Study on adsorption-degradation of 2,4-dichlorophenol by modified biochar immobilized laccase

Abstract

In this paper, biochar was modified by cetyltrimethylammonium bromide (CTAB) and KOH solution, and it was characterized by TGA, FT-IR, XRD, BET, SEM. Then, the modified biochar (MB) was used to immobilize free laccase (FL) by adsorption method to prepare modified biochar immobilize laccase (MBL). The adsorption and degradation performance for 2,4-DCP via MB, FL, MBL were studied. The results showed that under the optimal conditions, the adsorption rate of MB on 2,4-DCP was up to 42.5%, adsorption capacity was 85.13 mg/g, and the adsorption of 2,4-DCP by MB was proved to conform to the pseudo-second-order model and the Langmuir adsorption isotherm model; the maximum degradation rate of FL on 2,4-DCP was 97.7%, and the degradation of 2,4-DCP by FL was proved to conform to the first-order kinetic model; under the optimal conditions, the removal rate of MBL on 2,4-DCP can reach almost 100%. MBL combines physical–chemical adsorption and biodegradation, and the contribution of biodegradation is greater than adsorption. Finally, the possible degradation mechanism and pathways of 2,4-DCP were given via high-performance liquid chromatography (HPLC) analysis and gas chromatography-mass spectrometry (GC–MS) analysis.