Preparation of LR/EPI hydrogel-based Liquorice residue and the removal of Cu2+ from wastewater

Heavy metal ions cause serious harm to the ecological environment and human health, so it is urgent to treat the heavy metal ions in water. LR/EPI hydrogel was prepared with Licorice residue and epichlorohydrin (EPI) as cross-linking agent. The effects of solution pH, contact time, and initial concentration on the adsorption of Cu2+ in water by hydrogel were investigated. The results showed that LR/EPI hydrogel exhibited good adsorption performance. When hydrogel adsorbs for 120 min, it can achieve the adsorption equilibrium. At the Cu2+ concentrations of 700 mg/L, pH=4, and adsorption time of 120 min, the maximum adsorption capacity of LR/EPI hydrogel is 134.25 mg/g. The adsorption process conforms to the secondary kinetic model and the Langmuir adsorption and other temperature modes, and the adsorption process is adsorbed by chemical adsorption.