A functionalized activated carbon adsorbent prepared from waste amidoxime resin modified with H₃PO₄ and ZnCl₂ and its excellent adsorption of Cr (VI)

With the application of resins in various fields, a large number of waste resins that are difficult to treat have been produced. The wastewater containing chromium produced by industry has seriously polluted the soil and groundwater environment, thus endangering human health. Therefore, in this paper, a novel functionalized mesoporous adsorbent PPR-Z for adsorption Cr(VI), was prepared from waste amidoxime resin. The waste amidoxime resin was firstly modified with H₃PO₄ and ZnCl₂, and subsequently was carbonized by slow thermal decomposition. The static adsorption of PPR-Z conforms to the pseudo second order kinetic model and Langmuir isotherm, which verifies that the adsorption of Cr(VI) by PPR-Z is mainly chemical adsorption and belongs to single-layer adsorption. The saturated adsorption capacity of the adsorbent for Cr(VI) can reach 255.86 mg/g. The adsorbent could effectively reduce Cr(VI) to Cr(III) and reduce the toxicity of Cr(VI) during adsorption. PPR-Z exhibited selectivity for Cr(VI) in electroplating wastewater. The main adsorption mechanisms includes chemical reduction of Cr(VI) into Cr(III), electrostatic interaction and coordination interaction. Preparation of PPR-Z not only solves the problem of waste resin treatment, but also effectively controls the pollution of chromium, and realizing the concept of "treating waste with waste".