Decolorization of crystal violet from aqueous solutions by a novel adsorbent chitosan/nanodiopside using response surface methodology and artificial neural network-genetic algorithm.

A novel adsorbent of chitosan/nanodiopside nanocomposite (CS-NDIO) was synthesized as a green composite for the removal of crystal violet (CV) and characterized by techniques like XRD, FT-IR, BET, and FESEM analysis. The influence of parameters like molar ratios of CS to NDIO, initial pH of the solution, dosage of adsorbent, initial concentration of CV and contact time was investigated and evaluated by central composite design (CCD; 5 levels and 4 factors). Also, Hybrid model of (ANN) model with genetic algorithm (GA) optimization was applied to the experimental data get through CCD. The optimized molar ratio of CS-NDIO was found: 20/80. Optimal parameter choice for maximum CV adsorption process using CCD and ANN-GA were as follows: pH = 7.50 and 7.499, adsorbent mass: 0.0077 and 0.0077, CV concentration: 20.000 and 20.002 mg/L, and contact time: 25.00 and 25.00 min, respectively. The evaluation adsorption equilibrium and kinetic data were fitted with the Langmuir monolayer isotherm model (qmax : 104.66 mg g-1 and R2 : 0.9937) and pseudo-second order kinetics mechanism (R2 : 0.9978). Thermodynamic parameters (R2 : 0.9180, ΔH°: -74.93 kJ mol-1 , ΔG°: -12.89 kJ mol-1 , and ΔS°: 0.93 kJ mol-1  K-1 ) were calculated and indicating adsorption to be an exothermic and spontaneous process.