Degradation of rhodamine B by persulfate activated with green tea iron nanoparticles

Green iron tea nanoparticles (GT-Fe NPs) were used as persulfate(PS) activators to oxidize rhodamine B (RhB) in this study. Optimized oxidative degradation condition was 0.033 mM Fe, 5 mM PS at pH 3.0 and 298 K with an initial RhB content of 50 mg/L. After 120 min of RhB degradation utilizing GT-Fe NPs activated PS, 99% of RhB reduction was achieved, while 98% RhB reduction with PS activated by citric acid-Fe2+(CA-Fe) with the same amount of Fe2+. This RhB reduction was due to the delayed release of Fe(II) in the GT-Fe NPs. The addition of GT-Fe NPs enhanced the synthesis of OH center dot and SO4-center dot while inhibiting the formation of O-2(-)center dot. A possible RhB degradation pathway was the chromophore destruction and ring-opening processes using GT-Fe NPs/PS, which produced a range of low molecular weight carboxylic acids (oxalic acid, lactic acid, acetic acid, and formic acid). GT-Fe NPs seem to be a promising persulfate activator in comparison to common activators such as CA-Fe.

Automated summary

In this study, green iron tea nanoparticles (GT-Fe NPs) were used as persulfate (PS) activators to oxidize rhodamine B (RhB). Under optimized conditions (0.033 mM Fe, 5 mM PS, pH 3.0, 298 K), with an initial RhB content of 50 mg/L, 99% of RhB reduction was achieved after 120 min of degradation using GT-Fe NPs activated PS, compared to 98% reduction with PS activated by citric acid-Fe2+ (CA-Fe) using the same amount of Fe2+. The addition of GT-Fe NPs promoted the synthesis of OH• and SO4• while inhibiting the formation of O-2•. The possible degradation pathway of RhB involved chromophore destruction and ring-opening processes, forming low molecular weight carboxylic acids such as oxalic acid, lactic acid, acetic acid, and formic acid.