Polyethylenimine-Functionalized Corn Bract, an Agricultural Waste Material, for Efficient Removal and Recovery of Cr(VI) from Aqueous Solution

In this study, polyethylenimine-functionalized corn bract (PEI–CB) was first used to remove aqueous Cr(VI) via the “waste control by waste” concept. The results indicated that PEI–CB had an excellent performance for Cr(VI) removal and the maximum removal capacity was 438 mg/g. The adsorption of Cr(VI) was fitted to the Langmuir model, and kinetics of uptake could be described by a pseudo-second-order rate model well. Amine was proven to be the active center for Cr(VI) adsorption and partial reduction to Cr(III), while removal efficiency was enhanced at a lower pH value and higher temperature. Besides, nanosized Cr2O3 with a high purity was obtained by simple calcination of a Cr(VI)-laden adsorbent. Hence, this study provided a novel strategy for Cr(VI) wastewater remediation and pure Cr2O3 recovery. Prepared PEI–CB was then a promising alternative of low cost for replacement of the current expensive absorbent of removing Cr(VI) from wastewater from the view of sustainability.