Molybdenum disulfide (MoS2) promoted sulfamethoxazole degradation in the Fe(III)/peracetic acid process

Abstract

• MoS 2 /Fe(III)/PAA process was first developed to degrade sulfamethoxazole. • Fe(IV), 1 O 2 , HO ● , CH 3 C(O)O ● , and CH 3 C(O)OO ● were evidenced as reactive species. • Influencing factors were comprehensively studied. • Sulfamethoxazole degradation pathway was proposed with identifying oxidation products. • A continuous flow reactor configuration with MoS 2 -immobilized sponge was developed. Activation of peracetic acid (PAA) for pollutants degradation has been a hotspot recently. In this study, molybdenum disulfide (MoS 2 ) was first employed to enhance sulfamethoxazole (SMX) degradation in the Fe(III)/PAA process at pH 3.0. The addition of MoS 2 can not only accelerate the transformation from Fe(III) to Fe(II), but also can directly activate PAA. A series of reactive species including Fe(IV), 1 O 2 , HO ● , CH 3 C(O)O ● and CH 3 C(O)OO ● were generated in this Fe(III)/MoS 2 /PAA process, which was responsible for SMX degradation except 1 O 2 . The increase of MoS 2 dosage (0.025–0.2 g/L) accelerated SMX degradation, and the optimum pH was 3.0. The increase of either PAA (0.075–0.45 mM) or Fe(III) concentration (0.025–0.2 mM) also accelerated SMX degradation. However, the higher concentration of SMX, the addition of humic acid, and extra adding H 2 O 2 lowered the removal efficiency of SMX. Based on the identified products, possible pathways of SMX degradation initiated by electron transfer reaction were proposed. Furthermore, a continuous flow reactor configuration was employed to recycle the used MoS 2 , and the stable removal efficiency of SMX during 6 h reaction brings a new strategy for this process in practical use. This study developed an efficient method to remove SMX and provided a new idea for the PAA activation in water treatment.