Magnetically separable laccase-biochar composite enable highly efficient adsorption-degradation of quinolone antibiotics: Immobilization, removal performance and mechanisms

The tremendous potential of hybrid technologies for the elimination of quinolone antibiotics has recently attracted considerable attention. This current work prepared a magnetically modified biochar (MBC) immobilized laccase prod-uct named LC-MBC through response surface methodology (RSM), and LC-MBC showed an excellent capacity in the removal of norfloxacin (NOR), enrofloxacin (ENR) and moxifloxacin (MFX) from aqueous solution. The superior pH, thermal, storage and operational stability demonstrated by LC-MBC revealed its potential for sustainable applica-tion. The removal efficiencies of LC-MBC in the presence of 1 mM 2,2 '-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) for NOR, ENR and MFX were 93.7 %, 65.4 % and 77.0 % at pH 4 and 40 degrees C after 48 h reaction, respec-tively, which were 1.2,1.3 and 1.3 times higher than those of MBC under the same conditions. The synergistic effect of adsorption by MBC and degradation by laccase dominated the removal of quinolone antibiotics by LC-MBC. Pore-filling, electrostatic, hydrophobic, pi-pi interactions, surface complexation and hydrogen bonding contributed in the ad-sorption process. The attacks on the quinolone core and piperazine moiety were involved in the degradation process. This study underscored the possibility of immobilization of laccase on biochar for enhanced remediation of quinolone antibiotics-contaminated wastewater. The proposed physical adsorption-biodegradation system (LC-MBC-ABTS) pro-vided a novel perspective for the efficient and sustainable removal of antibiotics in actual wastewater through com-bined multi-methods.

Automated summary

This study prepared a magnetically modified biochar (LC-MBC) immobilized laccase product named LC-MBC through response surface methodology (RSM), and LC-MBC showed excellent removal capacity for NOR, ENR, and MFX. LC-MBC demonstrated superior stability and potential for sustainable application. The synergistic effect of adsorption by MBC and degradation by laccase dominated the removal process.