Enhancement of adsorption of Congo red dye onto novel antimicrobial trimellitic anhydride isothiocyanate-cross-linked ch
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Enhancement of adsorption of Congo red dye onto novel antimicrobial trimellitic anhydride isothiocyanate‑cross‑linked chitosan hydrogels Nadia A. Mohamed1,2 · Nouf F. Al‑Harby2 · Mawaheb S. Almarshed3 Received: 21 June 2019 / Revised: 8 October 2019 / Accepted: 8 December 2019 © Springer-Verlag GmbH Germany, part of Springer Nature 2019
Abstract The removal of the dyes from industrial wastewater is one of the main environmental requirements. In this work, three trimellitic anhydride isothiocyanate-crosslinked chitosan hydrogels, previously reported as novel antimicrobial agents, have been investigated for the first time as adsorbents for anionic Congo red (CR) dye from its aqueous solution. The hydrogels behave as polycationic materials. Their adsorption capacity for the CR dye increased significantly with increasing the temperature, with decreasing the solution pH and with an increase in their contents of cross-linking. Their adsorption fitted to the pseudo-second-order kinetic model. The adsorption isotherms conform to the Langmuir model with a maximum sorption capacity of 63.05 mg g−1 and removal efficiency of 96.59%. The results proved that the sorption process is remarkably controlled by chemisorption phenomenon. Based on the data of adsorption thermodynamics, the adsorption is an endothermic process. The regeneration and the reuse of the hydrogels were possible. Thus, incorporation between chitosan and the functional groups of the cross-linker into the same structure is efficiently enhanced the features of chitosan. It is a good manner for achieving appropriate systems as efficient adsorbents that can be considered as favorable candidates in the field of acidic dye removal. Keywords Functional chitosan hydrogels · CR dye · Adsorption characteristics
* Nadia A. Mohamed [email protected] 1
Department of Chemistry, Faculty of Science, Cairo University, Giza 12613, Egypt
2
Department of Chemistry, College of Science and Arts, Qassim University, Qassim, Saudi Arabia
3
Department of Chemistry, College of Science, Qassim University, Qassim, Saudi Arabia
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Polymer Bulletin
Introduction Textile, rubber, leather, plastic and paper industries discharge considerable amounts of wastewater effluents containing several kinds of synthetic dyestuffs. These dyes clearly appear in water even if they are at very low concentrations. This leads to an unacceptable coloration of the water, blocks the aquatic plants from sunlight that is essential for the photosynthesis process and also affects human life due to their allergic and carcinogenic effects [1–3]. Synthetic dyes are characterized by their chemical, physical, optical and thermal stabilities. This may be attributed to their complicated structures that resist effectively their degradation [4]. From an environmental point of view, the removal of these dyestuffs from their wastewater effluents before discharging into the environment is extremely essential. Industrial wastewater can be treated with several conventional physicochemical techni
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