Filtration of triazine herbicides by polymer-clay sorbents: Coupling an experimental mechanistic approach with empirical modeling

Ido Gardi, Shlomo Nir, Yael G. Mishael*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

41 Scopus citations

Abstract

Triazine herbicides detected in surface and groundwater pose environmental and health risks. Removal of triazine herbicides (simazine, atrazine and terbuthylazine) by polymer-clay composites was studied and modeled. Their binding by a poly 4-vinyl pyridine co styrene-montmorillonite (HPVP-CoS-MMT) composite was especially high due to specific interactions between the herbicides and polymer, mainly hydrogen bonds and π-π stacking. The binding kinetics to the composite was in the order of simazine > atrazine > terbuthylazine, which was in accord with their equilibrium Langmuir binding coefficients; 44,000, 17,500 and 16,500M-1, respectively, which correlated with herbicide accessibility to form specific interaction with the polymer. Simazine binding kinetics to the composite was significantly faster than to granulated activated carbon (GAC), reaching 93% vs 38% of the maximal adsorption within 10min, respectively. Herbicide filtration by composite columns was adequately fitted by a model which considers convection and employs Langmuir formalism for kinetics of adsorption/desorption. Filtration of simazine (10μgL-1) by composite columns (40cm long, which included 26g composite mixed with sand 1:40 (weight ratio)), was well predicted by the model with nearly 120L purified, i.e., effluent concentrations were below regulation limit (3μgL-1). Effluent concentrations from GAC columns exceeded the limit after filtering 5L. Experimental results and model predictions suggest that while GAC has a high capacity for simazine binding, the composite has higher affinity towards the herbicide and its adsorption is faster, which yields more efficient filtration by composite columns.

Original languageEnglish
Pages (from-to)64-73
Number of pages10
JournalWater Research
Volume70
DOIs
StatePublished - 1 Mar 2015

Bibliographical note

Publisher Copyright:
© 2014 Elsevier Ltd.

Keywords

  • Competitive adsorption
  • Filtration
  • Modeling
  • Polymer-clay composites
  • Simazine
  • Triazine herbicides

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