The peroxidase-like cleaning strategy for organic fouling of water treatment membranes based on MoS2 functional layers

Abstract

Efficient cleaning strategies play a key role in implementing sustainable and economic membrane operations during water treatments and purification. We proposed in this paper to construct the functional layers on the surface of PES substate using MoS2 nanosheets synthesized by a hydrothermal method, namely MoS2/PES membrane. The membrane structure and properties were characterized by SEM, XRD, EDS and FTIR. This is then followed by an evaluation of the membrane fouling of the functional layers, and in turn exploring the membrane cleaning strategy. The specific catalytic effects between MoS2 nanosheets with peroxidase-like activity, and the cleaning agent (H2O2) was subtly combined to endow MoS2 functional layers with specific catalysis. Humic acid (HA, as a representative organic foulant) having the filtration efficiency (~91 %) of MoS2/PES membrane was ~6 % higher than that of the pristine PES membrane. The flux recovery rate of MoS2/PES membrane (~75 %) was significantly larger than the PES membrane (~16 %) under optimized conditions. Results of 7 cycles of consecutive membrane fouling and cleaning demonstrated MoS2 functional layers not only relieved membrane fouling but also exhibited higher water flux. The outstanding performance of MoS2 functional layers could be explained by their stacked honeycomb pore-like structure and the catalytic characteristics of MoS2-like peroxidases. H2O2 was used to trigger the in-situ catalytic function of MoS2 layers, generating strong ROS and oxygen for the enhanced removal of organic foulants. This study provides new insights into devising a novel membrane cleaning strategy using advanced functional nanomaterials.