Preparation of Polyhydroxyalkanoate Microfiltration Membranes via Nonsolvent–induced Phase Separation Methods

Microfiltration membranes of polyhydroxyalkanoate (PHA), a biodegradable biomass plastic, were prepared via nonsolvent–induced phase separation methods. Dimethylformamide (DMF) was found to be the best solvent for the preparation among the four solvents examined (DMF, 1,4–dioxane, N–methyl–2–pyrrolidone, and dimethylsulfoxide); water at 25 ℃ was used as a nonsolvent. The polymer concentrations and casting temperatures were examined at 10% ～ 20% and 40 ～ 60 ℃, respectively. The surface pore size of the top surface of the asymmetric structure was found to depend on the polymer concentration and casting temperature. When the membrane was prepared at a polymer concentration of 18% and a casting temperature of 50 ℃, the membrane resistance and retention toward 0.3–m latex beads were 4.0 × 109 m–1 and 99%, respectively. The PHA membrane was stable at 25 ℃ even under wet conditions and degraded at 60 ℃ under wet conditions. The membranes developed from biodegradable biomass plastics will be useful as degradable filters to reduce filter media waste in food and biochemical industries by composting membranes containing foulants after filtration.