Urethane- and urea-modified polymeric sorbents enable efficient and selective removal of mercury(II) from water

Design and synthesis of the new polymeric adsorbents for selective and efficient removal of Hg²⁺ from water is an attractive target. Cross-linked poly (vinyl benzyl chloride) (PVBC) resin was prepared starting from vinyl benzyl chloride (90% mol) and ethylene glycol dimethacrylate (EGDMA) (10% mol) using suspension polymerization. Spherical PVBC beads (200–400 µm) were reacted with an excess of ethylenediamine and ethanolamine to give the corresponding pendant amine functions. Then, the aminated beads were reacted with butyl isocyanate to obtain the urea and urethane functional sorbents. These resins have good sorption capacities for mercury ions. Under non-buffered conditions, the highest mercury sorption capacities were found as 1.94 mmol Hg (II)/ g resin and 2.50 mmol Hg (II)/g resin for U-resin and PS-UR resin, respectively. pH-depending sorption experiments, kinetic measurements and adsorption isotherm models were investigated. The mercury-loaded resins can be regenerated and recycled by simple acid washings, without losing their activity. Consequently, the resins described are cost-effective adsorbents for the removal of mercury from waste water.