American Journal of Chemistry 2015, 5(3A): 1-6 DOI: 10.5923/c.chemistry.201501.01 Extraction of Cd(II) Ions by Emulsion Liquid Membrane (ELM) Using Aliquat 336 as Carrier A. L. Ahmad 1,* , M. M. H. Shah Buddin 1,2 , B. S. Ooi 1 1 School of Chemical Engineering, Universiti Sains Malaysia, Engineering Campus, Nibong Tebal, Malaysia 2 Fakulti Kejuruteraan Kimia, Universiti Teknologi MARA, Shah Alam, Malaysia Abstract In this work, the potentialities of vegetable oil to be incorporated as diluent in Emulsion Liquid Membrane (ELM) formulation was explored. Vegetable oil tested in this study are sunflower, corn and palm oil. A compatibility study was conducted to investigate its feasibility to be used as diluent in ELM. It is learned that corn oil showed a promising results to be incorporated in ELM to dissolve Span 80 and Aliquat 336 as surfactant and carrier in the membrane phase, respectively. The analysis showed that Aliquat 336 is highly selective towards Cd(II) as it able to remove almost all Cd(II) ions from the aqueous solution while Span 80 has assisted in the formation of a stable emulsion. The W/O emulsion was prepared using 0.1M NaOH as the internal phase while the membrane phase consist of 3 wt% Span 80 and Aliquat 336, dissolved in corn oil. The influence of stirring speed and extraction time on the solute removal efficiency was observed. The best performance of ELM in extracting Cd(II) ions was recorded at speed of 300 rpm for 15 min. 98.6% of Cd(II) ions were successfully removed from the external aqueous phase at this condition. Keywords Emulsion Liquid Membrane, Aliquat 336, Vegetable oil diluent, Cd(II) ions Extraction 1. Introduction Rapid industrialization which begun in 1960s has raised many critical issues regarding environmental pollution. One of them is the emission of heavy metal with a great potential to pollute the environment. In fact, Elbagermi et al. [1] reported on the dramatic increasing trend of heavy metal emission since the onset of industrial revolution. In the year 2013 alone, Department of Environment Malaysia reported that a total of 103,994.37 metric tonnes of industrial waste containing heavy metals were generated from various industries in this country [2]. Among the most common heavy metal found in polluted water includes arsenic, copper, cadmium, lead, chromium, nickel, mercury and zinc [3]. Apart from its ability to harm the ecosystem, extensive study carried out by World Health Organization (WHO) has revealed that exposure to these metals will eventually cause deleterious health effects in humans though some of them are nutritionally essential for a healthy life, but in a very small quantity [4]. As for cadmium, it is a toxic metal occurring naturally in the environment and it is considered as a pollutant emanating primarily from industrial and agricultural sources [5]. Due to its high solubility, cadmium can be easily absorbed by living * Corresponding author: chlatif@usm.my (A. L. Ahmad) Published online at http://journal.sapub.org/chemistry Copyright © 2015 Scientific & Academic Publishing. All Rights Reserved organisms and it can easily enters our food chain [6]. Study conducted by Kadaruddin [7] discovered that as much as 53 rivers in Malaysia’s river system were badly contaminated with cadmium from various sources, mainly manufacturing. Tremendous efforts have been carried out in minimizing the concentration of heavy metal in aqueous media using various physico-chemical treatment [8]. However, Emulsion Liquid Membrane (ELM) which was invented by Li [9] has shown a promising potential in the field of separation. In case of metal removal from aqueous media, ELM was reported to be successfully used in extracting numerous types of heavy metal ions for instance, Cr(VI) [10], Cu(II) [11] and Co(II) [12]. In addition, our previous work on ELM using TOA as carrier has recorded more than 98% of efficiency [13]. In this study, Aliquat 336 was used as the carrier to specifically extract Cd(II) ions. Aliquat 336 is a quaternary ammonium salts which reported to act as anion exchanger at wide range of feed pH [14] and its viscous characteristic has allowed the formation of a stable emulsion against shear. In fact, Aliquat 336 possess surfactant property [15] which is favourable in the production of a stable emulsion. ELM is a developed form of solvent extraction, with the difference that extraction and stripping process occur synchronously in the same unit [16]. In principal, ELM consists of internal (W) and external (W) phase and they were separated by the immiscible organic membrane phase (O) thus, forming W/O/W (water-in-oil-in-water) emulsion system. In this multiple emulsion system, the primary W/O