A series of organoclays with different surfactant arrangements were prepared by ion exchange. The resulting organoclays were investigated using a combination of characterization techniques, including XRD, FTIR, TG and N2 adsorption-desorption. In the present study, the pores within the organoclays were discussed on the basis of the microstructural parameters, including BET-N2 surface area, pore volume, pore size, surfactant loading and distribution. The results show that both BET-N2 surface area and pore volume decrease from low to high packing density of the surfactant as the average pore size increases. Two basic organoclay models were proposed for hexadecyltrimethylammonium bromide (HDTMAB) modified montmorillonites: 1) the surfactant mainly occupied the clay interlayer and 2) both the clay interlayer space and external surface were modified by surfactant. This study demonstrates that the pore structure of the resulting organoclays has a significant influence on the sorption efficiency and mechanism of p-nitrophenol onto the organoclays
