Preparation of chitosan/Co-Fe-layered double hydroxides and its performance for removing 2,4-dichlorophenol

Chitosan/Co-Fe-layered double hydroxides (CS/LDHs) were prepared by coprecipitation method, which is a kind of composite material with excellent properties. The structure of CS/LDHs was characterized by SEM, FTIR, and XRD, which proved that chitosan (CS) was successfully induced into hydrotalcite and CS/LDHs still possess the structural characteristics of hydrotalcite. The adsorption of 2,4-dichlorophenol (2,4-DCP) was studied with CS/LDHs and LDHs as adsorbent separately. The activity of immobilized laccase (L-CS/LDHs) with CS/LDHs as carrier is significantly better than that of the one (L-LDHs) using LDHs as carrier. Under the optimum conditions (pH = 6, 55 °C, 48 h), L-CS/LDHs exhibited better removal performance for 2,4-DCP (81.53%, 100 mg/L) than LDHs (63.55%); the removal of 2,4-DCP by L-CS/LDHs is excellent, exceeding 97% as its initial concentration below 60 mg/L. It includes the catalytic action of laccase and dechlorination of Fe³⁺ and Co²⁺, and the adsorption can be ignored under the optimal conditions. After 5 cycles, it maintained 67% (L-CS/LDHs) and 54% (L-LDHs) of the original removal.