Solution Characteristics for Adsorption of Copper Ion with Iron(III) Hydroxide from Aqueous Ammonia Solution

The distribution of copper ion species in aqueous ammonia solution is evaluated as a function of pH by a numerical approach. Adsorption of copper on colloidal iron(III) hydroxide in solutions of total ammonia (0.14-1.2 M) are performed at various values of pH. The maximum efficiency of adsorption occurs when the sum of the fractions of the species Cu(NH₃)²⁺, Cu(NH₃)₂²⁺ and Cu(NH₃)₃²⁺ in the solution reaches its maximum. With varied solution pH, the distribution of copper species is the determining factor for maximum adsorption, whereas the surface properties of the adsorbing particles show smaller effects under the test conditions.