Facile synthesis of chitosan-coated amino-functionalized microporous organic network for enhanced adsorption of bisphenols from aqueous solution

Herein, we reported the straightforward synthesis of chitosan-coated microporous organic network (CS-MON) designed to enhance the adsorption of bisphenols from water. Initially, an amino-functionalized microporous organic network was synthesized using 2,5-diethynylbenzene-1,4-diamine and 2,4,6-tris(4-bromophenyl)-1,3,5-triazine via a Sonogashira coupling reaction. Subsequently, a chitosan layer was introduced onto the network’s surface through a cross-linking polymerization, yielding the CS-MON. The incorporation of chitosan significantly improved water dispersibility and provided additional interaction sites for bisphenols. The adsorption performance and mechanism were systematically investigated. According to the Langmuir isotherm model, the material exhibited high adsorption capacity of 666.7, 602.4, and 450.5 mg/g. The rate constants k 2 of 0.163, 0.113, and 0.114 g/mg/min for bisphenol A, bisphenol F and bisphenol S, respectively, based on the pseudo-second-order model, outperforming many previously reported adsorbents. The adsorbent can maintain its adsorption capacity for bisphenol A across a wide range of pH levels and was unaffected by co-existing inorganic ions, ionic strength, and humic acid. Additionally, the adsorbent maintained an adsorption efficiency exceeding 95 % for bisphenol A even after 20 cycles. The remarkable adsorption performance was primarily governed by hydrogen bonding, π-π, π-π electron-donor-acceptor, and hydrophobic interactions. The CS-MON was also successfully used in flow-through filtration experiments and tested with real water samples, demonstrating its potential for application in wastewater treatment.