The effects of hydraulic conditions on the efficiency of PRO process and membrane fouling mechanism
The study investigated the effects of hydraulic conditions,such as effective osmotic pressure difference,operating pressure on the draw solution,and cross-flow shear force,on the efficacy of the pressure retarded osmosis(PRO)process.Tannic acid and sodium alginate were selected as model foulants,and the membrane fouling mechanism was analyzed using the XDLVO theory.The results revealed that tannic acid caused greater membrane fouling compared to sodium alginate,primarily due to its preferential adsorption on the porous support layer of the membrane.Higher effective osmotic pressure difference and cross-flow shear force enhanced water flux and power density levels in the presence of tannic acid as a foulant,but they also exacerbated membrane fouling.Nonetheless,the retention rate of tannic acid in the PRO membrane remained above 85％.Increasing the operating pressure on the draw solution reduced the effective osmotic pressure difference and water flux level,but it enhanced the power density and mitigated membrane fouling.The initial water flux decreased to 10.5L/(m2.h),while the capacity increased by 200％when the operating pressure was raised from 1bar to 4bar.XDLVO calculations demonstrated that tannic acid exhibited higher interface interaction energy,leading to its preferential adsorption and coalescence on the PRO membrane.Consequently,in conjunction with the hydraulic conditions,tannic acid resulted in more significant flux losses compared to sodium alginate.
pressure retarded osmosishydraulic conditionspower densityXDLVO theory
万方数据
维普
