Temperature Dependent Study for the Sequestration of Reactive Dye on the p-Nitrobenzaldehyde Grafted Chitosan Aerogel: A Novel Approach to Sustainable Dye Management
摘要
In this study, a novel p-nitrobenzaldehyde grafted chitosan (PNBgCs) aerogel was synthesized and evaluated for its effectiveness in removing Reactive Red 21 (RR-21) dye from contaminated water. Adsorption experiments were performed at temperatures of 300 K, 313 K, 318 K, and 323 K, under optimized conditions of pH 6.0 and 60-min contact time. The results revealed maximum adsorption capacities of 297.06 mg g−1, 301.80 mg g−1, 324.63 mg g−1, and 340.11 mg g−1 at increasing temperatures, indicating a temperature-dependent enhancement in adsorption capacity. This behaviour suggested that the adsorption process was endothermic. Response surface methodology was applied to validate the experimental data. The data fit well with the Freundlich isothermal model (R2 = 0.972), indicating a heterogeneous adsorption surface. The data also followed a pseudo-second-order kinetic model (R2 = 0.945). Thermodynamic studies supported the endothermic and entropy-driven nature of the adsorption, with isosteric heat values exceeding 40 kJ mol−1, confirming a chemisorptive mechanism. The PNBgCs aerogel demonstrated excellent reusability, maintaining over 90% adsorption efficiency after five cycles. Real water sample analysis showed 85.43% RR-21 removal from wastewater from Siyaram Textile Industries and 81.28% from Raymond MIDC samples. Sustainability assessments highlighted its low E-factor of 0.02, underscoring its eco-friendliness and economic viability. Overall, PNBgCs aerogel demonstrates high adsorption efficiency, reusability, and cost-effectiveness, establishing it as a promising candidate for sustainable wastewater treatment applications.