Transformation of household waste-watermelon rind into high-performance adsorbents: A low-cost and green strategy for dye removal

With the escalating severity of water pollution, developing safe and effective pollutant removal strategies has become an urgent priority. Consequently, numerous adsorbents have been synthesized and prepared. However, artificial synthesis inevitably involves the use of toxic components or solvents. In recent years, biomass-based materials have garnered significant attention due to their advantages of being non-toxic, harmless, abundantly available and low-cost. Several biomass-based adsorbents have already been developed and employed for pollutant adsorption. Nevertheless, to endow these biomass materials with high adsorption performance, modification methods such as crosslinking, pore creation, chemical grafting, and carbonization are widely applied. And these processes often involve the introduction of hazardous substances or require high energy consumption. Here, we present a facile and eco-friendly approach to fabricate porous and efficient aerogel adsorbents from biomass waste-watermelon rind, not only avoiding secondary contamination by using entirely green materials, but also circumventing energy-intensive processing procedures. The prepared watermelon rind aerogels demonstrate competitive adsorption performance for dyes and metal ions. Mechanistic analysis reveals that electrostatic interaction, π-π conjugation and hydrogen bonding between polar functional groups on the aerogel surface and target pollutants governs the adsorption process, while its hierarchical porous structure facilitates efficient pollutant transport and immobilization. By transforming household waste into a high-performance adsorbent, this work offers a sustainable and cost-effective solution for water purification, with significant potential for practical environmental applications.