Desirability numerical optimisation for cationic dye removal by Schiff base chitosan-glyoxal/microalgae/titanium...

Herein, Microalgae (Ma) and Titanium dioxide (TiO₂) were integrated to modify the matrix of Schiff base crosslinked chitosan-glyoxal (Chi-Gly) via hydrothermal process to produce a Schiff base chitosan-composite derivative adsorbent (Chi-Gly/Ma/TiO₂). The modified composite of Chi-Gly/Ma/TiO₂ was applied for cationic dye (Brilliant green, BG) removal. The functional groups, crystallinity, surface porosity, morphological features, and surface charge of Chi-Gly/Ma/TiO₂ were investigated utilising FTIR, XRD, BET, FE-SEM/EDX, and pH_pzc analyses, respectively. The Response surface methodology-Box-Behnken design (RSM-BBD) was employed for optimisation of three input parameters' impact (A: Chi-Gly/Ma/TiO₂ dosage (0.05-0.2 g/100 mL), B: pH (4-9), and C: contact time (30-180 min)) on BG dye removal response and the desirability function was employed to determine the optimal parameter values (Chi-Gly/Ma/TiO₂ dose = 0.2 g/100 mL; pH = 4.1; time = 180 min). Chi-Gly/Ma/TiO₂'s adsorptive performance was well identified using pseudo-second order (PSO) kinetic and Langmuir isotherm models (with a maximum monolayer adsorption capacity of 88.3 mg/g) signifying that the adsorption of BG by Chi-Gly/Ma/TiO₂ occurs on the surface layer of the adsorbent and mainly through chemisorption. The overall results of this research demonstrate that the produced Chi-Gly/Ma/TiO₂ composite absorbent has a high potential as an eco-friendly adsorbent for cationic BG dye removal.