纳米、微米一水草酸钙和二水草酸钙对非离子表面活性剂NP-40的吸附差异

Adsorption of Nonionic Surfactant NP-40 on Micron/Nano Calcium Oxalate Monohydrate and Dihydrate Crystals

为探究Ca Ox结石的形成机理,测定了不同浓度NP-40(cNP-40)存在下各尺寸COM或COD晶体的吸附量;采用X射线衍射和红外光谱研究吸附前后晶体是否发生晶相改变;采用ζ电位仪测定吸附后晶体表面的ζ电位随cNP-40的变化。结果表明:不同尺寸COM、COD对NP-40的吸附能力大小顺序为:50 nm>100 nm>1μm>>3μm>10μm;相同尺寸的晶体,COM的吸附量大于COD。随着cNP-40增加,3μm和10μm的COM、COD晶体的吸附曲线为S型,而50 nm、100 nm、1μm的COM、COD晶体的吸附曲线为直线型。加入NP-40后,ζ电位绝对值与各晶体的吸附密度成正相关。提出了草酸钙晶体吸附NP-40的分子模型。晶体尺寸越小,对NP-40的吸附量越大。非离子表面活性剂虽然自身不带电荷,但吸附到COM、COD晶体表面后可以通过位阻斥力来增加晶体悬浮液的稳定性,有利于抑制草酸钙结石的形成。

In order to study the formation mechanism of calcium oxalate （CaOx） stones, the adsorption amount ofCOD and COM with different sizes to NP-40 was detected by UV-Vis spectroscopy. Crystal phase transformationbefore and after adsorption was analyzed by XRD and FT-IR. potential of crystals after the adsorption of variousconcentration of NP-40 （CNPO） was measured by potential analyzer. The adsorption capacity of COM and CODwith different size to NP-40 was： 50 nm〉100 nm〉1μm〉〉3μm〉10μm. The adsorption quantity of COM wasgreater than COD of the same size. The adsorption curves of COM and COD with size of 3 μm and l0 μm are S-type, while the curves of COM and COD with size of 50 nm, 100 nm and 1 μm were linear-type. The absolutevalues of potential of crystals were positively related to the adsorption density to NP-40. The molecular model ofNP-40 adsorbed on CaOx crystals was proposed in this study. The smaller the crystal size is, the greater theadsorption amount of CaO crystals to NP-40 possess. Although nonionic surfactant itself is uncharged, it can beadsorbed onto COM and COD crystals and increase the stability of crystals suspension by steric hindrance, whichis conducive to inhibiting the formation of CaOx stones.