Facile preparation of microscale hydrogel particles for high efficiency adsorption of bisphenol A from aqueous solution.

Hydrogel microparticles (HMPs) were synthesized via reverse emulsion/UV light polymerization and employed as adsorbents for removing bisphenol A (BPA) from aqueous solution. Results demonstrated the smooth surface of HMPs, with particle size ranging from 137 to 535 μm. Functional groups, including -OH, C-O, C=O, and C-H, are all involved in BPA adsorption confirmed by FTIR. Effect of solution pH, contact time, and initial BPA concentration on adsorption process was examined. The adsorption capacity was found pH independent below pH 8.0 and decreased when pH values greater than 8.0. The maximum adsorption capacity of the HMPs for BPA was 174.77 mg/g. The adsorption process achieved an equilibrium state within 30 min by the pseudo-second-order kinetic rather than the other kinetic models and was fitted well with the Freundlich linear isotherm model. Also, the obtained isotherms reflected the formation of S-type isotherm curve according to Giles's classification. The BPA loaded on the HMPs could be totally regenerated by methanol/dimethylsulfoxide and can be used for five cycles maintaining 100% of adsorption capacity. When the HMPs were applied for the treatment of spiked real surface water, excellent results were also achieved indicating the high efficiency and potential of the adsorbent.