Efficiency of nano zero-valent iron application in soil under different incubation conditions

George Kofi Gordor

Master's thesis

Abstract:

Nano zero-valent iron (nZVI) is continuously being studied as its use as a stabilising chemical agent for remediating contaminated water and soils evolves. This study is focused on the efficiency of nZVI application in soil as a potential sorbent of the risk elements in soils under different incubation conditions. A set of leaching experiments in combination with geochemical modelling has been performed, with the emphasis on the leaching behaviour of contaminants and their release as a function of the liquid-to-solid ratio (L/S).The behaviours of Zinc (Zn), Lead (Pb), Cadmium (Cd), Arsenic (As) were investigated in control soils and test samples (amended with 1% (w/w) of nZVI) and the results were evaluated.Firstly, both the control and nZVI-treated soil samples were subjected to incubation in order to reach pseudo-equilibrium conditions under various moisture content. The pots were maintained at 0%, 30%, 60%, 90% and 130% of water holding capacity (WHC) for 3 months. The samples were dried and subjected to a set of laboratory experiments at L/S 2, 5, and 10 ml/g, respectively. The test included physico-chemical measurements and metal concentrations analyses. The influence of moisture content on the leaching behaviour was element specific. The best result for the stabilisation of Pb was observed at 60% moisture content, while 90% moisture content was the best condition for the stabilisation of Zn, Cdand As. The addition of nZVI to the soil generally increased pH across the various samples used and decreased the amount of metal(loids) leached from the samples. The effectiveness of immobilisation of contaminants by nZVI depends on several factors and as such deep analysis should be carried out before its use in the field.

Keywords

Nano-iron, Liquid-to-solid ratio, Chemical stabilisation, Soil contamination

Language used: English

Date on which the thesis was submitted / produced: 15. 12. 2017

Thesis defence

• Supervisor: Mgr. Martina Vítková, Ph.D.

Czech University of Life Sciences Prague

Faculty of Environmental Sciences

Master programme / field:
Geology / Environmental Geosciences