Chitosan-based molecularly imprinted sponge for selective recognition and recycling of dibenzothiophene from diesel

Recycling of high value-added dibenzothiophene (DBT) from diesel using adsorption technology is a convenient and economical strategy to realize "Resources Reuse", but the conventional adsorbents have the disadvantages of low adsorption selectivity and difficult retrieval. Herein, in this study, we elaborately designed and constructed a chitosan-based molecularly imprinted sponge (CS-MIS) with three-dimensional network structure via a bulk polymerization-lyophilization protocol. Batch adsorption experiments were conducted three replications to appraise the potential of CS-MIS for DBT adsorption. The influence of adsorbent dosage, initial DBT concentration, adsorption time and temperature on the adsorption performance were systematically investigated. The adsorption experimental results showed that CS-MIS exhibited a superior maximum adsorption equilibrium capacity of 15.17 mg/g for DBT compared to the chitosan-based non-imprinted sponge (CS-NIS; 6.34 mg/g). The DBT adsorption on CS-MIS coincided well with the pseudo-second-order kinetic and Langmuir isotherm models. The selective tests in the presence of multiple interfering molecules indicated the remarkable selective recognition of CS-MIS toward DBT with the relative selectivity coefficients for benzothiophene, indole, and fluorene of 1.99, 2.28, and 1.41, respectively. The notable selectivity of CS-MIS for DBT adsorption were mainly attributed to the imprinted sites matched well with DBT geometry on the surface of CS-MIS. Additionally, CS-MIS exhibited the excellent regeneration performance.