title: Novel heavy-metal adsorption material: ion-recognition P(NIPAM-co-BCAm) hydrogels for removal of lead(II) ions.
abstract: 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.
authors.affiliation: School of Chemical Engineering, Sichuan University, Chengdu, China.
authors.forename: Xiao-Jie
authors.initials: XJ
authors.lastname: Ju
authors.forename: Shi-Bo
authors.initials: SB
authors.lastname: Zhang
authors.forename: Ming-Yu
authors.initials: MY
authors.lastname: Zhou
authors.forename: Rui
authors.initials: R
authors.lastname: Xie
authors.forename: Lihua
authors.initials: L
authors.lastname: Yang
authors.forename: Liang-Yin
authors.initials: LY
authors.lastname: Chu
mesh_terms: D000180:Acrylic Resins; D000327:Adsorption; D043844:Crown Ethers; D020100:Hydrogels / Q000737:chemistry*; D007477:Ions; D007854:Lead / Q000302:isolation & purification*; D019216:Metals, Heavy / Q000302:isolation & purification; D013696:Temperature
chemical_list: D000180:Acrylic Resins; D043844:Crown Ethers; D020100:Hydrogels; D007477:Ions; D019216:Metals, Heavy; C052970:poly-N-isopropylacrylamide; D007854:Lead