Functionalized agarose hydrogel with in situ Ag nanoparticles as highly recyclable heterogeneous catalyst for aromatic organic pollutants

Green synthesis of chitosan/glutamic acid/agarose/Ag nanocomposite hydrogel as a new platform for colorimetric detection of Cu ions and reduction of 4-nitrophenol

In this study, the green synthesis of chitosan/glutamic acid/agarose/Ag (Chi/GA/Aga/Ag) nanocomposite hydrogel was obtained via in situ reduction of Ag ions during the crosslinking process of chitosan-agarose double network hydrogels. The rich hydroxyl, carboxyl and amino groups in both agarose, chitosan, and glutamic acid can effectively control the growth, dispersion and immobilization of nearly spherical Ag nanoparticles (70 nm) in the Chi/GA/Aga/Ag composite hydrogel. Glutamic acids can act as the structure-directing agents to induce the formation of chitosan/glutamic acid hydrogel. The mechanical strength of the Chi/GA/Aga/Ag composite hydrogel can be enhanced by the introduction of chitosan-agarose double network hydrogels, which guarantees that it can be directly used as a visual test strip of the Cu ions with a lower detection limit of 1 μM and an active catalyst for the reduction of 4-nitrophenol within 18 min. The quantitative and semi-quantitative measurement of Cu ions can be carried out by UV-visible absorption spectroscopy and visual measurement, which provided a convenient, portable, and "naked-eye" solid-state detection methodology.

Advances in gum-based hydrogels and their environmental applications

Gum-based hydrogels (GBHs) have been widely employed in diverse water purification processes due to their environmental properties, and high absorption capacity. More desired properties of GBHs such as biodegradability, biocompatibility, material cost, simplicity of manufacture, and wide range of uses have converted them into promising materials in water treatment processes. In this review, we explored the application of GBHs to remove pollutants from contaminated waters. Water resources are constantly being contaminated by a variety of harmful effluents such as heavy metals, dyes, and other dangerous substances. A practical way to remove chemical waste from water as a vital component is surface adsorption. Currently, hydrogels, three-dimensional polymeric networks, are quite popular for adsorption. They have more extensive uses in several industries, including biomedicine, water purification, agriculture, sanitary products, and biosensors. This review will help the researcher to understand the research gaps and drawbacks in this field, which will lead to further developments in the future.