Degradation of pharmaceutical contaminants by bubbling gas phase surface discharge plasma combined with g-C3N4 photocatalysis

The feasibility of using gas phase surface discharge with microporous bubbling for the degradation of pharmaceutical contaminants was evaluated. After 25 min of treatment, 82% removal of ibuprofen (with an initial concentration of 60 mg L-1) and 100% removal of tetracycline hydrochloride (with an initial concentration of 200 mg L-1) was achieved. To utilize the UV and visible radiation produced in the discharge process, a g-C3N4 photocatalyst was added into the solution to enhance the degradation efficiency. Adding 75 mg L-1 g-C3N4 can increase the removal of ibuprofen by 18% (initial concentration of 10 mg L-1) and tetracycline hydrochloride by 10% (initial concentration of 100 mg L-1) after 10 min of discharge treatment. The crystallinity of the used g-C3N4 became higher as the discharge treatment can planarize the g-C3N4 surface via oxidization. In addition, aqueous O-3, H2O2 and OH radicals under different conditions were measured to investigate the reaction mechanisms. The aqueous O-3 reaches saturation after 30 min of discharge but H2O2 kept accumulating during the two hour discharge. The average OH formation rate is 0.4191 mol L-1 min(-1) in distilled water but 0.5640 mol L-1 min(-1) with g-C3N4, which demonstrates the promotion of photocatalytic OH generation. Therefore, combining the bubbling gas phase surface discharge plasma with g-C3N4 photocatalysis leads to an extraordinary performance for the treatment of pharmaceutical additives.

Automated summary

The combination of gas phase surface discharge plasma with g-C3N4 photocatalysis shows remarkable efficiency in treating pharmaceutical contaminants, achieving significant removal rates for ibuprofen and tetracycline hydrochloride through degradation and promoting the generation of OH radicals.