Simultaneous removal of rhodamine B and Cr(VI) from water using cellulose carbon nanofiber incorporated with bismuth oxybromide: The effect of cellulose pyrolysis temperature on photocatalytic performance.

A series of biomass cellulose-derived carbon nanofibers (CCNF) were prepared at different pyrolysis temperatures in this study. Subsequently, this CCNF was combined with bismuth oxybromide (BiOBr) to form BiOBr/CCNF composite. The feasibility of BiOBr/CCNF as photocatalyst was investigated for the treatment against organic dye, rhodamine B (RhB) and inorganic metal ion, hexavalent chromium (Cr(VI)). The effect of the pyrolysis temperature on the properties (e.g., crystalline structure, functional group distribution, and graphitization degree) of the prepared CCNF was investigated in relation to its photocatalytic performance. A pyrolysis temperature over 800 °C resulted in CCNF with higher degrees of graphitization which was accompanied by a better photocatalytic performance of its composite against RhB and Cr(VI). Their reaction kinetic rates were estimated as 8.15 × 10-2 and 0.21 mmol/g/h, respectively (at the initial concentration of 10 mg/L), while their quantum yield values were 1.56 × 10-6 and 3.83 × 10-6 molecules per photon, respectively. BiOBr/CCNF catalysts were efficient enough to simultaneously remove RhB and Cr(VI) through the generation of active oxidative and reductive oxygen species, respectively. The strategies used in this study offer a new pathway for preparing cost-effective photocatalysts with biomass derived carbonaceous materials for the efficient removal of multicomponent contaminants in water.