Histidine-conjugated chitosan as efficient adsorbent for Congo red dye elimination from aqueous solution

Area of Science:

• Materials Science
• Environmental Chemistry
• Polymer Chemistry

Background:

• Wastewater contamination by synthetic dyes poses a significant environmental challenge.
• Chitosan, a biopolymer, is extensively studied for its adsorption properties but often requires modification to enhance performance.
• Developing efficient and cost-effective adsorbents is crucial for dye removal from industrial effluents.

Purpose of the Study:

• To synthesize histidine-conjugated chitosan (His-Cs) via a facile two-step method.
• To characterize the synthesized His-Cs using advanced analytical techniques.
• To evaluate the adsorption performance of His-Cs for Congo Red (CR) dye removal from aqueous solutions.

Main Methods:

• Two-step synthesis involving l-histidine, epichlorohydrin, and chitosan in an alkaline medium.
• Structural and morphological characterization using FTIR, XRD, SEM, and EDS.
• Adsorption experiments to determine CR dye removal efficiency, isotherm, and kinetic models.

Main Results:

• His-Cs was successfully synthesized with a high yield of 96.5%.
• Characterization confirmed the successful conjugation of histidine onto the chitosan backbone.
• His-Cs exhibited exceptional adsorption capacity for CR dye, achieving 99.17% removal efficiency.
• Adsorption equilibrium followed the Temkin model, and kinetics were described by the Elovich model.
• The adsorption process was found to be endothermic.

Conclusions:

• Histidine-conjugated chitosan (His-Cs) is a highly effective adsorbent for removing Congo Red dye.
• The synthesized His-Cs demonstrates superior adsorption capabilities compared to unmodified chitosan.
• His-Cs presents a viable and efficient material for the treatment of dye-contaminated wastewater.