Coagulation is commonly applied to treat Zn-bearing wastewater from smelting industries(smelting wastewater),and thus the Zn-bearing sludge was considerably produced,which should be solidified before safety disposal.H...Coagulation is commonly applied to treat Zn-bearing wastewater from smelting industries(smelting wastewater),and thus the Zn-bearing sludge was considerably produced,which should be solidified before safety disposal.Herein,we demonstrated a novel approach to recycle Zn effectively from smelting wastewater via an integrated Fe coagulation and hematite precipitation method.First,smelting wastewater was coagulated by adding ferric chloride to generate Fe/Zn-bearing sludge(sludge for short).Secondly,the sludge was dissolved to generate an acid solution containing 2.2 g/L of Zn and 39.2 g/L of Fe.Thirdly,the Fe/Zn-bearing solution was hydrothermally treated,and 89%of Fe was eliminated to highly purified hematite block,whereas the percentage of Zn lost was below 1.1%.Finally,the hematite precipitates were collected,and the supernatant was hydrothermally treated again with the addition of glucose.When the molar ratio of glucose to Fe in the supernatant was 1.5,over 99.5%of Fe was precipitated in hematite nanoparticles with a diameter of 10-100 nm,and the residual Fe was 21.5 mg/L.The loss of Zn was below 0.4%,and the residual Zn in the solution was 2169 mg/L,290 times of that in the smelting wastewater.The major mechanism for Fe removal was the hydrolysis of ferric nitrate into hematite,which was promoted by nitrate consumption in glucose oxidation.This paper is the first report of an environment-friendly method for enriching Zn without generating any waste.展开更多
基金This work was sponsored by the National Natural Science Foundation of China(Grant Nos.5157811&51878134,51678273 and 51878133)the Science and Technology Program of Jilin Province(Grant No.20190303001SF).
文摘Coagulation is commonly applied to treat Zn-bearing wastewater from smelting industries(smelting wastewater),and thus the Zn-bearing sludge was considerably produced,which should be solidified before safety disposal.Herein,we demonstrated a novel approach to recycle Zn effectively from smelting wastewater via an integrated Fe coagulation and hematite precipitation method.First,smelting wastewater was coagulated by adding ferric chloride to generate Fe/Zn-bearing sludge(sludge for short).Secondly,the sludge was dissolved to generate an acid solution containing 2.2 g/L of Zn and 39.2 g/L of Fe.Thirdly,the Fe/Zn-bearing solution was hydrothermally treated,and 89%of Fe was eliminated to highly purified hematite block,whereas the percentage of Zn lost was below 1.1%.Finally,the hematite precipitates were collected,and the supernatant was hydrothermally treated again with the addition of glucose.When the molar ratio of glucose to Fe in the supernatant was 1.5,over 99.5%of Fe was precipitated in hematite nanoparticles with a diameter of 10-100 nm,and the residual Fe was 21.5 mg/L.The loss of Zn was below 0.4%,and the residual Zn in the solution was 2169 mg/L,290 times of that in the smelting wastewater.The major mechanism for Fe removal was the hydrolysis of ferric nitrate into hematite,which was promoted by nitrate consumption in glucose oxidation.This paper is the first report of an environment-friendly method for enriching Zn without generating any waste.
