Immobilization of titanium dioxide on PAN fiber as a recyclable photocatalyst via co-dispersion solvent dip coating

Polyacrylonitrile (PAN) fiber coated with photocatalyst titanium dioxide (P25) was successfully fabricated by a dip coating process using dimethyl sulfoxide (DMSO)/ethanol (EtOH) as co-dispersion solvent. Photocatalytic performance of P25-coated PAN fibers was evaluated by degrading a model dye rhodamine B (RhB) in aqueous solution under ultraviolet (UV) light irradiation. The preparation parameters of P25-coated PAN fibers were optimized by an orthogonal design, and were found to be a P25 concentration of 0.05g/L, a ratio of 85/15 (v/v) DMSO/EtOH, and a take-up speed of 0.5m/min. A possible mechanism of co-dispersion solvent dip coating was proposed based on Hansen solubility parameters' theory. The P25-coated PAN fibers prepared at the optimum conditions had high dye removal efficiency. They also showed an excellent cycling performance for dye removal of up to 99% recovery over several cycles. The coating process has little impact on both the fiber strength and the breaking strength. The breaking strength of P25-coated PAN fibers was maintained even after several cycles. This study provides an easy-to-scale-up method for preparing P25-coated PAN fibers. The obtained P25-coated PAN fibers show great potential as a low-cost, easy handling, and recyclable photocatalyst for dye effluent treatment.