Cellulose mineralization with in-situ synthesized amorphous titanium dioxide for enhanced adsorption and auto-accelerating photocatalysis on water pollutant

It is a daunting task to balance the catalyst stability and exposure of active site of highly efficient immobilizing photocatalyst system for wastewater treatment. In this study, an in-situ mineralization method based on homogeneous system was proposed to directly construct amorphous TiO2 into cellulose hydrogel network as the crosslinker for efficiently and safely processing wastewater. This unique structure not only endowed TiO2/cellulose microsphere (TMS) with an adsorption capacity of 91.7 mg/g on methylene blue, which was approximately 14 times to cellulose microsphere containing commercial TiO2 nanoparticles, but also made TMS reusable due to its pH sensitive adsorption capacity. More interestingly, TMS exhibited an auto-accelerating process in decomposing Rhodamine B where the degradation intermediate could act as the receptor of photo-regenerated holes to improve photocatalytical activity. In further cyclic test, the degradation rate constant of intermediate-adsorbed TMS was up to 0.02 mg−1min−1. Moreover, the intermediate-adsorbed TMS obtained visible light responsive property, including a removal ratio of 86.3 % against tetracycline (c0 = 20 mg/L) in 120 min. This in-situ cellulose mineralization provides a new sight into the design of hydrogel immobilized catalyst system with high dispersion and active site exposure for efficient and safe water treatment.