J.Env.Sci. Tech., Spring 2004, No.20
Selective Removal of Heavy Metals from Ferric Chloride Caused
by Etching Processes by using Sulfide Precipitation
Amir Hossein Javid
Amir Hessam Hassani
Key words: Heavy Metals, Ferric Chloride, Precipitation, Sulfide
Nowadays, industrial waste waters consider as basic anxiety in all countries specially in developing and industrial wastes are the most environmental pollutants. There are many types of compounds in the industrial waste waters and heavy metals are considered as the most pollutants.
Chemical etching is a controlled corrosion process that is capable of maintaning tolorances of 1/1000 inch. Chemical etchant solutions have finite lifespans due to gradual, international contamination. When steel alloys are etched, the chief contaminants are heavy metals and iron, specially: Cd(II), Ni(II), Pb(II), Zn(II), Cr(II.III).In his Study selective removal of heavy metals investigated using sodium sulfide and ferric solfide. Last usages of mentioned compoundes in heavy metals removal showed that the effect of removal is maximum, in pH range approximately 5 to 10 but the results of this study showed that heavy metals precipitation can be accomplished in pH range 0 to 1. According to the results obtainedsodium sulfide affects better than other compounds and optimum concentration rate is 1 mol sodium sulfide per 1 mol non-ferros metals. Removal percent of Cd, Zn, and Fe(II) using above mentioned rate of sodium sulfide is 62.9%, 7.89%, 53.44%, 15.89%, respectively. According to the results, iron recovery percentage is low and the treated ferric chloride solution can be reused.