CHROMIUM TEAM

Ken AndrzejewskiYe Eun Oh

Jasmine Podell

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Goals

True classification of 7 chrome plating baths at various NEO Industries plants – What are the similarities and differences, and does it make a difference

Find alternatives for wash and soak tank disposal to save money and reduce toxicity

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Chrome Plating Bath Samples from

Portage, IN, North and South baths

Chrome Plating Bath Sample from Beaver

Dam, KY

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Wash Pit Waste SamplePortage, IN plant

Wash Pit Waste SampleBeaver Dam, KY plant

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ICP-OES Inductively Coupled Plasma - Optical

Emission Spectrometry Sample is nebulized to micro-droplet

particles which are passed through a plasma stream

Particles are excited and emit light Emission spectra are determined to identify

specified element

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ICP-OES

[Cr] ppm max min Int

50 101295 120 101175

20 41010 101.5 40908.5

10 22600 95.5 22504.5

5 10611.5 92 10519.5

2.5 5311 89.5 5221.5

1 2347 91.5 2255.5

0 179 78.5 100.5

Example: Calibration Test 1

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0 10 20 30 40 50 600

20000

40000

60000

80000

100000

120000

f(x) = 2017.50698099825 x + 590.804597379327R² = 0.999529064524506

Calibration Curve 1

Concentration (ppm)

Intensity

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Diphenylcarbazide (DPC) This includes use of 3M Sulfuric acid, DI

water, and DPC dissolved in Ethanol. Procedure

Take 3mL of each standard Add 200µL of Sulfuric acidCheck if they are acidicAdd 100µL of DI waterWait for 10 minutesRecord

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DPC Cont. The result

In presence of hexavalent Chromium, the solution turns magenta to red color

The higher the concentration, the darker the color

Make a 1:3 dilution of acidified standards with DI water and perform the DPC test

After the color appears, test them in UV-Vis

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DPC Cont. Problem

If the concentration is too high, the color will disappear very quickly

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DPC Cont.

Concentration (ppm) λ A λ max A

1 540 0.375 541 0.377

2.5 540 0.865 542 0.866

5 540 0.994 542 0.996

10 540 0.624 540 0.624

15 540 0.869 540 0.869

20 540 0.696 542 0.698

UV-Vis result (DPC on standards 1:3 dilution)

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Starch Indicator This process uses 0.5M Sulfuric acid, Potassium

iodide, starch indicator, DI water, and our chromium solutions.

Take 25mL volumetric flaskTake 20mL of the Chromium standard or

sample 3 drops of sulfuric acidA small spatula of Potassium iodide3 drops of starch indicatorDI water

Swirl the solution

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Starch Indicator Cont.

The color produced by this process is purple.

A lighter purple indicates less Chromium VI

A darker purple indicates more Chromium VI

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Starch Indicator Cont. The solutions are put into the UV-Vis Material absorbs at a certain wavelength Recorded the absorption at 540 nm and the

max wavelength and its absorbance Concentration of the samples can be

determined based on the absorbance and wavelengths of the standards

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Starch Indicator Cont.

Concentration (ppm) λ A λ max A

1 540 0.198 550 0.210

2.5 540 0.539 500 0.558

5 540 0.553 572 0.594

10 540 1.564 557 1.623

15 540 Out of Range

20 540 “

UV-Vis result (Starch indicator on standards)

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X-Ray Fluorescence Spectrometry of Wash Pit Solids

Element %

Cr 19.29 +/- 1.04

Fe 58.92 +/- 1.56

Pb 16.17 +/- 0.524

Zr 1.45 +/- 0.10

Mo 4.17 +/- 0.18

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Pictures

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Pictures

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Bibliography http://neoindustriesllc.com/index.php