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The adsorption of Pb(II), Ni(II), and Cr(VI) ions ontoRhizoclonium tortuosum(RT) was investigated in a batch mode operation. The two parameter (Langmuir and Freundlich) and three parameter models (Redlich–Peterson and Sips isotherm model) were used to depict the adsorption of metal ions ontoR. tortuosum. Sips isotherm model was provided the best fit to the adsorption equilibrium data. The adsorption kinetics was described by the pseudo-first-order, pseudo-second-order, and Elovich kinetic models. The pseudo-second-order model provides the best fit. The maximum monolayer adsorption capacity of the RT were found to be 66.08, 85.09, and 61.45 mg/g for Pb(II), Ni(II), and Cr(VI), respectively. The thermodynamic results showed that the adsorption process was endothermic, feasible, and spontaneous in nature. The ability of RT to remove the Ni(II) ions in column studies was explored. The effect of bed height, flow rate, and initial Ni(II) ion concentration were studied. The dynamic behavior of the column performance was studied using the bed depth service time (BDST) and Thomas models. This research was also further extended to treat the nickel contaminated plating industrial wastewater. The results showed that the RT can be utilized as better biosorbent for the removal of metal ions from industrial wastewater. [ABSTRACT FROM PUBLISHER]

Heavy metal pollution is a major environmental concern in many countries. Among heavy metals, chromium is one of the widely used despite being one of the most toxic metal ions. The present study deals with the evaluation of Cr(VI) biosorption using a novel fresh water algaRhizoclonium hookeri.Batch experiments were conducted and the maximum adsorption capacity was evaluated as 67.3 mg/g at pH 2 at a biomass dosage of 1 g/L and 1,000 mg/L initial Cr(VI) concentration. Fourier transform infrared spectroscopy analysis of alga before and after biosorption revealed a shift in the carboxylic O–H stretching vibration from 3,401 to 3,373 cm−1, which confirmed its involvement in biosorption of Cr(VI) byR. hookeri. Surface morphology of alga was examined using the scanning electron microscopy, which indicated the highly porous nature of biomass. Non-linear regression analyses of isotherm models revealed that the three-parameter model isotherms (Redlich–Peterson and Sips) better described the experimental data compared with two-parameter model isotherms (Langmuir and Freundlich). An analysis of the kinetic models (pseudo-first-order, pseudo-second-order and Elovich models) indicated that the experimental data followed pseudo-second-order kinetics. The thermodynamic parameters such as free energy, enthalpy and entropy were calculated and Cr(VI) biosorption was found to be a spontaneous and endothermic process. [ABSTRACT FROM PUBLISHER]