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Measuring Organic entrainment (6 replies)

Victor Bergman
10 months ago
Victor Bergman 10 months ago

I'd like to know if there is a methodology to measure organic entrainment in aqueous phase. I've found a methodology with UV-visible, but I was wondering if there is another way.

Bill Rico
10 months ago
Bill Rico 10 months ago

We measure entrainment in centrifuge and organic separate in tube beside of falcon.

A calibration coefficient change organic height (mm) to entrainment (ppm).

Bob Mathias
10 months ago
Bob Mathias 10 months ago

Any TOC/TOG method is suitable (Total Organic Carbon/Total Organic Grease).

For example, you can use oxidation methods (dichromate, UV,) or solvent extraction with C2Cl4 and IR detection.

The centrifugation is very convenient, but has very low precision in 0-50 ppm range.

The real problem is to differentiate between the dissolved organics and the suspended droplets (entrainment). I measure a centrifugated sample to have the dissolved organics content as a baseline.

One more thing - the TOC/TOG procedures for environmental measurements suggest "calibrated samples". I recommend use your organics (extractant + diluent in the correct proportion) for calibration.

Carl Jenkins
10 months ago
Carl Jenkins 10 months ago

I agree 100% with the explanations provided here; please can you show your methodology (sop) with UV?

David Kano
10 months ago
David Kano 10 months ago

I agree and would emphasize comments about the base line. Remember that

the dissolved diluent and extractant will not necessarily be in the same ratio as they are in the bulk organic. My experience is that diluent kerosene will dissolve preferentially compared to most copper ketoxime and aldoxime extractants. This dissolved content is what prevents hydro cyclones from getting down to even better entrainment levels.

Sugar Watkins
10 months ago
Sugar Watkins 10 months ago

I have recently investigated different options to determine low level organic entrainment in several aqueous phases at an USX mine.

Here are my findings:

•I looked first at TOC, UV, IR methods as they are relatively easy to setup and significantly cheaper than other analytical methods such as GC. These methods were not suitable for my samples due to the turbidity and/or interferences from dissolved species (e.g. chlorides) in the leaching solution. I would advise to check that your sample matrix is compatible with these methods.

•EP080/071: Total Petroleum Hydrocarbons (GC) is commonly used for water monitoring. Check first that your solvent and extractants show up in the chromatograph. There is also a 7 days holding period if you need to send your sample off-site.

•A lengthier, more expensive however more reliable option can be to develop your own GC method. It can be worth on the long-run.

Hope it helps.

Victor Bergman
10 months ago
Victor Bergman 10 months ago

Thank you so much for your responses. The UV method is made with a calibration curve, with different concentrations of loaded organic dissolved in ciclohexane (as found in a Phd. thesis of the USACH, Chile). A sample of the aqueous phase with organic entrainment is taken and put in contact with ciclohexane for total dissolution of the organic and separated for UV-Vis analysis.

Following these methodology, I think it would be possible to develop a calibration curve with other property.

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