To examine the effect of pH on aluminum species distribution in coagulation, synthetic water containing 5×10-4 mol/L NaHCO3 and NaNO3 in distilled water is prepared for control experiments. The final solution contains 2×10-4 mol Al/L which is the common dosage in practice. The solution isanalyzed subsequently by ferron assay after coagulants are added under rapid stirring at 120 rpm for 2 min.
This method is given by several researchers , but because of elapsed time and the fact that the ferron test is carried out in a buffered solution at around pH 5, can the results of this method be relevant to the species formed during an actual coagulation test with natural water? what about the effect of AL(OH)3 precipitation which is formed right after adding alum coagulant between pH 6 and 7?
I have some suggestion for you to obtain species diagram using some software. Medusa or Vminteq are the some free software. You can input your all the experimental conditions and then you can obtain species distribution with pH.
We can coagulate aluminum compounds using hydroxyl amine hydrochloride.At higher pH almost all metals will precipitate as hydroxides.
It depends what the natural water contains Mehrnaz. In my opinion, experiments are always best carried out using the natural water you are studying, if possible, to ensure the correct concentrations of, for example, natural organic matter. It is worth the effort of collecting the natural water and using the Jar Test approach to create real scenario conditions for the coagulation and flocculation processes. Attached is a paper which might be of use, there are many more in the public domain.
It depends what the natural water contains Mehrnaz. In my opinion, experiments are always best carried out using the natural water you are studying, if possible, to ensure the correct concentrations of, for example, natural organic matter. It is worth the effort of collecting the natural water and using the Jar Test approach to create real scenario conditions for the coagulation and flocculation processes. Attached is a paper which might be of use, there are many more in the public domain.
Hello Mehrnaz,
This diagram might help you.
Best regards from Spain,
Javier
I have taken these data fron theoretical estimations. It's very common the use of these type of diagrams.
I think you could refer to the aquatic chemistry textbook to find the constant. At least you could judge the predominant species in your artificial system.
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