Physicochemical effects on uncontaminated kaolinite due to electrokinetic treatment using inert electrodes

J Environ Sci Health A Tox Hazard Subst Environ Eng. 2008 Jul 1;43(8):810-22. doi: 10.1080/10934520801973972.

Abstract

To determine the consequences of applying electrokinetics to clay soils, in terms of mechanisms acting and resulting effects on the clay, tests were conducted in which an electrical gradient was applied across controlled specimens of English China Clay (ECC) using 'inert' electrodes and a 'Reverse Osmosis' water feed to the electrodes (i.e., to mimic electrokinetic stabilisation without the stabiliser added or electrokinetic remediation without the contaminant being present). The specimens in which electromigration was induced over time periods of 3, 7, 14 and 28 days were subsequently tested for Atterberg Limits, undrained shear strength using a hand shear vane, water content, pH, conductivity and zeta potential. Water flowed through the system from anode to cathode and directly affected the undrained shear strength of the clay. Acid and alkali fronts were created around the anode and cathode, respectively, causing changes in the pH, conductivity and zeta potential of the soil. Variations in zeta potential were linked to flocculation and dispersion of the soil particles, thus raising or depressing the Liquid Limit and Plastic Limit, and influencing the undrained shear strength. Initial weakening around the anode and cathode was replaced by a regain of strength at the anode once acidic conditions had been created, while highly alkaline conditions at the cathode induced a marked improvement in strength. A novel means of indicating strength improvement by chemical means, i.e., free from water content effects, is presented to assist in interpretation of the results.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aluminum Silicates / chemistry*
  • Chemical Phenomena
  • Chemistry, Physical
  • Clay
  • Electrochemistry / instrumentation
  • Electrochemistry / methods*
  • Electrodes
  • Hydrogen-Ion Concentration
  • Kaolin / chemistry*
  • Reproducibility of Results
  • Soil Pollutants / chemistry*
  • Water / chemistry

Substances

  • Aluminum Silicates
  • Soil Pollutants
  • Water
  • Kaolin
  • Clay