Amine-functionalized, multi-arm star polymers: A novel platform for removing glyphosate from aqueous media Lianna Samuel * , Ran Wang, Geraud Dubois, Robert Allen, Rudy Wojtecki, Young-Hye La ** IBM Almaden Research Center, 650 Harry Road, San Jose, CA 95120, USA highlights graphical abstract  Bioaccumulation of glyphosate ingested in even trace amounts can negatively impact health.  Rapid, efficient glyphosate adsorp- tion by mesoporous-like star-poly- mers with high amine functional group aerial density.  Ionic interactions which promote adsorption are affected by pH.  Glyphosate removal efficiency is greater than 85% for neutral and slightly basic conditions.  Maximum glyphosate adsorption ca- pacity is 229.017 mg glyphosate/g star-polymer. article info Article history: Received 12 August 2016 Received in revised form 8 November 2016 Accepted 10 November 2016 Handling Editor: Shane Snyder Keywords: Glyphosate removal Star polymer Adsorption Functionalized nanomaterials Water purification 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 poly- meric 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. © 2016 Elsevier Ltd. All rights reserved. 1. Introduction Population growth has driven the increased use of pesticides and herbicides in agriculture globally, to ensure adequate food supply. Glyphosate [Ne(phosphonomethyl) glycine] is the active * Corresponding author. ** Corresponding author. E-mail addresses: samuell@us.ibm.com (L. Samuel), yna@us.ibm.com (Y.-H. La). Contents lists available at ScienceDirect Chemosphere journal homepage: www.elsevier.com/locate/chemosphere http://dx.doi.org/10.1016/j.chemosphere.2016.11.049 0045-6535/© 2016 Elsevier Ltd. All rights reserved. Chemosphere 169 (2017) 437e442