# Recent Advances in Bio-Based Fluorescent Hydrogels for Adsorption and Sensing of Toxic Heavy Metal Ions

## TL;DR

This review discusses bio-based fluorescent hydrogels for removing and detecting toxic heavy metals in water, highlighting their advantages and recent developments.

## Contribution

The paper provides a comprehensive review of recent advances in bio-based fluorescent hydrogels for adsorption and sensing of heavy metal ions.

## Key findings

- Bio-based hydrogels like cellulose, chitosan, and alginate are effective for adsorbing heavy metals.
- Fluorescent sensors in these hydrogels enable sensitive detection through fluorescence quenching.
- Challenges and opportunities for improving these hydrogels are identified for future research.

## Abstract

Rapid industrialization and global population growth have led to numerous environmental issues. Among these issues, water polluted with toxic heavy metal ions (HMIs) has become a serious problem. Of the various removal methods, adsorption is considered to be one of the most widely used for purifying wastewater due to its simple operation, high adsorption efficiency, low cost and broad applicability. Bio-based hydrogels are becoming increasingly popular for water purification due to the variety of fabrication and modification methods available. These hydrogels act as adsorption aggregators, increasing the local concentration of HMIs. Bio-based fluorescent hydrogels with fluorescent sensors could be further used to sensitively detect the HMIs, accompanied by an obvious fluorescence quenching. The non-radiative energy transfer between the fluorescent sensor and the adsorbed metal ions is responsible for the sensitive detection. In this review, the recent progress of bio-based fluorescent hydrogels for the adsorption and sensing of toxic HMIs is fully summarized. According to the natural hydrogel sources, the bio-based hydrogels, including cellulose-, chitosan-, alginate- and lignin-based hydrogels, are discussed separately. Finally, the challenges, suggestions and opportunities involved in developing novel bio-based fluorescent hydrogels for the adsorption and sensing of toxic HMIs are presented.