Questions tagged [purification]

For questions about purification - the process of rendering something pure, clean of foreign or undesired elements. Not to be confused with [metallurgy] or [chromatography].

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1answer
48 views

Can we use HPLC to purify an organic reaction product?

I know HPLC is a form of column chromatography that uses high pressure to pump a sample mixture/eluent through a column. However, I'm not sure if this technique is being used to purify and isolate ...
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22 views

How to convert pepsin into powder form?

I have pepsin powder which is now hydrated due to humidity. I want to convert it back to the powder form. How to do it? I don't have access to a freeze-dryer . I prefer any cheap procedure other than ...
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1answer
41 views

Electrolytic refining of precious metals — why the anode rather than the cathode? [closed]

In electrolytic refining, metals like platinum and gold are deposited as anode mud. Why aren't they deposited on the cathode since they have higher reduction potential?
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1answer
52 views

Concentrating sulfuric acid

Since calcium oxalate is 3000 times less soluble than calcium sulfate, would it be possible to concentrate sulfuric acid from let's say 50% solution using following steps? : adding calcium carbonate ...
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50 views

Purifying Potassium-40

What method is commonly used for separating out potassium-40 from natural potassium with a purity grade around 95% or more? How much would one kilogram of potassium-40 cost if this method is used?
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1answer
26 views

How should I interpret and present my total protein amount? [closed]

I have a problem. I have purified a protein with method A and then B. After method A I have a protein concentration of 20 mg/ml and after method B a concentration of 18 mg/ml. Method B is dialysis and ...
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0answers
16 views

Choice of buffer pH to avoid aggregation

I want to purify IgG which has a theoretical pI of 6.4-9.0 with an anion exchange column. I also want to keep the pH of my buffers as low as possible and "outside" the range of the pI to prevent ...
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19 views

Change buffer in dialysis?

I have a protein that I purified in PBS buffer, pH 7. I will do dialysis to remove salt and will then further purify the protein with ion exchange chromatography. I will need to use another buffer (...
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1answer
133 views

How to conveniently separate Cd impurities from ZnO without contaminating it?

How could I separate Cd impurities from ZnO without contaminating it and without using overly expensive equipment or extremely dangerous solvents? I don't want to contaminate it by introducing other ...
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1answer
77 views

Would dissolving Mg in NH3 help me purify Mg from all elements other than Li, Na, K, Rb, Cs, Fr, Ca, Sr, Ba, Eu and Yb? [closed]

According to Wikipedia all of the alkali metals, as well as $\ce{Ca, Sr, Ba, Eu,}$ and $\ce{Yb}$ (also $\ce{Mg}$ using an electrolytic process[4]), dissolve in ammonia to give the characteristic blue ...
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1answer
87 views

How do I remove tetrabutylammonium perchlorate from an organic synthesis?

I am trying to remove tetrabutylammonium perchlorate (TBAP) from an organic synthesis where TBAP was used as an electrolyte. I am working with compounds containing the amide group. I have used flash ...
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1answer
94 views

In HPLC, how does column diameter affect the retention time?

I am using a smaller diameter column than my previous one keeping all other factors such as stationary phase, solvent, solvent gradient constant. (Obviously, flow rate will be less in smaller column). ...
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45 views

Remove ethanol from gasoline by mixing it with water?

I have read on forums that ethanol can be removed from commercial gasoline by mixing it with water, then draining water from the bottom to remove the water-ethanol solution (for example, with a ...
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0answers
23 views

What zeolite types are typically used to absorb CO and CO2 gases at maximum zeolite absorption temperature?

Me and my friends are doing a project involving carbon monoxide and carbon dioxide as products to be filtered, we are using zeolites and would like to know the zeolite type typically used to filter $\...
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3answers
740 views

Is there a method to separate iron from mercury?

The mercury is contaminated with iron. Is there any way to remove iron from mercury?
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1answer
67 views

Techniques to extract lipids

I am planning an experiment on how to isolate casein and part of the process involves removing any lipids that may still be in it after filtering the precipitated casein out of the milk. I have read ...
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2answers
646 views

Recrystallisation of dibenzylideneacetone

Recently, I carried out the synthesis of dibenzylideneacetone. I had a lot of problems with the purification process, especially the part involving recrystallisation. I was instructed to carry out the ...
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1answer
354 views

Shea Stearin Extraction by Dry Fractionation

I have been able fractionate palm oil and extract palm stearin using the following method: Melt the palm oil (over 80 °C) Keep the melted oil at 33.5 °C for 24 hours (using an immersion circulated ...
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1answer
4k views

When using a “dilute hydrochloric acid” solution, how diluted should it be?

Quite often when reading through some instructions or documentation or an outline that I've found online (EG: acid-base extractions), theres a step that involves using a "dilute hydrochloric acid ...
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1answer
949 views

How to acid-wash sand?

I need some acid-washed sand to smooth out boiling in diethyl ether synthesis. I aready have pre-washed sand for general filtration purposes, but it is not labeled as acid-washed. Unfortunately, I ...
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0answers
34 views

What is the future of water treatment, and why we don't use enough purified sea and freshwater? [closed]

I understand thermal and membrane distillation are very expensive and that slowed down their usage, but now we can bring 100% clean energy to power them. Except the set-up, the price of materials and ...
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0answers
44 views

Removing chloride ions from humic acid purification

I used HF and HCl in humic acid purification, and now I need to remove the Cl ions from solution. What should I do to remove the Cl ions? Do I just wash it with distilled water, or is there another ...
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1answer
3k views

How to separate sodium carbonate from sodium hydroxide?

I got a drain cleaner in dust form, which consists of $\ce{Na2CO3}$ and $\ce{NaOH}$. I wanted to extract the $\ce{NaOH}$ so I tried to heat the mixture in order to just melt the sodium hydroxide, but ...
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2answers
915 views

What acid can dissolve thorium dioxide?

In one of my projects (which is about alpha-voltaic cells, don't worry, I know that thorium isn't a strong alpha source, it's only for measurements) I would need to get water soluble thorium compound ...
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1answer
116 views

How to remove nitrose gasses from ozone gas mixture?

I produce ozone gas with an ozone generator based on corona discharge principle. These kind of ozone generators have the disadvantage that if $\ce{N2}$ is present, a bit of $\ce{NO}$ and $\ce{NO2}$ ...
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0answers
255 views

Refining Tin (Sn)

I am a Copper Cookware Tinner & have a problem in reusing much of the tin that I end up sweeping off the floor etc. Prob about 5kg over the year & it would be great to save this? Now, my ...
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1answer
3k views

Synthesis of Benzaldehyde and Aniline Schiff Bases

I have a problem while synthesize the schiff base. I synthesized using absolute ethanol as solvent and use reflux method for 4 hours generally. The problem occur on TLC where there is still two spot ...
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2answers
98 views

How does % purity on household products work?

For example, toilet bowl cleaner is 9.5% HCl. Does this mean that for every 90.5 moles of H2O (or other stuff) there is 9.5 moles of HCl? Does it mean that for every 90.5 g of H2O there are 9.5 g of ...
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1answer
178 views

Ester as a side product in the synthesis of bromoalkane from alcohol. Is it correct?

About 5 months ago, I answered a very interesting question albeit a very simple one. Why do we need sulfuric acid in creating alkyl bromide and not in creating alkyl iodide from alcohol and ...
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0answers
301 views

Multi-solvent recrystallization to extract solute from glycerol?

I have compound A contaminated with impurity B. Recrystallization in water would not yield pure compound A since impurity B is less soluble in it. The only solvent in which substances A and B have ...
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1answer
780 views

How to remove pyridine from Reaction mixture containing chiral molecule with diacetal protection group?

While working with chiral molecule, we have pyridine in our reaction mixture. Molecule has four chiral centre and protection group-diacetal and acetyl groups which may break in harsh conditions. ...
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1answer
302 views

Zinc Sulfate Purification

In the process for electrolysis for zinc, three things must be done: Leaching the ZnO Purifying the ZnSO4 by means of cementation Performing the electrolysis However, step 2, as it is presented by ...
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1answer
181 views

How do chemists measure purity in high purity metals and other reagents?

I have noticed that gold bars are often marked "999.9" fine: Whenever I have metallurgical assays done, they always seem to do them with ISP or DSP or whatever, some spectrometer-based system. These ...
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2answers
2k views

Pure substances have only one kind of atom

I read in a book recently that no substance is ever totally pure, even if we take great care to separate it from other substances. And also that pure substances contain only one kind of matter. But I ...
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1answer
728 views

Crystallization in a solution of 2 or more solutes

This is a very basic question I found myself wondering. For simplicity's sake, we'll say it is a super saturated aqueous solution of an equivalent measure of sugar and salt. As the solution cools and ...
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1answer
493 views

How does activated carbon trap impurities?

I've tried and I've tried to find an answer to this all over the web, but I can't seem to find an in depth explanation. To the best of my knowledge, activated carbon has a very microporous structure ...
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1answer
114 views

Minimizing Catalyst Residue in Vegetable Oil Hydrogenation

We are using a nickel catalyst in our hydrogenation process to help convert vegetable oil to vegetable wax. The issue is ensuring all additives are successfully removed once hydrogenation is complete. ...
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0answers
528 views

Purification of polar NHS esters

What are the options that I might be missing for the purification of a molecule with the following characteristic: Contains an activated ester that reacts with water (NHS) Reacts readily with ...
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1answer
267 views

Purification of isoborneol [closed]

How can I convert isoborneol powder to isoborneol flakes? I have made the isoborneol powder from reduction of camphor using sodium borohydride.
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1answer
2k views

Purification of the Hünig Base

My group uses a lot of Hünig base which needs to be dry and pure. The common procedure we use is to first distill from ninhydrin then from calcium chloride. Apparently the problem is that Hünig base ...
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1answer
1k views

How to separate two aqueous salts?

I have a mixture of two aqueous salts, $\ce{Cr(OH)3}$ and $\ce{NaNO3}$ and I'd like to separate them and purify the $\ce{Cr(OH)3}$ in order to make $\ce{KCr(SO4)12 . H2O}$ (Chromium Alum). Does any ...
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1answer
142 views

How to prepare elemental gallium from a mixture of gallium and aluminum nitrate?

How would one go about preparing and purifying elemental gallium from a mixture of aluminum(III) nitrate and gallium(III) nitrate?
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2answers
666 views

Removing aluminum oxide from impure silica

We have an assay for a mine. Our goal is to have only silica. Is there a cost effective way to extract the contaminants? The product is a fine powder called diatomaceous earth, or fossil shell flour. ...
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1answer
9k views

Why is the solid product washed with ice-cold solvent during in the last stages of recrystallisation?

Why is the solid product washed with ice-cold solvent during in the last stages of recrystallisation? Is this to remove soluble impurities? (for example) Well, what if the impurities were also ...
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1answer
69 views

Purify gas produced after reactions with sulfuric acid

Say, I preheat 50ml of 98% $\ce{H2SO4}$ and proceed with adding 25ml of 85% $\ce{HCOOH}$. The result of which is: $$\ce{H2SO4 + HCOOH -> CO + H2O}$$ Sulfuric acid will dehydrate formic acid ...
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0answers
107 views

How to make a sephadex slurry

I want to purify crude alpha-amylase with column chromatography. I am using a spehadex 75, But for some reason I can't find any information on how to make the slurry. I can quickly find tons of ...
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1answer
421 views

How to obtain pure alcohol from mixture of alcohol & carbonyl? (Grignard experiment) [closed]

If one discovers that after finishing up a Grignard reaction that their alcohol product has been contaminated with the carbonyl starting material, how could they separate the alcohol from the carbonyl ...
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1answer
5k views

Why is % yield in a purification table measured using activity instead of total protein?

I'm trying to understand why % yield is measured with activity instead of total protein in mg. According to my biochemistry notes, activity is "1.0 units of enzyme activity = 1.0 μmol of substrate ...
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0answers
2k views

Removal of calcium from calcium-ammonium nitrate?

I am interested in model rocketry, and need to produce small quantities of pottasium nitrate. For this process I need ammonium nitrate, but I only have calcium ammonium nitrate. Is there a simple ...
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1answer
25 views

How to liberate propylthiouracil

Two substances undergo a reaction that gives off propylthiouracil and another compound as products. Is there an additional compound I could throw into that sludgy product to strain off the $\ce{...