Study on Preparation and Performance of High Swelling Bentonite

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