Dear all, many documents are available on RG and via search engines, where Tributyl phosphate is the most cited solvent, mainly for extraction. My Regards

Dear Lyes Benharrat, lanthanide orthophosphates are generally more or less insulble in water and insoluble in organic solvents. For more information see the articles cited below which are available on RG. I also attach a pdf on this subject.

Article Preparation and Properties of Lanthanide Phosphates

Article A Study of the Solubility of Hydrated Orthophosphates of Ytt...

Dear all, many documents are available on RG and via search engines, where Tributyl phosphate is the most cited solvent, mainly for extraction. My Regards

This paper can help you

https://www.researchgate.net/publication/251239403_Preparation_of_Lanthanide_Orthophosphates_by_Crystallisation_From_Phosphoric_Aacid_Solution

https://pubs.rsc.org/en/Content/ArticleLanding/CP/2003/B302280N#!divAbstract

I fully agree with Abdelkader Dehbi in that hot phosphoric acid would be a good choice to dissolve lanthanide orthophosphates.

Thanks for all of you. I appreciate your help. I need to check with solvents proposed and see what will be the result.

Lanthanides orthophosphates are insoluble in water and organic solvents including TBP. There even mostly insoluble in acidic aqueous solution. The classical way to dissolve Ln phosphates is to make an alkaline attack (with NaOHor Na2CO3), the Ln orthophosphates are converted into Ln hydroxydes, then the mother liqour (solution of Na3PO4) is removed and the Ln(OH)3 can be dissolved into any type of acid.

Hi Lyes

have you tried to dissolve it in pure hydrochloride acid (HCl) or sulfuric acid (H2SO4)? the orthophosphates salts are usually soluble in strong mineral acids. all the best.