Microgram amounts of copper(II) in one liter of water are quantitatively separated selectively as copper(II) acetate with oleic acid surfactant at pH range 6.5—7.5. The floated scum is separated, after shaking for few seconds, and measured colorimetrically at 700 nm. Beer’s law is obeyed in the concentration range (0.5—5) × 10−4 mol dm−3, {3.18—31.8 ppm of copper(II)}. Alternatively, the copper in the scum is eluted by nitric acid 0.1 mol dm−3, completed to the suitable volume required for copper atomic absorption measurement at 324.7 nm with 1 ppm detection limit. The different factors affecting the selective flotation of copper(II) have been studied. It has been found that iron(III) seriously depresses the flotation efficiency. The flotation mechanism is discussed. The method of the separation and determination is rapid and applicable to 50 ppb copper(II) concentration level in natural waters.

The determination of palladium under microgram concentration levels is generally hampered by insufficient sensitivity of the techniques used and or by a matrix effect. With the introduction of techniques, sensitivity problems have been drastically reduced.There are chemical and physical methods to increase the sensitivity and decreasing matrix effects, such as extraction 1,2 or preconcentration by solvent evaporation; however, in the presence of complex matrices with very low concentration of the analyte, these methods are seldom effective and are considered to be unsatisfactory. However, the development of a sensitive, accurate, precise and fast procedure using less sophisticated instruments is a vital process.The formation of extractable chelates of Pd(II) with dithizone 3 and dithiocarbamate 4 has been applied to the separation of Pd(II) from other platinum metal ions. Also, the extraction of Pd(II) halide complexes affords convenient separation.5 Oxime derivatives have also been used for extraction and the spectrophotometric determination of Pd(II).Flotation techniques are recommended as good separation and preconcentration 6-8 tools with most of the advancing factors previously mentioned. Recently, the flotation-separation step can be analytically completed spectrophotometrically 9 or by a suitable technique, such as atomic absorption spectrometry. 10 Such techniques acquire analytical importance as the flotation-separation step is selectively completed.Although many spectrophotometric methods have been reported for the determination of Pd(II) 6-8 , a simple, rapid and economical flotation-spectrophotometric method has been developed for the concentration and determination of trace Pd(II) in different matrices using HOL as a surfactant and HHB as a chelating reagent. This reagent is more sensitive and specific than many of the reagents reported for Pd(II). 3,4 Moreover, this method involves the determination of trace Pd(II) after selective separation by floatation, those eliminating the effect of foreign ions and increasing the sensitivity. Also, the direct determination of Pd(II) in the surfactant phase decreases its determination time and loss during the determination. Another advantage of the present investigation is that the data obtained spectrophotometrically were attained by the simplest colorimetric analysis method.A literature survey showed that ion-flotation followed by a spectrophotometric determination of Pd(II) is rarely reported.11,12 Also, no attempt has been found for using HHB in this concern. Fortunately, in this investigation, HHB finds its role for a direct spectrophotometric determination of Pd(II), and also gives high performance in the preconcentration of Pd(II) via its flotation as HHB-Pd colligend. Experimental ReagentsPalladium stock solutions were prepared by dissolving 1 g PdCl 2 (Merck) in 3 ml HCl followed by dilution to 250 ml using doubly distilled water or ethanol. For the analysis of simulated ores, a Pd stock solution was prepared by dissolving 1 g of Pd wire in few ml of ...

No abstract

Egypt 4-Phenylthiosemicarbazide (HPTS) was investigated as a new collector for the flotation of platinum(IV). The metal ion forms a (1: 2) pale green complex with HPTS in the aqueous solution. An intense clear green layer was formed, after flotation, by adding oleic acid (HOL) surfactant. The composition of the float is 1: 2 (Pt : HPTS). A highly selective and sensitive spectrophotometric procedure was proposed for the determination of microamounts of Pt(IV) as its floated complex. The flotation-determination method was achieved in the pH range 3 -7. Beer's law was obeyed up to 6X 10-5 mol 1-1(11.7 ppm). The interferences from various foreign ions were avoided by adding excess HPTS. The molar absorptivities of Pt-HPTS and Pt-HPTS-HOL systems are 2X103 and 4.7X1031 moL1 cm-1 at 660 and 690 nm, respectively. The formation constants of the species formed in the presence and absence of HOL are calculated. The method was successfully applied to the determination of Pt(IV) in its allied materials. A mechanism of flotation is suggested.

The extraction and preconcentration of a metal complex via surfactant-mediated phase separation was studied. A sensitive, selective and low-cost methodology for the determination of micro amounts of thorium, lanthanum and yttrium ions, using Eriochrome Cyanine R (ECR) with a flotation step prior to spectrophotometric determination was developed. The precipitate in the scum layer was quantitatively collected, stripped with 4 ml of 3% HCl and measured spectrophotometrically at 540 nm for Th(IV) and at 650 nm for both La(III) and Y(III). The stripping of Th(IV), La(III) and Y(III) from the scum layer was carried out in one step with different mineral acids. The stripping efficiency was found to be quantitative in the case of HCl. An excess amount of ECR was used to eliminate the interfering effects of various foreign species. The proposed procedure was applied to the determination of Th(IV), La(III) and Y(III) spiked in natural water samples and in some ore samples. Additionally, the mechanism of flotation of the metal chelate was proposed to be due to a physical interaction between the metal chelate and the oleic acid surfactant through the Van der Waals force.