Photocatalytic degradation of Congo red dye using innovative cerium titanate nanorods embedded in a cellulose-based hydrogel

This work used a simple technique to prepare a novel cerium titanate nano-rods embedded in a cellulose-based hydrogel with high photo catalytic degradation activity. The composite hydrogel was prepared by embedding different amounts of cerium titanate nano-rods (Ce/Ti-NRs) into a crosslinked carboxymethyl cellulose/polyacrylamide polyelectrolyte complex (CMC/PAM) as a matrix material. The physico-chemical properties of the Ce/Ti-NRs, CMC/PAM, and cerium titanate nano-rods embedded in a cellulose-based hydrogel (Ce/Ti-NRs/CMC/PAM) were investigated by FT-IR, XRD, BET, TEM, SEM, and EDX techniques. The photo-degradation efficiency of the prepared composite hydrogel was investigated for their ability to simultaneously adsorb-degrade Congo red dye (CR) under different conditions such as the dosage of composite hydrogel, dye solution pH and temperature, degradation time, initial dye concentration, and agitation rate. Also, the kinetics of the CR degradation process was evaluated. The obtained data fits well using pseudo-first order kinetic model with R2 equal to 0.911 and calculated equilibrium capacity value (22.44 mg/g) closer to the corresponding experimental values (23.193 mg/g) than those of pseudo-second order model with R2 equal to 0.888 and calculated equilibrium capacity value (34.78 mg/g). The linear plot of the intra-particle model indicated that the simultaneously adsorb-degrade of CR dye by the composite hydrogel is likely to be complex. It involves both film diffusion (boundary layer diffusion) and intra-particle diffusion. The optimum developed composite hydrogel shows high simultaneously adsorb-degrade photo catalytic activity superior to other published results as it degraded 91.68% of CR dye only after 90 min.