Pristine micro-mesoporous chitosan beads constructed by molecular-cluster template method with excellent adsorption...

The structural flexibility of Natural biopolymer chitosan (CS) brings challenges to preparing pristine CS adsorbents with high specific surface area and outstanding adsorption performance, thereby limiting their application in the adsorption field. This study combined the droplet method with an innovative molecular cluster template strategy to develop a series of pristine chitosan beads (CSBs) with high specific surface area and approximate micropore structures. The prepared CSBs possess the capability to selectively and efficiently adsorb anionic dyes (Acid Chrome Blue K (ACBK) and Sunset Yellow (SY)) in neutral water. Notably, the maximum adsorption capacities of CSB-21 for ACB-K and SY reached to 934.7 mg/g and 898.0 mg/g, respectively. The adsorption processes of dyes on CSB absorbents are in accordance with spontaneous, endothermic, monolayer adsorption mechanism. In addition, the adsorption capacity of CSB-21 for SY maintained above 90% in four reusable cycles. This work has developed a novel molecular-cluster template method for preparing pristine chitosan beads with near-microporous structures, offering a potential approach for utilizing chitosan as an adsorbent materials, while concomitantly providing a class of environmentally friendly, highly efficient adsorbents with significant potential for wastewater treatment applications.