title: Amine-functionalized, multi-arm star polymers: A novel platform for removing glyphosate from aqueous media.
abstract: We describe a novel method for efficiently removing glyphosate from aqueous media via adsorption onto highly functionalized star-shaped polymeric particles. These particles have a polystyrene core with more than 35 attached methacrylate polymer arms, each containing a plurality of pendant amines (poly(dimethylamino ethyl methacrylate): PDMAEMA) that are partially protonated in water. Kinetic studies demonstrate that these star-polymers successfully remove up to 93% of glyphosate present in aqueous solution (feed concentration: 5 ppm), within 10 min contact time, outperforming activated carbon, which removed 33% after 20 min. On these star-polymers, glyphosate adsorption closely follows the Langmuir model indicating monolayer coverage at most. Ionic interaction between the protonated amines and glyphosate's dissociated carboxylic and phosphoric acid groups lead to effective glyphosate capture even at feed concentrations below 1 ppm. Surface charge of these star polymers and dissociation of glyphosate are both influenced by pH, thus glyphosate removal efficiency increases from 63% to 93% when pH increases from 4.2 to 7.7. NMR studies conducted with butylamine as a proxy for these polymeric particles confirm that the amine group binds with both glyphosate's carboxylic and phosphoric acid groups when its concentrations are in a 2:1 or higher molar ratio with glyphosate.
authors.affiliation: IBM Almaden Research Center, 650 Harry Road, San Jose, CA 95120, USA. Electronic address: samuell@us.ibm.com.
authors.forename: Lianna
authors.initials: L
authors.lastname: Samuel
authors.affiliation: IBM Almaden Research Center, 650 Harry Road, San Jose, CA 95120, USA.
authors.forename: Ran
authors.initials: R
authors.lastname: Wang
authors.affiliation: IBM Almaden Research Center, 650 Harry Road, San Jose, CA 95120, USA.
authors.forename: Geraud
authors.initials: G
authors.lastname: Dubois
authors.affiliation: IBM Almaden Research Center, 650 Harry Road, San Jose, CA 95120, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Allen
authors.affiliation: IBM Almaden Research Center, 650 Harry Road, San Jose, CA 95120, USA.
authors.forename: Rudy
authors.initials: R
authors.lastname: Wojtecki
authors.affiliation: IBM Almaden Research Center, 650 Harry Road, San Jose, CA 95120, USA. Electronic address: yna@us.ibm.com.
authors.forename: Young-Hye
authors.initials: YH
authors.lastname: La
mesh_terms: D000327:Adsorption; D000588:Amines / Q000737:chemistry*; D002606:Charcoal; D005998:Glycine / Q000031:analogs & derivatives* / Q000032:analysis / Q000302:isolation & purification; D007700:Kinetics; D008689:Methacrylates / Q000737:chemistry*; D009757:Nylons / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D000097797:Glyphosate
chemical_list: D000588:Amines; D002606:Charcoal; D005998:Glycine; D008689:Methacrylates; D009757:Nylons; D011108:Polymers; D014874:Water Pollutants, Chemical; D000097797:Glyphosate; C407037:poly(2-(dimethylamino)ethyl methacrylate)
keywords: Adsorption; Functionalized nanomaterials; Glyphosate removal; Star polymer; Water purification