Statistical optimization of Basic Blue 41 dye biosorption by Saccharomyces cerevisiae spent waste biomass and photo-catalytic regeneration using acid TiO2 hydrosol

AbtractFactorial experiments with five factors; stirring rate, process time and temperature, initial dye concentration and biosorbent dosage at three levels were conducted based on central composite design of experiments to investigate their effect on Basic Blue 41 dye biosorption onto bioethanol fermentation spent waste biomass of Saccharomyces cerevisiae. A highly statistically significant quadratic model at 95% confidence level (p < 0.0001,R20.9612andRadj20.9386) was developed to charcterize the influence of these variables on biosorption effeciency. Response surface methodology was employed to optimize the process, recording maximum biosorption % of ≈94% (23.5 mg/g) under static condition, within 14 h at 20 °C using 0.6% biosorbent in an initial dye solution of 150 mg/L. Approximately 92% of adsorbed dye was desorbed by elution with self-clean acid TiO2 hydrosol (pH 2) and the regenerated biosorbent was employed for four successive cycles. The photo-catalytic degradation of the desorbed dye under ultraviolet illumination (8 W) followed the pseudo first order kinetic model (R2 0.9687) with apparent rate constant Kapp of ≈0.0043 min−1. The proposed integrating biosorption with self-clean desorption and photo-catalytic degradation process, resulted in no secondary pollution in the form of any concentrated wastes, thus has important environmental and economic aspects.