... , widely as sewage treatment reagent, biological fertilizer (nutrients) and feed additive, paint, production materials, catalyst, purification, disinfectants, magnetic materials ... -89 ferrous sulfate FeSO4 (7H2O - 90%, titanium dioxide content of p content of TiO2 than 0.75%, ... cr3 +, replace expensive by sodium sulfite, aw, sulfur dioxide, etc. Advantages are not toxic carcinogenic stimulate chloride ( ...