Ferrocene modified g-C3N4 as a heterogeneous catalyst for photo-assisted activation of persulfate for the degradation of tetracycline

Abstract In this study, the oxidative degradation of tetracycline (TC) by ferrocene-modified graphite phase carbon nitride (Fe/g-C3N4) activated persulfate (PS) under light-assisted conditions is examined. The materials are characterized by a series of methods such as SEM, TEM, XRD, FTIR, XPS, etc. This article explores the influence of the amount of sulfate, the initial concentration of pollutants, the amount of catalyst, and the pH value on the reaction system. When the amount of PS added reaches 2.5 mM and the catalyst dosage is 1 g L−1, the Fe/g-C3N4/PS/Vis exhibit the best performance for tetracycline removal. In 60 min, the removal of tetracycline reaches 93% under its natural pH. In the reaction system acidic neutral conditions are more conducive to degrade TC. The results show that the doping of ferrocene inhibits the recombination of electron-hole pairs in the g-C3N4, expands the light response range to speed up the removal rate of tetracycline. At the same time, iron cycle generated by ferrocene modification helps to activate persulfate to produce sulfate radicals with strong oxidizing properties. Sulfate radicals, hydroxyl radicals, superoxide radicals and holes are the main active species proved by ESR test and the quenching experiments. The synergy between photocatalysis and PS activation promotes the production of active species and the tetracycline removal. The results show that the Fe/g-C3N4 composite material activated persulfate under visible light is an effective method to remove tetracycline from water.