Surface grafting with diverse charged chemical groups mitigates calcium phosphate scaling on reverse osmosis membranes during municipal wastewater desalination

Karthik Rathinam, Akshay Modi, Dietmar Schwahn, Yoram Oren, Roni Kasher

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

Calcium phosphate scaling on reverse osmosis (RO) membranes during the desalination of municipal wastewater remains a major problem. This study modified RO membranes by graft polymerization using hydrophilic methacrylate monomers to reduce scaling and investigated the effects of surface charge and exposed functional groups on scaling during municipal wastewater desalination. Grafting was performed using negatively charged, neutral, positively charged, and mixed charge monomers. Testing the modified membranes during RO desalination of a solution simulating treated domestic wastewater effluents from the Shafdan wastewater reclamation plant in Israel revealed improved antiscaling performance by grafted membranes compared with the pristine (unmodified) membrane. In particular, membranes grafted using neutral and mixed charge monomers showed the best antiscaling tendencies: 25.6% and 27.6% decrease in flux, respectively, compared with a 59.1% decrease using the pristine membrane. These results, together with physico-chemical characterization, suggested that calcium phosphate precipitation and scaling on the grafted RO membranes are driven mainly by electrostatic and dipole–dipole interactions between charged chemical groups exposed on the membrane surface and ionic species in the test solution; these interactions are minimized in membranes grafted with neutral or mixed charge poly (methacrylate) groups, resulting in enhanced antiscaling performance. This study provides insight into the antiscaling mechanisms of hydrophilic poly (methacrylate) chains grafted on RO membranes, and thus can potentially aid efforts to mitigate calcium phosphate scaling during RO desalination of municipal wastewater.

Original languageEnglish
Article number120310
JournalJournal of Membrane Science
Volume647
DOIs
StatePublished - 5 Apr 2022

Keywords

  • Antiscaling
  • Calcium phosphate scaling
  • Graft polymerization
  • Municipal wastewater
  • Reverse osmosis membrane

ASJC Scopus subject areas

  • Biochemistry
  • General Materials Science
  • Physical and Theoretical Chemistry
  • Filtration and Separation

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