Efficient degradation of tetracycline in wastewater by novel biochar-based photocatalytic materials: performance, photocatalytic mechanism and degradation pathways

The rapid increase in antibiotic contaminants such as Tetracycline (TC) in aquatic environments poses significant threats to human health and ecosystems. This study presents a novel Mn-Al layered double hydroxide (LDH) composite with rice husk biochar (RHBC) as a highly efficient visible light photocatalyst for the degradation of TC in wastewater. The Mn-Al-LDH/RHBC composite was synthesized via a simple co-precipitation method and characterized by UV-vis DRS, PL, TRPL, EIS, and TPR tests, confirming its wide visible spectral absorption, low electron-hole recombination rate, and high charge transfer efficiency. Photocatalytic performance tests showed that Mn-Al-LDH/RHBC achieved a 90.10% TC degradation efficiency within 90 min of irradiation. Mechanistic studies using EPR and DFT analysis identified <middle dot>OH and <middle dot>O-2(-) as the primary reactive species in TC degradation. Additionally, QSAR analysis demonstrated a reduction in the biotoxicity of TC and its intermediates post-degradation. This work offers a new insight for the utilization of biomass waste and the improvement of Mn-Al-LDH/RHBC photocatalytic performance, and extends the broad potential application of biochar-based photocatalyst in antibiotic-contaminated wastewater treatment applications.