Preparation And Performance Of MoS₂-FeOOh Catalytic Composite Membrane

Membrane technology,which has the advantages of fast and effective,simple process and continuous operation,has been extensively used in many water treatment processes including producing potable water,seawater and brackish water desalination,and industrial and municipal wastewater reclamation.However,organic membranes are prone to problems such as low permeation flux and membrane fouling in the water treatment process,among which irreversible fouling is a key factor affecting the long-term stable operation of the membrane.Many researchers have paid more attention to the study of reversible pollution and less attention to the mitigation of irreversible pollution.Therefore,it is necessary to develop a membrane that can alleviate irreversible pollution.Studies have shown that doped iron oxide catalyst is an effective measure to alleviate irreversible pollution.However,due to the slow reaction rate,the improvement efficiency is reduced.However,as an excellent nano-cocatalyst,molybdenum disulfide（MoS₂）can promote the Fenton-like reaction to efficiently catalyze the degradation of pollutants.Therefore,the MoS₂ iron oxide composite material is combined with the membrane matrix to make the membrane have catalytic self-cleaning ability and achieve the purpose of alleviating irreversible membrane pollution.In this paper,MoS₂ nanosheets were synthesized by a hydrothermal method,and the preparation parameters such as the ratio of precursor,hydrothermal temperature,and hydrothermal time were sequentially optimized.The study found that the MoS₂ nanosheets prepared under the conditions of molar ratio Mo:S=1:4,hydrothermal temperature 220℃,hydrothermal time 24 h have the best catalytic activity.The study found that the catalytic activity of MoS₂-FeOOH(3×10^-4 mol)prepared when loading was 3×10^-4 mol was the best,and its p H range was wide and its stability was good.Different concentrations of MoS₂-FeOOH were ultrasonically dispersed in a solvent,and then doped into polyethersulfone（PES）casting solution to prepare a MoS₂-FeOOH/PES composite ultrafiltration membrane.The study found that the composite ultrafiltration membrane UF-M3 prepared when the ultrasonic time is 1.5 h and the MoS₂-FeOOH/PES mass ratio is 0.15 has the best anti-pollution performance,the pure water flux of the composite ultrafiltration membrane reaches 337.0 L/（m²·h）,which is 1.5 times that of pure PES membrane.At the same time,the membrane flux recovery rate（FRR）has also increased from 34.6%of pure PES membrane UF-M0 to 88.7%.In the process of filtering macromolecular dyes,after catalyzed self-cleaning,the flux recovery rate of the composite membrane can reach more than 90%,which means that a composite ultrafiltration membrane with high permeation flux,good anti-pollution performance and catalytic self-cleaning ability has been successfully prepared.Different concentrations of MoS₂-FeOOH were mixed into the organic phase to prepare composite nanofiltration membranes.The study found that after adding MoS₂-FeOOH,the hydrophilicity,permeation flux and anti-fouling performance of the nanofiltration membrane have been improved.When the MoS₂-FeOOH concentration is 0.02 wt%,the composite nanofiltration membrane NF-M2 has the best anti-pollution performance.The pure water flux of the composite nanofiltration membrane is 48.4 L/（m²·h）,which is 1.5 times that of the pure PA nanofiltration membrane,the composite nanofiltration membrane flux recovery rate（FRR）increased from 60.0%of pure PA membrane to 75.4%.In the process of filtering small molecule dyes,the composite nanofiltration membrane,which was heavily polluted by dyes,recovered more than 90%of the membrane permeation flux after being catalyzed and self-cleaned,which shows that the composite nanofiltration membrane has a good application prospect in the treatment of printing and dyeing wastewater.