A review on the role of tailoring surfactant in silica for oily wastewater remediation / Hafizah Hamdin and Norhusna Mohamad Nor

The oil wastewater may contribute to toxicity effects which affecting ground water resources. In addition, it is also responsible in emitting foul odor. There are several separation techniques which can solve the pollution such as adsorption. Most of the previous researches showed a promising result in using activated carbon as an adsorbent to reduce the concentration of oily wastewater, where the COD and BOD values are reported to be very low. However, it is anticipated in using silica as a replacement for activated carbon, due to its physical and chemical properties are comparable with activated carbon. To improve the ability of silica as a novel adsorbent in oily wastewater, various types of surfactant were analysed in this research work. The surface of silica nanoparticles that was modified with various surfactants such as cetyltrimethylammonium bromide (CTAB), cetyltrimethylammonium chloride (CTAC), cetylpyridinium chloride (CPC) and cetylpyridinium bromide (CPB), under various preparation methods have been studied. Studies shows that the efficiency of oily wastewater remediation can be increased with the presence of porous materials. The pore structure of the materials is very important to determine the ability to perform adsorption. The objectives of this research are; i) to analyze the effect of various types of surfactants that were modified on porous silica adsorbent and ii) to study the effect of different preparation methods in tailoring the surfactants on porous silica adsorbent toward oily wastewater application. Optimum conditions and possible surface modification mechanism for silica nanoparticles have been discussed. Based on the study, it reveals that silica-CTAB modified was the most promising materials for adsorption purpose It is found that modified silica-CTAB has the highest size of pore and the surface area which are 0.98 nm and 840 m2/g respectively. It is also showing that sol-gel method is the most effective preparation method because it can create very fine powders and produces compositions not possible by solid-state fusion. In conclusion, the addition of surfactant in the silica matrix affects the porosity of porous silica by increasing the surface area and pore volume.