| Author | Zhu, Ling |
| Call Number | AIT Thesis no.EV-99-3 |
| Subject(s) | Soil remediation
|
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of
Science, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Abstract | The goal of the study was to investigate the feasibility of removing heavy metals from the
tlu·ee types of tropical soil which is different in character, by chelation in supercritical carbon
dioxide. The selected topsoil were Karat sandy soil, Pakchong kolinitic soil, and Rangsit
acid sulfate soil. Copper was used as the model contaminant while Hexafluoracetylacetone
(HF A) as a chelating agent.
This study was consisted of two parts include
( 1) The investigation of the effect of density, temperature, methanol modifier, extraction
time, HF A/Cu molar ratio, soil pH, moisture content and contaminant level on the
extraction efficiency and
(2) The comparison of the recovery yield, cost, and waste disposal problem between
Supercritical fluid extraction and solvent extraction which is widely used in real site
remediation.
For the first part, The result indicated that, under optimum condition of SFE, 82%, 74%, 56%
removal of copper can be achieved for Korat, Pakchong and Rangsit soils, respectively.
Increased the density from 0.25 to 0.75 g/ml, it was found to have negligible effect on the
copper recovery. At constant density (0.55 g/ml) increased the temperature from 40 °c to 80
°C were found to have negative effect on Rangsit soil and negligible effect on Korat and
Pakchong soil. Adding methanol at 5% had the highest yield for all tlu·ee kinds of studied
soils. The dynamic extraction time was conducted varying from 5 to 35 min. The pH appears
to be an important factor determine the extraction efficiencies. The effective pH range has
lied between 3 to 10. Addition of a small amount of water to the soil samples can
significantly increase the extraction efficiency. Extraction of higher contaminated soil get
higher recovery. The possible reasons were discussed.
For the second pru1, by comparison between the two methods, it is discovered that both SFE
and solvent extraction can yield quite similar removal efficiency. However, SFE is an
environmental-friendly method for removing heavy metal in contaminated soil while
conventional method created the waste disposal problem. It is important to conduct further
study in order to reduce the treatment cost of the new SFE technique and enable it to be
commercially accepted. |
| Year | 1999 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Environmental Engineering (EV) |
| Chairperson(s) | Preeda Parkian; |
| Examination Committee(s) | Ozaki, Hiroaki ;Apisit Eiumnoh ; |
| Scholarship Donor(s) | Asian Institute of Technology; |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 1999 |