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41 votes

Why isn't pressure filtration popular compared to vacuum filtration?

It's much easier to assemble a system that's safe under external pressure than one that's safe under internal pressure. Convex flasks and tubes resist external pressure better than internal pressure. ...
jeffB's user avatar
  • 1,592
21 votes
Accepted

What is a Herzberg?

Herzberg filtration speed: The time taken to filter $\pu{100 mL}$ water at $\pu{20 ^\circ C}$ through a filter area of $\pu{10 cm2}$ at a constant pressure of $\pu{5 cm}$ water column (Thomas ...
Mathew Mahindaratne's user avatar
18 votes
Accepted

What is the scientific term to describe the operation of a bong?

I think the term describing the initial process of separation of the solid phase (dust particles) from the gas phase via bubbling is a wet scrubbing process. On an industrial scale, it's more ...
andselisk's user avatar
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12 votes
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How are N95 masks different from dust masks?

The short answer to your question "What's the science behind the N95 filter?" is that it is what's called a tortuous path filter, removing particulates from a flow of contaminated air by impact and ...
airhuff's user avatar
  • 17.5k
10 votes

Why isn't pressure filtration popular compared to vacuum filtration?

Pressure filtration is commonly used in industrial applications outside of the lab. In this case vessels and process lines are usually made from metal or plastic and can be easily designed to operate ...
ChemEPhD's user avatar
  • 101
10 votes
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Sintered vs perforated plate Büchner funnels

The thing on the left is not usually a called a Büchner funnel, but a frit. Frits are generally meant to be used for stuff that can be redissolved afterwards, because they tend to clogg permanently, ...
Karl's user avatar
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9 votes

How are N95 masks different from dust masks?

From official 3M Q&A brochure (emphasis mine): Can N95 respirators filter particles that are really small like smoke, soot and ash? Yes. Particulate filters employ multiple mechanisms that are ...
andselisk's user avatar
  • 38k
8 votes

Sintered vs perforated plate Büchner funnels

I agree with user55119's suggestions (see the comment I have copy and pasted below): For the sintered glass filter, add an inch or two of diatomaceous earth (Celite). Wet it under vacuum with solvent ...
Mathew Mahindaratne's user avatar
7 votes

Why isn't pressure filtration popular compared to vacuum filtration?

I'd like to expand on some points that have been mentioned in the comments by @IvanNeretin, @Karl and @electronpusher, but IMHO deserve some more attention: As @electronpusher commented, aspirator (...
cbeleites unhappy with SX's user avatar
6 votes

Why isn't pressure filtration popular compared to vacuum filtration?

Positive pressure filtration is extremely common, probably even more common than vacuum filtration. source: https://andyjconnelly.wordpress.com/2016/09/28/syringe-filters/
DavePhD's user avatar
  • 40.7k
6 votes

How are N95 masks different from dust masks?

The principle on which they depend isn't that different. This does not mean, however, that you can wear a dust mask instead of an N95. From the Review article of "Respiratory Protection" from the New ...
CoffeeIsLife's user avatar
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6 votes
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What kind of filter can remove zeolite dust from ethanol?

Since this never got a proper answer I thought I'd come back with a follow-up. Essentially the root cause was low quality sieves (I had just picked the cheapest I could find on the internet). There ...
Jason C's user avatar
  • 1,172
6 votes

Removing carbon matter from molten beeswax

Hydrogen peroxide as suggested will possible just bleach the particles, not remove them. I think also, that the miscibility with an aqueous solution and wax may be a problem here. There are probably ...
raptorlane's user avatar
5 votes
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Separating citric acid from sugar

Citric acid is relatively soluble in ethanol (62g/100g) whereas sucrose is relatively insoluble in ethanol (1g/170ml). There are many different kinds of sugars and sucrose is probably not the primary ...
Ben Welborn's user avatar
  • 1,576
5 votes

Why isn't pressure filtration popular compared to vacuum filtration?

I worked as a grad student in organic chemistry labs and both vaccuum lines and compressed air are very common. The reason most filtering setups uses vaccuum (especially for gross extraction after ...
foudian1's user avatar
5 votes
Accepted

Does wet fabric filter smoke better than dry fabric?

The composition of smoke is not well-defined. On the one hand, some smokes could be considered aerosols of solid particles or liquid droplets only (no gaseous material worth considering). These smokes,...
James Gaidis's user avatar
4 votes
Accepted

How to effectively wash the precipitate or crystals on the filter and why?

Every time the precipitation on filter is washed, there is a certain constant volume $V_\mathrm{ret}$ of washing fluid retained on the filter. If the initial concentration of impurity is $c_0$, then ...
andselisk's user avatar
  • 38k
4 votes
Accepted

Home made dispersion/solution with detectable >0.1μm particles

Try to get some clay and shake it vigorously with water. Let it settle for a several hours. Test your filter with the supernatant water and collect the filtrate in a very clean glass tumbler. Colloids ...
AChem's user avatar
  • 41k
4 votes
Accepted

Is there a filtration method that can be used to separate solids and liquids without filter paper?

You neither state the size of the particles to retain/remove, nor the chemistry of the suspension you deal with; in this regard, your question should be improved. E.g., is the solution acidic/neutral/...
Buttonwood's user avatar
  • 30.1k
3 votes

how to measure the efficiency of carbon filter [or of activated carbon/charcoal]?

You might try a something like a VOC sensor before and after your filter. Just let some gasoline (or diesel, or nail polish, or whatever) evaporate in a fixed volume box (you could measure the amount ...
datenheim's user avatar
  • 192
3 votes

Separation of 2 compounds ( Powder )

If the powdered compounds are of different density you can separate them based on density in a liquid that does not dissolve them. For example, if you want to separate caffeine (density=1.36 g/cm3) ...
Chris's user avatar
  • 31
3 votes

How can I filter dissolved PVA from water

Rig up a column that you can fill with granular activated carbon (GAC). Throw batting on either end to prevent carbon fines from entering your dissolution chamber. Replace the carbon when you reckon ...
Pete's user avatar
  • 358
3 votes
Accepted

To what degree an N99 active coal filter can protect against products of burning paraffin oil?

Activated carbon's forte is vapor adsorption of hydrocarbons due to the activated carbon's high surface area, and this mask is probably very good at adsorbing fumes from hot parafin. However, ...
airhuff's user avatar
  • 17.5k
3 votes

Homemade filter paper

Apparently, the particles of your solid are either very small, or / and not crystalline. This may complicate filtration, though this is one of the reasons filter papers used in the chem labs are sold ...
Buttonwood's user avatar
  • 30.1k
3 votes
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Is there a practical re-use value gained by grinding up activated carbon that is spent/saturated?

No. Grinding activated carbon will not change anything relevant. The reason is because surface area does not have an effective influence on the usefulness of activated carbon. Activated carbon is ...
Maurice's user avatar
  • 28.6k
3 votes

How does functionalized activated charcoal work?

No. It is not a precipitation reaction. It is physical reaction. The pores are made of the rest of the membranes of the cells. When wood is overheated in air, it burns. When this is done without too ...
Maurice's user avatar
  • 28.6k
3 votes
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How do I filter a solution of very fine manganese dioxide?

Pulkit Sharma: Per your request. One solution for filtering $\ce{MnO2}$ is to use a sintered glass funnel under vacuum. Fill the funnel ~halfway with a slurry (water or organic solvent) of Celite, ...
user55119's user avatar
  • 16.8k
3 votes

Activated carbon filter desorb smells with dropping temperature?

The vendor is apparently handwaving to satisfy a customer with a natural reason. Activated carbon is usually prepared at 1000 C! No fruity smells or odors should survive at this temperature from any ...
AChem's user avatar
  • 41k
3 votes

Removing carbon matter from molten beeswax

I'm not sure how to induce agglomeration of the burnt particles to speed up their sedimentation. I'd try one or both of the following: Maintain the wax in its molten state longer without stirring, ...
Chæth's user avatar
  • 92

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