Alkaline Amino Acid-Modified Hyper-Crosslinked Polymers and Their Efficient Adsorptive Removal of Phenolic Compounds from Water or Cyclohexane

A novel strategy of synthesis was discovered based on Friedel-Crafts reaction and nucleophilic substitution, and the basic amino acid modified hyper-cross-linked polymers (HCPS) were successfully produced, namely HCPS-Lys, HCPS-His, HCPS-Arg. The Friedel-Crafts alkylation structured predominant microporosity for the intermediate polymer with high Brunauer-Emmett-Teller (BET) surface area (SBET, 869-1106 m2/g) and total pore volume (Vtotal, 1.39-1.71 cm3/g). The basic amino acid was developed as the chemical modifier and grafted on the HCPS using the nucleophilic substitution to obtain the final polymer with plentiful heteroatoms. In aqueous solution, the HCPS-Arg exhibited the superb adsorption of 2-naphthol with a predicting maximum capacity (qmax) of 350.36 mg/g, and the adsorption reached equilibrium within 100 minutes. In organic solvents, the HCPS-His had the optimum adsorption effect for 2-naphthol, the maximum capacity (qmax) was fitted to be 241.75 mg/g, and the adsorption achieved the equilibrium in close to 160 minutes. 95% ethanol and 0.01 mol/L NaOH could desorb phenolic compounds from the polymers. The adsorption mechanism indicated that acid-base interaction and microporous filling were the main driving forces for adsorption in aqueous solution, and π-π stacking was the main driving force for adsorption in cyclohexane solution.