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Hexavalent chromium reduction with scrap iron in continuous-flow system Part 1: effect of feed solution pH.
J Hazard Mater. 2008 May 01; 153(1-2):655-62.JH

Abstract

The reduction of hexavalent chromium by scrap iron was investigated in continuous system, using long-term column experiments, for aqueous Cr(VI) solutions having low buffering capacities, over the pH range of 2.00-7.30. The results showed that the initial pH of Cr(VI) solution significantly affects the reduction capacity of scrap iron. The highest reduction capacity was determined to be 19.2 mg Cr(VI)/g scrap iron, at pH 2.50, and decreased with increasing the initial pH of Cr(VI) solution. A considerable decrease in scrap iron reduction capacity (25%) was also observed at pH 2.00, as compared to pH 2.50, due to the increased contribution of H(+) ions to the corrosion of scrap iron, which leads to a rapid decrease in time of the scrap iron volume. Over the pH range of 2.50-7.30, hexavalent chromium concentration increases slowly in time after its breakthrough in column effluent, until a steady-state concentration was observed; similarly, over the same pH range, the amount of solubilized Cr(III) in treated column effluent decreases in time, until a steady-state concentration was observed. The steady-state concentration in column effluent decreased for Cr(VI) and increased for Cr(III) with decreasing the initial pH of Cr(VI) solution. No steady-state Cr(VI) or Cr(III) concentrations in column effluent were observed at pH 2.00. Over the entire studied pH range, the amount of Fe(total) in treated solution increases as the initial pH of column influent is decreased; the results show also a continuously decrease in time of Fe(total) concentration, for a constant initial pH, due to a decrease in time of iron corrosion rate. Cr(III) concentration in column effluent also continuously decreased in time, for a constant initial pH, over the pH range of 2.50-7.30. This represents an advantage, because the amount of precipitant agent used to remove Fe(total) and Cr(III) from the column effluent will also decrease in time. The optimum pH for Cr(VI) reduction with scrap iron in continuous-flow system was established at the value of 2.50.

Authors+Show Affiliations

Faculty of Industrial Chemistry and Environmental Engineering, Politehnica University of Timisoara, Timisoara, Romania. marius.gheju@chim.upt.roNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

17933460

Citation

Gheju, M, et al. "Hexavalent Chromium Reduction With Scrap Iron in Continuous-flow System Part 1: Effect of Feed Solution PH." Journal of Hazardous Materials, vol. 153, no. 1-2, 2008, pp. 655-62.
Gheju M, Iovi A, Balcu I. Hexavalent chromium reduction with scrap iron in continuous-flow system Part 1: effect of feed solution pH. J Hazard Mater. 2008;153(1-2):655-62.
Gheju, M., Iovi, A., & Balcu, I. (2008). Hexavalent chromium reduction with scrap iron in continuous-flow system Part 1: effect of feed solution pH. Journal of Hazardous Materials, 153(1-2), 655-62.
Gheju M, Iovi A, Balcu I. Hexavalent Chromium Reduction With Scrap Iron in Continuous-flow System Part 1: Effect of Feed Solution PH. J Hazard Mater. 2008 May 1;153(1-2):655-62. PubMed PMID: 17933460.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Hexavalent chromium reduction with scrap iron in continuous-flow system Part 1: effect of feed solution pH. AU - Gheju,M, AU - Iovi,A, AU - Balcu,I, Y1 - 2007/09/06/ PY - 2006/07/26/received PY - 2007/05/03/revised PY - 2007/09/04/accepted PY - 2007/10/16/pubmed PY - 2008/7/3/medline PY - 2007/10/16/entrez SP - 655 EP - 62 JF - Journal of hazardous materials JO - J Hazard Mater VL - 153 IS - 1-2 N2 - The reduction of hexavalent chromium by scrap iron was investigated in continuous system, using long-term column experiments, for aqueous Cr(VI) solutions having low buffering capacities, over the pH range of 2.00-7.30. The results showed that the initial pH of Cr(VI) solution significantly affects the reduction capacity of scrap iron. The highest reduction capacity was determined to be 19.2 mg Cr(VI)/g scrap iron, at pH 2.50, and decreased with increasing the initial pH of Cr(VI) solution. A considerable decrease in scrap iron reduction capacity (25%) was also observed at pH 2.00, as compared to pH 2.50, due to the increased contribution of H(+) ions to the corrosion of scrap iron, which leads to a rapid decrease in time of the scrap iron volume. Over the pH range of 2.50-7.30, hexavalent chromium concentration increases slowly in time after its breakthrough in column effluent, until a steady-state concentration was observed; similarly, over the same pH range, the amount of solubilized Cr(III) in treated column effluent decreases in time, until a steady-state concentration was observed. The steady-state concentration in column effluent decreased for Cr(VI) and increased for Cr(III) with decreasing the initial pH of Cr(VI) solution. No steady-state Cr(VI) or Cr(III) concentrations in column effluent were observed at pH 2.00. Over the entire studied pH range, the amount of Fe(total) in treated solution increases as the initial pH of column influent is decreased; the results show also a continuously decrease in time of Fe(total) concentration, for a constant initial pH, due to a decrease in time of iron corrosion rate. Cr(III) concentration in column effluent also continuously decreased in time, for a constant initial pH, over the pH range of 2.50-7.30. This represents an advantage, because the amount of precipitant agent used to remove Fe(total) and Cr(III) from the column effluent will also decrease in time. The optimum pH for Cr(VI) reduction with scrap iron in continuous-flow system was established at the value of 2.50. SN - 0304-3894 UR - https://www.unboundmedicine.com/medline/citation/17933460/Hexavalent_chromium_reduction_with_scrap_iron_in_continuous_flow_system_Part_1:_effect_of_feed_solution_pH_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0304-3894(07)01294-0 DB - PRIME DP - Unbound Medicine ER -