Thioamide-modified polyethyleneimine from sulfur-based, water-mediated Willgerodt-Kindler reaction and its applications in iodine/dye adsorption

The preparation of functional polymers by directly using sulfur (S) as starting substrate under mild condition is an instructive guide for achieving effective downstream conversion of S. In this study, using S, polyethyleneimine (PEI), and terephthalaldehyde (TA) as starting materials, a type of thioamide-decorated PEI derivative (PEI-S-TA) was successfully prepared by water-mediated Willgerodt-Kindler (W-K) multicomponent reaction at room temperature. The chemical structure and basic properties of PEI-S-TA were characterized. The dual downstream applications of PEI-S-TA for iodine capture and Congo red (CR) dye adsorption were investigated based on the structural characteristic of PEI-S-TA (with N/S-containing polyamine skeleton and aromatic moieties). Experimental results showed that PEI-S-TA could effectively adsorb iodine in vapor (at 75 °C), cyclohexane and aqueous phases, with equilibrium adsorption capacities of ∼ 5930, 2385 and 1992 g −1 , respectively. In addition, PEI-S-TA demonstrated selective adsorption for the anionic dye CR, with a maximum adsorption capacity of ∼ 600.3 mg g −1 and satisfactory adsorption rate.