title: Immobilization in cement mortar of chromium removed from water using titania nanoparticles.
abstract: Because of the high toxicity of chromium, particularly as Cr (VI), it is removed from industrial effluents before their discharge into water bodies by a variety of techniques, including adsorption. Ultimate disposal of the sludge or the adsorbate, however, is a serious problem. While titania, in nanoparticle form, serves as a very good adsorbent for chromium, as an additive, it also helps to increase the compressive strength of mortar and concrete. Combining these two properties of the material, titania nanoparticles were used to adsorb chromium and then added to mortar up to a concentration of 20% by weight. The compressive strength of the resulting mortar specimens that replaced 15% of cement with chromium laden titania showed an improved strength than that without titania, thus confirming that this material had positive effect on the mortar strength. Leachate tests using the Toxicity Characteristics Leaching Procedure (TCLP) confirmed that the mortar sample chromium leachate was well within the permissible limits. The proposed technique thus offers a safe and viable method for the ultimate disposal of toxic metal wastes, in general, and those laden waste chromium, in particular.
authors.affiliation: National University of Sciences and Technology (NUST), Islamabad, Pakistan.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Husnain
authors.affiliation: National University of Sciences and Technology (NUST), Islamabad, Pakistan.
authors.forename: Ishtiaq Ahmed
authors.initials: IA
authors.lastname: Qazi
authors.affiliation: National University of Sciences and Technology (NUST), Islamabad, Pakistan. Electronic address: wasimkhlaiq@nice.nust.edu.pk.
authors.forename: Wasim
authors.initials: W
authors.lastname: Khaliq
authors.affiliation: National University of Sciences and Technology (NUST), Islamabad, Pakistan.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Arshad
mesh_terms: D002857:Chromium / Q000737:chemistry* / Q000302:isolation & purification; D019245:Compressive Strength; D003252:Construction Materials; D053758:Nanoparticles / Q000737:chemistry*; D012722:Sewage; D014025:Titanium / Q000737:chemistry; D014466:Ultraviolet Rays; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000302:isolation & purification
chemical_list: D012722:Sewage; D014874:Water Pollutants, Chemical; D002857:Chromium; C009495:titanium dioxide; C074702:chromium hexavalent ion; D014025:Titanium
keywords: Adsorption; Chromium leachate; Compressive strength; Mortar; Titania nanoparticles; Toxic chromium