495
lands also have literally massive surface areas of concrete in their
roadways, sidewalks and parking lots, and buildings and bridges.
Innovative investigators have posed the interesting question of
whether new concretes could be made with surfaces that somehow
contribute to smog reduction. To many this notion might seem
odd, but the technological basis for the idea is there.
Chapter 10 discussed the development of “self-cleaning” concretes.
The self-cleaning action was described as originating with the incorporation of photocatalytic nanoparticles, typically titanium dioxide,
into coatings for concrete or directly embedded in outer surfaces.
Self-cleaning action itself works via the photocatalytic conversion
of various compounds into other forms. Many pollutants in the air
have similar constituents that can be catalytically transformed, in
this case by contact with photocatalytically active concrete surfaces.
To test this general idea, an innovative Italian company, Italcementi,
has tried several experiments involving the use of photocatalytic
concrete, including its use on heavily trafficked roadways. (These
experiments are described in more detail in Section 10.2 on selfcleaning and antipollutant concrete.) Reductions in pollutant levels
were found to occur. Problems in making approaches such as this
efficacious are, of course, enormous and include needing to assure
long-acting photocatalytic action at a high level. Normal heavy urban
dirt cannot easily be eliminated through photocatalytic action, for
example, and could easily reduce immediate efficiencies (but it
might be washed away more easily). Little is known about longterm behavior. Ideas like this should be explored, however, if our air
pollution problems in urban areas are ever to be solved. Even if not
applicable in a broad way to existing urban fabrics, perhaps materials like this could be used in the immediate surroundings of our
important historical monuments that are threatened by pollutants.
soil remediation
Pollutants in our soils and ground waters come from many causes,
including all too common accidental discharges of hazardous
chemicals from manufacturing or processing centers, or, unfortunately, still deliberate discharges of questionable materials. These
discharges can contaminate large areas due to moving ground
waters and even find their way into rivers and other water bodies
(see Figure 11.12). As noted, many nanoparticles have reactive
qualities that interact with various contaminants and transform
them into more benign forms. The issue is how to get them into
contact with contaminants that are underground.
Environmental Benefits and Impacts
lands also have literally massive surface areas of concrete in their
roadways, sidewalks and parking lots, and buildings and bridges.
Innovative investigators have posed the interesting question of
whether new concretes could be made with surfaces that somehow
contribute to smog reduction. To many this notion might seem
odd, but the technological basis for the idea is there.
Chapter 10 discussed the development of “self-cleaning” concretes.
The self-cleaning action was described as originating with the incorporation of photocatalytic nanoparticles, typically titanium dioxide,
into coatings for concrete or directly embedded in outer surfaces.
Self-cleaning action itself works via the photocatalytic conversion
of various compounds into other forms. Many pollutants in the air
have similar constituents that can be catalytically transformed, in
this case by contact with photocatalytically active concrete surfaces.
To test this general idea, an innovative Italian company, Italcementi,
has tried several experiments involving the use of photocatalytic
concrete, including its use on heavily trafficked roadways. (These
experiments are described in more detail in Section 10.2 on selfcleaning and antipollutant concrete.) Reductions in pollutant levels
were found to occur. Problems in making approaches such as this
efficacious are, of course, enormous and include needing to assure
long-acting photocatalytic action at a high level. Normal heavy urban
dirt cannot easily be eliminated through photocatalytic action, for
example, and could easily reduce immediate efficiencies (but it
might be washed away more easily). Little is known about longterm behavior. Ideas like this should be explored, however, if our air
pollution problems in urban areas are ever to be solved. Even if not
applicable in a broad way to existing urban fabrics, perhaps materials like this could be used in the immediate surroundings of our
important historical monuments that are threatened by pollutants.
soil remediation
Pollutants in our soils and ground waters come from many causes,
including all too common accidental discharges of hazardous
chemicals from manufacturing or processing centers, or, unfortunately, still deliberate discharges of questionable materials. These
discharges can contaminate large areas due to moving ground
waters and even find their way into rivers and other water bodies
(see Figure 11.12). As noted, many nanoparticles have reactive
qualities that interact with various contaminants and transform
them into more benign forms. The issue is how to get them into
contact with contaminants that are underground.
Environmental Benefits and Impacts