Determination of Mercury and Manganese by Using New Reagent Azo after Cloud Point Extraction for Some Environmental Sample in Iraq

and Mn +2 by Cloud Point Extraction (CPE) method. Procedure which was developed for the separation and preconcentration and the procedure are simple, cheap, fast and environmental safety. The parameters affecting could point extraction, such as concentrations of reagent, volume of triton X-100, pH, equilibrium of temperature and time-consuming were studded. Under the optimum condition the linear range 2-14 μg L −1 for mercury and 2-16 μg L −1 for manganese at pH 7. The detection limit was 0.75, 0.4 μg L −1 and relative standard deviation was 1.3%, 1.4% respectively, the recovery of analytes was found 96-98.7%, 97-99.7%. The method was applied to the determination of manganese (II) and mercury(II) of wastewater of Rustimiyah city in Iraq.


Regents
All the chemicals used were of analytical reagent grade; deionize water use to diluting the samples. Hydrochloric acid (BDH), Triton X-100 (Merck), Sodium hydroxide (BDH), sodium nitrate (BDH), thymol (BDH), ethanol (Merck), manganese sulphate mono hydrate (GCC), 3-amino phenol (BDH). About 1000 µg L −1 stock solution of Mn +2 and Hg +2 were prepared by dissolving 0.1353, 0.159 g of mercury(II) chloride and manganese sulphate mono hydrate an appropriate amount of deionized water and diluting to the mark in 100 mL volumetric flask. Working stock solution was prepared daily from the stock by appropriate dilution with water. Stock solution of HTMCDAP reagent was prepared by dissolving 0.258 g in 0.5 mL of 10%(V/V) TritonX-100 and diluting to the mark in 100 mL. Non-ionic surfactant, TritonX-100 10%(V/V) was prepared by dissolving 10 mL Triton X-100 in hot deionize water and diluting to the mark in 100 mL volumetric flask. 0.01 M hydrochloric acid and 0.01 M sodium hydroxide use to adjust pH.

General Procedure for CPE
Aliquots 10 mL of a solution containing a known amount of Mn +2 , Hg +2 ions, 10% (v/v), Triton x-100 and reagent was adjusted the pH by 0.01 M HCl, 0.01 M NaOH. The mixture was shaken for 1 min and left to stand in a thermo-stated bath at 70°C for 15 min. Separation of the phases was achieved by centrifugation at 4100 rpm for 15 min the remaining of micelle phase was dissolved by ethanol, Mn +2 and Hg +2 ions were measured by UV-Vis spectrophotometer at λ max 444 and 423 nm.

Synthesis and Characterization of Reagent
The synthesis of 3-[(5-hydroxy-3-6,6-trimethylclohexa2,4-dienyl)diazenyl]phenol scheme(1) was synthesized according to the reported method by dissolved 3g (0.027 mol) of C6H4(NH2)(OH) in 5 mL of concentrated hydrochloric and 5 mL deionized water and diazotized below 5°C with (0.75 g, 0.01 mol) of sodium nitrite. The resulting diazonium chloride solution was added drop wise with cooling to solution of thymol 4g (0.026 mol) dissolved in 5 mL of alkaline ethanol; the solid product was filtered and crystallized from hot ethanol.

The FTIR Spectrum of Ligand HTMCDAP and Complexes
The FTIR spectra of free ligand showed an appearance of broad band's at (1438 cm −1 ) refer to the frequency of azo group confirmed that a synthesized dye containing azo group (Veerachalee et al., 2007). Table 1 and Fig. 1 showed the broad bands of ligand HTMCDAP in KBR disk.
The FTIR spectra of free ligand showed two bands at (3429, 3178 cm −1 ) refer to the frequency of ν(OH) of phenolic group respectively, while in the metal complexes observed that the disappearing of one band for ν(OH) vibration in the spectra of Hg-HTMCDAP and Mn-HTMCDAP, indicating the coordination of phenolic oxygen with metal ions (Mohammed and Asniza, 2010). The spectra bands of the free ligands at1438 cm −1 refer to azo group ν( N = N) shifting to higher bands in the metals complex's observed at (1458,1454 cm −1 ). The infrared spectra of the complexes have shown some other new bands which appeared in the range (582-520 cm −1 ), (594-51 cm −1 ) and (482-424 cm −1 ), (466-405 cm −1 ) are due to the ν(M-O) and ν(M-N), respectively (Al-Bayati et al., 2013;Nakamoto, 1997) for Mn-HTMCDAP and Hg-HTMCDAP. Figure 1 to 3 shown the FTIR for Ligand and complex's.

Ultraviolent Spectrum of Ligand HTMCDAP and Hg-HTMCDAP and Mn-HTMCDAP
The UV-Vis spectrum of HTMCDAP shown maximum absorption at 294 nm due to the (π→π*), the azo group (N = N) gives an absorption in the 397 nm (Kirkan and Gup, 2008). The complex with Hg-HTMCDAP and Mn-HTMCDAP the maximum absorption were appeared at 444 and 423 nm while the ligand at 397 nm maximum absorption. Figure 4 to 6 shown the UV/VIS for ligand and complexes.

C.H.N Analysis
The results of element analysis of new reagent HTMCDAP were explain in Table 2.
Schem 1. The chemical structure of Reagent HTMCDAP

Effect of pH
The pH plays a critical role on metallic complex formation and has been a significant parameter for CPE, the aqueous solutions on the extraction yield of Mn +2 and Hg +2 as HTMCDAP reagent were investigated in the pH range 4-14, the maximum sensitivity for CPE was obtained at pH 7 the results are shown in Fig. 7. In more acidic solutions due to protonation the reagent while in the basic solution due to formation of charged hydroxyl-M-HTMCDAP mixed complexes or precipitation of metal ions in the form of hydroxides. So as the pH 7 was chosen.

Effect of HTMCDAP Concentration
The concentration of reagent is important indicator as to whether the reagent action processed completely. The effect of HTMCDAP concentration on the absorbance was investigated within range (1×10 −5 -9×10 −5 ) mol L −1 , the results are shown in Fig. 8. Shows that the measured absorbance increases when the concentration of HTMCDAP increases and then suddenly decreased up concentration 7×10 −5 mol L −1 , therefore 7×10 −5 mol L −1 was chosen. Figure 9 has shown effect of surfactant volume on the cloud point extraction of Mn +2 and Hg +2 . Different volumes of 10% (v/v) Triton X-100 ranging from (0.1-1) mL, the highest absorbance was found at 0.8 mL of 10% (v/v) Triton X-100 up this TritonX-100 volume, the analytical signal starts to decrease. This can be attributed to an increase in viscosity of the surfactant phase. Thus, 0.8 mL of 10% (v/v) Triton X-100 was used as optimal.

Effect of Equilibrium Temperature and the Incubation Time
The effects of the equilibrium temperature and the incubation time are important factors in (CPE) and efficient separation of phases. Absorbance was investigated in the range of 40-95°C and 5-35 see and the results is shown in Fig. 10 and 11. Excellent absorbance was found at temperature 85°C for Hg +2 and 70°C for Mn +2 at higher temperature could cause decomposition of the complex. It was also observed the maximum absorbance found at 25 and 30 min for Hg +2 and Mn +2 thus, selected 25 and 30 min.

Interferences Study
The effect of most diverse ions expected in the wastewater sample of Rustimiyah city in Iraq on the determination of 14 µg L −1 Hg +2 and 16 µg L −1 Mn +2 under the optimal condition, cations may react with reagent and anions may form complex's with Hg +2 and Mn +2 thus, extraction efficiency decreases. Table 3 shown the effect of Interferences ions.

Calibration Graph
Employing the optimum conditions established by CPE procedure to determination Hg +2 and Mn +2 , the calibration graph response to the Beer law over the concentration 2-14 µg L −1 for mercury and 2-16 µg L −1 for manganese with correlation coefficient 0.9982, 0.9961 are shown in Fig. 12 and 13. All other analytical characteristics data are summarized in Table 4.

Accuracy and Precision
The accuracy and precision of proposed methods were determined Hg (II) and Mn (II) at two concentration level of by analyzing eight replicate sample of each concentration. Table 5 show high reproducibility of results and precision of the methods.

Analytical Application
The proposed methods was applied to the quantitative determination of Hg (II) and Mn(II) in wastewater of Rustimiyah city in Iraq. It was gave a good accuracy and precision as shown in Table 6.

Conclusion
Cloud point extraction is cheapens, easy, safe and versatile pre-concentration technique to determine Hg(II) and Mn(II) by UV/VIS. In proposed method the ligand HTMCDAP is a sensitivity and selectivity for determination of Hg(II) and Mn(II) in wastewater sample and gave a good RSD and low limit of detection.