Carboxyl carbon nanotubes strengthened tailorable chitosan imprinted polymers for selective adsorption of dibenzothiophene in hydrogenated diesel

Abstract

Selectively capturing and adsorbing high-valued dibenzothiophene (DBT) from hydrogenated diesel is a meaningful and economic tactic for sulfide resource recovery. The design of efficient adsorbents with desirable adsorption capacity, high selectivity and simple retrieval is still challenging. In this work, an imprinting polymerization coupling freeze-drying approach was adopted to elaborately prepare carboxyl carbon nanotubes (CCNT) strengthened chitosan (CS) molecularly imprinted polymers (MIPs-CCNT/CS) for non-destructive adsorption of DBT. The introduction of CCNT into CS-based imprinted matrix improved thermal and mechanical stability and enriched adsorption sites of MIPs-CCNT/CS, thus enhancing DBT adsorption ability with the maximum adsorption capacity of 30.58 ± 1.24 mg/g under the optimized adsorption conditions. The Langmuir isotherm and pseudo-second-order kinetics models were verified to fit satisfactorily with the adsorption procedures of MIPs-CCNT/CS towards DBT. Benefiting from the presence of plentiful DBT imprinted cavities, MIPs-CCNT/CS maintained a superior recognition for DBT in the quaternary stimulated diesel, and the relative selectivity coefficients of DBT for benzothiophene (BT), indole, and fluorene with respect to the control non-imprinted adsorbent (NIPs-CCNT/CS) were 2.19, 2.34, and 2.10, respectively. After six adsorption–desorption experiments, the adsorption capacity of MIPs-CCNT/CS toward DBT remained stable (20.67 ± 0.53 mg/g). The preliminary exploration for actual hydrogenated diesel demonstrated that MIPs-CCNT/CS has benign industrial application prospect in the separation and recycling of high value-added DBT.