Application of cryogels with noble metal nanoparticles as flow through catalyst for "green" decomposition of phenol derivatives

Chlorinated derivatives, including pesticide fungicides and insecticides, are extensively applied in agriculture, disinfection, and industry, yet their persistence leads to severe contamination of aquatic environments[1-2]. Conventional bioremediation methods are insufficient for removing these pollutants, which has stimulated the development of catalytic approaches to degrade stable chloro-organic compounds effectively[3-5]. In the current study a range of catalytic strategies has been designed to address the degradation of persistent organic pollutants. In this investigation, the formation of metal-coordinated chitosan gels were analyzed via rheological measurements (G′ and G″). using Medusa modeling mechanism of gel formation was proposed. Ionic gels were further transformed into covalently cross-linked macroporous cryogels containing in situ immobilized Pd or Pt nanoparticles through redox-driven reactions. The catalytic efficiency of these cryogels for degrading chloro-organic contaminants in continuous water treatment was evaluated, with PdNPs and PtNPs uniformly dispersed as nanosized particles within the porous polymer structure. The degradation kinetics of o-chlorophenol, p-chlorophenol, and 2,4-dichloro-phenol were investigated using catalysts with varying Pd and Pt loadings. Conversion increased with higher formic acid excess and elevated temperatures, reaching 80–90% at 80 °C. The CHI–GA–PdNPs cryogel demonstrated superior hydrogenation activity at pH 6 compared to CHI–GA–PtNPs, though no marked difference was observed at pH 3. Batch-mode termination studies and control experiments were conducted to explore catalyst deactivation, with silver nitrate addition showing limited benefit. Overall, this catalytic platform holds promise for application in flow-through systems and for broader use in the synthesis of valuable chemicals.