High-capacity adsorption of dissolved hexavalent chromium using amine-functionalized magnetic corn stalk composites

• The amine-functionalized magnetic bio-sorbent was prepared for Cr(VI) uptake.
• The physicochemical characteristics were measured by XRD, SEM, FTIR, VSM and XPS.
• The optimum pH for high removal efficiency of Cr(VI) was found at 3.0(±0.1).
• The adsorption followed the pseudo second order model and Langmuir model.
• The adsorption process was spontaneous and endothermic.

Easily separable amine-functionalized magnetic corn stalk composites (AF-MCS) were employed for effective adsorption and reduction of toxic hexavalent chromium [Cr(VI)] to nontoxic Cr(III). The saturated magnetization of AF-MCS reached 6.2 emu/g, and as a result, it could be separated from aqueous solution by a magnetic process for its superparamagnetism. The studies of various factors influencing the sorption behavior indicated that the optimum AF-MCS dosage for Cr(VI) adsorption was 1 g/L, and the maximum adsorption capacity was observed at pH 3.0. The chromium adsorption perfectly fitted the Langmuir isotherm model and pseudo second order kinetic model. Furthermore, characterization of AF-MCS was investigated by means of XRD, SEM, TEM, FT-IR, BET, VSM and XPS analysis to discuss the uptake mechanism. Basically, these results demonstrated that AF-MCS prepared in this work has shown its merit in effective removal of Cr(VI) and rapid separation from effluents simultaneously.

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