Whey is the liquid residue of cheese production and contains large amount of organic matter, mainly protein and lactose. Direct discharge of whey means nutrition waste and environmental pollution. How to utilization of lactose is key point for whey preparation by membrane technology. Recently, the nanofiltration technology has great applications in food industry field. In this study, nanofiltration technology has been developed for separation of lactose from whey solution. Two kinds of model feed, the lactose solution and the whey solution, were investigated in order to compare the characterization of NF membranes performance. The effects of operation parameters such as trans-membrane pressure, temperature and feed pH were observed. In addition, a preferable cleaning method was proposed and the cleaning results were investigated
Polyethersulfone(PES)/Sulfonated polysulfone(SPSF) blend ultrafiltration membranes at different SPSF contents were prepared using a phase inversion technique. The morphological structures of PES/SPSF blend ultrafiltration membranes with different sulfonation degree were characterized using SEM. The results shown that the PES/SPSF blend ultrafiltration membranes had good retention to PEG1000 (99.8%) and high water permeate flux (27.2Lm-2h-1) at 0.1MPa.
Polyvinylidene fluoride (PVDF) hydrophobic membrane has been prepared by phase inversion method. The effects of concentration of PVDF, different processes of preparations, and different surface roughness on hydrophobic capability of membrane surface (water contact angle, WCA) have been investigated. The results showed that, hydrophobic ability of PVDF membranes decreased with the increasing concentration of PVDF. WCA of membrane prepared by was increasing. Membrane surface hydrophobic ability increased with the increasing surface roughness. The contact angle of membrane comes to 141° with dry process and 10% PVDF concentration.
The polyethersulfone/sulfonated polysolfone (PES/SPSF) blend ultrafiltration (UF) membranes with excellent performance were prepared by immersion phase inversion technique. The effects of degree of sulfonation (DS) of SPSF, PES/SPSF ratio, temperature of coagulation bath on the membrane porosity, pure water flux and rejection of PEG were investigated. The results show that the membrane performance with low molecular weight cut-off (MWCO) is excellent when the SPSF with 30% DS is added and the blending ratio of PES/SPSF is 4/1. The temperature of coagulation bath affects the structure of the membrane.
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