Extractive Separation of Cadmium(II) using Cyanex 923 from Ammonium Thiocyanate Medium

Abstract

A selective and effective solvent extraction method has been developed for the separation of cadmium(II) using Cyanex 923 in toluene. Cadmium(II) was quantitatively extracted using 0.1 M Cyanex 923 in toluene from 1.0 M ammonium thiocyanate media. The extracted cadmium(II) was quantitatively stripped with 3.0 M nitric acid from organic phase and determined spectrophotometrically with PAR at 520 nm. The optimum extraction conditions have been evaluated by studying parameters such as ammonium thiocyanate concentration, Cyanex 923 concentration, equilibration time, various diluents, diverse ions, and stripping agents. The selective and sequential separation of cadmium(II) from other cations was achieved in binary as well as multicomponent mixtures. The method was extended for the separation of cadmium from spent nickel-cadmium batteries, some aquatic plants and zinc blende. The reliability of the method is assured by a comparison of the results with those obtained using AAS.

Supported Liquid Membranes for the Removal of Pharmaceuticals from Aqueous Solutions

“…Previous studies proved that this complex species formation between the contaminant and the organic extractant does not only depend on the equilibrium constant of the reaction mechanisms, but also on the viscosity effect of the organic extractants which is governed by Stokes-Einstein equation [16,26]. The variation of permeability coefficient with Cyanex 923 concentration was reported by different studies for the removal of iron(III) [16] cadmium(II) [18], and phenolic compounds [27]. The optimum concentration of Cyanex 923 required for a quantitative extraction, depends on the nature of the feed and stripping phase, temperature and pH [28].…”

“…Therefore, Cy923 diluted in kerosene was selected to extract diclofenac. Cy923 is considered a cheaper extractant with better stability compared to tributylphosphate [18,26].…”

“…The characteristics of both membranes are mentioned in the previous section. The use of PVDF as support for liquid membrane has been reported by various research studies for the separation, recovery, and extraction of different chemicals [17,18,30].…”

“…SLMs have been extensively used for the recovery of metals from industrial process streams. Several authors have reported the recovery of metal and anions such as copper, zinc, nickel, Cr (VI), Hg, and cadmium through liquid membrane contactors [15][16][17][18].…”

“…Diclofenac([2-(2,6-Dichloroanilino)phenyl]aceticacid) and ibuprofen (methylpropyl)phenyl)propanoic acid) are typical representatives of analgesic non-steroidal anti-inflammatory pharmaceutical compounds (NSAIDs).these types of drugs are easily accessible and sold over the counter [19].Traces of diclofenac are found in the effluent of water and was listed in the European first watch substances list [23] and for ibuprofen was found in sewage treatment plants effluents and surface water at concentrations ranging from 600 to 85,000 ng/L in parts of Europe, Canada, and USA [9,[13][14][15][16][17][18][19][20][21][22][23]. In addition to anti-inflammatory, the emergence of psychiatric drugs in drinking water has garnered a lot of scientific interest, particularly with regard to the effects of longterm exposure.…”