functionalised polymer proton donors 3

[damienmorton]

Hi - I am working on a product that requires a concentrated acid, but this product must also be non-toxic, non-corrosive, non-hazardous, and non-regulated.

I looked into carborane superacid, but this stuff is too exotic and too expensive.

Instead, I have been looking into ion-exchange resins, such as polyacrylic acid and functionalised polystyrene. The physical form of these acids are such that they are far less corrosive and toxic than the monomer forms.

The idea is to have dried ion-exchange resin which is then immersed in the solution it is intended to react with, looking for a very fast reaction speed, hopefully similar to the liquid-liquid reactions I have currently got.

I suspect that even the smallest and most porous ion-exchange-resin beads will give reaction speeds orders of magnitude slower than the liquid-liquid reactions.

Im wondering if anyone has any suggestions about forms of polyacrylic acid or polystyrene sulfonic acid that would be considered non-toxic and non-corrosive, while enabling reaction speeds similar to liquid-liquid reactions.

 

[Demon3]

I would try polystyrene sulfonic acid as you've mentioned. That's a strong acid. Much stronger than carboxylic acids.

Also try Nafion membranes. They are sulfonated fluoropolymer used commercially.

These won't be corrosive as long as you keep them as for example the sodium salt. Then, when you want them to react, convert that to the free acid by washing with water.

Chris DeArmitt PhD FRSC CChem

 

[unclesyd]

Not knowing your end use you may want to look at NTA (nitrilotriacetic acid) and EDTA. I would check the Dow, EDTA, and Ascend Materials (Solutia) website for NTA. DuPont has done a lot of work with the Carboxylics along with Sulfonic.
In some processes Adipic Acid is being used a Proton Donor.

 

[damienmorton]

Thanks for your thoughts - really appreciate it.

I say that this product needs to be non-toxic, non-hazardous, non-corrosive and non-regulated, because I want be able to walk into a boardroom and demonstrate its safety by eating/drinking some of the contents of the product. The people I need to convince are looking for safety reasons to say no, and this kind of demo will go a long way towards convincing them.

I also need a very concentrated acid, that can produce about 3+ mols of protons per Litre of solution. Reason for this is the product has weight and volume constraints.

Initially I looked into solutions of food-grade acids, such as citric, malic, tartaric and so on. Citric is regulated as class-8 corrosive in concentrations above 25%. Malic and tartaric appear to be non-regulated, but I wasn't able to find if they have been properly tested for corrosiveness (i.e. by using a in-vitro skin corrosion test). Even if these acids were able to meet the strict legal definition of non-corrosive, they are used in much lower concentrations as chemical skin peels, which leaves me open to questions about safety.

I had looked at EDTA, but I couldn't see any reason why a concentrated solution of this acid would be considered less corrosive than any other acid. Perhaps I am mistaken? Same goes for Adipic Acid - why would a concentrated solution of this acid be less corrosive than, say, Citric Acid?

NTA appears to be a possible carcinogen, which rules out my boardroom demonstration.

Wikipedia says that skin corrosion is caused by "acid-base catalysis of ester and amide hydrolysis". It crossed my mind that perhaps there are proton donors that are structurally incompatible with acid-base catalysis of ester and amide hydrolysis. I was thinking of molecular structures, but the macromolecular structures of PAA and PSA hydrogels seem to be also effective.

The appeal of solid-phase acids is for several reasons. Skin corrosion is caused mostly by the conjugate base rather than the protons. In solid-phase acids, the conjugate base remains attached to the matrix, which physically minimises the opportunity for reaction with skin. This is the structural incomparability but on a macro scale rather than on a molecular scale. Also, Polyacrylic Acid and Polystyrene Sulphonic Acid appear to be less toxic than salt, especially in their gel forms.

Question is - is there a form of these solid-phase acids that is proton-dense, and with kinetics similar to the liquid-liquid reactions I have that are working.

 

[patprimmer]

Your drinking from it does not prove it is long term safe, just that you believe it is safe enough or you are desperate or foolhardy. Indicating you might be foolhardy might actually undermine your credibility.

Proper long term test data is a much more compelling argument to intelligent informed people.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

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for site rules

 

[damienmorton]

You're right, of course. Eating/drinking the contents is the carnival way to demonstrate safety, aimed at people who's concentrations run out after the first 140 characters of a document.

 

[unclesyd]

I whole heartily agreed with patprimmer eating or drinking for a product to demonstrate it's properties is an absolute No,No. everywhere I've worked or been associate with drinking are eating anything in the lab or comes out of the lab is firing offense. As it was put to me even though we distill things we are not a Jack Daniels Distillery.

I've been looking several years for information on a product CT-90 made by the late Liquid Carbonics Company in the 60"s 70's. One use for the product was as metal cleaning agents. It could be tailored for cleaning specific metals or the dissolve specific soils. It very low concentrations it was a excellent corrosion inhibitor and at higher concentrations it would dissolve the metal/metals. If I recall correctly this chemical was considered a the time as nontoxic and extremely safe and when asked about skin contact the representative said you could drink it. No one verified his claim. At the time there was no MSDS. If you could find a reference to it this might be a good candidate for testing.

We were considering it as a replacement for Chromate CTE treatment, but MIC got in the way. It one CTW system it to the Chromate film off the steel in about a day and w week later we were experiencing exponential expansion of the Bugs of Rust that were kept in check by the Chromate.

 

[unclesyd]

In reference to the CT-90 product mentioned above the metal cleaning formulations were call RD-16 Fe or the metal they were supposed to be used on. Again If I recall correctly these material was originally made to to clean residue around Nuclear Reactors System.

You might want to contact De Nora if you go the membrane way. they worked with us on some membranes for a Electrolytic Dimerization Process. i don't recall whether they made the membranes or were acting as a third party supplier while they worked with us on Anodes.

http://www.denora.com/Company/Worldwide/DeNoraTech/tabid/92/Default.aspx

 

[unclesyd]

Not knowing the objective of your request here is one possibility of generating Protons by an electrolytic cell. We make one our intermediate chemicals in an electrolytic cell. We have also made some organic acids by means of an electrolytic cell.

http://www.physorg.com/news/2011-05-renewable-energy-simpler-t

hought.html