Enhancing photocatalytic performance by immobilizing varying TiO2 contents on composite regenerated cellulose membrane: an environmentally reusable membrane

The composite regenerated cellulose membranes (CRCMs), a combination of regenerated cellulose membrane (RCM) with titanium dioxide (TiO₂), offer an effective solution for wastewater treatment by facilitating easy recovery and reuse of photocatalysts. In contrast to other synthesized polymer membranes, CRCMs not only ensure the good dispersion of TiO₂ but also exhibit excellent photoactivity and are made from eco-friendly materials. The fabrication process involved adding TiO₂ immediately after dissolving microcrystalline cellulose in a tetrabutylphosphonium hydroxide/dimethyl sulfoxide solution. The membranes were then cast and coagulated with propylene carbonate. The objective of this study was to optimize TiO₂ content per membrane and thoroughly investigate the resulting properties and photoactivity of the CRCMs. The X-ray analysis showed that CRCMs were successfully incorporated without change in the phase composition. By scanning electron microscopy images, as the TiO₂ content increased (from 0 to 20 mg), the membrane thickness increased in the order 63.1, 97.9, 110.5, 136.3, and 143.1 µm, respectively. Notably, when the content was 15 mg and 20 mg per membrane, TiO₂ agglomeration occurred, and the photocatalytic efficiency decreased. The CRCM with 10 mg TiO₂ (CRCM10) was considered the optimal membrane due to the highest permeability (16.3 L.m⁻².h⁻¹.bar⁻¹) and the best methylene blue (MB) removal ability (about 96% after 180 min of decomposition). Conversely, higher TiO₂ content proved unfavorable for photoactivity, with CRCM15 and CRCM20 showing significantly lower MB removal efficiencies of 59.7% and 42.2%, respectively. The reusability of CRCM10 was stable, maintaining an MB removal efficiency of 80% after four cycles. This research offers an environmentally friendly, cost-effective, and scalable approach for wastewater treatment.

Graphical abstract