| Summary: | Herein, a novel biomaterial of crosslinked chitosan-glutaraldehyde combined with Bacillus subtilis biomass (CHS-GLU/BCL) was synthesized via hydrothermal synthesis to effectively remove the anionic dye (Acid red 88; AR88) from synthetic wastewater solution. The physicochemical properties of the CHS-GLU/BCL biomaterial were characterized using XRD, SEM-EDX, FTIR and pHpzc studies. To optimize the adsorption efficiency of CHS-GLU/BCL for AR88 dye removal, a Box-Behnken design (BBD) was utilized. The experiment utilized three independent variables including, the dosage of CHS-GLU/BCL (A: 0.02–0.1 g/100 mL), the contact time (B: 5–30 min), and the pH of the AR88 solution (C: 4–10). The investigation of adsorption kinetics confirms that the AR88 dye adsorption onto the CHS-GLU/BCL biomaterial mainly follows the pseudo first order (PFO) versus the pseudo second order (PSO) kinetic model. Moreover, the isotherm data fits the Langmuir isotherm model with R2 of 0.98. The maximum monolayer adsorption capacity (qmax) of AR88 dye onto CHS-GLU/BCL biomaterial was determined to be 148 mg/g at acidic pH conditions (pH = 4.2). The adsorption mechanism of AR88 and dye onto the biomaterial surface can be related to many contributions, such as hydrogen bonding, n-π interactions, and electrostatic attraction. A reusability study indicated that the CHS-GLU/BCL adsorbent successfully adsorbed AR88, where the reduced adsorption across five cycles is related to structural changes of the biocomposite. Hence, the biomaterial CHS-GLU/BCL has a good affinity for adsorbing anionic dye species from aqueous media. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2024.
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