Ait-Akbour Rachid, Boustingorry Pascal, Leroux Fabrice, Leising Frédéric, Taviot-Guého Christine
Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand, France; CNRS, UMR 6296, ICCF, F-63171 Aubière, France.
CNRS, UMR 6296, ICCF, F-63171 Aubière, France; CHRYSO, 7 rue de l'Europe, F-45300 Sermaises, France.
J Colloid Interface Sci. 2015 Jan 1;437:227-234. doi: 10.1016/j.jcis.2014.09.027. Epub 2014 Sep 19.
This study deals with the adsorption of PolyCarboxylate Poly(ethylene glycol) esters (PCP) superplasticizers on Na-, Mg- and Ca-saturated Montmorillonite (Mmt) clays. The interactions have been examined through different experimental methods: adsorption isotherms, zeta potential measurements and sedimentation experiments. It was found that PCP adsorption depends both on the architecture of PCP molecules and the nature of cation located on the interlayer exchange sites of the Montmorillonite. Whatever the PCP, a larger amount was adsorbed on Na-Mont than on Mg-Mont or Ca-Mont. This indicates the occurrence of two adsorption mechanisms: (i) a superficial adsorption via electrostatic interactions between the carboxylate groups of PCP and positively charged sites on clay surfaces, (ii) intercalation of ether units of the PCP grafts in the interlayer space by displacement of water molecules coordinated to the exchangeable cations. Furthermore, despite the weak negative values of the zeta potential, the addition of PCP promotes the stability of the suspensions which is attributed to steric repulsion acting between particles.
本研究探讨了聚羧酸聚（乙二醇）酯（PCP）高效减水剂在钠、镁和钙饱和蒙脱石（Mmt）粘土上的吸附情况。通过不同的实验方法对相互作用进行了研究：吸附等温线、ζ电位测量和沉降实验。结果发现，PCP的吸附既取决于PCP分子的结构，也取决于位于蒙脱石层间交换位点上的阳离子的性质。无论哪种PCP，在钠蒙脱石上的吸附量都比在镁蒙脱石或钙蒙脱石上的吸附量更大。这表明存在两种吸附机制：（i）通过PCP的羧基与粘土表面带正电的位点之间的静电相互作用进行表面吸附，（ii）PCP接枝的醚单元通过置换与可交换阳离子配位的水分子而插入层间空间。此外，尽管ζ电位为微弱的负值，但PCP的加入促进了悬浮液的稳定性，这归因于颗粒之间的空间排斥作用。
