Novel heavy-metal adsorption material: ion-recognition P(NIPAM- co-BCAm) hydrogels for removal of lead(II) ions

• Published in: Journal of hazardous materials 2009-08, Vol.167 (1), p.114-118
• Main Authors: Ju, Xiao-Jie, Zhang, Shi-Bo, Zhou, Ming-Yu, Xie, Rui, Yang, Lihua, Chu, Liang-Yin
• Format: Article
• Language: English
• Subjects: Acrylic Resins; Adsorption; Applied sciences; Chemical engineering; Crown Ethers; Exact sciences and technology; Hydrogel; Hydrogels - chemistry; Ion-recognition; Ions; Lead - isolation & purification; Metals, Heavy - isolation & purification; Pb ion removal; Pollution; Temperature; Thermo-sensitive polymer
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2008.12.089

A novel polymeric lead(II) adsorbent is prepared by incorporating benzo-18-crown-6-acrylamide (BCAm) as metal ion receptor into the thermo-responsive poly( N-isopropylacrylamide) (PNIPAM) hydrogel. Both stimuli-sensitive properties and the Pb 2+-adsorption capabilities of the prepared P(NIPAM- co-BCAm) hydrogels are investigated. The prepared P(NIPAM- co-BCAm) hydrogels exhibit good ion-recognition and Pb 2+-adsorption characteristics. When crown ether units capture Pb 2+ and form BCAm/Pb 2+ host–guest complexes, the lower critical solution temperature (LCST) of the hydrogel shifts to a higher temperature due to both the repulsion among charged BCAm/Pb 2+ groups and the osmotic pressure within the hydrogel. The adsorption results at different temperatures show that P(NIPAM- co-BCAm) hydrogels adsorb Pb 2+ ions at temperature lower than the LCST, but undergo desorption at temperature higher than the LCST due to the “stretch-to-shrink” configuration change of copolymer networks which is triggered by the change in environmental temperature. This kind of ion-recognition hydrogel is promising as a novel adsorption material for adsorption and separation of Pb 2+ ions. The adsorption and desorption of Pb 2+ could be rationally achieved by simply changing the environmental temperature.