Superior fenton-like degradation of tetracycline by iron loaded graphitic carbon derived from microplastics: Synthesis, catalytic performance, and mechanism

Carbon-based catalyst (Fe-MPC) derived from microplastics was fabricated by facile iron impregnation and carbonization. Fenton-like degradation of tetracycline (TC) was investigated using Fe-MPC as catalyst. Effect of experimental factors, including H2O2 concentration, initial TC concentration, solution pH, temperature, anions, and natural organic matter, was examined to evaluate the catalytic performance. Under the conditions of Fe-MPC 0.02 g/L, H2O2 1.0 mM, pH 4.3, TC 40 mg/L, and temperature 25 °C, TC removal of above 83% is obtained within 10 min. The Fe-MPC catalyst displays superior catalytic performance to previous reports, as verified by the large rate constant (0.2571 min−1) and high specific TC removal (approximate 1500 mg/g catalyst). Fe-MPC catalyst was characterized by multi-techniques. Reduced iron species are uniformly distributed on graphitic carbon, and they act as active sites for H2O2 activation. The hydroxyl radicals are evidenced to be the dominant active radicals for Fenton-like degradation of TC by quenching experiments and electron spin resonance. Possible degradation pathways of TC are proposed based on the identified intermediates. This work brings a novel strategy of “waste treating waste” by the conversion of microplastics into Fenton-like catalyst for wastewater treatment.