Moisture sorption ISOTHERMS are useful in predicting shelf-life stability and in calculating the variations of moisture content during drying, storage and packaging.In this study, the moisture sorption ISOTHERMS for pretreated seedless grape were determined using a static-gravimetric method at 40, 50, 60 and 70oC, and the effect of pretreatment solutions on the ISOTHERMS was investigated. In order to describe the sorption moisture ISOTHERMS, the BET, GAB and Halsey equations were tested to fit the experimental data by using non-linear regression analysis method. According to the modeling results, the GAB and Halsey equations gave the best fit for the samples. The net isosteric heat of desorption was calculated according to the obtained ISOTHERMS at different moisture content.

Moisture sorption ISOTHERMS are useful in food dehydration, storage and packaging. Because of the complex food composition, experimental measurements are necessary for prediction of the ISOTHERMS. Moisture sorption ISOTHERMS of Thompson seedless raisins were determined at 30, 40, 50, 60, 70 and 80oC, using the standard static gravimetric method developed by the European cooperation project COST 90. GAB, Smith, Oswin, Halsey, Henderson and Arcy-Watt equations were fitted to the experimental data. The experimental data were fitted well with D’Arcy-Watt equation at 30 to 70 and with GAB equation at 80ºC. The Isosteric heat of sorption was determined (4.79) kj/mol.

Potassium is one of the most important crop nutrients. Its plant uptake generally is more than other nutrients, except for nitrogen. Soluble and exchangeable form, of potassium are available to plants but there is also a considerable amount of potassium in clay interlayer’s and crystal structure of primary and secondary minerals which may became partially available to paints .Adsorption of potassium on soil colloidal surfaces is an important phenomenon which needs more research. To study this phenomenon three different soils series including Dehno (Torriorthent), Lavark (Haplargid) and Lordegan (Calcixeroll) were used. Each of the soil samples were treated with calcium chloride to allow their exchangeable sites to be saturated with calcium ion. Then the calcium-saturated soils equilibrated with increasing initial concentrations of potassium. The final concentration of potassium measured and adsorped potassium was calculated from the difference between initial and final potassuium concentrations. Langmuir, Frundlich, Temkin and Initial mass models were used to describe the adsoption data. Results revealed that all four models were relevant, but the degree of fitness to langmuir model was lower than those of Frundlich, Temkin and Initial mass models. Maximum adsorption (Xm) and adsorption afinity (K) of Langmuir model, capacity (n) and afinity (K) parameters of Frundlich, parameters of Temkin model (A and B)and reserve soil pool (RSP) parameter of initial mass model were also estimated.

Introduction: Laccases are potent enzymes that are capable of oxidizing various phenolic and non-phenolic compounds as well as resistant environmental pollutants. One of the most effective methods for improving their properties, such as increasing the stability of these enzymes and even increasing their activity, is the immobilization of laccases on different carriers. In the process of immobilization, the enzyme is bonded to a solid carrier which is insoluble in the reaction mixture. In this process, the movement of the enzyme in space is severely restricted, while its catalytic activity is still maintained. One of the carriers used to create recyclable biocatalyst systems is mineral. Minerals as inorganic carriers are inexpensive, abundant in nature, readily available, and also have high biocompatibility. The objective of the present study was to investigate the adsorption properties of Laccase enzyme from T. versicolor fungus on montmorillonite K10 and zeolite minerals using Langmuir, Freundlich, Temkin and Dubinin– Radushkevich ISOTHERMS. Materials and Methods: For this study, the pure laccase enzyme (> 10U mg-1), 2, 2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid (ABTS) substrate and montmorillonite K10 mineral (with a specific surface area of 220-270 m2/g and a cation exchange capacity (CEC) equal to 30 meq 100 g-1) were purchased from Sigma-Aldrich. Zeolite mineral was provided from a mine located in southeast Semnan province. Scanning electron microscopy (SEM) images of both minerals, CEC of zeolite with sodium acetate solution (pH=8. 2) and zeolite surface area were determined. X-ray Diffraction (XRD) and X-ray Fluorescence (XRF) analyzes of zeolite mineral were also done. In order to immobilize laccase on the minerals, 200 mg of both minerals were activated by shaking with 0. 5N HNO3 for 2 hours and a solution of 2% 3-aminopropyltriethoxylane in acetone. The activated minerals were treated by a 5% solution of glutaraldehyde in a 0. 1M sodium acetate buffer (pH=5) and were shaken for 24 hours with 0. 25-2. 0 mg of the laccase dissolved in the buffer. Langmuir, Freundlich, Temkin and Dubinin– Radushkevich ISOTHERMS were determined. The experiment was carried out at a constant temperature of 20° C. The results were analyzed using the MSTATC software and the means of the data were compared using Duncan’ s multiple range test. Results and Discussion: Based on the results, the zeolite type was clinoptilolite with a chemical formula of (Na, K, Ca)2. 5Al3(Al, Si)2Si13O36. 12H2O. Moreover, BET Surface Area, Langmuir Surface Area, t-Plot Micropore Area and t-Plot External Surface Area of zeolite were 40. 2712, 645. 4780, 3. 5188 and 36. 7524 m2/g, respectively. Laccase absorption on montmorillonite K10 showed the highest compliance first with the Dubinin– Radushkevich model (R2=0. 97) and then with the Langmuir adsorption isotherm model (R2=0. 96). Based on the D-R model, the theoretical monolayer sorption capacity (qm) and the constant of the sorption energy (ß ) of montmorillonite K10 were 3 mg/g and 0. 62 (×103 mol2/J2), respectively. According to theAccording to the According to theAccording to theAccording to theAccording to the According to theAccording to theAccording to the According to theAccording to the According to the Langmuir isotherm, there was probably a homogeneous distribution of active sites on the montmorillonite K10 mineral surface. On the other hand, laccase adsorption on zeolite showed the best compliance with the Freundlich model (R2=0. 87). Accordingly, sorption capacity (KF) of zeolite was 0. 05 mg/g (L/mg)1/n. The amount of n parameter as an indicator of the favorability of sorption process was 1. 49 demonstrating favorable absorption condition. The values of R2 obtained for Temkin isotherm model were, however, equal in both minerals (R2=0. 62 for montmorillonite K10 and R2 = 0. 61 for zeolite), and based on this model, the adsorption process was likely to be exothermic. According to the values of the equilibrium parameter (RL) of montmorillonite K10, the absorption was favorable. However, with increasing the initial concentration of laccase, the amount of RL approached zero indicating the laccase adsorption on the mineral is more favorable at higher initial concentrations of laccase. Based on % Removal parameter, the highest percentage of laccase adsorption on montmorillonite K10 and zeolite was related to concentrations of 250 and 125 mg/L, respectively, which showed a statistically significant difference with other concentrations. Conclusion: In general, laccase absorption on montmorillonite K10 showed the best fit with Dubinin– Radushkevich and Langmuir adsorption isotherm models. On the other hand, adsorption of laccase on zeolite mineral showed the best fit with Freundlich model. A higher degree of steric hindrance and conformational changes in the enzyme structure is likely to occur and subsequently, the catalytic efficiency of the enzyme complexes may decrease. Therefore, montmorillonite is more suited to be used as a carrier of laccase enzymes. However, complementary studies such as kinetic tests will help to make final decisions.

Herbicides are the main sources of soil and water pollution in paddy fields. Herbicides mobility to the surface and ground water is a major concern for human health and the environment. It is, therefore, necessary to investigate their fate and their interactions in natural ecosystems. To meet this purpose, field experiments were conducted to measure kinetic of thiobencarb dissipation in soil and water at Dashtnaz and Gharakhail agricultural research stations, Mazandaran. Also, its adsorption and desorption ISOTHERMS were determined in the soil samples. Thiobencarb concentration was monitored in soil and water (soil solution) via sampling during 315 and 60 days periods, respectively. Adsorption ISOTHERMS were carried out in equilibrium concentration ranged from 0 to 26 mg L-1. Desorption ISOTHERMS were measured in three equilibrium concentrations. The results of field experiments revealed that thiobencarb concentration is declined with time rapidly and reaches to a steady state after approximately 30 days. Experimental data were successfully described using the first order kinetics equation. Thiobencarb half-lives were determined 7 and 10 days in Dashtnaz and Gharakhail water, respectively.In both soils, thiobencarb concentration was strongly varied in early stages of soil sampling. The variations were reduced with discontinuation of irrigation. Similar to water, thiobencarb concentration in soils was gradually decreased with time, and arrived to a relatively constant concentration after about 110 days. First order kinetic equation described correctly the change in thiobencarb dissipation in soils. Thiobencarb half-lives were calculated 93 and 114 days for Dashtnaz and Gharakhail soils, respectively. Adsorption ISOTHERMS indicated that thiobencarb is strongly adsorbed on soil particles. Thiobencarb was desorbed very slowly and a strong hysteresis was observed between adsorption and desorption ISOTHERMS. Calculations revealed that thiobencarb is a persistence and non-leacher herbicide in the soil, due to its strong adsorption and high hydrophobic coefficient.

Background and objectives: Organic black grapes produced in Sardasht, West Azerbaijan province in Iran, contain resveratrol and flavonoids and high amount of melatonin with health benefits. The relationship between equilibrium moisture content and water activity at specified temperature is expressed as sorption ISOTHERMS. Moisture sorption ISOTHERMS are useful in predicting shelf-life stability and in calculating the variations of moisture content during drying, storage and packaging. In physical, chemical and microbial analysis of food, data obtained from adsorption and desorption curves are very important factors. Isotherm curves are able to predict the maximum moisture retention in foods during processing. In this study, the moisture sorption ISOTHERMS of grape pulp (Siah-Sardasht cultivar) were determined using a static-gravimetric method at 30, 40, 50, 60 and 70° C with water activities over the range of 0. 1-0. 9. Material and methods: Black grapes were obtained from a vineyard in Sardasht (West Azerbaijan province). Nine saturated salt solutions with degree of purity over 98% were used for generating a range of relative humidity. In order to describe the sorption moisture ISOTHERMS, the BET, GAB, Henderson, Darcy-watt and Halsey equations were tested to fit the experimental data by using non-linear regression analysis method. The models were sorted based on the least mean absolute percentage error (P<10%), RMSE and χ 2, and the highest R-square. The isosteric heat was determined using the Claussius– Clapeyron equation. Results: At all of temperature levels, moisture sorption isotherm curves of grape pulp were of type III, according to BET. Moisture sorption ISOTHERMS obtained in this work were affected by temperature, and the equilibrium moisture content generally increased with temperature elevation. According to the evaluated parameters in the tested models, P-value of Darcy-Watt model was consistently less than 10 % and its RMSE and χ 2 were lowest, indicating its reliability in predicting moisture sorption behavior of grape pulp. According to results of predicting moisture sorption in the grape pulp, it is concluded that BET and GAB models can be used only at high temperatures. The isosteric heat showed a marked increase with decreasing moisture content especially at the levels less than 0. 3% (d. b). Conclusion: At the studied range of water activity, the equilibrium moisture content values of grape pulp increased with increasing temperature, and no reverse temperature effect was observed in the range of water activities studied here. In spite of presence of sugar in the black grape pulp, no inversion phenomenon was observed in the relationship between equilibrium moisture content and water activity. Darcy-Watt was found to be the best model offering fits over the entire water activity and temperature range. The isosteric heat decreased with increasing the moisture content probably due to the fact that pulp water properties approached to that of free water.

The adsorption of lead (Pb) ions from an aqueous solution onto shrimp shell was evaluated in the present study. Several such important parameters influencing the adsorption of Pb (II) ions as initial pH, equilibrium time as well as different initial concentrations of Pb (II) ions was evaluated. The results indicated that the pseudosecond-order kinetic model could describe the kinetics of Pb adsorption by the adsorbent. With increase in Pb concentration from 100 to 1000 mgL-1, the level of Pb adsorbed by shrimp shell increased from 9 mg g-1 to 90.2 mg g-1. Increasing suspension pH from 4 to 7 enhanced the adsorption of Pb. Further increase in pH from 7 to 10 resulted in decrease in the adsorption of the metal ion. The average adsorption of Pb by the adsorbent at pHs 6 and 7 exceeded 95 percent. The Sips and Freundlich models well described the adsorption of Pb ISOTHERMS, data. Infrared spectrum analysis of adsorbent (prior to, and after adsorption of Pb) showed that the N atoms of the amine functional groups played a major role in shrimp shell for the adsorption of Pb.