Study on Preparation and Performance of High Swelling Bentonite

ABSTRACT For improving the expansibility of natural Ca-based bentonite (Ca-Bent), the Ca-Bent was modified with sodium dodecyl benzene sulfonate(SDBS)-Na2CO3 complex agent by microwave semi-dry method. And the ratio of Na2CO3 to SDBS, microwave power, radiation time and initial temperature on the modification were studied. Furthermore, X-ray diffraction (XRD) patterns and infra-red spectrum (IR) were carried out to characterize , which obtain microstructure of samples. The result showed that the optimized experimental parameters are obtained as follows: Na2CO3 to SDBS ratio 1:1, radiation time 2min, microwave power 600W and initial temperature 120K. Besides, under the optimization conditions, the modified bentonite has swelling volume of 68.5mL/g, cation exchange capacity of 56.2mmol/102g and yield point and plastic viscosity ratio of 1.67, respectively. A comparison of the single factor experiment and orthogonal experiment indicates that the SDBS and Na2CO3 have synergistic effect in the process of modification, especially, under the optimum microwave condition, Na2CO3 increased the anion activity of SDBS, which enhanced the hydrophilicity of modified bentonite. The experimental result show that the process improves the swelling volume of bentonite and the comprehensive performance. So, the modified bentonite was a perfect additive in water drilling mud.