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NEW ZERO VALENT IRON (NZVI) FOR REMEDIATION OF
HEAVY METALS CONTAMINATED WATER
WAN ZUHAIRI WAN YAACOB , TENGKU NURADIBAH TENGKU KHALID, ABDUL
RAHIM SAMSUDIN & NORAZNIDA KAMARUSZAMAN
INTRODUCTION
Heavy metals are very toxic, highly persistent and non-degradable. They can contaminate
the environment (i.e. groundwater) and may pose very serious risk to health and our
ecosystems. This study was conducted to develop new zero valent iron (NZVI) using two
reduction processes :-
1) Reduction by heating a mixture of iron + carbon + lime
2) Chemical reduction using FeCl2.4H2O + NaBH4
There were two types of iron used in this study, i.e. iron ore from Jerantut and iron
concretion in basaltic rock from Kuantan Pahang. Source of lime was from Bukit
Panching in Kuantan and carbon from coconut shells.
CONCLUSIONS
ZVI materials produced by heating reduction
These materials have high Specific Surface Area (SSA) and Cation Exchange
Capacity (CEC). The SSA and CEC values increased with the increasing
percentage of iron in the sample and increasing temperature used in this study
(maximum 950oC). These materials also have high buffering capacity, capable
to increase the pH values of contaminated water from 4 to 10. The adsorption
capacity for Pb is also very high and is largely controlled by the percentage of
iron and the heating temperature used.
ZVI materials produced by chemical reduction
The results of NZVI produced from chemical reduction such as color, particle
size, SEM image and XPS data indicate that nano Zero Valent Iron has been
successfully developed in this study. This platy micro-texture material has
nano size particles and contains zero valency iron. However, additional
chemical tests are still required to get the information on sorption capacity,
SSA and CEC values of this new material.
RESULTS
Address: Geology Programme, School of Environmental Sciences and Natural Resources, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600, Bangi, Selangor, Malaysia.
Tel: 603-89215390 Fax: 603-89215490 E-mail: [email protected] website : www.ukm.my/zuhairi @ http://geo-environment.blogspot.com/
ACKNOWLEDGEMENT: The authors wish to thank Universiti Kebangsaan Malaysia for giving permission to attend this
conference. The authors would also thank Ministry of Higher Education (MOHE) for providing the research grant to undertake this
project (FRGS UKM-ST-07-FRGS0022-2010). Finally, the authors thank Mr. Muhammad Farid Adnan for technical assistance in the
Laboratory.
MATERIALS & METHODS
Zero Valent iron
(ZVI)
Figure 1. Application of Zero Valent Iron (ZVI) for remediation of contaminated
groundwater
17.8 g FeCl2·4H2O + 50mL of
absolute ethanol and distilled
water solution (4:1, v/v)
8.47 g of NaBH4 + 220mL of
distilled water to produce ~1M
solution
The NaBH4 solution was added to the Fe2+
solution (40–50 drops/min) while stirring
the reaction mixture well
Black particles of nZVI
2) Chemical reduction using FeCl2.4H2O + NaBH4
Sample ID Iron Concretion or
Iron Ore (%)
Powdered
Limestone (%)
Carbon
(%)
ZVI 1 95 2.5 2.5
ZVI 2 90 5 5
ZVI3 80 10 10
1) Reduction by heating together iron + carbon + lime
Figure 2a. A mixture of iron,
lime and carbon BEFORE
heating
Figure 2b. Zero Valent Iron
produced AFTER heating
Sampel
ID
Temperature
(°C)
Surface Area
(m2/g)
Cation Exchange Capacity
CEC (meq/100 g)
ZVI 1 550 °C 5.62 28.00
ZVI 2 550 °C 7.01 15.13
ZVI 3 550°C 29.07 34.53
ZVI 1 750 °C 8.06 28.39
ZVI 2 750 °C 8.44 47.82
ZVI 3 750 °C 34.43 53.43
ZVI 1 950 °C 10.54 60.28
ZVI 2 950 °C 23.90 156.75
ZVI 3 950 °C 40.64 238.65
1) Reduction by heating together iron + carbon + lime
Table 2. Surface area and CEC values of ZVI 1, 2 and 3 after heating at 550, 750
and 950oC
Figure 4. The amount of heavy metal (Pb) adsorbed by ZVI materials (a) ZV1 (b) ZVI2 (c) ZVI3
Sample ID pH
(Before)
pH
(After)
Electrical conductivity
EC(µs), (Before)
Electrical conductivity
EC(µs), (After)
ZVI 1 4 10.15 676 376
ZVI 2 4 10.87 676 328
ZVI 3 4 11.18 676 296
Table 3. pH and EC values before and after the sorption tests on ZVI samples
Figure 5. Distribution Coefficient or sorption parameter (Kd) of ZVI at different temperatures. (a) 550oC; (b) 750oC and (c) 950oC
2) Chemical reduction using FeCl2.4H2O + NaBH4
Figure 6. Particle size distribution of nZVI using
Master-Sizer.
Figure 7. Scanning Electron Microscope (SEM) of nZVI
produced from chemical reduction showing platy texture.
Figure 8. X-ray Photoelectron Spectroscopy (XPS) data of nZVI produced from chemical reduction.
The result indicates the zero valency of ZVI.
Figure 3. Nano Zero Valent Iron
(NZVI) after chemical reduction
(a) (b) (c)
(a) (b) (c)
Table 1. The mixture percentage of iron, lime and carbon used in this study
