I am conducting a batch test with a locally produced adsorbent with a major constituent of Calcium oxide and adsorbate (carbarmazepine, sulfamethoxazole and diclofenac). I want to keep the pH constant, how can I achieve this?,
Thanks in advance for your contributions
Amen Ekhosuehi Some use "initial pH" where the initial pH is adjusted with HCl or NaOH
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while others use buffers Tris and phosphate at low ionic strength to prevent competition from the adsorbate.
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but accoridng to
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ionic strength of the buffer "reduces biosorptive removal of adsorptive pollutant by competing with the adsorbate for binding sites of biosorbent."
It is a case by case basis. if your target is metal than pH drift during sorption (releases H+ ion for instance) may affect sorption as the metal may have limited solubility at certain pHs.
Chapter Does Sustainable Management of Biodegradable Sludge Exist at...
(Fig. 5)
and
https://www.nature.com/articles/s41598-018-31660-7
In short, maintaining pH whilst preventing unwanted consequences is the "Elephant in the room" in the biosorption process
Thank you Shukor for your insightful answer. As you rightly mentioned i was using ''Initial pH'' but i discovered that there is always a deviation at the end of the experiment. for instance, when my initial pH was 4, the final pH was 7 at the end of the experiment. Initial pH 10 ended up with final pH with 8 at the end of the experiment
You can use pH sensor that can measure and show the pH reading continuously, or optimize the process with a separate trial by observing the pH change with time. If the change is negligible, then no need to check it continuously once it is set. Additionally, if the change is more, then first find out the buffering capacity of the material and then proceed. The continuous change in pH can affect the adsorption and will not show the actual capacity.
Before you ascertain the exact pH, u need to run the experiment varying the pH first. The optimum pH is what u will keep constant. First of all , check the pH of the solution u are working with and run experiment with it first. Then adjust the pH using NaOH or HCl depending on the exact pH u want to work with.
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