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All the experiments were performed in batch mode for biosorption of Ni2+ ions from aqueous solution using Sargassum filipendula. All the process parameters of Ni2+ ions biosorption was optimized by using response surface methodology. The effect of four independent variables temperature (20°C-40°C), pH (3-6), initial Ni2+ ions concentration (50-150 mg/L) and biosorbent dosage (1.0-2.5 g/L) on biosorption of Ni2+ ions were studied. The biosorbent was characterized by using Fourier transform infrared spectroscopy, field emission electron microscopy, and energy dispersive X-ray spectroscopy. The optimized values of four variables were found as temperature of 41.5°C, initial Ni2+ ions concentration of 83.18 mg/L, biosorbent dosage of 1.97 g/L and pH of 5.4 which resulted in 68.45% removal of Ni2+ ions. The Redlich-Peterson isotherm model was found to be the best fitted to experimental data of Ni2+ ions biosorption with higher value of R2 and smaller value of Δq%. The best fitted kinetic model was noticed as pseudo-first-order kinetic model (R2 > 0.98) which shows that the rate limiting step was physisorption. Thermodynamic parameters (ΔG° = -0.097 to -4.060 kJ/mol, ΔH° = 79.175 J/mol, ΔS° = 0.270 J/mol K) of Ni2+ ions biosorption showed that the process was spontaneous, feasible and endothermic in nature. The biosorption and desorption efficiency were decreased up to 8.5% and 12%, respectively after four successive cycles. Therefore, the present study demonstrated that S. filipendula can be used as biosorbent for Ni2+ ions biosorption from the synthetic wastewater effectively and economically. [ABSTRACT FROM AUTHOR]

A thermodynamic equilibrium analysis on steam reforming process to utilize acetone-butanol-ethanol-water mixture obtained from biomass fermentation as biorenewable fuel has been performed to produce clean energy carrier H 2 via non-stoichiometric approach namely Gibbs free energy minimization method. The effect of process variables such as temperature (573–1473 K), pressure (1–10 atm), and steam/fuel molar feed ratio ( F ABE  = 5.5–12) have been investigated on equilibrium compositions of products, H 2 , CO, CO 2 , CH 4 and solid carbon. The best suitable conditions for maximization of desired product H 2 , suppression of CH 4 , and inhibition of solid carbon are 973 K, 1 atm, steam/fuel molar feed ratio = 12. Under these conditions, the maximum molar production of hydrogen is 8.35 with negligible formation of carbon and methane. Furthermore, the energy requirement per mol of H 2 (48.96 kJ), thermal efficiency (69.13%), exergy efficiency (55.09%), exergy destruction (85.36 kJ/mol), and generated entropy (0.29 kJ/mol.K) have been achieved at same operating conditions. [ABSTRACT FROM AUTHOR]

Thermodynamic equilibrium analysis has been adopted for oxidative steam reforming of butanol-ethanol mixture (B-E) as renewable source obtained from Acetone:Butanol:Ethanol (ABE) fermentation to produce H 2 by using Gibbs free energy minimization method. The effects of pressure (1–10 atm), temperature (573–1473 K), steam/fuel molar feed ratio ( f O1 = 9 and 12), O 2 /fuel molar feed ratio ( f O2 = 0–3), and B-E mixture compositions (50–90%B) on equilibrium compositions of H 2 , CO, CO 2 , CH 4 , and carbon are performed. The maximum H 2 yield (65.456% for f O2 = 0 and 58% for f O2 = 0.75) has been achieved at f O1 = 9, 90% B mixture, 1 atm, and 973 K. The yields of CO, CO 2 , and CH 4 with respect to maximum H 2 are 53.390%, 44.384%, and 2.225% for f O2 = 0, and 45.677%, 53.269%, and 1.053% for f O2 = 0.75, respectively. Energy required per mol of H 2 , thermal and exergy efficiencies for the process are also evaluated to utilize the potential of B–E mixture for H 2 production. [ABSTRACT FROM AUTHOR]

In this work, S. filipendula was used as biosorbent for biosorption of Cd 2+ ions from aqueous solution in batch mode. The effect of four independent variables, initial Cd 2+ ions concentration (50–100 mg/L), pH (3–6), biosorbent dosage (0.5-1.0 g/L), and temperature (25–35 °C) on Cd 2+ ions biosorption was examined. The central composite design under response surface methodology was used to design the experimental runs and to investigate the interaction effects of variables. The biosorbent was characterized by using FESEM-EDS and FTIR techniques. Optimum values of four variables were obtained as pH (5.7), temperature (34.2 °C), initial Cd 2+ ions concentration (50.8 mg/L), and biosorbent dosage (0.99 g/L) with 99.56% removal of Cd 2+ ions. The maximum biosorption capacity was found to be 103.5 mg/g at 35 °C. The experimental data of Cd 2+ ions biosorption were fitted to six kinetic models and six isotherm models. The biosorption of Cd 2+ ions followed the pseudo second order kinetics. It confirms that chemisorption was the rate limiting step. On the basis of R 2 value close to 1.0 and very small value of Δq%, Redlich-Peterson was found as best fitted model for Cd 2+ ions biosorption. Thermodynamic study shows that Cd 2+ ions biosorption process on S. filipendula was feasible, spontaneous and endothermic in nature. Desorption study shows that after four successive biosorption-desorption cycles 81.63% and 86% of desorption and biosorption efficiency were attained, respectively. Thus, the present study proved that S. filipendula can be used as biosorbent for Cd 2+ ions biosorption from aqueous solution effectively and economically. [ABSTRACT FROM AUTHOR]

Abstract: The thermodynamic analysis of steam reforming of methanol without and with fractional removal of H2 and CO2 in adsorption, membrane and adsorption-membrane hybrid reactor systems to produce fuel cell grade H2 with minimal carbon formation is investigated. The results indicate that the removal of undesired CO2 by CO2 adsorbent is most effective process for the production of high purity H2 than H2 removal by membrane. However, the membrane is effective only above 30% H2 removal. It is possible to obtain H2 yield of 2.6 with negligibly small amount of CO and carbon formation at T = 405 K, P = 1 atm, 80% removal of CO2 and 100% methanol conversion. Identical results are achieved even at lower temperature of 345 K in adsorption-membrane hybrid reactor system at 80% removal of H2 and CO2. Thus high grade H2 can be produced by single step process and further processing to reduce CO by PROX reactor is not necessary. [Copyright &y& Elsevier]