Department of Inorganic and Analytical Chemistry, University of Geneva, 30 Quai Ernest-Ansermet, CH-1205 Geneva, Switzerland.
Soft Matter. 2016 May 7;12(17):4024-33. doi: 10.1039/c5sm03023d. Epub 2016 Mar 21.
Positively charged layered double hydroxide particles composed of Mg(2+) and Al(3+) layer-forming cations and NO3(-) charge compensating anions (MgAl-NO3-LDH) were synthesized and the colloidal stability of their aqueous suspensions was investigated in the presence of inorganic anions of different charges. The formation of the layered structure was confirmed by X-ray diffraction, while the charging and aggregation properties were explored by electrophoresis and light scattering. The monovalent anions adsorb on the oppositely charged surface to a different extent according to their hydration state leading to the Cl(-) > NO3(-) > SCN(-) > HCO3(-) order in surface charge densities. The ions on the right side of the series induce the aggregation of MgAl-NO3-LDH particles at lower concentrations, whereas in the presence of the left ones, the suspensions are stable even at higher salt levels. The adsorption of multivalent anions gave rise to charge neutralization and charge reversal at appropriate concentrations. For some di, tri and tetravalent ions, charge reversal resulted in restabilization of the suspensions in the intermediate salt concentration regime. Stable samples were also observed at low salt levels. Particle aggregation was fast near the charge neutralization point and at high concentrations. These results, which evidence the colloidal stability of MgAl-NO3-LDH in the presence of various anions, are of prime fundamental interest. These are also critical for applications to develop stable suspensions of primary particles for water purification processes, with the aim of the removal of similar anions by ion exchange.
positively charged layered double hydroxide particles composed of Mg(2+) and Al(3+) layer-forming cations and NO3(-) charge compensating anions (MgAl-NO3-LDH) were synthesized and the colloidal stability of their aqueous suspensions was investigated in the presence of inorganic anions of different charges.
带正电荷的层状双氢氧化物颗粒由 Mg(2+)和 Al(3+)层形成阳离子和 NO3(-)电荷补偿阴离子(MgAl-NO3-LDH)组成,并在不同电荷的无机阴离子存在下研究了其水悬浮液的胶体稳定性。
The formation of the layered structure was confirmed by X-ray diffraction, while the charging and aggregation properties were explored by electrophoresis and light scattering.
X 射线衍射证实了层状结构的形成,而电泳和光散射则探索了其荷电和聚集特性。
The monovalent anions adsorb on the oppositely charged surface to a different extent according to their hydration state leading to the Cl(-) > NO3(-) > SCN(-) > HCO3(-) order in surface charge densities.
单价阴离子根据其水合状态在带相反电荷的表面上以不同程度吸附,导致表面电荷密度的 Cl(-) > NO3(-) > SCN(-) > HCO3(-)顺序。
The ions on the right side of the series induce the aggregation of MgAl-NO3-LDH particles at lower concentrations, whereas in the presence of the left ones, the suspensions are stable even at higher salt levels.
该系列右侧的离子在较低浓度下诱导 MgAl-NO3-LDH 颗粒的聚集,而在左侧离子存在下,即使在较高盐水平下,悬浮液也稳定。
The adsorption of multivalent anions gave rise to charge neutralization and charge reversal at appropriate concentrations.
多价离子的吸附在适当浓度下导致电荷中和和电荷反转。
For some di, tri and tetravalent ions, charge reversal resulted in restabilization of the suspensions in the intermediate salt concentration regime.
对于一些二价、三价和四价离子,电荷反转导致悬浮液在中间盐浓度范围内重新稳定。
Stable samples were also observed at low salt levels. Particle aggregation was fast near the charge neutralization point and at high concentrations.
在低盐水平下也观察到稳定的样品。在电荷中和点附近和高浓度下,颗粒聚集很快。
These results, which evidence the colloidal stability of MgAl-NO3-LDH in the presence of various anions, are of prime fundamental interest.
这些结果证明了 MgAl-NO3-LDH 在各种阴离子存在下的胶体稳定性,这具有首要的基础意义。
These are also critical for applications to develop stable suspensions of primary particles for water purification processes, with the aim of the removal of similar anions by ion exchange.
这些对于应用也至关重要,目的是通过离子交换去除类似的阴离子,从而开发用于水净化过程的初级颗粒的稳定悬浮液。