Journal articles on the topic 'Keywords {sorption isotherm'

HighlightsMoisture sorption isotherms of rice and husk flour composites were determined.Adsorption isotherms were best modeled by the Chung-Pfost and Oswin equations.Desorption isotherms were best modeled by the Polynomial and Chung-Pfost equations.The Modified Oswin model was the best for both adsorption and desorption.Abstract. Empirical models describing isotherms specifically for adsorption and desorption have not been described for rough rice and husk flour composites. Such models are vital for process control and monitoring operations which use rice husk and rice flours or their mixtures for food or material processing. The current study was undertaken to determine the moisture sorption isotherms of rice husk flour, rough rice flour and their mixtures subjected to different temperature levels. Effects of rice husk flour to rough rice flour ratio of 0:1 (0.0%), 1:49 (2.0%), 1:16 (5.9%), and 1:0 g/g (100.0%) on rough rice moisture isotherms at temperature levels of 20°C, 40°C, and 60°C were investigated. The dynamic dewpoint isotherm technique (DDI) was used to generate accurate isotherms. Several empirical models were tested to fit the experimental EMC data. All the isotherms showed typical sigmoidal type 2 shapes. The equilibrium moisture content (EMC) over equilibrium relative humidity (water activity) ranging from 10% to 95% showed temperature dependence. Hysteresis was evident for all samples, with a decreasing level at a higher temperature. Rice husk flour to rough rice flour ratio, as a factor, showed a significant effect on the EMC of rough rice. The EMC decreased with an increase in rice husk flour levels. Chung-Pfost and Oswin were the two best models for describing adsorption isotherm, and Polynomial and Chung-Pfost were the best models for fitting the desorption isotherm. Modified Oswin model was the best model amongst the two-variable models for describing both adsorption and desorption isotherms. Keywords: Empirical models, Equilibrium moisture content, Rice husk flour, Rough rice flour, Sorption isotherms.

The kinetics and equilibrium adsorption isotherm of cadmium (II) adsorption onto Dacryodes edulis (native peer seed) biomass was studied using a nonlinear approach, which is unpopular but proven in some literature to be more reliable and easier. In optimizing the process, about 98% removal of the cadmium ion was achieved within five minutes at pH 7 by contacting just 30 mg of the Dacryodes edulis seed biomass with the adsorbate solution of a concentration of 100 mg/L. Non-linear investigation of the kinetics and adsorption isotherms of the process was done using the R console statistical and computing software. The results indicated that the Elovich mechanism and the Freundlich adsorption isotherm most suitably described the kinetics and adsorption isotherm, respectively, of the process as provided by their least values of the sum of squared residuals (SSR). This outcome implied a chemical adsorption (chemisorption) mechanism and a multi-layer coverage by the cadmium ions on heterogeneous active sites of the biomass surface with a Freundlich constant or capacity factor, Kf of 27.83 mg g-1, heterogeneity factor, 1/n of 0.2614 and Elovich constants, α and β of 7.0 mg g−1 s−1 and 1.0 g mg-1, respectively. These findings indicate that Dacryodes edulis seed biomass has a good potential for cadmium (II) adsorption. Keywords: Dacryodes edulis, Elovich kinetic model, Freundlich isotherm, Langmuir isotherm, Nonlinear

The sorbent XAD-OXINE was prepared by covalently binding 8-hydroxyquinoline onto the surface of the macroporous copolymer Amberlite XAD-2 to give about 20% surface coverage. Sorption, onto both XAD-2 and XAD-OXINE, of the magnesium-containing species that are present in solutions of magnesium ion and picolinic acid was studied by the column equilibration/atomic absorption technique at solution pH of 6.00 and 7.50 and ionic strength of 0.25. By using solutions containing various amounts of added magnesium and picolinic acid, in which the ratio of the two metal–ligand complex species, MgP+/MgP2, varied greatly (P− is the ligand picolinate), it was shown that neither the species Mg2+ nor the species MgP+ sorb to an appreciable extent onto the parent polymer XAD-2, but the neutral species MgP2 sorbs strongly and exhibits a linear isotherm. Then, by measuring the sorption isotherm of the species Mg2+ on XAD-OXINE in the absence of picolinic acid, by measuring the overall sorption of magnesium-containing species on XAD-OXINE in the presence of picolinic acid, and by assuming that the sorption of the species MgP2 onto XAD-OXINE was about the same as it was on XAD-2, it was possible to show that the species MgP+ sorbs strongly onto XAD-OXINE, and exhibits linear sorption isotherms. Thus, XAD-OXINE sorbs all three species Mg2+, MgP+, and MgP2. Keywords: Amberlite XAD-2, immobilized oxine, magnesium ion.

Abstract.The published data on equilibrium moisture content vs. equilibrium relative humidity (EMC-ERH) for wood pellet do not cover the range of temperature and relative humidity to which a pellet is exposed to during its storage and handling. A few published EMC-ERH relations covering a wider range of temperatures and relative humidity are available for solid wood (lumber) and wood chips. The question is whether the data for solid wood is applicable to wood pellets. For this research, we examined the sorption isotherms of wood pellets and solid wood. The analysis shows that EMC for solid wood is higher than the EMC for wood pellet for a relative humidity larger than 30%. The slope of EMC-ERH isotherm for solid wood in the range of 30%-70% is slightly steeper than the slope of isotherm for wood pellet, indicating the pellet’s EMC is less sensitive to ERH when compared to EMC-ERH for solid wood. Keywords: EMC, ERH, Densified biomass, Equilibrium moisture content, Equilibrium relative humidity, Solid wood, Wood pellets.

Abstract. Understanding of moisture sorption isotherms (MSI) is critical for predicting the stability of wood during handling, transport, and storage. The aim of this study was to evaluate the adsorption and desorption isotherm characteristics of high-pressure (HP) treated paulownia wood and to identify the best-fitting model to describe its sorption behavior. The equilibrium moisture contents (EMCs) of HP-treated paulownia wood were obtained using a static gravimetric method under different storage conditions: three temperatures (20°C, 30°C, and 40°C) and five water activity (aw) levels (0.32 to 0.95). Results showed that HP parameters did not significantly affect the MSI trend of treated groups. Eight modified models (modified Chung-Pfost, modified Henderson, modified Oswin, modified Halsey, Chen-Clayton, Guggenheim-Anderson-de Boer (GAB), simply modified GAB, and Peleg) were fitted to the experimental data. The Chen-Clayton model (temperature-dependent) produced randomized residuals and the best prediction performance for both adsorption and desorption among all models. Net isosteric heat of adsorption and desorption decreased from 7.55 to 4.84 kJ mol-1 and from 18.1 to 12.2 kJ mol-1, respectively, with an increase in EMC from 7.5% to 10%. The isosteric temperature (Tß) was 352 K for adsorption and 335 K for desorption, between which all the adsorption and desorption reactions proceeded at the same rate. All thermodynamic functions were adequately characterized by a power law model. Keywords: Equilibrium moisture content, High-pressure treatment, Modeling, Moisture sorption isotherm, Paulownia wood, Temperature, Thermodynamic analysis.

AbstractArsenic (As) has the potential to negatively affect soils and groundwater quality, and cause several public health challenges. It is usually concentrated and released during metal mining of ores that contains arsenic-bearing minerals. Remediation strategies are in place to avoid pollution. In this study, bauxite from Awaso, Ghana, was characterised, and its ability to sequester As was tested under varying conditions of temperature, Eh and pH. The study showed that the best particle size in the range utilised was 80% passing 2 mm as it allowed easy percolation, and As removal was about 95%. The reaction is a favourable pseudo-second order reaction that is spontaneous and thermodynamically stable and compares well with the Langmuir Sorption Isotherm. About 80% sorption was achieved within 20 minutes of contact with low desorption rate of less than 1.8%. The study thus concludes that bauxite is a good filter for arsenic. Keywords: Arsenic, Bauxite, Filter, Sorption, Isotherm

This study reports the results of the elucidation of the sorption-desorption mechanism of Zn(II) and Cd(II) on chitin through the determination of capacity, energy, and rate constant of sorption as well as the investigation of their desorption properties in NaCl and Na2EDTA solutions. The chitin was isolated through deproteination followed by demineralization of crab (Portunus pelagicus Linn) shell using NaOH solutions. The sorption of both metal ions followed the Langmuir isotherm model, resulting the sorption capacities of 3.2 x 10-4 and 2.8 x 10-4 mol g-1 for Zn(II) and Cd(II), respectively, and sorption energies of 15.1 kJ mol-1 for Zn(II) and 17.9 kJ mol-1 for Cd(II). It was also observed that Zn(II) was sorbed slightly faster than Cd(II) with first order sorption rate constants of 2.82 x 10-3 min-1 for Zn(II) and 2.61 x 10-3 min-1 for Cd(II). The result of the desorption experiment showed that Cd(II) and especially Zn(II) could only be exchanged by Na(I) after desorbing those metal ions by strong chelating agent of EDTA2-. The easier desorption of Zn(II) than Cd(II) by EDTA2- must be attributed by the smaller sorption energy of Zn(II) and by harder acid property of Zn(II) than Cd(II) as EDTA2- contained hard electron donor elements. Keywords: sorption, desorption, chitin, Zn(II), Cd(II)

The objective of this study was to investigate the biosorption of Cu (II) and Ni (II) ions from aqueous solution by calcium alginate beads. The effects of solution pH, contact time and initial metal ion concentration were evaluated. The results showed that maximum Cu (II) removal (93.10%) occurred at pH of 9.0, contact time of 120 minutes and initial ion concentration of 10 mg/L while that of Ni (II) was 94.6%, which was achieved at pH of 8.0, contact time of 120 minutes and initial ion concentration of 10 mg/L. The equilibrium data fitted well to the Langmuir Isotherm indicating that the process is a monolayer adsorption. The coefficients of determination, R2, values for the Langmuir Isotherm were 0.9799 and 0.9822 respectively for Cu (II) and Ni (II) ions. The values of the maximum biosorption capacity, Qo, were 10.79 and 6.25 mgg-1 respectively. The kinetic data also revealed that the sorption process could best be described by the pseudo – second order kinetic model. The R2 values for the pseudo – second order kinetic plots for Cu (II) and Ni (II) were 0.9988 and 0.9969 respectively. These values were higher than those for the pseudo – first order plots. The values of the biosorption capacity qe obtained from the pseudo – second order plots were very close to the experimental values of qe indicating that the biosorption process follows the second order kinetics. This study has therefore shown that calcium alginate beads can be used for the removal of Cu (II) and Ni (II) ions from wastewaters. Keywords: Keywords: Adsorption, Calcium alginate, Isotherm, Langmuir, Pseudo- first order, Pseudo-second order

Abstract. In Nigeria, most of the brewery industries discharge their wastewater directly into the water body without adequate treatment. Wastewater from the brewery processes contains some heavy metals which in this study, attempts were made to reduce their concentration using activated carbon. Batch studies were carried out using date palm seeds activated carbon in the removal of lead (Pb), chromium (Cr), and cadmium (Cd) ion from industrial wastewater under conditions such as contact time and adsorbent dosage. Pb and Cr concentration in the wastewater were brought within World Health Organization (WHO) maximum limit of 0.01 and 0.05 mg/L for water, respectively, at 60 min of contact time across all the considered adsorbent doses of 10×103, 20×103, 30×103, and 40×103 mg/L while Cd concentration was brought within the WHO maximum limit of 0.003 mg/L at 80 min of contact time using 30×103 mg/L of the adsorbent. The sorption data fitted well into Langmuir isotherm which was very suitable for describing the sorption equilibrium with high regression values (>0.98). This study showed that date palm seeds activated carbon is suitable for the adsorption of Pb, Cr, and Cd, and as such could be used as a cost effective adsorbent in the treatment of brewery and other industrial wastewater. Keywords: Activated carbon, Adsorbent dose, Adsorption, Brewery wastewater, Contact time, Date palm seeds, Heavy metals.

HighlightsGlyphosate sorption using bio-based adsorbents was investigated in this study.Biochars showed poor sorption of glyphosate in comparison to the activated carbons.Total pore volume of bio-based adsorbents played a key role in sorption of glyphosate.Abstract. This study examined the glyphosate sorption ability of different bio-based materials, including biochars and activated carbons synthesized from Douglas fir, kraft lignin, and mixed wood pellets. All the biochars showed poor sorption of glyphosate in comparison to the activated carbons derived from biochars and the commercial powdered activated carbon (PAC) investigated in this study. All the biochar-derived activated carbons produced in the laboratory showed comparable glyphosate sorption in comparison to PAC. The activated carbons synthesized from Douglas fir biomass showed the highest glyphosate sorption among the activated carbons investigated. Langmuir and Freundlich isotherms were used to describe the adsorption kinetics of glyphosate onto activated carbons. Adsorption capacity showed better correlation (R2 = 0.989) with the total pore volume in comparison to the Brunauer-Emmett-Teller (BET) surface area and microporosity. The results of batch desorption tests indicated that the biochar-derived activated carbons and PAC showed >60% glyphosate retention. The results of this study indicate that activated carbons derived from biochars produced with thermochemical conversion processes could effectively sorb herbicide such as glyphosate similarly to commercial activated carbon and could be used either as a replacement for PAC in water treatment plants or for on-site treatment of agricultural runoff water. Keywords: Adsorption, Desorption, Herbicides, Kraft lignin, Model isotherms, Pore volume.

Abstract. This study focuses on the modeling of sorption characteristics of three varieties of soybeans (Akras R2, Lono R2, and Podaga R2). Three pretreatments related to post-harvest conditions were tested on the soybean varieties: (1) freshly harvested soybeans, (2) soybeans subjected to three drying and wetting cycles, and (3) soybeans subjected to three freezing and thawing cycles. The adsorption and desorption experiments were conducted at 5°C, 10°C, 15°C, 20°C, 25°C, and 30°C using a dynamic equilibrium relative humidity (ERH) apparatus. Equilibrium moisture content (EMC) and the corresponding ERH were measured. The parameters calculated for the modified Halsey equation are applicable for storage temperatures above 10°C in the relative humidity (RH) ranges of 10% to 80% for desorption and 30% to 80% for adsorption. No significant differences were found in sorption isotherms among the soybean varieties. However, the soybean varieties responded differently to the different pretreatments (i.e., drying/wetting and freezing/thawing cycles). The adsorption isotherms of Akras and Lono soybeans showed significant differences at 10°C to 30°C when subjected to drying and wetting cycles, while Akras and Podaga soybeans showed significant differences in the same temperature range when subjected to freezing and thawing cycles. The effect of drying and wetting cycles on the desorption isotherms was found only for Akras soybeans at 10°C and 15°C below 63% and 71% RH, respectively, and for Lono soybeans at 25°C and 30°C above 69% RH for both temperatures. In general, the effect of both pretreatments on the sorption isotherms of soybeans was a reduction in EMC of up to 20%, when compared to fresh samples at selected storage temperatures. The findings of this study serve as a primary tool for developing a lookup table for safe storage guidelines for soybeans. Keywords: Equilibrium moisture content, Equilibrium relative humidity, Halsey equation, Oswin equation, Soybeans.

Abstract. Using the right equilibrium moisture content (EMC) relationship is critical for implementing successful aeration strategies and for determining the safe storage moisture content of grains and oilseeds. The oil content of sunflower seeds substantially affects the moisture equilibrium relationship, implying that a specific set of model parameters for each oil content range should be obtained. To overcome this practical limitation, the Enhanced Halsey model was developed incorporating a new parameter (D) to characterize the effect of oil content on the original Modified Halsey model. The constants A, B, C, and D of the model were obtained for a wide range of temperatures, moisture and oil contents. The simplicity of the Enhanced Halsey model and the possibility of adapting EMC as a function of oil content make the Enhanced Halsey model valuable for engineering applications (e.g., aeration controllers) and for predicting the safe storage moisture content of seeds with different oil contents, such as sunflower. Keywords: Composition, Grain, Isotherms, Oilseed, Relative humidity, Sorption, Storage quality.

Adsorptive removal of chromium ion in aqueous medium using activated sweet potato peel (SPP) was studied in a laboratory-scale fixed bed column. Specifically, the effect of process parameters such as bed depth, flowrate and chromium ion concentration in aqueous solution, on the adsorption efficiency of the acid modified sweet potato peel was examined. Column adsorption analysis showed that at the flow rate of 0.5 cm3/min, bed height of 6 cm and column influent concentration of 30 mg/dm3, the optimum chromium (VI) ion removal of 87.5% was attained with the equilibrium adsorption capacity of 2.4548 mg/g. Continuous adsorption models such as Yoon-Nelson, Adam-Bohart and the Bed-Depth Service Time (BDST) model, were used to analyse the experimental data and based on correlation coefficient, BDST model best aligned with the obtained experimental data with correlation coefficient, R2, value of 96.43%. The bed capacity, No, and the rate constant, Ka, were calculated as 4.259 mg/dm3 and 0.01045 L/mgmin respectively at optimum column conditions. Results confirmed that acid modified SPP can be used to remove or reduce concentrations of Cr (VI) ions to allowable limits before disposal into water bodies. Keywords: Continuous sorption, chromium ions, sweet potato peel, kinetic isotherms, breakthrough curves

Abstract. A dynamic, process-based model of surface water acidification, MAGIC7, has been applied to four representative alpine lakes in the Tatra Mountains (Slovakia and Poland). The model was calibrated for a set of 12 to 22-year experimental records of lake water composition. Surface water and soil chemistry were reconstructed from 1860 to 2002 and forecast to 2050 based on the reduction in sulphur and nitrogen emissions presupposed by the Gothenburg Protocol. Relatively small changes in the soil C:N ratios were not sufficient to simulate observed changes in NO3‾ concentrations, so an alternative empirical approach of changes in terrestrial N uptake was applied. Measured sulphate sorption isotherms did not allow calibration of the pattern of sulphate response in the lakes, indicating that other mechanisms of S release were also important. The lake water chemistry exhibited significant changes during both the acidification advance (1860 to 1980s) and retreat (1980s to 2010). An increase in lake water concentrations of strong acid anions (SAA; 104–149 μeq l–1) was balanced by a decline in HCO3‾ (13–62 μeq l–1) and an increase in base cations (BC; 42–72 μeq l–1), H+ (0-18 μeq l–1), and Alin+ (0–26 μeq l–1). The carbonate buffering system was depleted in three lakes. In contrast, lake water concentrations of SAA, BC, H+, and Alin+ decreased by 57–82, 28–42, 0–11, and 0–22 μeq l–1, respectively, the carbonate buffering system was re-established, and HCO3‾ increased by 1–21 μeq l–1 during the chemical reversal from atmospheric acidification (by 2000). The MAGIC7 model forecasts a slight continuation in this reversal for the next decade and new steady-state conditions thereafter. Gran alkalinity should come back to 1950s levels (0–71 μeq l–1) in all lakes after 2010. Partial recovery of the soil pool of exchangeable base cations can be expected in one catchment, while only conservation of the current conditions is predicted for three lakes. Even though the pre-industrial alkalinity values of 16–80 μeq l–1 will not be reached due to the insufficient recovery of soil quality, the ongoing chemical improvement of water should be sufficient for biological recovery of most alpine lakes in the Tatra Mountains. Keywords: MAGIC, atmospheric deposition, sulphate, nitrate, base cations, aluminium, alkalinity, pH

O fósforo (P) é o nutriente mais limitante ao cultivo nos solos tropicais, que, geralmente, apresentam alta capacidade de adsorção de P. Alguns atributos químicos e físicos do solo como o teor de argila, pH, CTC efetiva e matéria orgânica influenciam na dinâmica de adsorção. O objetivo deste estudo foi avaliar o processo de adsorção do fósforo em um Latossolo Vermelho Amarelo (LVA) e um Neossolo Quartzarênico (RQ) da região de transição Cerrado-Amazônia, e avaliar os atributos dos solos que influenciam na dinâmica de adsorção do P. Os ensaios de sorção foram realizados pelo método “Batch” ou em batelada e à partir dos dados obtidos foram construídas curvas obtendo a equação linearizada de Langmuir, com as quais foram determinados os valores de capacidade máxima de adsorção de P (CMAP), a constante relacionada com a energia de ligação (KL) e o fator capacidade de P máximo (FCPmáx). Houve diferença na CMAP, KL e FCPmáx dos solos estudados, sendo que os maiores valores foram encontrados no LVA, devido principalmente ao maior teor de argila em relação ao RQ. A matéria orgânica foi um dos poucos atributos que tiveram correlação negativa com os atributos de adsorção, ressaltando sua importância no manejo para aumentar a eficiência da adubação fosfatada. Palavras-chave: Latossolo Vermelho Amarelo; Neossolo Quartzarênico; Isotermas de adsorção. Phosphorus adsorption in soils of tropical regions ABSTRACT: Phosphorus (P) is the most limiting nutrient for cultivation in tropical soils, as they generally have high P adsorption capacity. Some chemical and physical attributes of soil such as clay content, pH, effective cation exchange capacity (ECEC) and organic matter influence the adsorption dynamics. The objective of this study was to evaluate the behaviour of the phosphorus adsorption process in a Red-Yellow Latosol and a Quartzarenic Neosol from the Cerrado-Amazon transition region, and to evaluate the soil attributes that influence the adsorption dynamics of the soil of the phosphorus. Sorption tests were performed using the “Bach” method, from the Langmuir linearized equation, the maximum P adsorption capacity (MPAC), the constant with the binding energy (KB) and the maximum capacity factor (PCFmax) were selected. There was a difference in MPAC, KB and PCFmax of the studied soils, and the highest values ​​were found in the Red-Yellow Oxisol, mainly due to the higher clay content in relation to theTypic Quartzipisamment. Organic matter was one of the few attributes that had a negative correlation with the adsorption attributes, highlighting (emphasizing) it’s importance in (soil) management to increase the efficiency of phosphate fertilization. Keywords: Red-Yellow Latosol; Quartzarenic Neosol; adsorption isotherms.

The paper aims to present research results obtained at the study of equilibrium and kinetics of U(VI)aq sorption on in situ generated Fe2O3 x nH2O from model solutions. The studied systems represent U(VI) solutions with CU(VI) = 5-30 mg·L-1 for which maximum U(VI) removal efficiencies (%RU(VI) = 95.98) on in situ generated Fe2O3’”nH2O were obtained in the following working conditions: pH = 8.75, tcontact = 30 min, : =1:75 and stirring rate 250 RPM. The Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models were used to study U(VI) sorption equilibrium. Langmuir isotherm with the correlation coefficient R2 (0.9808) suggests that it involves physical interactions. Freundlich (R2 = 0.8349) and Temkin (R2 = 0.8715) models describe well the sorption process suggesting that there also exists a chemical component, complexing and/or co-precipitation. The kinetic modelling according to the pseudo-first and pseudo-second order models, respectively has demonstrated that the U(VI) sorption equilibrium follows the pseudo-second order equation suggesting a chemical component of the process. Keywords: uranium, sorption/precipitate flotation, adsorption isotherms modelling, kinetics

The presence of heavy metals in surface water, which is common in mining area pose harmful effect to human health and the environment. Recently, cocopeat has been studied as an effective sorbent material for removing heavy metals from wastewater. In this study, kinetic was done by analyzing the distribution of the heavy metal in sorbent material and liquid phase after mixing 50 mg/L solution of lead (Pb2+) and zinc (Zn2+)in single solute system with 0.1 g of coco-peat, that were consequently shaken at 5, 10, 15, 30, 60, 120, 180 and 360 minutes. To determine the equilibrium adsorption isotherm for each heavy metal, the solutions of 10, 20, 30,40 and 50 mg/L of Pb2+ and Zn2+ were prepared separately. Two different pH levels (natural pH, and pH 4) were setto describe the sorption behavior of Pb2+ and Zn2+ of each heavy metal.Using data from batch experiments, appropriate kinetic (time dependency) and equilibrium (isotherm) models were fitted on the sorbent material and liquid phase concentrations to determine adsorption parameters. Pseudo second-order kinetic model fitted well to the kinetic data due to chemisorption that happened during experiments. In other hand, Langmuir model fitted well to the equilibrium, this indicates that the sorption of lead and zinc on coco peat is monolayer and that the adsorbent’s surface is homogenous. The increase of heavy metals adsorption following the increase of pH might be due to negative charge of coco peat surface. Pb2+ adsorbed more than Zn2+ because ion with high hydration enthalpy will have smaller amount of ion adsorbed. The hydration enthalpies for Pb2+ and Zn2+ are 23 kJ/kg and 113 kJ/kg, receptively. Considering all the factors that we have discussed, cocopeat has high efficiency to remove the heavy metals from wastewater. Keywords: Coco-peat, adsorption, batch experiment, kinetic, equilibrium.

O babaçu (Orbignyamartiana), palmeira abundante no Nordeste brasileiro, apresenta grande potencial econômico nas regiões em que é produzida. Seu fruto é dividido em quatro partes: epicarpo, mesocarpo, endocarpo e amêndoa. Todas estas partes possuem aplicações industriais. Sua farinha, obti- da a partir do mesocarpo, tem tido crescente aceitação no setor alimentício, sem, no entanto, apresentar na literatura muitos estudos a respeito de suas isotermas de sorção, importantes para predizer a estabili- dade química e física em função do conteúdo de água e o teor de umidade que impedem o crescimento dos microrganismos. Assim, os objetivos deste trabalho foram estudar o comportamento das isotermas de adsorção da farinha de babaçu comercial às temperaturas de 25 e 40°C, selecionar o modelo que melhor se ajusta aos dados experimentais e estimar o calor isostérico de sorção. As isotermas foram construídas pelo método gravimétrico, que consiste na medição do ganho de massa da amostra quando colocada em contato com soluções salinas que proporcionaram diferentes umidades relativas nas temperaturas de 25 e 40°C. Para os ensaios de adsorção, foram empregadas amostras de farinhas de babaçu previamente secas. A seleção do melhor modelo foi feita com base no coeficiente de determinação e no qui-quadrado. Todos os modelos testados apresentaram bons ajustes nas temperaturas estudadas, sendo que a 25 °C os modelos de Henderson e Peleg apresentaram os melhores ajustes, enquanto que a 40°C, o de GAB foi o mais adequado Os calores isostéricos de adsorção apresentaram comportamento inversamente proporcional à umidade de equilíbrio. Palavras-chave: Farinha de Babaçu. Isoterma de sorção. Calor isostérico. DETERMINATION OF THE ADSORPTION ISOTHERM AND SORPTION HEAT OF COMMERCIAL BABASSU FLOURABSTRACT: The babassu (Orbignyamartiana), abundant palm in the Brazilian Northeast, has great social, economic and cultural potential in the regions where it is produced. Its fruit is divided into four parts: epi- carp, mesocarp, endocarp, and almond. All these parties have industrial applications. His flour, obtained from the mesocarp, has had increasing acceptance in the food industry, without however, presenting many studies in the literature about their sorption isotherms that are important for predicting the chemical and physical stability as a function of water content and moisture content that prevents the growth of microor- ganisms. The objectives of this work were to study the behavior of the adsorption isotherms of commercial babassu flour at temperatures of 25 and 40 ° C, select the model that best fits the experimental data and estimate the isosteric heat of sorption. The isotherms were constructed by the gravimetric method, which consists in measuring the mass gain of the sample when placed in contact with saline solutions that pro- vided different relative humidities at 25 and 40 ° C. For the adsorption experiments, samples of babassu flour were dried previously. The selection of the best model was based on the coefficient of determination and chi -square test. All tested models showed good fits in the temperatures studied. For the adsorption at 25 ° C Henderson and Peleg models showed a better fit, while at 40 ° C the GAB was the better model. The isosteric heats of adsorption presented inversely proportional to the equilibrium moisture behavior. KEYWORDS: Babassu flour. Sorption isotherm. Isosteric heat. DETERMINACIÓN DE LAS ISOTERMAS DE ADSORCIÓN Y DEL CALOR DE SORCIÓN DE HARINA DE “BABAÇU” COMERCIALRESUMEN: El “babaçú” (Orbignyamartiana), una “palmera” abundante en el nordeste del Brasil, tiene un gran potencial social, económico y cultural en las regiones donde se produce. Su fruto se divide en cuatro partes: epicarpio, mesocarpio, endocarpio y almendras. Todas estas partes tienen aplicaciones industria- les. Su harina de mesocarpio ha tenido creciente aceptación en la industria alimenticia, pero no hay mu- chos estudios en la literatura acerca de sus isotermas de sorción que son importantes para la predicción de la estabilidad química y física como una función del contenido de agua y contenido de humedad que evita el crecimiento de microorganismos. Los objetivos de este trabajo fue estudiar el comportamiento de las isotermas de adsorción de harina de “babaçú” comercial a temperaturas de 25 y 40 °C, seleccionar el modelo que mejor se ajusta a los datos experimentales y estimar el calor isostérico de sorción. Las isoter- mas fueron construidas por el método gravimétrico, que consiste en medir la gaño de masa de la muestra cuando está en contacto con soluciones salinas que proporcionaron diferentes humedades relativas a 25 y 40 °C. Para los experimentos de adsorción se utilizaron muestras de harina de “babaçú” previamente seca. La selección del mejor modelo se basa en el coeficiente de determinación y de “qui-quadrado”. To- dos los modelos utilizados muestran buenos ajustes en las temperaturas evaluadas. Para la adsorción a25 °C modelos de Henderson y Peleg, presentaron los mejores ajustes, mientras que a 40 °C modelo de GAB fue el más adecuado. Los calores isostéricos de adsorción mostraron inversamente proporcional al comportamiento de la humedad de equilíbrio.PALABRAS CLAVE: Harina de “babaçú”. Isoterma de sorción. Calor isotérico.