Current World Environment

Chitosan-Based Hydrogels for Sustainable Wastewater Treatment: A Comprehensive Review on Dye and Heavy Metal Removal

Anju Sangwan¹ , Sarita Singh² and Jyoti Rani¹ ^*

¹ Centre of Excellence for Energy and Environmental Studies, Deenbandhu Chhotu Ram University of Science and Technology, Murthal, Sonepat, Haryana India

² Department of Biomedical Engineering, Deenbandhu Chhotu Ram University of Science and Technology, Murthal, Sonepat, Haryana India

Corresponding author Email: jyoti.energy@dcrustm.org

DOI: http://dx.doi.org/10.12944/CWE.20.3.3

Abstract

Rapid industrialization increases water contamination from synthetic dyes (Congo red, Crystal violet, etc.) and heavy metals (Pb²+, Cd²+, etc.), driving the need for more efficient water treatment methods to address these contaminants. This review highlights recent breakthroughs in chitosan hydrogel material as an advancement in wastewater treatment methods. Biopolymers have been observed to have a substantial ability to absorb liquids, owing to their -OH, -NH2, and -COOH functional groups, which enable electrostatic interactions, hydrogen bonding, and ion exchange. In quantitative analysis, it is well established that chitosan hydrogels exhibit adsorption capacities ranging from 263.2 mg/g to 1492.95 mg/g for various dyes, including Methylene Blue, Congo Red, Tartrazine, and Basic Red 46, with removal efficiencies of 89%-99%. An adsorption capacity of 61.4 mg/g to 458.7 mg/g is seen for heavy metal ions such as Pb²+, Cd²+, Cu²+, and Cr6+ at an efficacy of removal of above 90% of all optimized systems. Modified chitosan hydrogels containing cellulose, bentonite, lignin, graphene oxide, and halloysite nanotubes have been shown to exhibit increased strength, porosity, and recyclability, with efficacy above 80% after five adsorption-desorption cycles. Kinetics indicate a pseudo-second-order process, thereby indicating that a large number of adsorptions are of a chemical nature. The concentration-equilibrium data were best fit by a Langmuir isotherm, indicating a single-layer adsorption process. In thermodynamic studies, it was concluded that the adsorption of all materials is an endothermic and spontaneous process. This analysis critiques recent breakthroughs in efficacy, working mechanisms, and practical feasibility of chitosan hydrogels in wastewater treatment systems.

Keywords

Adsorption; Chitosan; Dye; Hydrogels; Heavy Metal; Wastewater Treatment

Copy the following to cite this article:

Sangwan A, Singh S, Rani J. Chitosan-Based Hydrogels for Sustainable Wastewater Treatment: A Comprehensive Review on Dye and Heavy Metal Removal. Curr World Environ 2025;20(3). DOI:http://dx.doi.org/10.12944/CWE.20.3.3

Copy the following to cite this URL:

Sangwan A, Singh S, Rani J. Chitosan-Based Hydrogels for Sustainable Wastewater Treatment: A Comprehensive Review on Dye and Heavy Metal Removal. Curr World Environ 2025;20(3).

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