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B. Gunawardana et al.
12.2 Materials and Methods
12.2.1 Materials
High purity chemicals such as PCP powder (ACS grade, 98%), 2,3,4,6tetrachlorophenol (2,3,4,6-TeCP, Supelco, 98%), 2,4,6-trichlorophenol (2,4,6-TCP,
Aldrich, 98%), 2,4-dichlorophenol (2,4-DCP, Aldrich, 99%), analytical standards of
PCP, phenol, chlorophenol isomers in methanol and nickel sulphate (NiSO 4 .6H 2 O,
>98%) were purchased from Sigma-Aldrich. Analytical grade solvents (ethyl acetate,
acetone), sulphuric acid (H 2 SO 4 ), and hydrochloric acid (HCl) were obtained from
Ajax Finechem. A stock solution (5000 mg/L) of individual CPs, i.e. PCP, 2,3,4,6TeCP, 2,4,6-TCP, and 2,4-DCP was prepared with the use of ethyl acetate as the
solvent. Deionized (DI) water with resistivity of 18.20 Mcm was prepared using a
Millipore-Q system and used for all the experiments. For the preparation of deoxygenated DI water (DW), the DI water was first degassed at 80 °C and 100 kPa for
one hour using a vacuum pump and then sparged with O 2 -free N 2 gas for half an
hour (dissolved oxygen level <0.2 mg/L).
The bimetal particles, i.e. nickel-coated ZVI (Ni/Fe) were synthesized as
explained by.Kim and Carraway (2000) The ZVI used for the preparation of Ni/Fe
particles was electrolytic iron powder (<100 mesh, North American Höganäs). Before
using for Ni/Fe synthesis, the ZVI particles were pre-treated with H 2 SO 4 (Liu et al.
2006). For the acid pre-treatment, as-received ZVI particles (500 g) were added to
1 N H 2 SO 4 solution (1.5 L), the mixture was agitated for 30 minutes at 100 rpm
and room temperature using a rotary shaker, and rinsed with DW. Post-rinsing of the
particles with DW, they were dried under continuous purging of N 2 gas for 4 hours
at 100 °C and then stored under N 2 gas environments until use for the synthesis
of Ni/Fe bimetals. The Ni/Fe particles were prepared using a reductive adsorption
method (Kim and Carraway 2000). A reaction solution with Ni was prepared by
adding a known volume of a Ni stock solution (2 ml of 2.4% Ni solution prepared
with NiSO 4 .6H 2 O and 10% H 2 SO 4 ) to 200 ml of DW water (pH of the prepared
solution = 1.60). Then, 100.0 (±0.01) g of acid pre-treated ZVI was added to the
solution (Kim and Carraway 2000). The mixture containing the Ni and ZVI was
placed on a rotary shaker and agitated for one hour at 100 rpm and followed by rinsing with DW and acetone, air-dried at room temperature, and stored under O 2 -free
N 2 gas to use for the experiments. The Ni
2+ solution was analysed for total Ni concentration pre- and post-exposure to acid-washed ZVI using the atomic absorption
spectroscopy (AAS). The AAS results showed 92% Ni removal from the solution
after Ni/Fe synthesis. Hence, based on the AAS analysis, the content of Ni deposited
on the Ni/Fe bimetallic particles was calculated to be 442 ppm (mg of Ni per kg of
Fe).
B. Gunawardana et al.
12.2 Materials and Methods
12.2.1 Materials
High purity chemicals such as PCP powder (ACS grade, 98%), 2,3,4,6tetrachlorophenol (2,3,4,6-TeCP, Supelco, 98%), 2,4,6-trichlorophenol (2,4,6-TCP,
Aldrich, 98%), 2,4-dichlorophenol (2,4-DCP, Aldrich, 99%), analytical standards of
PCP, phenol, chlorophenol isomers in methanol and nickel sulphate (NiSO 4 .6H 2 O,
>98%) were purchased from Sigma-Aldrich. Analytical grade solvents (ethyl acetate,
acetone), sulphuric acid (H 2 SO 4 ), and hydrochloric acid (HCl) were obtained from
Ajax Finechem. A stock solution (5000 mg/L) of individual CPs, i.e. PCP, 2,3,4,6TeCP, 2,4,6-TCP, and 2,4-DCP was prepared with the use of ethyl acetate as the
solvent. Deionized (DI) water with resistivity of 18.20 Mcm was prepared using a
Millipore-Q system and used for all the experiments. For the preparation of deoxygenated DI water (DW), the DI water was first degassed at 80 °C and 100 kPa for
one hour using a vacuum pump and then sparged with O 2 -free N 2 gas for half an
hour (dissolved oxygen level <0.2 mg/L).
The bimetal particles, i.e. nickel-coated ZVI (Ni/Fe) were synthesized as
explained by.Kim and Carraway (2000) The ZVI used for the preparation of Ni/Fe
particles was electrolytic iron powder (<100 mesh, North American Höganäs). Before
using for Ni/Fe synthesis, the ZVI particles were pre-treated with H 2 SO 4 (Liu et al.
2006). For the acid pre-treatment, as-received ZVI particles (500 g) were added to
1 N H 2 SO 4 solution (1.5 L), the mixture was agitated for 30 minutes at 100 rpm
and room temperature using a rotary shaker, and rinsed with DW. Post-rinsing of the
particles with DW, they were dried under continuous purging of N 2 gas for 4 hours
at 100 °C and then stored under N 2 gas environments until use for the synthesis
of Ni/Fe bimetals. The Ni/Fe particles were prepared using a reductive adsorption
method (Kim and Carraway 2000). A reaction solution with Ni was prepared by
adding a known volume of a Ni stock solution (2 ml of 2.4% Ni solution prepared
with NiSO 4 .6H 2 O and 10% H 2 SO 4 ) to 200 ml of DW water (pH of the prepared
solution = 1.60). Then, 100.0 (±0.01) g of acid pre-treated ZVI was added to the
solution (Kim and Carraway 2000). The mixture containing the Ni and ZVI was
placed on a rotary shaker and agitated for one hour at 100 rpm and followed by rinsing with DW and acetone, air-dried at room temperature, and stored under O 2 -free
N 2 gas to use for the experiments. The Ni
2+ solution was analysed for total Ni concentration pre- and post-exposure to acid-washed ZVI using the atomic absorption
spectroscopy (AAS). The AAS results showed 92% Ni removal from the solution
after Ni/Fe synthesis. Hence, based on the AAS analysis, the content of Ni deposited
on the Ni/Fe bimetallic particles was calculated to be 442 ppm (mg of Ni per kg of
Fe).