Solubility of Heavy Metals

 

Metal precipitation is primarily dependent upon two factors: the concentration of the metal, and the pH of the water. pH2O has managed to adjust and control the precise pH level for precipitations of each unique metal

 

 

High pH corresponds to high hydroxide concentrations. Visual representations of the pH values that promote metal precipitation are displayed in the above graphs. Each figure represents the solubility of an individual metal at various pH values. All of the figures illustrate how the solubility of a particular metal is directly controlled by pH. The y-axis displays the concentration of dissolved metal in the wastewater in milligrams/liter (mg/L). Notice the wide variation in scale. The upper part of the scale shows a dissolved concentration of 100 mg/L. The lowest number on the scale is 0.001 mg/L. These solubility graphs display regions where the metals are soluble or insoluble. The region above the shaded areas for each metal signifies that the metals precipitate as metal hydroxides. This is referred to as the precipitation region. The region below or outside of the shaded area illustrates where the metals are dissolved in solution, no precipitation occurs, and no metal removal takes place.

 

Solubility Graph
A graph that reveals the solubility of metals(through the formation of metal hydroxides) at specific pH values

 

Precipitation
defines a material's ability to go into solution (dissolve). Materials that are soluble readily dissolve in solution and do not precipitate. Substances that are insoluble do not easily dissolve in solution and stay in their solid form. The goal of metals removal in wastewater is to produce conditions so that metals are insoluble. the formation of metal hydroxides at specific pH values

 

Precipitation Region
The region on a solubility diagram that indicates the appropriate concentration and pH value for a metal to form a solid precipitate

 

Solubility
Solubility defines a material's ability to go into solution (dissolve). Materials that are soluble readily dissolve in solution and do not precipitate. Substances that are insoluble do not easily dissolve in solution and stay in their solid form. The goal of metals removal in wastewater is to produce conditions so that metals are insoluble.

 

 

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