Preparation and Characterization of a New Bis-Uracil Chitosan-Based Hydrogel as Efficient Adsorbent for Removal of Anionic Congo Red Dye

Abstract

A new hydrogel, based on chitosan crosslinked with 2-chlorophenyl-bis(6-amino-1,3-dimethyluracil-5-yl) methane, (2Clph-BU-Cs), has been successfully created. Various instrumental techniques such as elemental analysis, FTIR, SEM, and XRD were used to prove its structure. Its removal efficiency for anionic Congo red (CR) dye under different conditions for industrial wastewater treatment was studied. For optimizing the conditions to maximize CR dye removal, the impacts of temperature, contact time, pH, and initial concentration of the dye on adsorption capacity were investigated. The removal of the dye was pH-dependent, with a much higher value achieved at pH 4 than at pH 7 and 9. The maximum adsorption capacity of the hydrogel was 93.46 mg g−1. The model of adsorption process was fitted to the pseudo-second-order kinetic model. The intraparticle diffusion demonstrated the multi-step nature of the adsorption process. The thermodynamic results showed that the adsorption process was endothermic because of the positive value of enthalpy (43.70 kJ mol−1). The process of adsorption at high temperatures was spontaneous, according to the values of ∆G0. An increase in randomness was seen in the value of ∆S°. Generally, the investigated hydrogel has the potential to be used as a promising effective reusable adsorbent for industrial wastewater remediation.

Biodegradable Polymers in Biomedical Applications: A Review—Developments, Perspectives and Future Challenges

“…Scientists appreciate chitosan for its properties and are betting on its use especially in tissue engineering as a scaffold for subcutaneous tissues. Chitosan exhibits high biocompatibility with tissues, is biodegradable, non-toxic and above all shows antimicrobial properties [37][38][39][40][41]. It is slightly less commonly used in drug delivery systems because it is difficult to solubilize in body fluids [41].…”

Enhanced Redox Cycle of Rod-Shaped MIL-88A/SnFe2O4@MXene Sheets for Fenton-like Degradation of Congo Red: Optimization and Mechanism

“…The pH of the catalytic medium significantly impacts the Fenton-like degradation aptitude of CR dye; therefore, the degradation process was scrutinized in a wide pH scale (3)(4)(5)(6)(7)(8)(9)(10)(11) for 30 min, as demonstrated in Figure 4b. It was deduced that a highly acidic medium is the best pH medium to degrade CR since its degradation% was 94.54% after 30 min at pH = 3.…”

“…The chemical structure complexity of CR endows it with superhigh stability in aquatic media and high degradation resistance [ 6 ]. Consequently, purification strategies have been instigated and progressed to conquer the hazard of CR, including precipitation, flocculation, biodegradation, adsorption, ozonation, and advanced oxidation processes (AOPs) [ 7 , 8 , 9 , 10 ].…”

Poly (Vinyl Alcohol) Hydrogels Boosted with Cross-Linked Chitosan and Silver Nanoparticles for Efficient Adsorption of Congo Red and Crystal Violet Dyes

“…Thus, it should be chemically modified to improve its stability in acidic media and make it a superb option as an adsorbent for dyes. Modification was achieved via the insertion of functional groups into its structure [12,13]; via grafting using functionalizing monomers [14]; through the polymer blending [15]; and via the incorporation of chemical cross-linkers [16][17][18].…”