The Application Of Cloud Point Extraction Combined With Flame Atomic Absorption In Analysis Of Different Forms Trace Cr、Cd And Pb

It is very important to identify and determine accuratly chemical forms of heavymetals in environmental samples because the toxicity, migration and the seriousharmfulness of heavy metals largely depende on the available metals.New methods combined flame atomic absorption spectrometry (FAAS) of highselectivity with cloud point extraction of high enrichment ability for determinationof water-soluble Cr(III), Cr(VI) in soil and Pb, Cd in water. Moreover, researcheswere conducted to analyze morphological distribution of Cr of detoxificationchromic slag and nearby soils of the chromium residue field and leach availablearsenic in acid soil. The researches were described as follows:(1)Determination of water-soluble Cr(III) and Cr(VI) in soil by flame atomicabsorption spectrometry after cloud point extractionA new method has been developed for the determination of water-soluble Cr(III)and Cr(VI) in soil by flame atomic absorption spectrometry after cloud point extracti-on. In the proposed approach, Cr(III) and AC form a complex, emulsifier octyl Polyethylene glycol phenol ether (OP) as surfactant. In order to separate Cr(III) fromother metal ions, Cr(III) was extracted into the surfactant phase. In order to getthe total available chromium, Cr(VI) is reduced to Cr(III) by ascorbic acid. Somefators which influenced the efficiency of cloud point extraction in detail were studiedand optimized. Under the optimized conditions, as the extraction volume were10mLand50mL the calibration graphs of Cr(III) were A=-4.99238×10-4+0.25206C andA=0.00102+0.42451C, the calibration graphs were linears in the range of0.01～0.5μg·mL-1and0.004～0.2μg·mL-1μg·mL-1, and the correlation coefficient were0.9972and0.9988, respectively. The relative standard deviation (R.S.D) were4.8%and4.5%(n=9). The recoveries of water-soluble Cr(III) and Cr(VI) of the samples wereranged from90%to115%indicated this method was satisfactory for trace analysis ofwater-soluble Cr(III) and Cr(VI) in soil.(2) Determination of trace Pb, Cd in water by flame atomic absorptionspectrometry after cloud point extraction A novel method was developde for the determination of trace Pb, Cd in waterby flame atomic absorption spectrometry. The present work used AC as chelatingagents, OP was used as surfactant and DTAC as sensitizing agent. And someconditions that affected the efficency of cloud point extration were reaseared. Underthe optimized conditions, the calibration graphs of Cd and Pb wereA=-0.03134+1.57412C and A=0.00164+0.14587C, the calibration graphs linear inrange of0.02~0.50μg·mL-1and0.01~0.40μg·mL-1, and the correlation coefficientwere0.9994and0.9999. The relative standard deviations (RSD) of Cd and Pb were2.3%and4.4%. The recoveries of Cd and Pb in water were ranged from95%to105%.(3) Morphological distribution of Cr of detoxification Chromic Slag and nearbysoils of the Chromium residue fieldTo evaluate whether the chromic slag was detoxicated thoroughly, we analyzedthe morphological distribution of heavy metal Cr of the detoxification chromic slagand the nearby soil of the chromium residue field using the extraction agent of Tessier,and determined the Cr by flame atomic absorption spectrometry after microwaveextraction. We mainly studied exchangeable ionic state, carbonate bound statechromic and Fe-Mn oxide bound state, the results showed the detoxification methodused by this chromium residue field made the bioavailability of Cr lower significantly.And the peripheral soil of the chromium residue field has not been polluted, but thecontent of carbonate bound state chromic and Fe-Mn oxide bound state chromic inthe detoxification chromic slag is still high, so there are some potential safetyproblems in peripheral soil of the chromium residue field.(4) A research for leaching available arsenic of acidic red soilThis paper explores the extraction method by extracting the red soil inZhengzhou Academy Institute of Agricultural Sciences as the experimental objects.The pH between4and6of the GBW07406-GSS-6national standard yellow red soilwas choosen as comparison experiments. In order to research the extract efficiency,a series experiment was studied using doubly deionized water,0.1mol·L-1HCl、Na3PO4、1.0mol·L-1NH4Cl、K3PO4、NaH2PO4、KH2PO4and H3PO4. Finally,1.0mol·L-1Na3PO4was chosen as the leaching agent.