Influence of synthesis method in preparation of HDTMA+- and HDPy+-illites/smectites

Abstract

Intercalation of cationic surfactants hexadecylpyridinium (HDPy+) and hexadecyltrimethylammonium (HDTMA+) into the interlayer space of homoionic (Na+-, Ca++- and Zn++-) illites/smectites using three methods (solution intercalation, solid–solid reaction and microwave irradiation) was investigated in this study. The changes in the surfaces and structures of the organo-illites/smectites with cationic surfactant were characterized using X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR).The results showed that the intercalation of surfactant cations was complete within 24h, 15min and 2min by conventional method, solid–solid reaction and microwaves irradiation, respectively. HDPy+t and HDTMA+ surfactants were retained by Zn++-illites/smectites suggesting important surface properties (CEC=80meq/100g clay, SBET=116.5m2/g) and developed acid–base properties (point of zero proton charge PZC, density charge σH). HDPy+ cation loading was effective suggesting that the aromatic polar group is favored for intercalation. Different configurations of surfactants within interlayer space of clay mineral were proposed based on the basal spacings which increased with surfactant loading. The presence of symmetrical and asymmetrical vibration bands of the –CH2 group in the IR spectrum of the modified illites/smectites and the variation of their frequencies and their intensities confirmed the results obtained by XRD.