Conventional and sonication-assisted biosorption of Remazol Orange RGB dye by active kefir biomass

Abstract

Purpose: To investigate the enhancement of the dye removal efficiency of the active kefir biomass with the assistance of sonication. Theory and Methods: SEM, FTIR and BET analyses were used to characterise the kefir biomass. Conventional and sonication assisted biosorption experiments were carried out simultaneously in batch mode. Kinetic data were analysed using pseudo-first order, pseudo-second order, intraparticle diffusion and Elovich kinetic models to determine the biosorption kinetics. Freundlich, Langmuir and Temkin isotherm models were used to further analyse the biosorption mechanism. Results: Biosorption of dye increased with the rise in temperature and the decrease in initial pH and initial concentration of dye in both processes. At all examined process conditions due to the assistance of sonication higher biosorption yields were obtained and the time for biosorption to reach equilibrium was significantly reduced. 74.62% and 95.18% dye removals were achieved at pH 2, initial dye concentration of 100 mg L-1 and 25 degrees C for conventional and sonication assisted biosorption that the equilibrium was attained respectively in 210 and 45 minutes. Modelling studies showed that the biosorption kinetics of dye by conventional and sonication assisted process could be expressed respectively with the pseudo-first and pseudo-second order models, while the biosorption equilibrium for both processes could be expressed with the Langmuir isotherm model that gives maximum bioaccumulation capacities of 90.33 and 107.99 mg/g for the conventional and sonication assisted methods. Thermodynamic analysis confirmed that biosorption processes are spontaneous, favorable and endothermic. Conclusion: The results demonstrated that the kefir biomass is an effective biosorbent for dye removal and sonication is an effective and useful method to improve the biosorption processes with living organisms.