Spectrophotometric Determination of Trace Amounts of Pentachlorophenol in Water after Preconcentration with Mixed Oxide of Iron (III) and Magnesium


Faculty of Education, Gifu University; Yanagido, Gifu-shi 501-1193 Japan

A simple and rapid method for the determination of trace amounts of pentachlorophenol (PCP) in water was proposed. The proposed adsorbent was prepared as follows; a suspension of mixed hydroxide, which was prepared by mixing 20 mL of 1 mol dm−3 of iron (III) chloride and 30mL of 4moldm−3 of magnesium chloride, diluting the mixture to 1dm3 with distilled water, and precipitating mixed hydroxide with sodium hydroxide, was separated through filter paper (No.2, 12cm) under suction. The residue was dried at 450°C for 30 min in an oven. A 0.6g portion of adsorbent was added to 200mL of test solution. After adjusting the pH from 11 to 12, the suspension was stirred for 60 min and filtered with a 1 μm membrane filter. The residue on the filter was stirred in 1.5 mL of 5 mol dm−3 of sulfuric acid and 10 mL of 1 mol dm−3 of sodium sulfate, and was extracted with 4 mL of 1-pentanol. The absorbance of the extract was measured at 215 nm against 1-pentanol. PCP ranging from 10 to 80 ppb could be determined. NH4+, Ca2+, CO32−, SO42−, BO3, F, SiO42− and PO43− as much as 1×10−3moldm−3 did not interfere, but up to 1×10−4 mol dm−3 of NO2 and NO3 interfered. Molecular sieves 5A coated with mixed oxide of iron (III) and magnesium was applied to the chromatographic separation of chlorophenols.

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