Product category:
Materials Testing
News Release from: Metrohm UK | Subject: Applikon ADI2016 Titrolyzer
Edited by the Manufacturingtalk Editorial
Team on 13 September 2006
Online alkali analysis during production
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's used in all 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 Manufacturingtalk on 22 May 2008 at 8.00am (UK)
Related stories
Process chemicals can be analysed on-line
Metrohm has combined the best aspects of laboratory and online systems to produce the 875 ProcessLab: a fully customised, automated at-line system for analytical testing.
Determining water levels in lubricating oils
It is impoirtant to determine the presence of water in machinery lubricating oils, which is why Metrohm is offering its 831 KF Coulometer to give reliable results over a long period.
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 of the 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 however 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%. Request a free brochure from Metrohm UK ...
Recommended Analyzers for on -line alkali analysis: For single steam and single chemistry applications: Applikon ADI2016 Titrolyzer For multiple streams and multiple chemistries: Applikon ADI2040.
• Metrohm UK: contact details and other news
• Email this article to a colleague
• Register for the free Manufacturingtalk email newsletter
• Manufacturingtalk Home Page
Search the Pro-Talk network of sites
