Study on the adsorption performance of Cu2+ in wastewater by red mud

Abstract

The treatment of copper-nickel wastewater has consistently posed a challenging problem in the field of environmental protection. In this experimental study, the adsorbent used was prepared from Bayer's method-derived red mud (RM). The adsorption characteristics of RM adsorbent on Cu2+ in copper-nickel wastewater, as well as the impact of Ni2+ on the removal effectcy of Cu2+, were investigated. The adsorption performance of Cu2+ in copper-nickel wastewater by adsorbent dosage, adsorption time and pH were investigated, and the adsorption mechanism was discussed. The adsorption process conformed to the pseudo-second-order kinetic model (R2 =0.986) and the Langmuir model (R2 =0.989), indicating that it was a monolayer chemical adsorption process. The raw materials were characterized using various techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray fluorescence (XRF). The results indicated that the adsorption process of Cu2+ and Ni2+ on RM was primarily influenced by surface chemical groups such as O-H, C-O-C, Si-C, and Si-O, among others. The adsorption rate of Cu2+ by RM could achieve 100% when the concentration of Cu2+ solution was 100 mg/L, with an optimal dosage of adsorbent at 0.20 mg/L and the best adsorption effect observed after 240 min. The adsorption of Cu2+ and Ni2+ by RM exhibits unidirectional competitive adsorption behavior. Furthermore,in competitive adsorption experiments, RM exhibits good selectivity towards Cu2+, with Ni2+ exhibiting minimal inhibitory effect on Cu2+ when the two elements coexist. Therefore, this paper offers potential research value for the large-scale application of RM in copper-nickel wastewater treatment processes.