Regulation of clay particles charge for design of protective electrokinetic barriers

• Published in: Journal of hazardous materials 2018-09, Vol.358, p.165-170
• Main Authors: Korolev, V.A., Nesterov, D.S.
• Format: Article
• Language: English
• Subjects: Electrokinetic barrier; Point of zero charge; Point of zero net proton charge; Pollution treatment; ζ-potential
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2018.06.023

•Clays can be used as a material for electrokinetic protective reactive barriers.•Alkaline treatment results in a negative charge and acidic treatment cause a positive charge of clay particles.•Positively charged clay particles will bind anionic toxicants, and negatively charged ones will adsorb cationic ones.•Clays’ surface charge properties and barrier’s protective characteristics change at the point of zero charge (p.z.c.).•In the raw ‘kaolin/illite clay/montmorillonite clay’ p.z.c. values shift to the alkaline area of pH. Coupled electrokinetic protective reactive barriers (PRB) are considered as a perspective technology for the treatment of contaminated groundwater. Design of PRB is directly connected with a problem of barrier material choice. Clays can be considered as an appropriate material due to high adsorptive properties and relative cheapness. The barrier internals are formed by clay surface charge properties. We revealed that acidic and alkaline treatment of clay is an effective way to affect its protective properties so that clay can be used to treat various pollutants. Surface charge and electrokinetic properties of clays were characterized by point of zero charge (p.z.c.), point of zero net proton charge (p.z.n.p.c.) and ζ-potential at different pH. Suspensions of 3 main clay types were studied by microelectrophoresis and potentiometric titration methods. At pH > p.z.n.p.c. clayey barrier adsorbs predominantly cationic toxicants and at pH