Basic Study on the Remediation Technology
433
referred to as nickel chloride) were clearly the most effective at accelerating the
removal of mercuric sulfide. Both iron and nickel are in the group of eight
transition elements and thus have similar chemical characteristics. None of them,
for example, forms an amalgam with mercury.
As Fig. 7 showing the results of the powder analysis with X-ray demonstrates,
when artificially contaminated soil was heated to 100 °C, no peak in the
generation of iron oxide was observed, but as the heating temperature rose to
200 and 300 °C, the peak in the generation of iron oxide became more
prominent, the iron chloride was denatured, and iron oxide was generated. Some
nickel chloride was also denatured and nickel oxide was generated. This shows
that the denaturation of transition metal compounds such as iron and nickel
when they are heated has significant effect in the evaporation and removal of
mercuric sulfide. Further, it is thought that the influence of chloride in transition
metal compounds when they are heated cannot be ignored because the denatured
products do not contain chloride components.
As a result, iron chloride was clearly the most effective compound at
accelerating evaporation, and in the form of iron, it is abundant in the
environment and is thus considered to have little environmental impact. We have
concluded that iron chloride is the most appropriate compound to serve as a
catalyst.
3.4
Effect of the Addition of Iron Chloride
We added iron chloride to the artificially contaminated soils made with quartz
sand and volcanic ash soil and examined the effects of heating temperature and
the amount of iron chloride added on the percentage of mercury removed by
heating. We heated the artificially contaminated soils to 200 and 300 °C to
examine the relationship between heating temperature and mercury removal
percentage over time. We examined the relationship between the amount of
mercury removed and the amount of iron chloride used over time by changing
the amounts of iron chloride added. The amounts of iron chloride added to the
soils were equal to, 10 times greater than, and 100 times greater than the amounts
of mercury mol contained in the artificially contaminated soils made for the tests.
Figures 8 to 11 show the test results.
As Figs. 8 and 9 show, as the amount of iron chloride was increased, the
percentage of mercuric sulfide removed when the artificially contaminated soils
were heated to 200 °C increased. After 2 h of heating, when the amount of iron
chloride added to the artificially contaminated soils was 100 times greater than
the amount of mercury mol contained in the artificially contaminated soil made
with quartz sand, almost 95% of the mercuric sulfide was removed. However,
even when the amount of iron chloride added to the artificially contaminated soil
made with volcanic ash soil was the same as that added to artificially
contaminated soil made with quartz sand, only about 60% of the mercuric
sulfide was removed. As Figs. 10 and 11 show, when the artificially contaminated
soils were heated to 300 °c, regardless of the amount of iron chloride added, at
433
referred to as nickel chloride) were clearly the most effective at accelerating the
removal of mercuric sulfide. Both iron and nickel are in the group of eight
transition elements and thus have similar chemical characteristics. None of them,
for example, forms an amalgam with mercury.
As Fig. 7 showing the results of the powder analysis with X-ray demonstrates,
when artificially contaminated soil was heated to 100 °C, no peak in the
generation of iron oxide was observed, but as the heating temperature rose to
200 and 300 °C, the peak in the generation of iron oxide became more
prominent, the iron chloride was denatured, and iron oxide was generated. Some
nickel chloride was also denatured and nickel oxide was generated. This shows
that the denaturation of transition metal compounds such as iron and nickel
when they are heated has significant effect in the evaporation and removal of
mercuric sulfide. Further, it is thought that the influence of chloride in transition
metal compounds when they are heated cannot be ignored because the denatured
products do not contain chloride components.
As a result, iron chloride was clearly the most effective compound at
accelerating evaporation, and in the form of iron, it is abundant in the
environment and is thus considered to have little environmental impact. We have
concluded that iron chloride is the most appropriate compound to serve as a
catalyst.
3.4
Effect of the Addition of Iron Chloride
We added iron chloride to the artificially contaminated soils made with quartz
sand and volcanic ash soil and examined the effects of heating temperature and
the amount of iron chloride added on the percentage of mercury removed by
heating. We heated the artificially contaminated soils to 200 and 300 °C to
examine the relationship between heating temperature and mercury removal
percentage over time. We examined the relationship between the amount of
mercury removed and the amount of iron chloride used over time by changing
the amounts of iron chloride added. The amounts of iron chloride added to the
soils were equal to, 10 times greater than, and 100 times greater than the amounts
of mercury mol contained in the artificially contaminated soils made for the tests.
Figures 8 to 11 show the test results.
As Figs. 8 and 9 show, as the amount of iron chloride was increased, the
percentage of mercuric sulfide removed when the artificially contaminated soils
were heated to 200 °C increased. After 2 h of heating, when the amount of iron
chloride added to the artificially contaminated soils was 100 times greater than
the amount of mercury mol contained in the artificially contaminated soil made
with quartz sand, almost 95% of the mercuric sulfide was removed. However,
even when the amount of iron chloride added to the artificially contaminated soil
made with volcanic ash soil was the same as that added to artificially
contaminated soil made with quartz sand, only about 60% of the mercuric
sulfide was removed. As Figs. 10 and 11 show, when the artificially contaminated
soils were heated to 300 °c, regardless of the amount of iron chloride added, at