Title: Extraction of Heavy Metals from Sewage Sludge with Phosphoric Acid
Abstract: On basis of chemical extraction technology, H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> PO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> has been used to remove heavy metals from the industrial sewage sludge. At the laboratory scale, heavy metals Zn, Pb, Cd, Ni, Cr and Cu were extracted synchronously from the sewage sludge. The results showed that H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> PO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> concentrations had a significant effect on the extraction efficiency of heavy metals. The extraction efficiency increased gradually with H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> PO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> concentrations increasing, and 5% H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> PO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> was the optimal condition with the extraction efficiency of six heavy metals for Zn 79.71%, Pb 99.1%, Cd 87.15%, Ni 70.57%, Cr 78.01%, and Cu 60.91%, respectively. The species distribution of heavy metals in sewage sludge played an important influence on the extraction of heavy metals. From the analysis of species distribution of heavy metals before and after extraction, it was found that the extraction of heavy metals except for Pb came mainly from four fractions that were, exchangeable, bounding to carbonates, bounding to iron and manganese oxides, and bounding to organic matter. However, the residual fraction of Pb can almost be extracted completely. It was presumed that the extraction of heavy metals was mainly controlled by three aspects: the effect of H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> , the coordination reaction, and the precipitation reaction. On the synergistic effect of H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> , the coordination reaction predominated in the process of extraction compared with the precipitation reaction.
Publication Year: 2010
Publication Date: 2010-06-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 3
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