Removal of selenium from water with kaolinite
The description relates to a composition and a method for reducing the concentration of selenium in water. Contaminated water is contacted with a kaolinite clay characterized by a removal efficiency for selenatearsenate of at least 40 wt % at ambient temperature. The adsorption process is fast. Following sufficient contact, the water is separated from the kaolinite clay. In a preferred form, the kaolinite clay has high surface acidity.
1. A composition for removing selenium from contaminated water comprises:
a) a kaolinite clay selected from the group consisting of kaolinite, nacrite, halloysite, dickite, and odinite, wherein the kaolinite clay has a surface acidity such that the pH of its slurry in water is less than 6 at 1 weight %;
b) a water phase with pH in the range of 4 to 9,
wherein the kaolinite dosage to the volume of the contaminated water is in the range from about 1 to about 20 g/liter.
2. The composition of claim 1 , wherein the clay is kaolinite.
3. The composition of claim 1 , wherein the kaolinite clay has a surface acidity such that the pH of its slurry in water is less than 5 at 1 weight %.
4. A composition according to claim 1 in unit dosage form for treating a volume of contaminated water, the kaolinite dosage to the volume of the contaminated water is in the range from about 5 to about 15 g/liter of contaminated water.
5. A method for removing selenium from contaminated water which comprises contacting the contaminated water with:
a) a kaolinite clay selected from the group consisting of kaolinite, nacrite, halloysite, dickite, and odinite, wherein the kaolinite clay has a surface acidity such that the pH of its slurry in water is less than 6 at 1 weight %;
b) a water phase with pH in the range of 4 to 9,
wherein the kaolinite dosage to the volume of the contaminated water is in the range from about 1 to about 20 g/liter.
6. The method of claim 5 , wherein the clay is kaolinite.
7. The method of claim 5 , wherein the kaolinite clay has a surface acidity such that the pH of its slurry in water is less than 5 at 1 weight %.
8. A method according to claim 5 in unit dosage form for treating a volume of contaminated water, the kaolinite dosage to the volume of the contaminated water is in the range from about 5 to about 15 g/liter of contaminated water.