Bioremediation of Cu(II) contaminated water by Saccharum officinarum: effect of oxalic acid modification on equilibrium, kinetic and thermodynamic parameters

Abideen Idowu Adeogun,Kayode Olubunmi Akiode,Mopelola Abidemi Idowu,Sikiru Akiyeye Ahmed

doi:10.1186/s40643-016-0085-9

Abideen Idowu Adeogun, Kayode Olubunmi Akiode + Show 2 more

Open Access

https://doi.org/10.1186/s40643-016-0085-9

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Abstract

Copper is one of the heavy metals whose presence in aquatic environment in higher concentration poses a major threat to the environment. This is due to their toxic effects on the plants, animals and human health. Biosorption an innovative biotechnological technique with superior advantages was used for the remediation of Cu2+ from aqueous solution in this study. Biosorbent was prepared from raw (RAWB) and oxalic acid modified (OAMB) Saccharum officinarum. They were characterized by scanning electron microscopy (SEM/EDAX), fourier transform infrared (FTIR), and X-ray diffraction (XRD) for surface morphological study. Experimental data obtained from batch equilibrium studies were subjected to two-parameters [Freundlich, Langmuir, Tempkin and Dubinin–Radushkevich (D–R)] and three-parameter [Redlich–Peterson (R–P), Sips, Hill and Toth] isotherm models. Kinetic data were analysed with pseudo first-order, pseudo second-order, Elovich and Avrami kinetic models. The results of proximate analysis and characterization show that the oxalic acid modification affected the biosorbents content, surface modifications and the functional groups present. The experimental data from the equilibrium studies were best fitted to the isotherms with R 2 >0.9 for the OAMB and RAWB. The adsorption energies (E) from the D-R isotherms were found to be 0.36 and 0.06 kJ/mol for OAMB and RAWB respectively, which is indication of physisorption favoured processes. Pseudo second-order model best fitted the data with a coefficient of determination (R 2) of above 0.998 with an average relative and hybrid errors lower than 5 %. Intraparticulate diffusion model analysis showed that the adsorption process develops in two stages as rapid and slow phase. Changes in standard free energy (∆G°), enthalpy (∆H°) and entropy (∆S°) for the biosorption processes were estimated using the thermodynamic equilibrium model. The calculated thermodynamics parameters indicated that the process is spontaneous and endothermic in nature. This study revealed the feasibility of Cu2+ removal through biosorption processes using S. officinarum biomass as biosorbent. The improved surface morphology for increase biosorption by oxalic acid modification is also favourable. The biosorption process for the removal of the Cu2+ is pH dependent as the efficiency increased from 36.4 to 65.3 % for raw biomass while the OAMB has increase efficiency from 57.5 to 88.6 as the pH increases from 2 to 6.

Highlights

Copper is one of the heavy metals whose presence in aquatic environment in higher concentration poses a major threat to the environment
Presence of heavy metals in aquatic environment is a major threat to the environment
This is due to their toxic effects on the plants, animals and human health

Summary

Introduction

Copper is one of the heavy metals whose presence in aquatic environment in higher concentration poses a major threat to the environment. This is due to their toxic effects on the plants, animals and human health. Presence of heavy metals in aquatic environment is a major threat to the environment It is important to reduce the concentration of copper in industrial effluent to acceptable level before discharge into stream or other receiving water bodies

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