Chitosan coated cotton-straw-biochar as an admirable adsorbent for reactive red dye

• Published in: Results in engineering Vol. 15; p. 100515
• Main Authors: Doondani, Priyanka, Gomase, Vaishnavi, Saravanan, D., Jugade, R.M.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.09.2022; Elsevier
• Subjects: Adsorption; Chitosan-oxalic acid-biochar; Dyes; Reactive red 21; Water treatment; Water treatment; Chitosan-oxalic acid-biochar; Dyes; Adsorption; Reactive red 21
• ISSN: 2590-1230; 2590-1230
• DOI: 10.1016/j.rineng.2022.100515

Cotton straw generated biochar was coated with chitosan using oxalic acid as a crosslinking agent. This chitosan-oxalic acid-biochar composite was characterized and analyzed for adsorption of synthetic azo-dye Reactive Red 21. Batch as well as column studies in fixed bed mode were carried out. The monolayer adsorption capacity was found to be 125.1 mg g−1 at pH 5.0, with just 90 min of adsorption highlighting this as super-sorbent material. Langmuir as well as Redlich-Peterson isotherms exhibited best fit models with the experimental data. Kinetics studies suggested a pseudo second order adsorption process in agreement with Langmuir isotherm. The thermodynamics of adsorption disclosed the fact that process is purely enthalpy-driven, spontaneous, and exothermic in nature. The presence of biopolymer, organic cross-linker, and biowaste altogether in a single adsorbent material led to an excellent super-sorbent for the dye. The effect of cationic, anionic, and non-ionic surfactants on the adsorption efficiency has also been studied. •Super-sorbent chitosan oxalic acid biochar (COB) composite was synthesized.•First ever report of removal of RR-21 anionic dye.•The adsorption capacity was found to be 125.1 mg g−1•Langmuir and Redlich-Peterson isotherm model fitted best with experimental data.