Preparation of composites with MgAl-LDH-modified commercial activated carbon for the quick removal of Cr from aqueous solutions.

Abstract The problem of soil and water contamination caused by Cr discharged from dyeing, electroplating and metallurgical industries has become increasingly serious, which is a potentially great threat to the environment and public health. Therefore, it is essential to develop a quick, efficient and low-cost adsorbent for the remediation of Cr-contaminated wastewater. In this work, we successfully prepared MgAl-LDH/ commercial activated carbon nanocomposites (LDH-CAC) with hydrothermal. The effects of activated carbon type and loading on LDH-CAC were investigated. Moveover, we also have examined the adsorption capacity and adsorption behavior of LDH-CAC on Cr(VI), and proposed a potential removal mechanism. Lastly, the reusability of LDH-CAC was researched. The results showed that the prepared LDH-CAC@1 had the best removal performance at the commercial activated carbon type of CAC-103 and activated carbon loading of 1.0 g. The adsorption behavior study, on the other hand, indicated that LDH-CAC @1 could reach adsorption equilibrium within 10 min with a maximum adsorption capacity of 116.7 mg/g, which was significantly better than MgAl-LDH (10.7 mg/g) and CAC (21.3 mg/g). The primary removal mechanisms included adsorption-coupled reduction, ion exchange, surface precipitation, and electrostatic attraction. Reusability experiment revealed that the removal efficiency of LDH-CAC@1 decreased by 25.1% after four cycles, which illustrated the promising reusability of LDH-CAC@1.This study provides an effective adsorbent with a remarkably fast reaction, which has positive environmental significance for the treatment of Cr (VI) wastewater.