Laccase-loaded CaCO3 sustained-release microspheres modified SBES anode for enhance performance in the remediation of soil contaminated with phenanthrene and pyrene

Abstract

This study aimed to enhance the efficiency of SBES in remediating polycyclic aromatic hydrocarbon (PAH)-contaminated soils by modifying the anode with laccase. The experiment involved four SBES anodes: a carbon nanotube-modified anode (CNT), a free laccase-modified anode (Lac), a gelatin-encapsulated laccase-modified anode (Lac-Gel), and a CaCO3 sustained-release microsphere-loaded laccase-modified (CaCO3-SMs@Laccase) anode (Lac-SMs). The CaCO3-SMs@Laccase notably extended the active period of laccase, with laccase activity in the Lac-SMs measured at 1.646 U/g after 16 days, which was significantly higher than the 0.813 U/g observed in the Lac-Gel group and the 0.206 U/g in the Lac group. The superior electricity generation and degradation efficiency observed in the Lac-SMs group were due to the sustained enzymatic activity provided by the CaCO3-SMs@Laccase. The prevention of anode acidification through CaCO3 decomposition, and promote the forward progress of electrochemical reactions. The phenanthrene (Phe) and pyrene (Pyr) removal efficiency in the soil of the Lac-SMs reached 90.78 % and 84.72 %, surpassing those of the Lac-Gel (80.36 % and 79.14 %), Lac (79.38 % and 69.31 %), and CNT (63.22 % and 56.98 %). The degradation pathway from Pyr to Phe was possible started with hydroxylation. In addition, the laccase also transformed the predominant microbial communities and metabolism pathways.