Bioremediation of 2,4,6-trichlorophenol by extracellular enzymes of white rot fungi immobilized with sodium alginate/hydroxyapatite/chitosan microspheres

• Published in: Environmental research 2024-07, Vol.252 (Pt 2), p.118937-118937, Article 118937
• Main Authors: Wu, Jing, Gao, Dawen, Wang, Litao, Du, Xuran, Zhang, Zhou, Liang, Hong
• Format: Article
• Language: English
• Subjects: 2,4,6-Trichlorophenol; Biodegradation; Crude enzymes; Degradation pathway; Immobilization; White rot fungi
• ISSN: 0013-9351; 1096-0953
• DOI: 10.1016/j.envres.2024.118937

Hydroxyapatite, a calcium phosphate biomass material known for its excellent biocompatibility, holds promising applications in water, soil, and air treatment. Sodium alginate/hydroxyapatite/chitosan (SA-HA-CS) microspheres were synthesized by cross-linking sodium alginate with calcium chloride. These microspheres were carriers for immobilizing extracellular crude enzymes from white rot fungi through adsorption, facilitating the degradation of 2,4,6-trichlorophenol (2,4,6-TCP) in water and soil. At 50 °C, the immobilized enzyme retained 87.2% of its maximum activity, while the free enzyme activity dropped to 68.86%. Furthermore, the immobilized enzyme maintained 68.09% of its maximum activity at pH 7, surpassing the 51.16% observed for the free enzyme. Under optimal conditions (pH 5, 24 h), the immobilized enzymes demonstrated a remarkable 94.7% removal rate for 160 mg/L 2,4,6-TCP, outperforming the 62.1% achieved by free crude enzymes. The degradation of 2,4,6-TCP by immobilized and free enzymes adhered to quasi-first-order degradation kinetics. Based on LC-MS, the plausible biodegradation mechanism and reaction pathway of 2,4,6-TCP were proposed, with the primary degradation product identified as 1,2,4-trihydroxybenzene. The immobilized enzyme effectively removed 72.9% of 2,4,6-TCP from the soil within 24 h. The degradation efficiency of the immobilized enzyme varied among different soil types, exhibiting a negative correlation with soil organic matter content. These findings offer valuable insights for advancing the application of immobilized extracellular crude enzymes in 2,4,6-TCP remediation. [Display omitted] •Immobilized enzymes on the new carrier possess good temperature and pH stability.•The removal of 2,4,6-TCP from the soil by immobilized enzymes was 72.9% in 24h.•Degradation products of 2,4,6-TCP by immobilized enzyme were investigated.