Microfluidic preparation of thiol-containing monodisperse polymer microspheres and their adsorption of Pb2+ in water

A novel polymerizable monomer containing carbon-carbon double bond and disulfide bond, 2-(((2-(pyridin-2-yldisulfanyl)ethoxy)carbonyl)amino) ethyl acrylate (PDSECAE), was first designed and synthesized, and then used to prepare thiol-containing monodisperse polymer microspheres with different sizes from 20 μm to 500 μm by means of microfluidic technique, UV-induced polymerization and dithiothreitol reduction in sequence. The chemical structures of PDSECAE and the microspheres were confirmed by NMR, FTIR and RAMAN, and the thiol content was determined by UV–vis spectrophotometer. Having the largest specific surface area, microspheres of 20.0 μm in diameter were utilized in adsorption of Pb 2+ in water, and the maximum adsorption capacity reached 104.4 mg/g at pH 6.0 and 25 °C. After the adsorbed Pb 2+ was removed by ethylenediaminetetraacetic acid disodium salt, the regenerated thiol-containing microspheres could be reused and their adsorption capacity still remained 85% of its initial value after 5 recycles. Efficient adsorption performance and easy reusability make the thiol-containing polymer microspheres show promising applications to adsorption of heavy metal ions.