Green sonochemical synthesis, kinetics and functionalization of nanoscale anion exchange resins and their performance as water purification membranes

Abhispa Sahu; Rabia Sheikh; Jordan C Poler

doi:10.1016/j.ultsonch.2020.105163

Green sonochemical synthesis, kinetics and functionalization of nanoscale anion exchange resins and their performance as water purification membranes

Ultrason Sonochem. 2020 Oct:67:105163. doi: 10.1016/j.ultsonch.2020.105163. Epub 2020 May 8.

Authors

Abhispa Sahu¹, Rabia Sheikh¹, Jordan C Poler²

Affiliations

¹ Department of Chemistry, University of North Carolina at Charlotte, Charlotte, NC, United States.
² Department of Chemistry, University of North Carolina at Charlotte, Charlotte, NC, United States. Electronic address: jcpoler@uncc.edu.

PMID: 32416575
DOI: 10.1016/j.ultsonch.2020.105163

Abstract

This paper reports on sonochemically catalyzed atom transfer radical polymerization (SONO-ATRP) polyelectrolyte synthesis and chain-end functionalization to single-walled carbon nanotubes (SWCNT). This all aqueous process is kinetically facile without use of initiator, or reducing agents and with very low concentrations of catalyst. The process achieves high functionalization density of polymer onto the SWCNTs. These functionalized nanoscale resins (NanoResins) exhibit high performance as fast and sustainable water purification materials. SONO-ATRP of vinyl benzyl trimethyl ammonium chloride (vbTMAC) was performed in aqueous medium resulting in short polyelectrolyte strands with high atom economy and high monomer conversions (93%) at room temperature using a thin probe sonicator (144Wcm^-2, 20 kHz, for 4 h). Kinetics analysis showed first order kinetics with respect to monomer concentration in presence of or absence of sonication power. Low temperature SONO-ATRP functionalization of SWCNTs is achieved within two hours without added reducing agent while similar functionalization density using reducing agents without sonochemistry required 12 h under reflux conditions. Functionalized NanoResin membranes were tested against surrogate analyte and demonstrated high performance Thomas Model breakthrough curves with a maximum adsorption capacity of 139 ± 1 mgg^-1 and water flux of 692 Lm^-2h^-1bar^-1 at one atmosphere pressure. Moreover, these materials are easily regenerated and reused without loss of performance or degradation.

Keywords: Atom transfer radical polymerization; Kinetics; Polyelectrolyte functionalized SWCNTs; Sonochemistry; Sustainable materials synthesis and reuse; Water purification.