Study On The Color Reaction Of Chromium (VI) With Derivatives Phenylfluorone

Since the discovery of chromium metal elements in the late 18th century, Chromium and its compounds has been widely used in industrial production.It is widely used in metallurgical, chemical, refractory and other industries. In the electroplating industry as its gloss and high hardness, high wear resistance feature, chromium is often used as a decorative coating to increase resistance and wear resistance products. Because in the air chromium can form a stable oxide film, so the chrome plating can maintain the original color and luster for a long time in the air. Due to chromium and its compounds is widely used in many industrial production, the resulting chromium-containing wastewater has become an important environmental pollution, the toxic effects on the human body from chromium compounds has taken more and more attention.This article has two parts, reviews, and experimental parts: the reviews mainly introduces some of the major methods of analysis on chromium in recent years, expresses the advantages and disadvantages of each method,indicates the direction of future development methods of analysis on chromium. Experimental parts study the color reaction of 2-hydroxy-3-methoxy phenylfluorone and 3,5-dibromo-4- (2,4-dihydroxy) phenylazo phenyl Fluorone with chromium (VI) respectively.During the color system of 2 - hydroxy -3-- methoxyphenylfluorone ketone (HMPF), we studyed the color reaction and photometric of HMPF and chromium (VI) in the presence of the cationic surfactant cetyltrimethylammonium bromide (CTMAB). Investigated the performance of the color reaction in different surfactant, temperature, color time and the amount of reagent conditions. Discussed the influence of various ions and determine the optimal experimental conditions. We found in buffer solution of HAc-NaAc medium,when the PH=5.0, 2-hydroxy-3-methoxy phenylfluorone formed a 2:1 stoichiometric complexes with chromium (VI). The maximum absorption wavelength is 536nm.When the chromium contenting is in the 0-350μg / L ,law is obeyed in the range,.The apparent molar absorption coefficient isε= 2.45×10⁵L·mol^-1·cm^-1. The detection limition is 3.69ug / L. When the analysis is used to determine the content of chromium in electroplating wastewater, the effect is better.When pH=5.5,we studied the photometric properties and color reaction of the 3,5-dibromo-4- (2,4-dihydroxy) with chromium (VI), in the HAc-NaAc buffer solution and the presence of CTMAB, 3,5 - dibromo -4-- (2,4-dihydroxy) phenylazo phenylfluorone as chromogenic agent. We discussed the influnce of the surfactant, temperature, color time and the amount of reagent conditions on the color reaction. The detection limition of the color reaction was 3.01ug / L, the apparent molar absorptivity obtained by the slope of the working curve is 5.59×10⁵L·mol^-1·cm^-1.When CTMAB excess, the molar ratio of the complexes formed by chromium (VI) and DBARPF is 1:2, with the continuous transformation and molar ratio method. We used the above methed testing the total content of chromium in the electroplating wastewater .