Hydrogel-Based Adsorbent Material for the Effective Removal of Heavy Metals from Wastewater: A Comprehensive Review

Abstract

Water is a vital resource that is required for social and economic development. A rapid increase in industrialization and numerous anthropogenic activities have resulted in severe water contamination. In particular, the contamination caused by heavy metal discharge has a negative impact on human health and the aquatic environment due to the non-biodegradability, toxicity, and carcinogenic effects of heavy metals. Thus, there is an immediate need to recycle wastewater before releasing heavy metals into water bodies. Hydrogels, as potent adsorbent materials, are a good contenders for treating toxic heavy metals in wastewater. Hydrogels are a soft matter formed via the cross-linking of natural or synthetic polymers to develop a three-dimensional mesh structure. The inherent properties of hydrogels, such as biodegradability, swell-ability, and functionalization, have made them superior applications for heavy metal removal. In this review, we have emphasized the recent development in the synthesis of hydrogel-based adsorbent materials. The review starts with a discussion on the methods used for recycling wastewater. The discussion then shifts to properties, classification based on various criteria, and surface functionality. In addition, the synthesis and adsorption mechanisms are explained in detail with the understanding of the regeneration, recovery, and reuse of hydrogel-based adsorbent materials. Therefore, the cost-effective, facile, easy to modify and biodegradable hydrogel may provide a long-term solution for heavy metal removal.

Cellulose-based hydrogel for adsorptive removal of cationic dyes from aqueous solution: isotherms and kinetics

“…Swelling ratio (SR) is controlled by the porosity and chemical functionality of the adsorbent. 39 The hydrophilic nature of the chitosan (–NH 2 group) and NCC (–OH group) is responsible for the initial rise in the SR. The SR of the hydrogel beads gradually increased from 55 to 83% and attained the equilibrium after 8 h (Fig.…”

Formulation and Evaluation of Chitosan-Gelatin Thermosensitive Hydrogels Containing 5FU-Alginate Nanoparticles for Skin Delivery

“…The 5FU solution and 5FU-Alg-Np-loaded chitosan-gelatin-based hydrogels were prepared. Chitosan and gelatin solutions when mixed together, electrostatic interaction occurs, which results in interpenetrating self-assemble soft aqueous pores as a result of amide bonds formation [ 37 ]. These soft pores were filled with 5FU solution and/or 5FU-Alg-Np to form drug-loaded hydrogels.…”

Recent Advances in Adsorptive Nanocomposite Membranes for Heavy Metals Ion Removal from Contaminated Water: A Comprehensive Review

“…Numerous attempts have been undertaken in the field of wastewater treatment using hydrogels. In the majority of studies, research concentrated on the capacity of hydrogels to remove organic poisonous dyes and inorganic hazardous heavy metal ions, with a current emphasis on emerging contaminants [ 42 , 44 ].…”