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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: yaacobzw@ukm.my 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