CdS/PANI/ZSM-5 hollow spheres: A photocatalyst for efficient SBX degradation

Abstract

Polyaniline (PANI) coated hollow sphere cadmium sulfide (CdS) were dispersed on zeolite socony mobil-5 (ZSM-5) and then the CdS/PANI/ZSM-5 composite was first used for the photocatalytic degradation of sodium butyl xanthate (SBX) in sulfide mineral processing wastewater. SEM, TEM-EDS, XRD, UV–vis-DRS and BET tests were used to characterized the CdS/PANI/ZSM-5 composite. Compared with pure hollow CdS, the addition of PANI and ZSM-5 obviously improved the photocatalytic efficiency of SBX with the degaradation rate of 99% for 70 min. Meanwhile, the experiments with different amount of CdS/PANI/ZSM-5 and different mass ratio of ZSM-5 were also carried out, which indicated that 35 mg CdS/PANI/ZSM-5 with a content of 50% ZSM-5 possessed the highest photocatalytic degradation efficiency for SBX. The photocatalytic mechanism of CdS/PANI/ZSM-5 for SBX was investigated by electrochemical impedance spectroscopy (EIS), transient photocurrent response, active species trapping experiments and XPS tests. The enhanced catalytic activity was related to two aspects: (1) the generated electrons (e-) and holes (h+) by CdS and PANI could be transferred in opposite directions which could prevent the recombination of photogenerated e- and h+; (2) the doping of ZSM-5 could improve not only the dispersibility of the catalyst, but also the adsorption ability of SBX.