Solubility is not to be confused with the ability to 'dissolve' a substance, because the solution might also occur because of a chemical reaction. For example, zinc 'dissolves' (with effervescence) in hydrochloric acid as a result of a chemical reaction releasing hydrogen gas in a displacement reaction.
All three kidney, liver and lungs purify the blood. The lungs help remove carbon dioxide, the kidneys remove water-soluble waste and the liver removes fat soluble wastes and many other impurities from the blood....ref:http://www.pharmainfo.net/answers/pharmaquestion/which-organ-purifies-blood.
The kidneys provide a hormonal mechanism for the regulation of blood pressure by managing blood volume. The reninâangiotensinâaldosterone system of the kidneys regulates blood volume. In response to rising blood pressure, the juxtaglomerular cells in the kidneys secrete renin into the blood.