An Improved Ion Chromatographic Method for Fast and Sensitive Determination of Hexavalent Chromium and Total Chromium Using Conductivity Detection

2019 ◽  
Vol 57 (10) ◽  
pp. 939-943
Author(s):  
Thyagarajan Shanmugam ◽  
Joseph Selvaraj ◽  
Uvaraj Mani
Keyword(s):  
Ground Water ◽  
Potassium Permanganate ◽  
Hexavalent Chromium ◽  
Water Samples ◽  
Natural Waters ◽  
Exchange Chromatography ◽  
Preparation Technique ◽  
Total Chromium ◽  
Potassium Permanganate Solution ◽  
Chromium Determination

Abstract Chromium exists in its two stable oxidation states including trivalent chromium (Cr (III)) and hexavalent chromium (Cr (VI)) in natural waters. Chromium is an essential micronutrient in the trivalent form; however, the hexavalent form of chromium is considered to be a carcinogen. It is important to determine the chromium content along with speciation. There are a number of methods available for chromium determination. Speciation of chromium is essential to know the exact composition of chromium. Ion exchange chromatography is one of the techniques used to determine Cr (VI). The proposed method can be used to perform the speciation of Cr (III) and Cr (VI). It is a two-step process: first Cr (VI) is determined, followed by total chromium determination by treating the sample with potassium permanganate solution to oxidize the Cr (III) present in the sample to Cr (VI) and determining it as Cr (VI). Conductivity detector is used for the detection. Addition of potassium permanganate solution to the ground water samples for oxidizing the Cr (III) to Cr (VI) is the newly adopted sample preparation technique. The effect of potassium permanganate oxidation is studied in detail in the proposed method. This method can be used for chromium speciation in river water and ground water samples.

Direct Spectrophotometric Analysis of Cr(VI) Using a Liquid Waveguide Capillary Cell

2008 ◽  
Vol 62 (1) ◽  
pp. 107-115 ◽  
Author(s):  
Tatiana G. Levitskaia ◽  
Matthew J. O'Hara ◽  
Sergei I. Sinkov ◽  
Oleg B. Egorov
Keyword(s):  
Ground Water ◽  
Water Samples ◽  
Natural Waters ◽  
Direct Determination ◽  
Concentration Data ◽  
Actual Surface ◽  
Optical Absorbance ◽  
Vis Spectroscopy ◽  
Liquid Waveguide Capillary Cell

Hexavalent chromium Cr(VI) is a notorious ground water contaminant toxic to humans and animals. Assessment of an exposure risk for aquatic receptors necessitates frequent Cr(VI) concentration data from a range of surface and groundwater locations at Cr(VI) contamination sites. In this work, we demonstrate that enhanced ultraviolet–visible (UV-vis) spectroscopy using a liquid waveguide capillary cell (LWCC) offers an easy-to-use and economical methodology for the determination of chromate anion CrO42− in Hanford natural waters without chemical pretreatment and generation of hazardous waste. Direct determination of CrO42− in actual surface and ground water samples with the complexities of competing ions, dissolved organics, and other potential interfering agents was achieved by measuring the chromate optical absorbance at 372 nm. For a 100 cm path length LWCC, the detection limit for chromate was found to be as low as 0.073 ppb. A quantitative relationship between the intensity of the absorbance signal and water pH allowed for the straightforward calculation of total Cr(VI) content in natural water. The described method is applicable for in-field monitoring of Cr(VI) in environmental water samples at trace levels.

Etching of LLDPE and LLDPE/HDPE blends

1996 ◽  
Vol 54 ◽  
pp. 200-201
Author(s):  
M. S. Bischel ◽  
J. M. Schultz
Keyword(s):  
Potassium Permanganate ◽  
Morphological Features ◽  
Narrow Fraction ◽  
Potassium Permanganate Solution ◽  
Commercial Applications ◽  
Microscopy Techniques

Despite its rapidly growing use in commercial applications, the morphology of LLDPE and its blends has not been thoroughly studied by microscopy techniques. As part of a study to examine the morphology of a LLDPE narrow fraction and its blends with HDPE via SEM, TEM and AFM, an appropriate etchant is required. However, no satisfactory recipes could be found in the literature. Mirabella used n-heptane, a solvent for LLDPE, as an etchant to reveal certain morphological features in the SEM, including faint banding in spherulites. A 1992 paper by Bassett included a TEM micrograph of an axialite of LLDPE, etched in a potassium permanganate solution, but no details were given.Attempts to use n-heptane, at 60°C, as an etchant were unsuccessful: depending upon thickness, samples swelled and increased in diameter by 5-10% or more within 15 minutes. Attempts to use the standard 3.5% potassium permanganate solution for HDPE were also unsuccessful: the LLDPE was severely overetched. Weaker solutions were also too severe.

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