Adsorption of methanol from methanol–water mixture by activated carbon and its regeneration using photo-oxidation process

Abstract

Activated carbon (AC) has been used as an adsorbent for centuries as a result of its ability to remove a large variety of compounds from contaminated waters. The objective of this study was to investigate the removal of methanol by adsorption and the use of advanced oxidation process for the regeneration of the exhausted AC as an alternative to thermal, biological, and chemical methods that are currently applied. Several experimental tests were carried out to examine the ability of AC for adsorbing methanol from methanol–water mixture. The results show fast saturation of the AC and short breaking time, especially for solutions consisting of methanol above 3% vol. However, adsorption capacity of exhausted AC with methanol, after washing, showed an improvement in its adsorption capacity over that of fresh AC. This improvement may be due to that methanol may harsh the surface of AC causing an increase in the sizes of pores and cavities. Large cavities were micrograph using scanning electron microscope (SEM). After saturation, AC was regenerated using the photo-catalytic process, the adsorption capacity of AC was fully restored. The results showed that the titanium dioxide with the aid of UV light can easily regenerate the AC by oxidizing the organic compounds adsorbed on the surface of AC. It was observed that the increase of UV light intensity had a positive effect on adsorption capacity. However, the increases of TiO2 concentrations had a limited effect on the adsorption capacity of the AC.