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Effects of humic acid and surfactants on the aggregation kinetics of manganese dioxide colloids
Abstract The aggregation of common manganese dioxide ($ MnO_{2} $) colloids has great impact on their surface reactivity and therefore on their fates as well as associated natural and synthetic contaminants in engineered (e.g. water treatment) and natural aquatic environments. Nevertheless, little is known about the aggregation kinetics of $ MnO_{2} $ colloids and the effect of humic acid (HA) and surfactants on these. In this study, the early stage aggregation kinetics of $ MnO_{2} $ nanoparticles in $ NaNO_{3} $ and Ca($ NO_{3} $)2 solutions in the presence of HA and surfactants (i.e., sodium dodecyl sulfate (SDS), and polyvinylpyrrolidone (PVP)) were modeled through time-resolved dynamic light scattering. In the presence of HA, $ MnO_{2} $ colloids were significantly stabilized with a critical coagulation concentration (CCC) of ∼300 mmol·$ L^{−1} $ $ NaNO_{3} $ and 4 mmol·$ L^{−1} $ Ca($ NO_{3} $)2. Electrophoretic mobility (EPM) measurements confirmed that steric hindrance may be primarily responsible for increasing colloidal stability in the presence of HA. Moreover, the molecular and/or chemical properties of HA might impact its stabilizing efficiency. In the case of PVP, only a slight increase of aggregation kinetics was observed, due to steric reactions originating from adsorbed layers of PVP on the $ MnO_{2} $ surface. Consequently, higher CCC values were obtained in the presence of PVP. However, there was a negligible reduction in $ MnO_{2} $ colloidal stability in the presence of 20 mg·$ L^{−1} $SDS.
Effects of humic acid and surfactants on the aggregation kinetics of manganese dioxide colloids
Abstract The aggregation of common manganese dioxide ($ MnO_{2} $) colloids has great impact on their surface reactivity and therefore on their fates as well as associated natural and synthetic contaminants in engineered (e.g. water treatment) and natural aquatic environments. Nevertheless, little is known about the aggregation kinetics of $ MnO_{2} $ colloids and the effect of humic acid (HA) and surfactants on these. In this study, the early stage aggregation kinetics of $ MnO_{2} $ nanoparticles in $ NaNO_{3} $ and Ca($ NO_{3} $)2 solutions in the presence of HA and surfactants (i.e., sodium dodecyl sulfate (SDS), and polyvinylpyrrolidone (PVP)) were modeled through time-resolved dynamic light scattering. In the presence of HA, $ MnO_{2} $ colloids were significantly stabilized with a critical coagulation concentration (CCC) of ∼300 mmol·$ L^{−1} $ $ NaNO_{3} $ and 4 mmol·$ L^{−1} $ Ca($ NO_{3} $)2. Electrophoretic mobility (EPM) measurements confirmed that steric hindrance may be primarily responsible for increasing colloidal stability in the presence of HA. Moreover, the molecular and/or chemical properties of HA might impact its stabilizing efficiency. In the case of PVP, only a slight increase of aggregation kinetics was observed, due to steric reactions originating from adsorbed layers of PVP on the $ MnO_{2} $ surface. Consequently, higher CCC values were obtained in the presence of PVP. However, there was a negligible reduction in $ MnO_{2} $ colloidal stability in the presence of 20 mg·$ L^{−1} $SDS.
Effects of humic acid and surfactants on the aggregation kinetics of manganese dioxide colloids
Huangfu, Xiaoliu (author) / Wang, Yaan (author) / Liu, Yongze (author) / Lu, Xixin (author) / Zhang, Xiang (author) / Cheng, Haijun (author) / Jiang, Jin (author) / Ma, Jun (author)
2015
Article (Journal)
English
Effects of humic acid and surfactants on the aggregation kinetics of manganese dioxide colloids
| Springer Verlag | 2015
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