Preparation Of Conductive Carbon-based Forward Osmosis Membrane And Its Research On Membrane Pollution Alleviatio

Forward osmosis(FO)has been identified as one of the best strategies to deal with the increasing global water shortage due to its advantages of low energy consumption and good effluent quality.At present,FO technology is widely used in the fields of seawater desalination and wastewater treatment.However,membrane fouling still hinders the performance of FO technology in long-term applications.Therefore,alleviating membrane fouling is one of the main ways to improve membrane performance.Electrochemical coupled with membrane technology has received more and more attention in controlling membrane fouling due to its favorable characteristics such as easy process control,stable performance,and environmental friendliness.In this paper,a conductive carbon-based FO(CPFO)membrane was prepared using a conductive carbon membrane(CM)as the substrate.CM has excellent electrical conductivity,but its macroporous and rough surface pose challenges for the preparation of PA layers.The interlayer of polydopamine nanoparticles(PDANPs)was prepared in CM by suction filtration,and the inner surface of CM was modified to successfully prepare a PA layer with excellent permselectivity.The effects of the deposition amount of PDANPs on the surface morphology,chemical composition,and permeability of the PA layer were also explored.Then,the prepared CPFO membrane was used to conduct anti-fouling experiments.The anti-fouling properties of CPFO membranes in treating pollutants with different charges(rhodamine B with a positive charge,eriochrome black T with a negative charge)and uncharged polyethylene glycol were explored.And then the effects of different voltages,initial concentrations of solutions,and p H on the antifouling performance were also explored.The intermediate layer of PDANPs modified the surface defects of CM to form a small pore size and highly hydrophilic surface layer,which provided the basis for the preparation of the PA layer.The study showed that with the increase of the deposition amount of PDANPs,the thickness and cross-linking degree of the PA layer increased while the roughness first decreased and then increased.When the deposition amount of PDANPs was 10 m L,the pore diameter and porosity of the modified CM substrate surface were 0.25±0.03μm and 29.8±1%.When MPD concentration of 3.0 wt%and TMC concentration of 0.15 wt%were used to prepare the PA layer,the permeability performance of the CPFO membrane reached the best at this time,the water flux was10.75 L/(m~2·h),the reverse salt flux was 1.83 g/(m~2·h),and the special salt flux was is0.17.In the anti-fouling experiment,when+1.5 V voltage was applied,compared with no voltage,the membrane flux of rhodamine B wastewater treated by CPFO membrane increased by 21.57%after 8 h operation,and the flux recovery rate increased by 4.5%,which was the result of the combined action of CPFO membrane oxidation and electrostatic repulsion.When-1.5 V voltage was applied,the flux of eriochrome black T wastewater treated by CPFO membrane increased by 14.47%,and flux recovery rate increased by 4.1%due to the electrostatic repulsive force.Under the conditions of+1.5 V and-1.5 V,the membrane pollution of rhodamine B and eriochrome black T wastewater increased with the increase of initial solution concentration and p H.The results of CPFO membrane treatment of polyethylene glycol wastewater show that the applied voltage and p H of the initial solution have no obvious effect on wastewater without charge,and the concentration of initial pollutants increases,and the membrane fouling increases.For the CPFO antifouling experiment,the antifouling performance of the charged surface film depends on the nature of the contaminant,that is,the charge.When the pollutant and the membrane surface have the same charge,the membrane fouling is reduced.When the pollutant and the membrane surface have opposite charges,the membrane fouling is aggravated.In this paper,a new conductive FO membrane prepared from the conductive substrate is proposed to alleviate membrane fouling,which provides a useful insight for FO fouling control.