Cation-bioimprinted mesoporous polysaccharide/sol-gel composites prepared in media containing choline chloride-based deep eutectic solvents

A study on the Pb(II) imprinting performed within mesoporous sulphated biopolymer/siloxane composites, prepared in media containing deep eutectic solvent (DES), is described. In general, the process of imprinting resulted in greatly increased surface areas relatively to the corresponding nonimprinted composites [up to fivefold (from 76 m(2) g(-1) to 360 m(2) g(-1)) for fucoidan (Fuc) and up to twofold (from 208 m(2) g(-1) to 351 m(2) g(-1)) for chondroitin sulfate (CS) composites], the diminishing of mean pore size (from 3.3-4.6 nm to 2.9-3.4), and higher biopolymer contents (from mass fractions of 0.42-0.52 to 0.46-0.68). The sorption features depended a great deal on the biopolymer/DES combination. The best CS composite, allowed for 12% capacity and 20% binding strength, as well as Pb(II)/Cd(II) selectivity enhancements. The largest of the capacities was obtained with the imprinted Fuc/DES-E composite, 86 mg g(-1), a 10% increase. Concerning the selectivity [Pb(II) versus Cd(II)], there was a significant increase for the CS composites (from 1.0-1.1 (alpha(qmax))/1.1-1.2 (alpha(K)) to 1.3-1.4 (alpha(qmax))/1.3-1.6 (alpha(K))]. In particular, the DES-E CIC presented high selectivity factors (alpha(qmax) 3.0/alpha(K) 3.2) in line with those of the microporous version (alpha(qmax) 2.0/alpha(K) 3.3) but showing a significant increase in terms of the alpha(qmax) selectivity. (c) 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 137, 48842.