Bacillus subtilis bacteria @ chitosan biopolymer for Reactive Orange 16 dye removal: multivariable optimization and desirability functions by response surface methodology

• Published in: BIOMASS CONVERSION AND BIOREFINERY
• Main Authors: Agha, Hasan M.; Wu, Ruihong; Jawad, Ali H.; Alothman, Zeid A.
• Format: Article; Early Access
• Language: English
• Published: SPRINGER HEIDELBERG 2025
• Subjects: Energy & Fuels; Engineering
• Online Access: https://www-webofscience-com.uitm.idm.oclc.org/wos/woscc/full-record/WOS:001423083000001
• ISSN: 2190-6815; 2190-6823
• DOI: 10.1007/s13399-025-06626-1

In this work, chitosan (CHS) carbohydrate biopolymer was modified with biomass of Bacillus subtilis bacteria (BCLS) to produce a new biocomposite adsorbent (CHS@BCLS). Several analyses including XRD, FTIR, SEM-EDX, and pHpzc were utilized to investigate the properties of CHS@BCLS. The applicability of CHS@BCLS as an effective adsorbent was evaluated towards removal of toxic textile dye namely Reactive Orange 16 (RO16) from aqueous environment. A statistical modeling using Box-Behnken design (BBD) was implemented to optimize the CHS@BCLS efficacy in adsorbing RO16 dye. Thus, three independent parameters were involved in the experiment such as the dose of CHS@BCLS (A, 0.02-0.1 g/100 mL), the contact time (B, 20-180 min), and the RO16 solution pH (C, 4-10). The kinetic study confirms that the adsorption of RO16 through the CHS@BCLS biocomposite follows a pseudo-second order (PSO). Furthermore, Freundlich isotherm model was the best model to describe the isotherm data, and the calculated maximum adsorption capacity of CHS@BCLS biocomposite (qmax) was recorded to be 120 mg/g. The biosorption of RO16 by the CHS@BCLS biocomposite is facilitated by several pathways including electrostatic forces, n-pi interactions, and hydrogen bonding. Hence, the output of this research work shows the effectiveness of the CHS@BCLS biocomposite towards removal of toxic textile dyes from contaminated water.