Green Fabrication of Sustainable Porous Chitosan/Kaolin Composite Membranes Using Polyethylene Glycol as a Porogen: Membrane Morphology and Properties

One of the major challenges in membrane manufacturing today is to reduce the environmental footprint by promoting biobased raw materials and limiting the use of toxic solvents. In this context, environmentally friendly chitosan/kaolin composite membranes, prepared using phase separation in water induced by a pH gradient, have been developed. Polyethylene glycol (PEG) with a molar mass ranging from 400 to 10,000 g center dot mol(-1) was used as a pore forming agent. The addition of PEG to the dope solution strongly modified the morphology and properties of the formed membranes. These results indicated that PEG migration induced the formation of a network of channels promoting the penetration of the non-solvent during the phase separation process, resulting in an increase in porosity and the formation of a finger-like structure surmounted by a denser structure of interconnected pores of 50-70 nm in diameter. The hydrophilicity of the membrane surface increased likely related to PEG trapping in the composite matrix. Both phenomena were more marked as the PEG polymer chain was longer, resulting in a threefold improvement in filtration properties.

Automated summary

One major challenge in membrane manufacturing is to reduce environmental impact by using biobased materials and limiting toxic solvents. Environmentally friendly chitosan/kaolin composite membranes were developed using phase separation induced by a pH gradient. Addition of PEG as a pore forming agent significantly modified the morphology and properties of the membranes, leading to increased porosity and formation of a finger-like structure with interconnected pores. The hydrophilicity of the membrane surface also increased, resulting in a threefold improvement in filtration properties.