天然钙蒙脱土的钠化改型和有机化改性

用碳酸钠作为钠化剂对天然钙蒙脱土进行了钠化改型,用CTAC、CTAB、C18三种插层剂分别对钠蒙脱土进行了有机插层改性。对钠化改型前后的蒙脱土进行了XRD、FTIR分析,对有机改性前后的蒙脱土用XRD、SEM、FTIR和TG-DTA等进行了表征和分析。结果表明:钙蒙脱土经钠化改型后,层间距增大,结晶度变差,活性增强;CTAC、CTAB、C18三种改性剂都能使蒙脱土的晶层间距有较大提高,其中,尤以C18改性剂的有机化效果最为显著;蒙脱土有机改性前后外观变化十分显著;有机改性蒙脱土的结构水无明显变化,层间吸附水显著减少,疏水的有机插层剂主要进入蒙脱土层间,大量脱去层间吸附的水分子,对晶体结构本身并无影响。有机改性后,蒙脱土的吸附水与层间水的脱水温度与脱水量均显著降低,有机插层剂的大量插入,改变了原土的亲水性使之变为疏水,并提高了其热稳定性。

Na+ -transformation and Organic Modification of Ca-MMT

Calcium cations (Ca~ 2+ ) in Ca-MMT were first exchanged with sodium cations (Na~+) of Na-2CO-3, and CTAC, CTAB and C- 18 were separately used to organically modify the Na-transformed Ca-MMT. The MMT was analyzed by means of XRD and FT-IR before and after the Na~+-transformation, and characterized and analyzed by means of XRD, SEM, FTIR, TG-DTA and other measures before and after the organic modification. The results showed after the Na~+-transformation the interlayer-spaces of MMT expanded, its crystallinity decreased, and reactivity increased; CTAC, CTAB and C- 18 were all good interaction agents of MMT, and C- 18 was the best; the appearance of MMT changed obviously before and after the organic modification; the structure water of organo-MMT (OMMT) changed little, but its interlayer water was largely excluded, the hydrophobic intercalation agents mainly entered the galleries of MMT and expelled the interlayer water there, which had no influence on MMT crystalline structure; after the organic modification, the desorbing temperature and mass of the adsorption water between the clay layers decreased remarkably, with plenty of organic molecules intercalated into its galleries, MMT changed to be hydrophobic from its original hydrophilic, moreover its heat stability was greatly elevated.