Green Polyurethane Foam Coated With a Copolymer Containing TiO2 Nanoparticles Through Non-Solvent Induced Phase Separation: A Photocatalytic Water Cleaning Approach

Abstract

The expansion of human population in many parts of the world is increasing the demand for fresh water and the contamination of water by contaminants such as dye, and others requires efficient, easy-to-use, cheap and environmentally sustainable technologies to perform water purification tasks. In this work, nanostructured eco-friendly bio-based castor oil polyurethane foams that can remove heavy metal ions from contaminated water were customized to add another function associated with the photodegradation of organic molecules. To this end, nanostructured polyurethane foams (containing cellulose-halloysite nanocomposite units) were coated with poly(styrene)-b-(polyethylene-ran-butylene)-b-polystyrene (SEBS) by non-solvent induced phase separation (NIPS) process for the first time. The deposition of the coating also allowed the incorporation of titanium dioxide (TiO₂) nanoparticles by applying a new strategy, in which the nanoparticles were suspended in the non-solvent prior to the NIPS process. These modulated and mixed technologies have generated polyurethane foams capable of degrading at least 10% of methylene blue dye through photocatalysis. The photocatalytic system is inactivated by pH where pH = 2.0 does not promote photocatalysis but the process is activated in water pH. The effect of photocatalysis generated with only 0.5% by mass of TiO₂ in the foam, approximately 10 mg of TiO₂, was 9.22% and 10.02% for approximately 20 mg.