Equilibrium, kinetics, and mechanism of lead adsorption using zero-valent iron coated on diatomite. Issue 39 (20th August 2016)

• Record Type: Journal Article
• Authors: Pojananukij, N.; Wantala, K.; Neramittagapong, S.; Neramittagapong, A.
• Is Part Of: Desalination and water treatment. Volume 57:Issue 39(2016)
• Page Start: 18475
• Page End: 18489
• Publication Date: 2016-08-20
• Subjects: Adsorption -- Heavy metals -- Kinetic adsorption isotherms -- Thermodynamics -- Adsorption mechanism; Saline water conversion -- Periodicals; Saline water conversion; Water -- Purification; Periodicals; 628.167
• DOI: 10.1080/19443994.2015.1092890
• Languages: English
• ISSNs: 1944-3994

Abstract

Abstract: The lead adsorption performances of zero-valent iron coated on diatomite (ZVI-D) were investigated. ZVI-D was prepared by impregnation of diatomite with iron sulfate solution, and followed by reducing with sodium borohydride. The zero-valent iron of ZVI-D was confirmed by XPS. The adsorption performances were tested in a batch reactor with an initial lead concentration in the range of 100–1, 250 mg/L. It was found that a lead adsorption isotherm could be described by Langmuir equations with a maximum adsorption capacity of 158.73 mg/g at 298 K. The mean adsorption energy ( E ) of 54.78 kJ/mol was determined by using Dubinin–Radushkevich isotherm. The kinetics of Pb 2+ adsorption was fitted with a pseudo-second-order model. From the thermodynamic study, it was found that the adsorption process was endothermic and spontaneous. An adsorption mechanism was proposed by using XPS data. Three steps of the adsorption were suggested, (i) Pb 2+ ions were oxidized to Pb 0 on ZVI active sites, (ii)ferrous ions reacted with the Pb 2+ to form FeOPbOH, PbO–Fe, PbO2 -–Fe2 O3, and PbO–FeOOH species on ZVI surface, and (iii) Pb 2+ turned to PbO2 –Si, PbO–Si, Pb(OH)2 –Al, and PbO2 –Al2 O3 on diatomite surface.