Optimization of negatively charged polysulfone membranes for concentration and purification of extracellular polysaccharides from Arthrospira platensis using the response surface methodology

Abstract

Arthrospira platensis (A. platensis), one of the successfully commercialized microalgae, can generate abundant extracellular polysaccharides (EPS). Separating the EPS from the culture medium is important to recycle the medium and further process the polysaccharide resource. To separate EPS from spent Arthrospira platensis culture medium, a negatively charged polysulfone (PSf) membrane was prepared by lending PSf with sulfonated PSf (sPSf), and was optimized using the response surface methodology. The optimal preparation conditions were found to be a PSf concentration of 12.5 w%, sPSf of 1.9 w% and PEG of 5.5 w% in N,N-dimetylacetamide. The hydrophilicity, porosity, mean pore size, infrared absorption spectrum, water uptake (WU), thickness and clean water permeability (CWP) were determined to characterize the membrane, and critical pressure was used to evaluate the fouling resistance of the membrane. The results show that sPSf was successfully incorporated in the optimized PSf/sPSf, and it had higher hydrophilicity, porosity, larger mean pore size, WU, CWP, thickness and higher EPS retention and lower protein retention than the pristine PSf membrane. The final EPS retention of the optimized membrane was higher than 96%.