With the continuous integration of semiconductor devices, the requirements of the size accuracy and surface quality of etched lead frames are stricter. The etchant is a key factor in the etching process and etched surface quality, while the effects of the difference in etchants on the etched surface morphology of Cu alloy have not been directly studied. In this study, aqua regia, acidic FeCl3 and two CuCl2 solutions were used as etchants, and different CuCrSn specimens were etched and characterized. The results show that the etching rate in aqua regia is high, and the grain orientation, grain boundary (GB) and dislocations have significant influences on the local etching rate. The preferential etching of some atomic planes forms steps between the grains with different orientations, and preferential etching around the GB and dislocation group forms grooves, resulting in high surface roughness. For the surfaces etched by the FeCl3 and CuCl2 etchants, the steps and grooves are blurred; thus, they are less rough. The CuCrSn alloy surface etched by the aqua regia is clean, with little Cr-rich particles, while high-density Cr-rich particles remain on the surfaces etched by the FeCl3 and CuCl2 etchants. For the same kind of etchant, the ion concentration can affect the etching mechanism, rate and the etched surface morphology.

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Xu, Qian, Wei Guo, Lanlan Jin, Qinghai Guo, and Shenghong Hu. "Determination of cadmium in geological samples by aerosol dilution ICP-MS after inverse aqua regia extraction." Journal of Analytical Atomic Spectrometry 30, no. 9 (2015): 2010–16. http://dx.doi.org/10.1039/c5ja00182j.

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He, Haihua, Jia Zhao, Bolin Wang, et al. "Highly Active AuCu-Based Catalysts for Acetylene Hydrochlorination Prepared Using Organic Aqua Regia." Materials 12, no. 8 (2019): 1310. http://dx.doi.org/10.3390/ma12081310.

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Development of a sustainable process for designing and synthesising an active and stable catalyst for hydrochlorination of acetylene is challenging, yet crucial, for industrial vinyl chloride monomer (VCM) production. Herein, direct synthesis of bimetallic AuCu catalysts using organic aqua regia (OAR) preparation methods was investigated. In comparison with conventional aqua regia (AR), bimetallic AuCu catalysts synthesised from OAR exhibit enhanced activity and stability. After careful characterisation of the catalyst samples using X-ray diffraction patterns (XRD), Scanning transmission electron microscopy (STEM), X-ray photoelectron spectroscopy (XPS), and Temperature-programmed desorption (TPD), this observation was justified for the following reasons: 1) the existence of sulphur and nitrogen atoms stabilised the cationic Au active sites, and 2) OAR helped to sustain the function of the Cu promotor by stabilising it. Advanced understanding on the importance of promoter stability has unveiled new perspectives for this research area.

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Koyuncuoğlu, Aziz, Akçakaya Dilek Işık, Sukas Özlem Şardan, and Haluk Külah. "Wet etching of platinum (Pt) electrodes for piezoelectric transducers using a thick photoresist mask." Micro and Nano Engineering 16, August 2022 (2022): 100153. https://doi.org/10.1016/j.mne.2022.100153.

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Platinum (Pt) is widely used in MEMS applications due to its inert nature and high temperature stability. In general, Pt is patterned using dry etching methods which require expensive machinery. In this study, we propose wet etching of Pt electrodes of piezoelectric transducers in hot Aqua Regia at 60 °C using a thick photoresist as a masking material. We showed that this method eliminates the need for metal hard mask and subsequent metal stripping, which may not be compatible with other structures on the process wafer. A stack of Si/Ti/Pt was used as a test sample to verify the effectiveness and chemical stability of AZ® 9260 and SPR™ 220-7 type photoresists in hot Aqua Regia. The optimized process was then successfully applied on a wafer with a pre-patterned pulsed laser deposited lead zirconate titanate (PLD-PZT) using SPR™ 220-7 photoresist. The suitability of the etching process was verified using optical imaging and SEM-EDS analysis. An etch resolution of 3.5 μm was achieved for 100 nm thick Pt thin films after 15 min immersion in hot Aqua Regia at 60 °C without any plasma cleaning. Using descum process with Ar plasma beforehand decreased the etching time down to 3:45 min and improved the minimum feature size down to 1 μm.

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Hasani, M., A. Khodadadi, S. M. J. Koleini, A. H. Saeedi, Y. Pérez-Pacheco, and A. M. Meléndez. "Platinum leaching from automotive catalytic converters with aqua regia." Journal of Physics: Conference Series 786 (January 2017): 012043. http://dx.doi.org/10.1088/1742-6596/786/1/012043.

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Ugajin, Hajime, Hayato Iwamoto, and Kei Kinoshita. "Direct Mixing Cleaning Method of Aqua Regia on Wafer." Solid State Phenomena 103-104 (April 2005): 245–48. http://dx.doi.org/10.4028/www.scientific.net/ssp.103-104.245.

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Lin, Wei, Rong-Wei Zhang, Seung-Soon Jang, Ching-Ping Wong, and Jung-Il Hong. "“Organic Aqua Regia”-Powerful Liquids for Dissolving Noble Metals." Angewandte Chemie International Edition 49, no. 43 (2010): 7929–32. http://dx.doi.org/10.1002/anie.201001244.

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Lin, Wei, Rong-Wei Zhang, Seung-Soon Jang, Ching-Ping Wong, and Jung-Il Hong. "“Organic Aqua Regia”-Powerful Liquids for Dissolving Noble Metals." Angewandte Chemie 122, no. 43 (2010): 8101–4. http://dx.doi.org/10.1002/ange.201001244.

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Siebe, Christina. "Heavy metal availability to plants in soils irrigated with wastewater from Mexico City." Water Science and Technology 32, no. 12 (1995): 29–34. http://dx.doi.org/10.2166/wst.1995.0452.

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The relationship between three different heavy metal fractions in soils irrigated for long periods of time with untreated wastewater from Mexico City and the metal uptake by alfalfa (Medicago sativa) was studied in order to evaluate actual accumulation levels in soils, as well as to establish which extracting solution characterizes most precisely the availability of selected heavy metals to plants. Cd, Pb, Cu and Zn were analyzed in aqua regia, 1 M NH4NO3 and water extracts from 50 soil samples and correlated with total contents in alfalfa tissue collected at the same sites. Heavy metal contents of the 3 fractions increase significantly with irrigation time, but European tolerance limits are slightly exceeded only for Cd at some sites. Plant uptake of Cd and Pb also increases the longer the soils have been irrigated and correlates best with aqua regia extracts from soils.

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Akhter, Faheem, Suhail Ahmed Soomro, and Vassilis J. Inglezakis. "Aqua Regia as a Competitive Leaching Agent for Metallic Impurity Removal from Rice Husk." Jurnal Kejuruteraan 34, no. 5 (2022): 861–64. http://dx.doi.org/10.17576/jkukm-2022-34(5)-13.

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Rice husk is widely recognized as significant biomass containing cellulose, lignin and silica. Usually, rice husk is combusted for energy purposes but it contributes to severe environmental pollution. Therefore, the integrated components of rice husk (i.e. silica) can be extracted and converted into value-added products. However, the metallic impurities must be removed before further extraction. Generally, rice husk is leached with conventional acids such as HCl and nitric acid, however, the present study has used aqua regia and compared the results with conventional acids. The leached rice husk samples were characterized using TGA, SEM and EDX. The results of the present work indicate that the aqua regia carries a significant leaching potential to remove metallic impurities from rice husk with 1 M and 2 M solutions removing more than 98% and 99% of impurities respectively. However, its brief chemical stability compels it to be prepared and used immediately.

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Dos santos, Antonio, Dinalva Schein, Mauro Cesar Marchetti, Estela Bresolin Pereira, and Arthur Rolim Stasiak. "Application of solid-liquid extraction with organic acids for recovery of precious metal from technological waste in disuse." International Journal for Innovation Education and Research 8, no. 8 (2020): 366–73. http://dx.doi.org/10.31686/ijier.vol8.iss8.2531.

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The electro and electronic industry has been increasing gradually, causing an increase in the generation of waste of electrical and electronic equipment, which have several components that have added value such as - for example - gold. Aiming at environmental protection, measures are sought for the recovery of these metals, through tests with several technologies such as leaching. This consists in separating the component from the solid part, transferring it to the liquid part, using acids. It is necessary to study acids that are less harmful to the environment. Thus, microprocessors of obsolete computers were collected, their characterization was carried out and the elements present in the pins were identified. After the characterization, the leaching stage was carried out, firstly with aqua regia; then with acetic and citric acids. The leaching results presented about 10 mg / L of gold with aqua regia and about 0.5 mg / L with citric acid.

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Torrinha, Maria Beatriz Q. L. F., Hugo A. M. Bacelo, Sílvia C. R. Santos, Rui A. R. Boaventura, and Cidália M. S. Botelho. "Uptake and Recovery of Gold from Simulated Hydrometallurgical Liquors by Adsorption on Pine Bark Tannin Resin." Water 12, no. 12 (2020): 3456. http://dx.doi.org/10.3390/w12123456.

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The recovery of critical and precious metals from waste electrical and electronic equipment (WEEE) is an environmental and economic imperative. Biosorption has been considered a key technology for the selective extraction of gold from hydrometallurgical liquors obtained in the chemical leaching of e-waste. In this work, the potential of tannin resins prepared from Pinus pinaster bark to sequester and recover gold(III) from hydrochloric acid and aqua regia solutions was assessed. Equilibrium isotherms were experimentally determined and maximum adsorption capacities of 343 ± 38 and 270 ± 19 mg g−1 were found for Au uptake from HCl and HCl/HNO3 (3:1 v/v) solutions containing 1.0 mol L−1 H+. Higher levels of acidity (and chloride ligands) significantly impaired the adsorption of gold from both kinds of leaching solutions, especially in the aqua regia system, in which the adsorbent underperformed. Pseudo-first and pseudo-second order models successfully described the kinetic data. The adsorbent presented high selectivity towards gold. Actually, in simulated aqua regia WEEE liquors, Au(III) was extensively adsorbed, compared to Cu(II), Fe(III), Ni(II), Pd(II), and Zn(II). In three adsorption–desorption cycles, the adsorption capacity of the regenerated adsorbent moderately decreased (19%), although the gold elution in acidic thiourea solution had been quite limited. Future research is needed to examine more closely the elution of gold from the exhausted adsorbents. The results obtained in this work show good perspectives as regards the application of pine bark tannin resins for the selective extraction of Au from electronic waste leach liquors.

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U. A., Augustine, Akpomie T. M., Balarabe S., and Ishaq B. "Determination of the Levels of Lead and Cobalt from Soils of an Irrigated Farmland in Lafia Nasarawa State-Nigeria Using Two Different Methods of Digestion." Academic Journal of Chemistry, no. 55 (May 15, 2020): 48–54. http://dx.doi.org/10.32861/ajc.55.48.54.

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Washing of vehicles (lorries, cars, buses and motor-bikes), clothes and kitchen utensils, bathing and the release of smoke from exhausts of motor-vehicles and other anthropogenic sources continuously increase the levels of heavy metals in water bodies, especially the Amba river of Lafia used for the irrigation of farmlands thereby resulting to contamination and elevation of heavy metals uptake by crops. This study was carried out to provide information on heavy metals concentration in soils of an irrigated vegetable farmland in Lafia. Soil samples were collected at surface levels of 0-30 cm depth. Samples were analyzed for pH, organic matter, electrical conductivity and soil particle sizes. The soil samples were digested using Aqua regia and Nitric acid methods of digestion. The concentrations of lead (Pb) and cobalt (Co) were determined by Atomic Absorption Spectrophotometric (AAS) technique. The values of soil pH ranged between 5.60 and 6.35, organic carbon between, 1.40-1.49 %, organic matter content between, 2.40 and 2.57 %, electrical conductivity between 100 and 240 μS cm –1 and clay, sand and silt content between 10.4-11.4 %, 82-85 % and 4.6-6.6 % respectively. Total concentration of extractable Pb and Co (Aqua regia method) ranged between 0.083–0.105 and 1.473 – 1.573 mg kg-1 respectively. The concentrations of heavy metals for Nitric acid method were as follows: Pb: 1.363-1.512 and Co: 0.060-0.086. Concentrations of heavy metals in both methods were all below DPR-EGASPIN (2002) and US EPA. (2014) recommended limits. The results showed that aqua regia method was more efficient than the Nitric acid Method of digestion.

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Teniola, Oluwasanmi Samuel, Abraham A. Adeleke, Simeon Ademola Ibitoye, and Moshood Dehinde Shittu. "Production of a Highly Concentrated Gold Solution from Aqua Regia Gold Leachate Using Sugarcane Bagasse Nanoparticles." Hungarian Journal of Industry and Chemistry 51, no. 2 (2023): 27–33. http://dx.doi.org/10.33927/hjic-2023-15.

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This study produced a highly concentrated gold solution using nanoparticles (NPs) synthesized from sugarcane bagasse as an adsorbent for gold(III) recovery from an aqua regia gold leached lean solution. A 100 kg sample of gold ore collected from a mining site in Iperindo was concentrated. Mineralogical characterization and a fire assay test of the ore were carried out. Atmospheric and agitation leaching were conducted using aqua regia. Sugarcane bagasse NPs were prepared and used to study the gold(III) adsorption kinetics. Gold-loaded sugarcane bagasse NPs were desorbed in a 4 M aqua regia solution. The results revealed that the ore has a low water retention capacity which renders it friable. A microscopic examination established the presence of gold particles and pyrite in the ore. Ore leaching was eminently favoured by agitation yielding a weight loss of 6.3 % when an acid concentration of 4 M was used, the temperature was 90 ºC and the leaching time was 30 minutes. Synthesized nanocellulose was able to adsorb gold(III) from the leachate optimally with the following process parameters: 14 mL/g of adsorbent, 106.2 minute-long contact time, a temperature of 56 ºC and an agitation rate of 45 rpm when the concentration of leachate was 84 mg/L. The adsorption efficiency of the sugarcane bagasse NPs is comparable with that of commercial activated carbon, namely 92 and 95 %, respectively. The study concluded that NPs synthesized from sugarcane bagasse could be effectively used when upgrading gold and in purification processes.

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Szymczycha-Madeja, Anna. "A Simple and Rapid Method for the Multielement Analysis of Wheat Crispbread Products by Inductively Coupled Plasma-Optical Emission Spectrometry." Journal of AOAC INTERNATIONAL 97, no. 6 (2014): 1656–61. http://dx.doi.org/10.5740/jaoacint.14-005.

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Abstract A simple and fast method for the determination of total concentrations of Ba, Ca, Cd, Cr, Cu, Fe, Mg, Mn, Ni, P, Sr, and Zn in wheat crispbreads using inductively coupled plasma-optical emission spectrometry was developed. Initially, three different sample preparation procedures, i.e., microwave-assisted digestion in an HNO3 and H2O2 mixture and solubilization in aqua regia or tetramethylammonium hydroxide solution were compared. The performance of these procedures was evaluated for precision, accuracy, and LOD of the elements. It was established that the application of aqua regia allows determining elements with LOD within 0.1–42 ng/mL, precision of 0.2–4.1%, and accuracy better than 5%. Furthermore, good agreement between measured and certified values of a National Institute of Standards and Technology certified reference material of wheat flour (SRM 1567a) was found. It was confirmed that the proposed method could be used successfully as an alternative to microwave-assisted acid digestion in routine multielement analyses of wheat crispbreads.

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Sulistiyani, Sulistiyani, Erfan Priyambodo, and Larasti Yogantari. "SILICA PURIFICATION FORM MERAPI VOLCANO SAND AS PHOTOVOLTAIC RAW MATERIALS." Jurnal Sains Dasar 4, no. 2 (2016): 122. http://dx.doi.org/10.21831/jsd.v4i2.9087.

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Purification of silica sand volcanic Mount Merapi has been done, for raw material photovoltaic. Leaching purification process is done using aqua regia solution, H2SO4, and HCl. Purification of silica sand of Mount Merapi as a raw material photovoltaic assumes that photovoltaic technologies that utilize solar energy is quite affordable, do not run out, and clean so that it will provide long term benefits are substantial. Stage purification process through grinding up to size 60 mesh, iron using magnetic separation, leaching of acid and alkaline leaching. Characterization of the samples using XRD and XRF. The result showed that Mount Merapi volcanic sand containing silica is high at 48-50%. XRD characterization results indicate that the silica in sand samples well as silicon dioxide or mineral has amorphous structure. Among aqua regia, H2SO4 and HCl leaching that has the ability to nicest namely the concentration of concentrated HCl and purified silica has a purity of 59%. Keywords: purification, silica, volcano sand

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39

Yakasai, Hafeez Muhammad, Mohd Fadhil Rahman, Nur Adeela Yasid, Siti Aqlima Ahmad, Mohd Izuan Effendi Halmi, and Mohd Yunus Shukor. "Elevated Molybdenum Concentrations in Soils Contaminated with Spent Oil Lubricant." Journal of Environmental Microbiology and Toxicology 5, no. 2 (2017): 1–3. http://dx.doi.org/10.54987/jemat.v5i2.407.

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Molybdenum is an essential trace element of which its pollution due to excessive levels are increasingly reported worldwide. One of the most important usage of molybdenum is as an engine lubricant. Pollution of spent oil lubricant due to indiscriminate dumping of the waste is an important source of molybdenum pollution. In this study, soil samples from various locations in Malaysia were taken from sites which are visible with the dumping of spent oil lubricant and were tested for the presence of soluble and insoluble molybdenum content. The highest concentrations of Mo found for both of the aqua regia digested and ammonium extracted soil sample were at 35.27 and 17.86 mg/Kg soil, respectively. The percentage of ammonium acetate (soluble) extractable Mo to total Mo measured as the aqua regia digested sample was also the highest at 50.64%. The results indicated an excessive content of molybdenum on these soils which warrant remediation process.

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Aide, Michael, Indi Braden, and Wesley Mueller. "Partitioning of Iron and Scandium in Soils Having Water Drainage Limitations." Applied and Environmental Soil Science 2009 (2009): 1–6. http://dx.doi.org/10.1155/2009/243482.

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Soil chemistry of Fe includes weathering reactions, adsorption, hydrolysis, complexation, and oxidation-reduction reactions. Soil chemistry for scandium (Sc) is similar, but Sc does not include oxidation-reduction reactions. To determine if geochemical analysis may be used to identify Sc partitioning with respect to Fe among the particle size fractions, two Alfisol and two Ultisol soils were assessed using an aqua-regia digestion to estimate Sc and Fe concentrations for whole soil and particle size separates. Aqua-regia digestion data showed Sc depletion relative to Fe in sand separate. Sand separate is largely composed on quartz sand and Fe-Mn-bearing nodules, which are redoximorphic features produced by alternating oxic and suboxic/anoxic conditions associated with seasonally fluctuating water tables. Relative partitioning of Fe and Sc in these soils warrants further study to assess if selective extractions could quantify the extent of modern or ancestral oxidation-reduction processes responsible in some soil features involved in soil genesis.

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King, Simon, and C. Barry Carter. "Morphology of Acid-Cleaned Heat-Treated MgO (100) Surfaces." Proceedings, annual meeting, Electron Microscopy Society of America 51 (August 1, 1993): 964–65. http://dx.doi.org/10.1017/s0424820100150654.

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The widespread use of the (100) MgO surface as a substrate for the deposition particularly of high-Tc super-conductors, and a wide variety of other materials such as titania, has provoked considerable interest in the morphology of the surfaces employed. In the above studies, (100) oriented MgO specimens have generally been prepared according to the method of Norton et al, in which foils are cleaned in acid, with the active ingredient being aqua-regia, after perforation by ion-milling and before a heat treatment in air, typically for 10-15 mins at 1350 °C. The surface morphology of specimens prepared in this manner is explored in this paper.Many of the features common to the aqua-regia cleaned and heat-treated thin-films are shown in the (100) zone-axis bright-field (BF) image of fig 1(a). The general morphology of these foils includes a high density of holes within the thinnest regions, whilst pores are in evidence in thicker areas.

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Teniola, Oluwasanmi Samuel, Abraham A. Adeleke, Simeon Ademola Ibitoye, and Moshood Deinde Shitu. "Leaching of a Nigerian Refractory Gold Ore Using Aqua Regia." American Journal of Engineering and Applied Sciences 15, no. 1 (2022): 118–25. http://dx.doi.org/10.3844/ajeassp.2022.118.125.

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Bonaccorso, F., G. Calogero, G. Di Marco, et al. "PFabrication of gold tips by chemical etching in aqua regia." Review of Scientific Instruments 78, no. 10 (2007): 103702. http://dx.doi.org/10.1063/1.2782682.

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Chang, K. L., C. K. Lee, J. W. Hsu, H. F. Hsieh, and H. C. Shih. "The etching behavior of n-GaP in aqua regia solutions." Journal of Applied Electrochemistry 35, no. 1 (2005): 77–84. http://dx.doi.org/10.1007/s10800-004-2565-4.

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Forte, Federica, Sofia Riaño, and Koen Binnemans. "Dissolution of noble metals in highly concentrated acidic salt solutions." Chemical Communications 56, no. 59 (2020): 8230–32. http://dx.doi.org/10.1039/d0cc02298e.

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Highly concentrated solutions of AlCl3·6H2O and Al(NO3)3·9H2O are safer and more environmentally friendly alternatives to aqua regia for the dissolution of gold and platinum group metals (Pd, Pt, Rh).

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Chen, Ming, and Lena Q. Ma. "Comparison of Three Aqua Regia Digestion Methods for Twenty Florida Soils." Soil Science Society of America Journal 65, no. 2 (2001): 491–99. http://dx.doi.org/10.2136/sssaj2001.652491x.

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Sheng, Peter P., and Thomas H. Etsell. "Recovery of gold from computer circuit board scrap using aqua regia." Waste Management & Research 25, no. 4 (2007): 380–83. http://dx.doi.org/10.1177/0734242x07076946.

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Conte, Marco, Catherine J. Davies, David J. Morgan, et al. "Aqua regia activated Au/C catalysts for the hydrochlorination of acetylene." Journal of Catalysis 297 (January 2013): 128–36. http://dx.doi.org/10.1016/j.jcat.2012.10.002.

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Sánchez, J., E. Castillo, P. Corredor, and J. Ágreda. "Determination of Mercury by Anodic Stripping Voltammetry in Aqua Regia Extracts." Portugaliae Electrochimica Acta 29, no. 3 (2011): 197–210. http://dx.doi.org/10.4152/pea.201103197.

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Wang, Xin Ye, Ya Ji Huang, Zhao Ping Zhong, Yong Xing Wang, and Liang Liang Xu. "In Furnace Capture of Heavy Metals by Sorbents during Simulated MSW Incineration." Advanced Materials Research 356-360 (October 2011): 1590–96. http://dx.doi.org/10.4028/www.scientific.net/amr.356-360.1590.

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Heavy metal capture experiments were carried out in a tube furnace to investigate the effect of different sorbents and Si-Al ratios on the capture of Zn, Cu, Pb, Cd and Cr during simulated MSW incineration. The incineration bottom ash was digested by aqua regia and HCl/HNO3/HF, then determined by ICP-AES. Experimental results indicate that HCl/HNO3/HF is more suitable for the digestion of incineration bottom ash than aqua regia; the volatilization capacities of the five metals during simulated MSW incineration at 1000°C follow the sequence of Pb > Cd > Cu > Cr > Zn; zeolite and limestone have a certain efficiency to capture Zn and Cr while kaolinite has no efficiency to capture all the five metals; the addition of kaolinite and zeolite can prevent the glass and brick powder from melting which can cause the package of heavy metals, but the addition of zeolite can promote Zn and Cr to form silicate, aluminate and aluminosilicate; the mixture of SiO2and Al2O3is in favor of the adsorption of Cd and Cr, but against the adsorption of Pb and Cu compared with single SiO2or Al2O3.

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Journal articles on the topic 'Aqua Regia'

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