The Influence Of Surfactants Existing In Draw Solution On The Characteristics Of Forward Osmosis

Forward Osmosis is a new treatment technology in water treatment industry.The research about properties and efficiency of forward osmosis is a hotspot in this field.The key to improving the performance of draw solution is to maintain a high water flux while suppressing the reverse diffusion.In this paper,we operated experiments to investigate the influence of surfactants on the forward osmosis process.The influence of nonionic surfactants on the osmolality,viscosity,water flux and reverse salt flux in different osmotic processes were analyzed,and the driving performance was evaluated.Driving performance of Triton X-100(nonionic surfactant)in draw solution was evaluated by measuring water flux and reverse salt flux in different types of membranes and osmosis modes.In this paper,the application effect of high osmotic pressure draw solution containing surfactants and inorganic salts was measured,its physicochemical properties were discussed,and its generalizability was evaluated.Finally,the model of water flux and reverse salt flux were established,and the values of correlation coefficient in the process of mass transfer were calculated to verify the superposition effect of pressure in the composite draw solution.By comparing the physicochemical properties of the permeable membrane and the draw solution before and after the addition of surfactant,it was found that the surfactant significantly improved the hydrophilicity of the membrane surface.The contact angle of the active layer of TFC membrane decreased by 65%.Surfactants reduced the porosity of the membrane surface,which would achieve high-performance reverse osmosis salt retention.However,it could also raise the viscosity of the drawing fluid.Through the forward osmosis test,it was found that the surfactant Triton X-100used in the experiment had different effects on different permeation modes and different permeable membranes.Triton X-100 had a better effect on the AL-DS(active layer contact with draw solution)mode which could decrease the reverse diffusion flux to 0.08g/L while no significant effect was observed on the reverse diffusion flux of Aquaporin-TFC membrane.The addition of inorganic salts to Triton X-100-containing complex draw solution showed a significant increase in water flux,with a maximum of 20.53(L/(m~2·h)).Through the data of water flux and the reverse salt flux of the composite draw solution,the segmented model was established to simulate.The permeability coefficient A(m/(s·Pa)),the reverse osmosis coefficient B(m/s),and the resistance coefficient K(m/s)under the experimental conditions were calculated by the RO(reverse osmosis)test.The models of forward osmosis flux and reverse salt flux were modified.The models was applied to the situation where the NaCl’s concentration is less than 1mol/L.