Chitosan-nTiO₂ Nanocomposite Synthesis and its Adsorptive Removal Capacity for Methylene Blue from its Aqueous Solution: Batch Adsorption Study and Modeling

The current work used chitosan (CS)-nTiO(2) nanocomposites (CTNCs) prepared with different CS:nTiO(2) mass ratios toward the MB dye removal from an aqueous medium in batch method at variable experimental conditions. The stability and competence of the nanocomposites were checked through characterization by SEM, FTIR, XRD, TGA, and BET. The highest removal of MB was 78 % with the adsorbent CS without nTiO(2) (CWT), 94.5 % with CS:nTiO(2)=1 : 1 weight ratio (CTNC1-1) and 80 % with CS:nTiO(2)=2 : 1 weight ratio (CTNC2-1) with 10 mgL(-1)of MB and 5 gL(-1) adsorbent dosages. The experimental observations obeyed the pseudo-2(nd)-order model, and rate-limiting steps were film diffusions for CWT, CTNC1-1 and intraparticle diffusion for CTNC2-1. Monolayer adsorption was established from the isotherm model. Langmuir adsorption capacities for MB were presented as CTNC1-1 (q(L)=34.31)>CTNC2-1 (q(L)=32.87)>CWT (q(L)=21.32). The sorption energy, as derived from Dubinin-Radushkevich isotherm model, showed physisorption for all three adsorbents. The scale-up design is reported. The statistical (R-2>0.98) and GA modeling (R-2>0.98) successfully predicted the percentage elimination of MB. Thus, CS-nTiO(2) nanocomposites are prepared as novel and environment-friendly adsorbents for dye removal.