AbstractIn this study, we investigate the adsorption properties of hydrogen florid (HF) and sulfur trioxide (SO3) on the surface of platinum decorated graphene (PtG) using density functional theory. We found one optimized configuration for HF and two ones for SO3 upon adsorption on the surface of PtG. Our result show significant adsorption on PtG with calculated energy adsorption of −73.6 (−54.2 BSSE) kJ/mol for HF at its only position and −172.4 (−144.8 BSSE) and −62.7 (−53.7 BSSE) kJ/mol for SO3 at its two positions; P1 and P2, respectively), whereas there is weak physisorption of these analytes on pristine graphene (PG). Results of charge analyses reveled interesting net charge transfer; while the direction of charge is from HF to PtG, reverse direction is found for SO3 for its two configurations. To deep understand the concept of adsorption properties, we used orbital analyses including density of states for interaction of mentioned analytes on the surface of PtG. تفاصيل المقالة

In order to produce biodiesel from waste cooking oil and optimize its yield, a two-stage process of esterification/ transesterification has been used in this study. First, we used the acidic catalysts H2SO4 in order to diminish the content of free fatty acid (FFA) in oil that caused reducing the oil acidity from 6.1% to 0.57% through esterification. Then, the biodiesel was produced by transesterification of resulted oil using heterogeneous CaO nanoparticles as catalyst. At each stage, the best possible conditions have been determined by applying Taguchi methodology for each major variable, including time, temperature, alcohol/oil molar ratio, and the amount of catalyst. The optimum conditions for esterification are achieved at 80°C temperature, 120 minutes time, 6:1 molar ratio of alcohol/oil, and H2SO4 content of 1% (w/w oil). The optimum condition for transesterification were found in 100 °C temperature, 90 minutes time, 8:1 molar ratio of alcohol/oil, and 3% (w/w oil) of CaO nanoparticles as catalyst. After applying full optimization of these two stages, the yield of the produced biodiesel has achieved 96.4%. تفاصيل المقالة

Zeolites are widely used in waste water and contaminated water refinement due to their great adsorption properties. However, Clinoptilolite (as one type of Zeolites) has a relatively low adsorption capacity at least for arsenic ions. Therefore, in order to increase the adsorption capacity, natural Clinoptilolite was modified with sulfuric acid and various tests were then conducted to determine the best conditions for obtaining the maximum capacity of adsorption. The results showed that parameters such as arsenic initial concentration, adsorbent's particles size, adsorbent dosage and solution pH affect the adsorption capacity. Arsenic maximum adsorption was obtained at pH 8. Furthermore, the maximum adsorption capacity was found to be in an adsorbent modified with 1 M acid. The contact time or the time of balance between the adsorbent and analyte was determined to be 240 min and the optimal amount of Zeolite to obtain was determined to be 480 g/L. The rate of arsenic removal under the optimal conditions is 27.69%. The modified Clinoptilolite capacity for arsenic adsorption increased with reducing the adsorbent particles size to 0.5 mm. Besides, among the three examined isotherms including the Langmuir, Freundlich and Dubinin-Radushkevich isotherms, the Langmuir and Freundlich models well described arsenic adsorption. Considering the more favorable adsorption efficiency of Clinoptilolite modified with sulfuric acid compared to natural Clinoptilolite, the modified one can be proposed as an appropriate and inexpensive adsorbent for arsenic removal in waste water refinement. تفاصيل المقالة

In this study, we used chicken eggshells as a low-cost catalyst for the esterification process of oil with a high fatty acid (FFA) content. We used the Taguchi method to optimize both esterification and transesterification steps. The waste chicken eggshell was calcinated at a temperature of 700°C for 4 hours to synthesize calcium oxide (CaO) active catalyst. The newly obtained catalyst was characterized by BET, TEM, and SEM. Then, this catalyst was employed for the transesterification of waste cooking oil. This work aimed to optimize critical parameters in preparing biodiesel production of waste cooking oil to maximize efficiency. Hence, the effects of reaction temperature, reaction time, catalyst amount, and methanol/ oil molar ratio on biodiesel yield were investigated and optimized through the Taguchi method. The maximum biodiesel efficiency is calculated to be 84% through transesterification at the following optimum conditions: the reaction temperature of 80°C, the reaction time of 1.5 h, the ratio of methanol/oil of 10:1, and the catalyst amount of 2% w/w. تفاصيل المقالة

Zeolites are widely used in wastewater and contaminated water refinement due to their great adsorption properties. However, Clinoptilolite (as one type of Zeolites) has a relatively low adsorption capacity at least for arsenic ions. Therefore, in order to increase the adsorption capacity, natural Clinoptilolite was modified with sulfuric acid and various tests were then conducted to determine the best conditions for obtaining the maximum capacity of adsorption. The results showed that parameters such as arsenic initial concentration, adsorbent's particles size, adsorbent dosage and solution pH affect the adsorption capacity. Arsenic maximum adsorption was obtained at pH 8. Furthermore, the maximum adsorption capacity was found to be in an adsorbent modified with 1 M acid. The contact time or the time of balance between the adsorbent and analyte was determined to be 240 min and the optimal amount of Zeolite to obtain was determined to be 480 g/L. The rate of arsenic removal under the optimal conditions is 27.69%. The modified Clinoptilolite capacity for arsenic adsorption increased with reducing the adsorbent particles size to 0.5 mm. Besides, among the three examined isotherms including the Langmuir, Freundlich and Dubinin-Radushkevich isotherms, the Langmuir and Freundlich models well described arsenic adsorption. Considering the more favorable adsorption efficiency of Clinoptilolite modified with sulfuric acid compared to natural Clinoptilolite, the modified one can be proposed as an appropriate and inexpensive adsorbent for arsenic removal in waste water refinement. تفاصيل المقالة