Abstract

Peanut shell adsorbents prepared by microwave pretreatment and maleic acid modification technology, were used to study the adsorption properties for Cr(VI). Meanwhile, structural characterisation, optimisation of adsorption conditions, isotherm adsorption and adsorption kinetics were critically investigated through experiments and detection techniques. XRD analysis showed that the crystallinity of peanut shells decreased significantly after microwave pretreatment. FTIR analysis testified that carboxyl groups and ester groups were successfully introduced into the structure of maleic acid modified peanut shells (MMPS). The results of orthogonal test and single factor experiments indicated that pH value had the greatest effect on Cr(VI) adsorption process. Moreover, the Cr(VI) adsorption rate (CrAR) reached the maximum value of 99.3 % under the optimal condition (MMPS dosage: 6g, adsorption time: 45 minutes, pH3, adsorption temperature: 80°C, Cr(VI) initial concentration: 30mg/L), which was much higher than that of unmodified peanut shells. The adsorption behaviour conformed to quasi-second-order kinetic equation and Langmuir isothermal adsorption model, and the adsorption was dominated by monolayer.