Preparation of a sulfonated coal@ZVI@chitosan-acrylic acid composite and study of its removal of groundwater Cr(VI).

Abstract

In this research, a new composite adsorbent (SC@ZVI@CS-AA) was designed and synthesized, and its application for the removal of Cr(VI) in groundwater was investigated. The interaction between SC@ZVI@CS-AA and Cr(VI) conformed to a pseudo-second-order model, and the adsorption process was dominated by chemisorption. The effects of material ratios, pH, temperature, SC@ZVI@CS-AA dosage, and coexisting ions on the removal of Cr(VI) were investigated. The removal efficiency of Cr(VI) by SC@ZVI@CS-AA reached 95%, and the reaction was significantly inhibited when SO42- was present. Thermodynamically, the adsorption of Cr(VI) proceeded spontaneously above 35°C (ΔGθ < 0). According to scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectrometry, and synchronous thermal analysis, the removal mechanism of Cr(VI) by SC@ZVI@CS-AA was attributed to electrostatic attraction and reduction. In addition, SC@ZVI@CS-AA had good cyclic adsorption performance. Overall, the SC@ZVI@CS-AA composite showed great potential in the remediation of Cr(VI)-contaminated groundwater.