Biosorption of Fe (II) from aqueous solution by brewing waste: equilibrium and kinetic studies

Abstract

The physicochemical analysis of surface water of Mooi and Vaal rivers network indicated that the concentration of iron was far above the required limit by the South Africa water regulation. In this study, brewing waste was used as biosorbent for the removal of iron from synthetic solution to develop strategies for remediation of Mooi and Vaal rivers network pollution. X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM), were used for the characterisation of the sorbent. BET was calculated using nitrogen and carbon dioxide adsorption data. Batch tests were conducted to evaluate the influence of sorbent concentration and pre-treatment on the iron removal. The brewing waste showed a removal percentage of 93% with residual iron concentration of 2.6 mg L−1 while the acid pre-treated brewing waste indicated 98% removal and 0.6 mg L−1 residual iron concentration. The adsorption equilibrium, based on correlation coefficients, was best described by Dubinin-Radushkevich and Langmuir, for raw and acid pre-treated brewing waste, respectively. The kinetic data were best described by pseudo-first-order with correlation coefficients (R2) of 0.9898 and 0.9968 for both raw and acid pre-treated brewing waste, respectively. The mass transfer coefficient indicates the intraparticle diffusion controls the rate of sorption of iron in this study