Stability of nTiO₂ particles and their attachment to sand: effects of humic acid at different pH

Abstract

Influence of humic acid (HA) on stability and attachment of nTiO₂ particles to sand was investigated. Results showed that HA can either promote or hinder nTiO₂. Influence of humic acid (HA) on stability and attachment of nTiO₂ particles to sand was investigated. Results showed that HA can either promote or hinder nTiO₂ stability, depending on pH and HA concentration. HA can either enhance or reduce nTiO₂ attachment to Fe oxyhydroxide coating at pH 5, depending on HA concentration. Results further showed that at pH 5, Fe oxyhydroxide coating reduced nTiO₂ attachment to sand in the absence of HA but increased nTiO₂ attachment in the presence of low concentration of HA. Derjaguin-Landau-Verwey-Overbeek (DLVO) theory was invoked to analyze particle-to-particle and particle-to-sand interactions in order to elucidate the roles of pH, HA, quartz, and Fe coating in controlling nTiO₂ stability and attachment. Overall, this study showed that changes in zeta potential of nTiO₂ and Fe coating due to pH changes and/or HA adsorption are the key factors that influence stability and attachment of nTiO₂. Influence of humic acid (HA) on stability and attachment of nTiO₂ particles to sand was investigated. Results showed that HA can either promote or hinder nTiO₂ stability, depending on pH and HA concentration. HA can either enhance or reduce nTiO₂ attachment to Fe oxyhydroxide coating at pH 5, depending on HA concentration. Results further showed that at pH 5, Fe oxyhydroxide coating reduced nTiO₂ attachment to sand in the absence of HA but increased nTiO₂ attachment in the presence of low concentration of HA. Derjaguin-Landau-Verwey-Overbeek (DLVO) theory was invoked to analyze particle-to-particle and particle-to-sand interactions in order to elucidate the roles of pH, HA, quartz, and Fe coating in controlling nTiO₂ stability and attachment. Overall, this study showed that changes in zeta potential of nTiO₂ and Fe coating due to pH changes and/or HA adsorption are the key factors that influence stability and attachment of nTiO₂. stability, depending on pH and HA concentration. HA can either enhance or reduce nTiO₂ attachment to Fe oxyhydroxide coating at pH 5, depending on HA concentration. Results further showed that at pH 5, Fe oxyhydroxide coating reduced nTiO₂ attachment to sand in the absence of HA but increased nTiO₂ attachment in the presence of low concentration of HA. Derjaguin-Landau-Verwey-Overbeek (DLVO) theory was invoked to analyze particle-to-particle and particle-to-sand interactions in order to elucidate the roles of pH, HA, quartz, and Fe coating in controlling nTiO₂ stability and attachment. Overall, this study showed that changes in zeta potential of nTiO₂ and Fe coating due to pH changes and/or HA adsorption are the key factors that influence stability and attachment of nTiO₂.