Simultaneous removal of heavy metal and organic contaminants using surfactant-modified adsorbents (SMADs)

Abstract

The concern over wastewater problems has led to the development of various treament technologies. Adsorption has been increasingly interesting due to its versatility. In this research, two types of surfactant-modified adsorbents (SMADs) were developed from natural zeolite and clay mineral by using a two-step surface modification technique. A monodification technique. A monolager of a cationic surfactant (CTAB) and a second layer of an anaionic surfactant (DOWFAX 8390) were formed on clinoptilolite and bentonite clay surfaces. The adsorption of organic compounds with different functional groups (benzene, phenol, benzoic acid, chlorobenzene and naphthalene) and heavy metal ions by SMADs wer investigated. For the organic adsorption, both surfactant-modified zeolite (SMZ) and surfactant-modified bentonit (SMB) exibited linear-type isotherms, suggesting that the adsorption is mainly through the partitioning process. SMZ was shown to enhance the sorption of organic compounds more than 3.5 times when compared to unmodified clinoptilolite; whereas SMB could increase organic sorption over 13 times when compared to ordinary bentonite. In the adsorption of heavy metal ions, SMZ was shown to be inferior to unmodified adsorbents. Different from SMB, the removal of cadmium ions significantly decrease from ordinary bentonite. It can be concluded that SMADs could be considered as effective potential adsorbents for heavy metal and organic contaminant removal from wastewater.