From solution? You mean AR? If it’s AR boil it down break down as much nitric as you can then make pyro sulfate it’s one of the only chemicals that can readily dissolve rhodium. It will turn into a salt. Rhodium bi sulfate. Then decant and filter the salt off. Then melt it and it will turn into a solid. Then dissolve it in warm water. Then there’s several different ways you can go. Either use sodium hydroxide. Or sulphamic (sp) acid and ammonium chloride with heat and it will turn into rhodium metal. There’s a couple good videos on here or YouTube that explain the process in more detail.