2. Materials and methods
2.1. Materials
The bentonite used in this study was purchased from Sigma Aldrich Chemie, Germany. The surfactant, hexadecyltrimethyl ammonium (HDTMA) chloride, was obtained from Aldrich
Chemicals Co. (WI, USA) and was used as such for the clay modification. TCP was supplied by Fluka, Switzerland. All other chemicals were purchased from E. Merck, India Ltd. The chemical composition of the original clay was reported in our earlier
publication [24].