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mcspencah

Electric conductivity of suspended particles

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Hello, I'm writing my thesis and i was wondering the following;

Do suspended particles in a solution conduct electricity?

I see a decrease in conductivity after separating suspended solids in a solution (starch and fibers in a potato fruit juice solution).

It's 10-20% reduction in conductivity. I'm wondering if this is a result of the separating of the solids or if there is another reason.

Thanks in advance.

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I assume it's an aqueous solution, which is polar. Starch has some polarity if I remember correctly, because carbohydrates have covalently-bond oxygen with unpaired electron pairs, although they're not very mobile, because they're macromolecules (very macro in the case of starch.) You should be watchful that you're not removing conductivity-enhancing ions like K+ or Ca2+ or similar also. But wait for the experts. I'm not one. Maybe just a cue for someone to further clarify.

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1 hour ago, mcspencah said:

Hello, I'm writing my thesis and i was wondering the following;

Do suspended particles in a solution conduct electricity?

I see a decrease in conductivity after separating suspended solids in a solution (starch and fibers in a potato fruit juice solution).

It's 10-20% reduction in conductivity. I'm wondering if this is a result of the separating of the solids or if there is another reason.

Thanks in advance.

This is posted in homework help, so was this a lab experiment you made?

If so can you provide more details for instance

How 'thick' was the original suspension ?
Did you make any tests with differeent amounts of particle removal?
How was the conductivity measured?
Have you heard of electrode polarisation?

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1 hour ago, mcspencah said:

a potato fruit juice solution

Is anyone actually extracting juice from potato fruit?

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Posted (edited)
1 hour ago, joigus said:

I assume it's an aqueous solution, which is polar. Starch has some polarity if I remember correctly, because carbohydrates have covalently-bond oxygen with unpaired electron pairs, although they're not very mobile, because they're macromolecules (very macro in the case of starch.) You should be watchful that you're not removing conductivity-enhancing ions like K+ or Ca2+ or similar also. But wait for the experts. I'm not one. Maybe just a cue for someone to further clarify.

I will look into the polarity, thank you for your answer. And the separating is done mechanically with centrifugal forces so they do not separate dissolved molecules.

34 minutes ago, studiot said:

This is posted in homework help, so was this a lab experiment you made?

If so can you provide more details for instance

How 'thick' was the original suspension ?
Did you make any tests with differeent amounts of particle removal?
How was the conductivity measured?
Have you heard of electrode polarisation?

No, i'm doing quality analysis in a running factory. I've only measured the conductivity with a simple pH/conductivity meter.

The juice is still full of other components like proteins,sugars and many other compounds.

But i'm seeing a pretty significant reduction in conductivity after the fibers and starch are separated from the juice so i was wondering if suspended solids do have an effect on electrical conductivity.

31 minutes ago, John Cuthber said:

Is anyone actually extracting juice from potato fruit?

Yes, to extract proteins

edit: from potato's, not potato fruit. The extracted juice from potato is called potato fruit juice 😛 

Edited by mcspencah

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2 hours ago, mcspencah said:

I will look into the polarity, thank you for your answer. And the separating is done mechanically with centrifugal forces so they do not separate dissolved molecules.

No, i'm doing quality analysis in a running factory. I've only measured the conductivity with a simple pH/conductivity meter.

The juice is still full of other components like proteins,sugars and many other compounds.

But i'm seeing a pretty significant reduction in conductivity after the fibers and starch are separated from the juice so i was wondering if suspended solids do have an effect on electrical conductivity.

Yes, to extract proteins

edit: from potato's, not potato fruit. The extracted juice from potato is called potato fruit juice 😛 

No answers to my two most crucial questions so read this for yourself.

http://www.vl-pc.com/index.cfm/technical-info/conductivity-guide/

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It's certainly odd. I'd have expected the opposite effect.
I can think of one possibility.

If the unfiltered juice contained intact cells and those were broken during the filtration process then it's possible that their contents were less conductive than the surrounding liquid.
That's possible, but seems unlikely- I'm not sure how you would test it.
 

Does it get hot during filtration?

Is it being filtered on an industrial scale- could you try with a smaller rig- say a laboratory scale  with a flask, funnel and filter paper?

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58 minutes ago, John Cuthber said:

It's certainly odd. I'd have expected the opposite effect.
I can think of one possibility.

If the unfiltered juice contained intact cells and those were broken during the filtration process then it's possible that their contents were less conductive than the surrounding liquid.
That's possible, but seems unlikely- I'm not sure how you would test it.
 

Does it get hot during filtration?

Is it being filtered on an industrial scale- could you try with a smaller rig- say a laboratory scale  with a flask, funnel and filter paper?

Thank you for the reply.

I'm unfortunately not allowed back at the factory as an intern because of the current epidemic so I'm not able to do more experiments.

The separating(done mechanically with industrial decanters with centrifugal force) process runs at normal temperatures because higher temperatures will denature the wanted proteins in the fruit juice.  And i think all cells are broken when the potato's are grinded into a pulp.

So from my understanding so far suspended solids shouldn't have an impact on conductivity? I'm finding a lot about the relation between dissolved solids and conductivity but not about suspended ones.

2 hours ago, studiot said:

No answers to my two most crucial questions so read this for yourself.

http://www.vl-pc.com/index.cfm/technical-info/conductivity-guide/

Thank you for the reply. I'm having trouble understanding electrode polarization. Doesn't this only happen with dissolved ions? And would an over-voltage mean an higher measured conductivity?

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Posted (edited)
1 hour ago, mcspencah said:

Doesn't this only happen with dissolved ions?

One thing you can say for sure.

If there were no dissolved ions conductivity would be very low.

I can see that English is not your first language, but the more information you can provide the better.

Do you still have access to the meter?
Can you tell us what make and model it is ?

If you know these things can you tell us if it is an ac or a dc type and if it is ac is it high frquency or low frequency?

It is a great shame you cannot investigae the variation of conductivity with amount (concentration) of the pulp material.

I did have a small wonder if the pulp fibres might spread out like tiny filaments and string out the ions along them so providing a network of conductive paths like tiny electric wires.

The point about polarisation is that ions congregate around electrodes of the opposite polarity to themselves and get in the way of each other.
This discourages futher ions from travelling towards that electrode. This may not happen in the original soup containing the pulp.
Overcoming this requires an additional voltage and a small handheld meter might not develop enough voltage to drive the measurement.

You say it was a conductivity/pH meter.

Did you also measure pH?

If so, was there any difference in reading between the 'soup' and the strained liquid?

Here is someone else who measured lower conductivity than expected in mixtures a bit like yours, due to pH.

Quote

https://iopscience.iop.org/article/10.1088/0967-3334/17/1/002/pdf

Abstract

Studies of gastric secretion were carried out on 14 subjects, some of whom had taken acid secretion inhibitors. In vitro studies were performed in an attempt to ascertain the effect of img8.gif and img9.gif ions on conductivity. There is a strong correlation between intragastric pH and conductivity for pH < 2, but none of the gastric samples were isotonic. The measured conductivity of the samples was therefore considerably lower than predicted for isotonic gastric juice.

Keywords: conductivity, electrical impedance tomography, gastric acidity, gastric secretion

 

Edited by studiot

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12 hours ago, studiot said:

One thing you can say for sure.

If there were no dissolved ions conductivity would be very low.

I can see that English is not your first language, but the more information you can provide the better.

Do you still have access to the meter?
Can you tell us what make and model it is ?

If you know these things can you tell us if it is an ac or a dc type and if it is ac is it high frquency or low frequency?

It is a great shame you cannot investigae the variation of conductivity with amount (concentration) of the pulp material.

I did have a small wonder if the pulp fibres might spread out like tiny filaments and string out the ions along them so providing a network of conductive paths like tiny electric wires.

The point about polarisation is that ions congregate around electrodes of the opposite polarity to themselves and get in the way of each other.
This discourages futher ions from travelling towards that electrode. This may not happen in the original soup containing the pulp.
Overcoming this requires an additional voltage and a small handheld meter might not develop enough voltage to drive the measurement.

You say it was a conductivity/pH meter.

Did you also measure pH?

If so, was there any difference in reading between the 'soup' and the strained liquid?

Here is someone else who measured lower conductivity than expected in mixtures a bit like yours, due to pH.

 

Thank you for the great reply's but i already found the answer. It seems that during the centrifugal separation the fruit juice get's diluted by about 15% which explains the drop in conductivity.

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6 hours ago, mcspencah said:

Thank you for the great reply's but i already found the answer. It seems that during the centrifugal separation the fruit juice get's diluted by about 15% which explains the drop in conductivity.

Thank you for coming back with further information. +1

I was right to want details of the method statement.

:)

 

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I don't know if your factory makes moonshine or what from your potatoes but coincidentally the Times (26 May p7 ) reports that

Quote

According to researchers from McMaster University in Canada in the latest issue of the journal Nutrients, even the potato is a source of high quality protein that helps with muscle gain  -  suprisingly for a food considered to be a classic carb.

Stuart Philips, the professor in the department of kinesiology who led the study, says that although the amount of protein found in a potato is small, when isolated it provided significant muscle benefits for women who took part in the trial.

A study at the University of Illinois previously found mashed potato to be as effective as sports drinks in boosting endurance in athletes........

 

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The proteins we extract from the potato's are used as a replacement for animal proteins. They are used in plant based meat, dairy, cheese and ice cream! It's a relatively new process and really interesting.

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Posted (edited)
41 minutes ago, mcspencah said:

The proteins we extract from the potato's are used as a replacement for animal proteins. They are used in plant based meat, dairy, cheese and ice cream! It's a relatively new process and really interesting.

Marvellous vegetable, the potato.

It was one important factor that powered the development of 19 century America.

If you ever visit Ireland, visit the American-Irish Folk museum.
Lot's on the history of the potato there, including the cooking and nutritional values.

Edited by studiot

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