Bionanocomposite Hydrogel for the Adsorption of Dye and Reusability of Generated Waste for the Photodegradation of Ciprofloxacin: A Demonstration of the Circularity Concept for Water Purification

Abstract

Adsorption has emerged as a simple and economical approach to water decontamination; however, it creates large amounts of secondary toxic waste following the removal of the effluents from the water. The present investigation introduces an innovative circular approach that tackles the serious problem of environmentally toxic secondary waste. Herein, TiO 2 nanorods (NRs) and a functionalized gum ghatti (Gg) biopolymer-based bionanocomposite hydrogel (TGB-hydrogel) were synthesized by free-radical graft polymerization and used to remove brilliant green (BG), which is a toxic dye. The dye-adsorbed TGB-hydrogel waste was then processed at 550 °C for 3 h and re-employed for the photocatalytic degradation of the antibiotic ciprofloxacin (CIP), after which the spent photocatalyst was reinstated for the adsorption of BG dye to complete the cycle. The ability of the TGB-hydrogel to adsorb the dye was studied in detail by varying the adsorbent dosage, initial dye concentration, pH, and temperature. Adsorption kinetics followed a pseudosecond-order kinetics model, whereas the adsorption isotherm followed the Langmuir isotherm model with a maximum adsorption capacity of 740.97 mg g −1 . The thermodynamic studies highlighted that the adsorption process was endothermic in nature. Furthermore, the obtained photocatalyst exhibited high photocatalytic efficiency, with 88.7% CIP degradation over 180 min due to a recombination delay of charge carriers, high light absorption, and the high surface area (179.33 m 2 g −1 ). The introduced circular approach concept is envisaged to be applicable to other processes that need to avoid unwanted secondary waste.

Enhanced Thermo‐Mechanical Stiffness, Thermal Stability, and Fire Retardant Performance of Surface‐Modified 2D MoS2Nanosheet‐Reinforced Polyurethane Composites

“…In C 1s scan, peaks located at 284.6, 286.2, and 288.4 eV can be ascribed to C‐C/C‐H, C‐O‐C/C‐OH, and COOH, respectively. Moreover, peaks at 533.1 and 531.7 eV in O 1s spectrum arises form C‐O and CO groups (Figure S2, Supporting Information) . This indicates the presence of PEG molecules on the surface of MoS 2 and possibly oxidation of some PEG molecules occurred during the reaction.…”

“…Moreover, peaks at 533.1 and 531.7 eV in O 1s spectrum arises form C-O and CO groups ( Figure S2, Supporting Information). [29] This indicates the presence of PEG molecules on the surface of The XRD experiments were conducted to investigate the structural features of MoS 2 , M-MoS 2 , and their PU composites. Figure 5 shows the XRD patterns of MoS 2 , M-MoS 2 , pristine PU, and PU/MoS 2 and PU/M-MoS 2 composites of various compositions.…”

Preparation and Flocculation Property of Cationic Chitosan‐DADMAC‐β‐Cyclodextrin Copolymer

“…This is due to the fact that more amine groups in chitosan are protonated at low pH, which increases the cationic strength of CDC and enhances the attraction to anionic dyes. [24,40,41] Moreover, at the optimal CDC dosage, the removal ratio of AB172 could reach more than 90% and the removal ratio of RO could reach more than 80% at pH 4 ∼ 10, which indicate that CDC can maintain a good flocculation effect in a wide pH range.…”

Tragacanth Hydrogel Integrated CeO2@rGO Nanocomposite as Reusable Photocatalysts for Organic Dye Degradation

“…Lately, the increasing demand for textile industries has accelerated the release of toxic dye waste‐water in the environment, which poses a considerable threat to human health and aquatic ecosystem . It is estimated that annually, ∼7×10 5 tons of textile dye is released in the waste‐water . Since most of these are non‐biodegradable in nature, different methods for waste‐water remediation have been developed, namely, ultrafiltration, adsorption, photocatalytic degradation, flocculation, coagulation, ion‐exchange etc .…”