Physicochemical study of microwave-synthesized organoclays

Abstract

In this work, microwave-synthesized organoclays were prepared and the physicochemical properties examined due to the importance and wide range of organoclay applications. Previous research studies have reported the synthesis of new organoclays, however, almost the same synthesis procedures have been used except for the small changes in reactant addition rate, solvent, and temperature. The standard organoclay preparation method involving intercalation, washing and drying steps is a time-consuming process with the intercalation step taking a few hours. Although it is a good laboratory method, the long time requirement for the synthesis forms a bottleneck in the industrial applications. In contrast to the conventional synthesis procedure, microwave irradiation makes it possible to complete the intercalation in a short time. Additionally the use of microwave for drying purposes will cause a further reduction in the time requirement. In this research, the organoclays were synthesized by using hexadecyltrimethylammonium bromide, a smectite from central Anatolia, and microwave irradiation. The organoclays were dried using freeze drying, microwave drying and oven drying. They were examined using X-ray diffraction, electron microscopy, IR spectroscopy, and thermal analysis to determine the effect of irradiation on the physicochemical properties. The d-spacings were determined to be 19.5 Å that is close to the values reported for the conventionally prepared organoclays. The results of FTIR analysis reveal that the confined amine chains adopted all-trans conformation as in the case of the conventional organoclays. Application of microwave irradiation at 360 W for 5 min is enough to achieve a 70% exchange efficiency which is comparable to the organic cation exchange efficiencies reported using conventional techniques. Except the surface morphology, drying conditions have no effect on the structural properties of organoclays. Therefore, it is concluded that the use of microwave irradiation in the intercalation step has the potentialities for industrial scale applications and microwave drying should also be considered in the last step of synthesis due to the very short drying time compared to other methods.