ENVE 201 Environmental Engineering Chemistry 1 Fluoride Dr. Aslıhan Kerç

Fluoride Removal of fluoride Addition of fluoride to optimum levels SIGNIFICANCE OF HIGH F - Cause mottled enamel (dental fluorisis)>2.0 mg/L If value < mg/L  no problem

Excessive dosage of fluoride result in bone fluorisis > 5 mg/L Removal of fluoride  passing water through defluoridation media such as tricalcium phosphate, bone char, bone meal, activated alumina

LOW FLUORIDE If F decreases, the dental caries increases. 1 mg/L F -  desirable for optimal dental health.

Chemistry of Fluorine F 2  Among most active elements known  Forms simple Fluoride compounds and complex ions.

 Fluoride added to public water supplies in the form of ; NaF CaF 2 HF Na 2 SiF 6 (sodium silicofluoride) H 2 SiF 6 (hydrofluosilisic acid) (NH 4 ) 2 SiF 6 (ammonium silico fluoride )

Methods of Determination Electrode Method Colorimetric Procedures Ion Chromotography ISE ( Ion Selective Electrode)

 USEPA MCL for Fluoride  4mg/L To protect against crippling skeletal fluorisis  Secondary MCL (not enforcable)  2 mg/L To protect against dental fluorisis