Potential of modified iron-rich foundry waste for environmental applications: Fenton reaction and Cr(VI) reduction

• Published in: Journal of hazardous materials Vol. 194; pp. 393 - 398
• Main Authors: Oliveira, Patrícia E.F., Oliveira, Leandro D., Ardisson, José D., Lago, Rochel M.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 30.10.2011; Elsevier
• Subjects: Adsorbents; Applied sciences; Bentonite; Carbon; Chemical engineering; chromium; Chromium - chemistry; clay; Clay (material); Contaminants; Cr(VI) reduction; Exact sciences and technology; Fenton reaction; Groundwaters; heat treatment; hematite; Hot Temperature; hydrodynamics; Hydrodynamics of contact apparatus; hydrogen peroxide; indigo carmine; iron; Iron - chemistry; Magnetics; Microscopy, Electron, Scanning; Natural water pollution; oxidation; Oxidation-Reduction; Pollution; Reactive barrier; Reactors; Reduction; remediation; Sand; Waste of foundry sand; Wastes; Water treatment and pollution; Fenton reaction; Waste of foundry sand; Cr(VI) reduction; Reactive barrier; Heat treatment; Dyes; Hydrogen peroxide; Hydrodynamics; Permeable reactive barrier; Inert atmosphere; Decontamination; Oxidation; Water pollution; Chemical reactivity; Ground water
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2011.08.002

► Waste of foundry sand thermally modified is so active in oxidation of dye with H 2O 2. ► It is good to reduce Cr(VI) species too. ► The waste is not hazardous. ► It can be applied as medium in reactive permeable barriers. ► Coal and bentonite in the waste can adsorb different contaminants. A magnetic fraction (15%) from a waste of foundry sand (WFS), composed of sand, carbon, bentonite clay and iron (10%) was modified by thermal treatment at 400, 600 and 800 °C under inert atmosphere. Mössbauer analyses showed that the thermal treatment increased the amount of Fe 3O 4 from 25 to 55% by reduction of Fe 2O 3 and highly dispersed Fe 3+ by the carbon present in the waste. The Fe 3O 4 caused a significant increase on the activity of two important reactions with application in environmental remediation: the Fenton oxidation of indigo carmine dye with H 2O 2 and the reduction of Cr(VI) to Cr(III). The magnetic fraction of WFS was also mixed with hematite (Fe 2O 3) and thermally treated at 400, 600 and 800 °C. This treatment produced large amounts of surface Fe 3O 4 and increased substantially the rate of Fenton reaction as well as Cr(VI) reduction. This reactivity combined with the presence of carbon (an adsorbent for organic contaminants), bentonite clay (an adsorbent for metallic contaminants) and the granulometry/packing/hydrodynamic features make WFS a promising material for use in reactive permeable barriers.