Application of chitosan/acid-treated biomass composite for dye wastewater treatment: Adsorption modeling using Box-Behnken Design

The use of chitosan polymer and acid-treated biomass composite as an eco-friendly and cost-effective solution for the removal of synthetic dyes from wastewater is a promising approach for sustainable wastewater treatment. The objective of the present investigation was to create a biocomposite (subsequently referred to as CHI/SFH-SA) by functionalizing chitosan (CHI) biopolymer with acid-treated biomass (sunflower husks-sulphuric acid (H 2 SO 4 ), SFH-SA). Methods such as pH pzc , XRD, CHNS-O, FTIR, BET, and FESEM were employed to investigate the physicochemical properties of CHI/SFH-SA. The CHI/SFH-SA biocomposite's ability to eliminate brilliant green (BG) dye from aquatic systems was evaluated. To optimize the adsorption efficacy of CHI/SFH-SA, the Box-Behnken Design (BBD) was implemented. The design took into account parameters such as A: CHI/SFH-SA dose (0.02–0.08 g), B: pH (4–10), and C: time (10–60 min). The BBD model results showed that an optimal pH of 9.2, a contact duration of 59.1 min, and a CHI/SFH-SA dosage of 0.061 g were found to be the most effective conditions for achieving maximal BG dye elimination (95.89 %). The Langmuir and Freundlich models agree with the experimental data on BG dye adsorption by CHI/SFH-SA. Negative ΔG° values (−10.67, −12.09, −13.51, −14.93 kJ/mol) indicate spontaneous adsorption. Endothermic adsorption can be estimated with a positive ∆H° value of 31.65 kJ/mol. The adsorption capacity of CHI/SFH-SA was 485.56 mg/g. H-bonding, n-π interactions, and electrostatic forces are the primary factors responsible for the significant adsorption of BG dye onto CHI/SFH-SA. This research offers an environmentally conscious and sustainable approach to fabricating effective adsorbents, thereby establishing a foundation for developing bioadsorbents derived entirely from bioresources (chitosan and biomass), which hold great promise as a substitute for cationic dye removal. ● A biocomposite (CHI/SFH-SA) was developed from chitosan (CHI) and sunflower husks-sulphuric acid (SFH-SA). ● The CHI/SFH-SA biocomposite's ability to eliminate brilliant green (BG) dye from aquatic systems was evaluated. ● The adsorption process of BG dye was optimized using the Box-Behnken Design (BBD). ● The Langmuir and Freundlich models are in good agreement with the experimental data of BG adsorption by CHI/SFH-SA. ● The adsorption capacity of CHI/SFH-SA was exceptional, with a value of 485.56 mg/g observed.