At pH 6.5 to 8.5, As III is present as uncharged arsenious acid, H3AsO3, under reducing conditions, whereas As V is present in the form of singly and doubly charged H2AsO4- and HAsO42- anions in oxidizing waters. Thus, processes that remove anions (e.g., anion exchange and activated alumina adsorption) are suitable for removing As V but not As III.
Hi there
Chemical oxidation of As(III) to As(V) is quite slow. This depends on the concentration and redox potential.
The lower the concentration of As(III) and the higher the redox potential (positive) the more likely is to get oxidised
What do you mean by fluorescence detection?
Thank you, Leonardo Pantoja Munoz .
Fluorescent detection, I mean that; for qualitative and quantitative (fluorescent / colorimetric) sensing of Arsenic in water using fluorescent ligands.
Are the fluorescent ligans specific for As(III)?
How are the ligands attached? is it a thiol?
What are the conditions for the fluorescent derivatisation reaction?
Dear, Leonardo Pantoja Munoz
I am yet to design fluorescent ligands for As; that are thiol based ligands, because thiol are more attractive towards, Ag, Au, As, Sn metals.
also thioamide derivatives and conjugate hydroxy ligand bases this too have affinity towards arsenic acids.
The binding between ligand and arsenic happens through direct binding of free thiol; or by binding of Nitrogen of imine, azine, amide based ligands; or by intermolecular hydrogen bonding of hydroxy ligand to arsenic.
My question is that, on varying the pH of arsenic(III) solution do it get oxidize to As(V) at any point ? Because I do effect of pH on fluorescent detection of As(III) in my study.
If you change the pH, (increase) you just need to keep the redox potential negative and not oxidation is expected.
Many free thiols are reducing agents anyways.
If you need to reduce the pH, As(III) becomes more stable and no oxidation occurs even at neutral redox potential or slightly positive.
You can just stick an electrode and measure the redox potential and pH at the same time
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