초록

A method is provided for removing heavy metal ions from an aqueous solution to yield a less contaminated aqueous effluent. The method comprises coprecipitating the heavy metal ions with a carrier precipitate which is formed in situ within the aqueous solution.

대표청구항 ▼

A method for removing heavy metal ions from an aqueous solution containing heavy metal ions and ferrous ions, comprising: (a) adding ferrous ions to said solution so as to increase the molar ratio of ferrous ions to heavy metal ions; (b) rapidly oxidizing in a reaction zone essentially all ferrous i

A method for removing heavy metal ions from an aqueous solution containing heavy metal ions and ferrous ions, comprising: (a) adding ferrous ions to said solution so as to increase the molar ratio of ferrous ions to heavy metal ions; (b) rapidly oxidizing in a reaction zone essentially all ferrous ions in said solution to ferric ions while controlling the pH of said solution with added base so as to rapidly form a substantially completely amorphous precipitate comprising a substantial proportion of ferric hydroxide and a substantial proportion of said heavy metal ions; and (c) separating said amorphous precipitate from said solution so as to form an effluent solution having a reduced concentration of heavy metal ions; wherein said aqueous solution contains ferrous ions and at least four heavy metals selected from the group consisting of copper, chromium, lead, nickel, cadmium, and zinc, and wherein said amorphous precipitate contains essentially all the iron introduced into said reaction zone and further contains at least four of said heavy metals, one of which being nickel, lead, or copper and two of which being chromium and zinc, removed by at least the percentage shown in the following table: ________________________________ - Heavy Metal Removal Efficiency ________________________________ chromium 100% nickel at least 94.3% copper at least 98.8% lead at least 99.5% cadmium at least 96.8% zinc at least 99.7% ________________________________ wherein at least 95% of all heavy metals in said aqueous solution are removed from said solution by said precipitate, and wherein the added base consists of aqueous ammonia, and wherein essentially none of said precipitate is recycled back to said reaction zone.