Effect of bamboo biochar preparation conditions on immobilization of laccase and its application

In this paper, bamboo biochar was prepared and used for laccase immobilization. Biochar was prepared under different conditions (pyrolysis temperature, heating rate and dwell time) to understand biochar characteristics impacts on enzyme activity. The results showed that the preparation conditions had an important effect on the content of carboxyl groups on biochar. And the specific surface area is not the key factor affecting laccase immobilization in this study, which is a little different than before. The highest immobilized laccase activity (1404.17 U/g) was obtained when the biochar was heated to 300 °C at the rate of 15 °C/min and stayed for 1.5 h, and the carboxy group concentration was 0.490 mmol/g. Compared with free laccase (FL), the immobilized laccase on bamboo biochar (LBC) showed higher thermo-tolerant performance, more excellent acid-proof ability and reusability. Without any mediators, LBC displayed high degradation efficiency (74.72 %, 85.88 % and 94.53 %, respectively) for bisphenol A (BPA), malachite green (MG) and methyl orange (MO) in water. Our research demonstrates that the content of carboxyl group in biochar plays a decisive role in the immobilization of laccase and LBC has excellent performance in the effective removal of toxicant in water, which makes it a promising candidate for environmental recovery.