Development of chitosan biopolymer by chemically modified orange peel for safranin O dye removal: A sustainable adsorbent and adsorption modeling using RSM-BBD

This study aimed to develop a biocomposite (hereinafter, CHI/OP-H2SO4) via the functionalization of chitosan (CHI) biopolymer by chemically modified orange peel (OP-H2SO4). The physicochemical characteristics of CHI/OP-H2SO4 were studied using methods such as pHpzc, XRD, FTIR, BET, and FESEM-EDX. The efficacy of the CHI/OP-H2SO4 biocomposite in removing cationic dye (safranin O, SAF-O) from aqueous solutions was assessed. The Box-Behnken Design (BBD) based on response surface methodology (RSM) was employed to optimize the adsorption performance of CHI/OP-H2SO4, considering factors such as A: CHI/OP-H2SO4 dose (0.02–0.08 g), B: pH (4–10), and C: time (10–60 min). The pseudo-first-order and Freundlich isotherm models align well with the experimental data of SAF-O adsorption by CHI/OP-H2SO4. The excellent adsorption capacity for CHI/OP-H2SO4 was recorded (321.2 mg/g). The notable adsorption of SAF-O onto CHI/OP-H2SO4 is attributed primarily to electrostatic forces between the acidic groups of CHI/OP-H2SO4 and the SAF-O cation, along with H-bonding, and n-π interactions. By transforming waste materials into valuable resources, this approach not only mitigates environmental impact but also produces a promising and sustainable adsorbent for the removal of cationic dyes, exemplified here by the effective removal of SAF-O dye. •A biocomposite of chitosan and functionalized orange peel with H2SO4 (CHI/OP-H2SO4) was synthesized.•The efficacy of the CHI/OP-H2SO4 in removing SAF-O dye was assessed.•BBD-RSM was employed to optimize the SAF-O dye adsorption.•The Freundlich isotherm model aligns well with the experimental data of SAF-O adsorption.•The excellent adsorption capacity for CHI/OP-H2SO4 was recorded (321.2 mg/g).