Hydrolytic degradation of methoxychlor by immobilized cellulase on LDHs@Fe3O4 nanocomposites

Abstract

In this study, we synthesized Fe3O4 using the co-precipitation method and then prepared magnetic carrier LDHs@Fe3O4 by immobilizing layered double hydroxide on Fe3O4 by in situ growth method. Cellulase was immobilized on this magnetic carrier by using glutaraldehyde as a coupling agent, which can be used for degrading Methoxychlor (MXC). The results demonstrated the maximum MXC removal efficiency of 73.4% at 45 °C and pH = 6.0 with excellent reusability. Through kinetic analysis, it was found that the degradation reaction conforms to the Langmuir–Hinshelwood model and is a first-order reaction. Finally, according to the EPR analysis, the active radicals in the system were found to be OH· and the degradation mechanism was proposed in combination with LC-MS. This study provides a feasible method for degrading organochlorine pesticides, which can be used for groundwater purification. HIGHLIGHTS Cellulase immobilized on magnetic LDHs carrier by covalent binding route.; The optimum temperature for the immobilized cellulase was 45 °C, indicating that magnetic LDHs can provide thermal acceleration of the degradation of the underlying cyclic oligomers.; The magnetic LDHs carrier can decrease the activation energy for MXC degradation reaction significantly.;

Keywords

• degradation mechanism
• immobilized hydrolase
• magnetic hydrotalcites
• organochlorine pesticides