Peaks characterized for pinene in the PBS/M-P sample are clearly visible, which can indicate that terpene was also adsorbed at the MMT surface in a greater amount than limonene. Moreover, for this series, there is a shift of peak assigned to stretching vibration of Si-O at 991 cm -1 for native MMT to lower wavenumber (983 cm -1 ), whereas for other samples, the maximum of the peak is at higher wavenumber (PBS/M-L 995 cm -1 and PBS/M-PL 1001 cm -1 ).