حذف انتخابي فلزات سنگين از محلول كلرورفريك ناشي از فرايند اسيدشويي توسط ترسيب به وسيله نمك هاي سولفيد

Selective Removal of Heavy Metals from Ferric Chloride Caused by Etching Processes by using Sulfide Precipitation

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 maintaining tolerances of 1/1000 inch. Chemical enchant solutions have finite lifespan due to gradual, international contamination. When steel alloys are etched, the chief contaminants are heavy metals and iron, specially: Cd(H), Ni(ll), Pb(lI), Zn(II), Cr(II, III) .In his Study selective removal of heavy metals investigated using sodium sulfide and ferric sulfide. Last usages of mentioned compounds 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 obtained sodium sulfide affects better than other compounds and optimum concentration rate is 1 mol sodium sulfide per 1 mol non-ferrous metals. Removal percent of Cd, Zn, and Fe(ll) using above mentioned rate of sodium sulfideis62.9%, 7.89%, 53.44%, 15,89%, respectively. Ace ording to the results, iron recovery percentage is low and the treated, ferric chloride solution can be reused.