Abstract
In this work, we conceived a novel vis/H2O2/Fe3+/nitrilotriacetic acid (NTA)/g-C3N4 system to address the bottlenecks of traditional homogeneous photo-Fenton reactions, i.e., the narrow pH application range and unsustainable electron supply by the ligand to metal charge transfer (LMCT) process. A strong synergistic effect was observed with efficient organic contaminant degradation in a broad pH range (3–8), and hydroxyl radical (HO•) was proved to be the primary active species. Intriguingly, we found that the mechanism of rate-limiting Fe3+ reduction process was highly pH-dependent. At acidic condition (pH 3.0), the reduction of Fe3+ was dominated by direct photogenerated electron (e−) transfer and LMCT reaction. However, as the pH increased to 7.0, it gradually converted into a superoxide radical (O2•−) mediated reduction process, which was mainly attributed to the enhanced electrostatic repulsion between g-C3N4 and iron species, and the species transformation from protonated HO2• to more active deprotonated O2•−. Notably, H2O2 played a triple role in this system including (1) serving as the precursor of O2•−(2) scavenging photogenerated holes (h+) to complete the closed-loop of photocatalytic reaction and (3) boosting the generation of HO•. Finally, the vis/H2O2/Fe3+/NTA/g-C3N4 system also featured with a strong water matrix resistance capacity (e.g., chloride, bicarbonate, Ca2+/Mg2+ and humic acid), which enables it a promising platform for practical wastewater purification.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call