Congo red attached poly(EGDMA–HEMA) microspheres as specific sorbents for removal of cadmium ions

✍ Scribed by Bekir Salih; Adil Denizli; Burhanettin Engin; Ali Tuncel; Erhan Piskin

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 900 KB
• Volume: 60
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19960509)60:6<871::aid-app10>3.0.co;2-#

✦ Synopsis

Poly[ethyleneglycoldimethacrylate (EGDMA)-hydroxyethylmethacrylate (HEMA)] microspheres (150-200 pm in diameter) were produced by suspension copolymerization of EGDMA and HEMA in an aqueous medium. Toluene was included in the formulations in order to produce water-swellable microspheres. Poly(viny1 alcohol) and benzoyl peroxide were used as stabilizer and initiator, respectively. Congo red was chemically attached to the microspheres as a metal chelating ligand for specific adsorption of heavy metal ions. These sorbents were characterized by an optical microscopy and a FTIR. Adsorption/ desorption of cadmium (Cd2+) ions from aqueous solutions on these sorbents were investigated in batch equilibrium experiments by using an atomic absorption spectroscopy with a graphite furnace atomizer. The maximum cadmium adsorption on to the dye-attached microspheres (i.e., by complex formation) was about 18.3 mg Cd2+ ions/g polymer, which was observed at pH 6.8. While adsorption onto the plain poly(EGDMA-HEMA) microspheres (i.e., nonspecific adsorption) was about 0.93 mg Cd2+ ions/g polymer at the same conditions. More than 90% of the adsorbed cadmium was desorbed in 1 h by using 2M NaCl as an eluant. The resorption capacity of the sorbent did not significantly decrease during repeated sorption-desorption cycling.