Removal Of Arsenic/Chromium Study By Graphitic Carbon Nitride Based Photocatalyst

With the rapid development of industry,the problem of heavy metal pollution in China has been increasingly serious.Wherein,arsenic and chromium pollution is particularly prominent,and the treatment of arsenic and chromium-containing wastewater needs further study.Photocatalytic technology is a highly efficient and energy-saving treatment method for pollutants driven by sunlight.Graphitic carbon nitride?g-C3N4?is an organic visible light-responsive photocatalyst,but its oxidizing ability is insufficient and the photogenerated electron and hole recombination rate is high,which limits its application.This study mainly focuses on the modification of g-C₃N₄ photocatalytic material,and applies it to the removal of heavy metal pollutants As???and Cr???in acidic water,and studies its mechanism.Firstly,g-C3N4 was modified by doping of PDI to obtain a composite material g-C₃N₄/PDI?gCP?.A synergistic effect was found in As???and Cr???conversion in the photocatalytic process.Unlike conventional titanium dioxide?TiO₂?,gCP hardly adsorbs As???,Cr???and As???,and exhibits excellent durability when As???and Cr???redox conversion synergistically.The study found that in addition to gCP generated holes?h⁺?,photogenerated electrons(e^–_cb)and superoxide radicals?·O₂^–?produced by reducing oxygen,the Cr?V?/H₂O₂ Fenton-like system formed by in-situ generated H₂O₂ and Cr???reduction intermediate Cr?V?has a decisive effect on the synergistic effect of As???and Cr???conversion.Then,a visible light responsive photocatalytic semiconductor Fe2V4O13?FeV?was coupled with gCP to obtain a composite photocatalyst gCP-FeV.Photoluminescence spectroscopy?PL?and photocurrent response test results show that the FeV loading effectively promotes the separation of photogenerated electron and hole in the composite catalyst.Compared with gCP,FeV loading not only significantly improves the oxidation efficiency of As????the time required to oxidize 100?M As???is reduced from 120 min to 25 min?,but also gives the composite catalyst excellent cycle performance.During the four-cycle experiment,the effect of reuse of the catalyst after use is better than the previous time.It was confirmed by quenching experiments that the active substances that gCP-FeV plays a major role in the oxidation of As???are h⁺and·O₂^–.