Effective adsorption of crystal violet dye on sugarcane bagasse-bentonite/ sodium alginate composite aerogel: Characterisation, experiments, and advanced modelling

A novel sugarcane bagasse-bentonite/sodium alginate (SCB-Ben/SA) composite aerogel was prepared as an effective green adsorbent via blending-cross-linking for the removal of crystal violet (CV) dye from aqueous solution. The equilibrium adsorption capacity of SCB-Ben/SA for CV was 839.9 mg/g at 0.8 mg/mL adsorbent dosage, temperature 303 K, pH 4, and 800 mg/L initial CV concentration, and presented a removal rate of 85%. Adsorption kinetics studied using the novel pseudo-first-order and pseudo-second-order (PFO-PSO) combined model showed that CV adsorption by SCB-Ben/SA was a complex process and did not include a single mecha-nism, but involved both chemical and physical adsorption reactions; however, chemisorption was the dominant kinetic mechanism. The dynamic characteristics of CV adsorption process achieved through the liquid film around SCB-Ben/SA and the pores inside SCB-Ben/SA was described satisfactorily and conveniently using the novel film-pore mass transfer (FPMT) model. A multilayer adsorption model was applied to further understand the CV adsorption behaviour of SCB-Ben/SA. The number of linked CV molecules per functional group varied from 0.53 to 0.63 for SCB-Ben/SA. The CV molecules were adsorbed on SCB-Ben/SA via mixed orientation. The adsorption isotherms and thermodynamics revealed that the multilayer adsorption process was endothermic and spontaneous. Overall, SCB-Ben/SA was found to be an efficient, low-cost, green, and recyclable adsorbent for organic dye removal.