Catalytic degradation of tetracycline hydrochloride by persulfate activated with nano Fe0 immobilized mesoporous carbon

In this study, mesoporous carbon (MC) supported nano Fe-0 was prepared from polyvinyl alcohol (PVA) using MnCO3 as template, which was used as the catalyst to activate persulfate (PS) for the removal of tetracycline hydrochloride (TC) from aqueous solution. The nano Fe-0 was immobilized on MC by liquid phase reduction to overcome the drawbacks of nano Fe-0 for persulfate (PS) activation, including being easily aggregated and oxidized. The experimental results showed that the nano Fe-0/MC + PS system achieved 92.1% of TC removal, while the MC + PS system and nano Fe-0 + PS systems showed 78.5% and 33.7% of TC removal, respectively. High removal efficiency in the nano Fe-0/MC + PS system could be attributed to the superior PS activation capability due to the synergistic effects of nano Fe-0 and MC. In order to better understand the removal mechanism, the effects of nano Fe-0 loading amount (c), dosage (m), PS/TC mole ratio (R-m) and initial pH on TC removal were evaluated in the nano Fe-0/MC + PS system. The results showed that the removal efficiency of TC was enhanced with the increase of nano Fe-0 loading amount and dosage, while slightly decrease with the increase of PS/TC mole ratio. The maximum removal of TC was 97.7% under the optimal conditions: c = 20%, m = 0.8 g/L, = 50/1 and pH = 5. According to the results of radical scavengers' studies and intermediates analysis, SO4 center dot-, which was produced from catalytic activation of PS by nano Fe-0 and Fe2+ on the surface of Fe-0/MC, plays a significant role for TC degradation in the nano Fe-0/MC + PS system. The Fe-0/MC + PS system exhibited a superior oxidation process for the removal of TC from aqueous solution with excellent stability and reusability of Fe-0/MC.