Green synthesis of FeCu@biochar nanocomposites through a mechanochemical method for enhanced tetracycline degradation via peroxymonosulfate activation

Biochar-based nanocomposites are recognized as promising catalysts for peroxymonosulfate (PMS) activation due to their cost-effectiveness, large surface area, and desirable activity. However, their conventional preparation involves laborious and energy-consuming high-temperature pyrolysis. In this study, we introduce an efficient approach to synthesize FeCu@BC nanocomposites using iron and copper chlorides with green tea via a mechanochemical method. Characterization results show that copper incorporation enhances the defect degree of biochar, increasing oxygen vacancies in FeCu@BC. Remarkably, FeCu@BC exhibits an outstanding efficiency of 92.24% in degrading TC, achieving more than 85% TC removal even under challenging conditions with varying pH levels and competing ions, making it a promising catalyst for practical applications. Through detailed investigations, we identify O2− and 1O2 as the primary active species responsible for TC degradation, supported by quenching and EPR tests. Furthermore, copper doping significantly improves electron transfer between FeCu@BC and PMS, promoting PMS activation during degradation. XPS analysis provides insights into the transformation of doped copper species, acting as potential active sites that facilitate PMS decomposition to generate O2− and 1O2. With significant advantages in cost-effectiveness and avoidance of energy-intensive pyrolysis, the mechanochemically synthesized FeCu@BC nanocomposites hold great promise for wide application in efficient wastewater treatment and environmental remediation.