Study on vacuum membrane distillation performance of PP/POE blending membranes prepared via thermally induced phase separation using bidiluent

Abstract in this study, polypropylene/polyethylene octene (PP/POE) blending membranes were prepared via thermally induced phase separation method and applied to vacuum membrane distillation (VMD). The influences of bidiluent ratio and polymer concentration in the casting solution on the structural properties (including porosity, hydrophobicity, permeability, and mechanical strength of the PP/POE blending membranes are fully investigated. The results suggest that the tensile strength can be significantly improved through blending PP with POE. The porosity of the blending membrane can be regulated by the polymer concentration. Meanwhile, the bidiluent ratio (soybean oil and dibutyl phthalate) can tailor the microporous structure and penetration property. The high permeate flux of the PP/POE blending membrane is obtained at a PP/POE blending ratio of 8:2, polymer concentration of 30 wt.%, and bidiluent (soybean and dibutyl phthalate) ratio of 5:5. To simulate the VMD application for seawater, separation permeability of the as-prepared PP/POE blending membranes are also characterized using 3.5 wt.% NaCl aqueous solution. The VMD results suggests that, at feed flow rate of 18 L h-1, vacuum degree of 0.09 MPa and feed temperature of 80 ℃, the blending membranes manifest much superior permeation and separation performance after around 60 h operation.