Product category:
Liquid Analysis: Titration, HPLC, IC
News Release from: Applikon Analytical | Subject: Alkali analysis
Edited by the Processingtalk Editorial
Team on 14 September 2006
On-line alkali analysis from Applikon
Throughout all industries, ranging from food to cars to steel, from microprocessors to chemicals, the concentration of alkali during the various stages of the production process is of vital importance
Throughout virtually all industries, ranging from food to steel, from microprocessors to chemicals including car making, the concentration of alkali during the various stages of the production process is of vital importance The alkali used in these industries may very well differ in make up and concentration, e.g a few percent of alkali in a potato peeling plant or concentrated ammonia in a wafer plant
This article was originally published on Processingtalk on 29 Nov 2007 at 8.00am (UK)
Related stories
On-line gas scrubber analysis
Gas scrubbing to remove particulates and noxious gases is one of the most common process units - on-line analysis is possible to bring the laboratory out to control the plant!
Process chemist needed for southern UK sales
As with all expanding companies, the Metrohm Applikon Division is seeking an additional member for their sales team in the south of England
They have one thing in common, that in all cases the concentration of the free hydroxyl ion and/or the total of free and bonded OH- play a decisive role in the process to produce a product with an acceptable quality.
It is very appealing to think that from measuring the pH value one can derive the alkali concentration.
However for several reasons this is not the case.
The mV value generated by free hydroxyl ions at the glass electrode (later in the measurement device converted to pH) is often suppressed by other ions.
Or the alkali is not fully dissociated so the pH value only is expressing part of the alkali.
Even in those rare cases when all conditions are right, still the accuracy achieved will be poor.
This is explained by the fact that the glass electrode works according to Nernst's law, meaning the logarithm of the concentration creates a linear (mV) signal.
Reversibly, obtaining concentration from the pH value, the signal has to be "de-logged", generating a big error.
The only method available to get the accuracy right is titration.
Because here the mV or pH value at the electrode is only a means to detect the equivalence potential, and from that the ml value of the consumed titrant (acid) coming from a burette.
This ml value is linear to the concentration of alkali.
Due to the steep shift in mV (pH) around the equivalence point the accuracy of the value is less significant .
With the availability of refined titration methods, controlled by the microprocessor, titrant volumes can be determined with an inaccuracy smaller than 0.05%.
Recommended analysers for on-line alkali analysis.
* For single steam and single chemistry applications: Applikon ADI2016 Titrolyser.
* For multiple streams and multiple chemistries: Applikon ADI2040 Process Analyser. Request a free brochure from Applikon Analytical ...
• Applikon Analytical: contact details and other news
• Email this article to a colleague
• Register for the free Processingtalk email newsletter
• Processingtalk Home Page
Search the Pro-Talk network of sites
