铁在水中的存在形式有简单的水合离子和复杂的有机、无机络合物形式;也可以存在于胶体、悬浮物和颗粒物中;可能以二价的形式存在;也可能以三价的形式存在。同时当水样暴露在空气中时,二价铁易被氧化为三价铁,特别是在有氧化剂(氯、溴、过氧化氢、过硫酸铵、硝酸等)存在时,氧化反应非常迅速。当水样pH>3.5时,易导致高价铁(三价)的水解沉淀。因此进行 Iron is present in water in the form of simple hydrated ions and complex organic and inorganic complex forms; it may also be present in colloids, suspensions and particulates; it may exist in its divalent form; it may also exist in its trivalent form . At the same time when water samples exposed to the air, ferrous iron is easily oxidized to ferric iron, especially in the presence of oxidants (chlorine, bromine, hydrogen peroxide, ammonium persulfate, nitric acid, etc.), the oxidation reaction is very rapid. When the water sample pH> 3.5, easily lead to high-priced iron (trivalent) hydrolysis precipitation. So proceed