Amputation of Remazol brilliant blue dye on crosslinked chitosan hydrogel: Statistical treatment and experimental evaluation.

The primary aim of this research is to comprehensively assess the applicability of chitosan biopolymer towards water treatment application and to enhance its adsorption capacity towards Remazol brilliant blue R-19 dye. This has been achieved through physical modification to obtain the material in hydrogel form and chemical modification by crosslinking it with barbituric acid. The characterization of the resulting Chitosan-barbituric acid hydrogel (CBH) was carried out using various analytical techniques such as SEM-EDX, FT-IR, TGA-DTA, XRD, and BET. CBH was employed as the adsorbent to eliminate R-19 dye from aqueous media. Utilizing response surface methodology (RSM), the parameters were fine-tuned, leading to the achievement of more than a 95% removal for R-19 dye. The adsorption behavior closely adhered to the Langmuir isotherm and pseudo-second-order kinetics. An interesting observation indicated that the rise in temperature leads to rise in adsorption capacity of CBH. The maximum adsorption capacities evaluated at 301.15 K, 313.15 K, 318.15 K, and 323.15 K were 566.6 mg g−1, 624.7 mg g−1, 671.3 mg g−1, and 713.5 mg g−1 respectively, in accordance with the Langmuir isotherm model. Examining the thermodynamics of the adsorption process revealed its spontaneous nature (ΔG = −21.14 to −27.09 kJ mol−1) across the entire temperature range. Furthermore, the assessment of the isosteric heat of adsorption (ΔH ads) was conducted using the Clausius–Clapeyron equation, with results indicating an increase in ΔH ads from 1.85 to 2.16 kJ mol−1 with temperature rise from 301.15 K to 323.15 K due to augmented surface loading. This suggested the existence of lateral interactions between the adsorbed dye molecules. The potential of adsorbent for regeneration was investigated, demonstrating the ability to reuse the material. Sustainability parameter calculated for synthesis process reflected a notably low E-factor value of 0.32 demonstrated the synthesis is environment friendly. [Display omitted] • Chitosan was crosslinked using barbituric acid to get hydrogel. • It was characterized and subjected to R-19 dye amputation. • The q m value was increased to 713.5 mg g−1at 323.15 K under optimum conditions. • RSM was used to optimize the pH, dose, time and concentration against temperature. • Studies of regeneration demonstrated that the adsorbent CBH is economically viable. [ABSTRACT FROM AUTHOR]