*Corresponding author e-mail: grsaad@sci.cu.ed.eg Received 20/3/2019; Accepted 28/04/2019 DOI: 10.21608/ejchem.2019.10855.1697 ©2019 National Information and Documentation Center (NIDOC) N OWADAYS, clay minerals are used extensively in a wide range of applications as nano additives for polymeric materials. Nevertheless hydrophilic characteristics of the nano additives reduce their degree of compatibility with polymeric chains. To overcome this problem it is necessary to modify the clay in order to render its surface more organophilic prior to the intercalation of the polymeric chains between its layers. In this work the Egyptian natural clay mineral montmorillonite (MMT) was modifed with two cationic organic modi- fers, namely hexadecyltrimethylammonium (HDTMA) and tributyl hexadecyl phospho- nium using two different procedures. The first, using the magnetic stirrer while the second using a high speed mixer at different mixing times from 0.5 up to 2.5 hr. The samples with and without organic modifiers were characterized by X-ray diffraction (XRD), infrared spectroscopy (IR), thermogravimetric analysis (TGA), scanning electron microscope (SEM) and transmission electron microscope (TEM). XRD results revealed that the basal spacing of the organo-montmorillonite (OMMT) prepared using high speed mixer was larger than that using magenetic stirrer. The best result was obtained after 1.5 hr stirring in the high speed mixer. The modification of MMT was confirmed by FTIR as determined from –CH 2 stretching vibration of the organic modifiers. The TGA analysis revealed that the MMT modified with tributyl hexadecyl phosphonium cation had high thermal stability than that modifed with hexadecyl trimethyl ammonium cation. The amount of surfactants within or- ganoclays were found to be about 19 and 24%, respectively, for hexadecyl trimethyl ammo- nium bromide and tributyl hexadecyl phosphonium bromide. SEM demonstrated that the modified MMT exhibited a massive thin layered structure with some large flacks and some interlayer spaces. TEM images of the prepared organoclays showed exfoliated structure. This work proved to enhance the economical value of the Egyptian natural resources. Keywords: Egyptian mineral montmorillonite, Organic modifcation, Basal spacing, High speed mixer. Modifcation of Egyptian Clay by Different Organic Cations Marwa E. Mohamed 1 , Gamal R. Saad 2 *, Alaa I. Eid 1 , Malak T. Abou El-khair 1 1 Composite Lab., Advanced Material Division, Central Metallurgical Research and Development Institute. 2 Department of Chemistry, Faculty of Science, Cairo University, Giza, Egypt. Egyptian Journal of Chemistry http://ejchem.journals.ekb.eg/ Egypt.J.Chem. Vol. 62, No. 10. pp. 1761- 1769 (2019) 136 Introduction Egypt is rich with mineral resources which when treated in an appropriate manner are converted to materials with high economic value that can be used in several industrial applications. One of these natural resources is the smectite clay which covers most of the eastern and western deserts [1]. Montmorillonite (MMT) is one member of the smectite clays that is commonly used as nano additives in small percentage in the synthesis of clay polymer nanocomposites [2-6]. These polymer nanocomposites have a wide range of applications in the feld of material science and technology [7-11] due to the enhanced thermal [12,13], physical and mechanical properties [14]. Also the barrier and fame retardant properties of the produced nanocomposites are improved [1 5]. MMT has 2:1 layered structure as each particle consists of hundreds or thousands of