Can Cu2ZnSnS4 nanoparticles be used as heterogeneous catalysts for sulfadiazine degradation?

• CZTS nanoparticles synthesized with solvents of deionized water and ethylene glycol were utilized in catalytic H 2 O 2 process. • CZTS-W exhibited higher recyclability and stability than CZTS-EG. • 1O 2 played the dominant role in SDZ degradation. • The catalytic mechanisms of CZTS-W/H 2 O 2 and CZTS-EG/H 2 O 2 systems were proposed. • The synergetic effect of Cu2+/Cu+ and low-valent sulfur/high-valent sulfur was in favor of H 2 O 2 activation. As a quaternary copper-based semiconductor, Cu 2 ZnSnS 4 (CZTS) is drawing growing attention and is anticipated as a promising photocatalyst, thanks to its large absorption coefficient, exceptional photostability, and theoretical power conversion efficiency. However, CZTS has never been used as an activator of H 2 O 2 for the degradation of refractory organic pollutants. In this study, the synthesis of CZTS nanoparticles obtained with diverse morphologies and crystallinities using solvents of deionized water (CZTS-W) and ethylene glycol (CZTS-EG) was examined in the activation of H 2 O 2 to degrade sulfadiazine (SDZ). The results revealed that CZTS coupled with H 2 O 2 could be an effective system for the degradation of SDZ. Compared to CZTS-EG, CZTS-W presented higher reusability in consecutive cycles with negligible leaching of copper. Reactive oxygen species quenching tests and electron paramagnetic resonance analyses illustrated that •O 2 −, •OH, and 1O 2 contributed to the degradation of SDZ, and 1O 2 prevailed over •O 2 − and •OH. The mechanistic investigation showed that efficient degradation could be associated to the effective recycling of Cu(II)/Cu(I) and low-valent/high-valent sulfur. Also, the degradation pathways of SDZ have been proposed through the detection of intermediate products. This study manifests that CZTS synthesized using deionized water is encouraging for the elimination of organic pollutants. [ABSTRACT FROM AUTHOR]