Green Chemistry Pollution Removal


Figure 1: Overview of the study methods and results, which demonstrate a new low-cost, sustainable material for reducing air and water pollution. Credit: © 2018 Zanoletti, Vassura, Venturini, Monai, Montini, Federici, Zacco, Treccani and Bontempi. Front. Chem. | doi: 10.3389/fchem.2018.000601

A new low-cost hybrid material is showing great promise at being an excellent remover of pollutants from contaminated air and water sources. The source material sodium alginate is derived from various species of algae and seaweeds. This means a low cost renewable source of starting material. These have a natural ability to absorb but lack mechanical strength which would be important for industrial usage. By combining with silica fume which is a waste byproduct of silica metal alloy manufacturing process, mechanical strength is increased. The synthesis of this hybrid material was accomplished using safe environmentally friendly materials of water, calcium iodate, and sodium bicarbonate (baking soda). Finally, a thin layer of titanium dioxide was added to give increased photocatalytic activity. This means it is a green material as well. This synthesis creates an organic-inorganic hybrid material that is strong and highly porous. The pores are quite small, size range of 2-50 nm for reference DNA is ~2 nm in diameter. This is what allows for absorption of pollutants from water or air.

This new hybrid material was then evaluated for its absorbance characteristics to facilitate removal of various contaminants. The first evaluation was the ability to absorb the dye methylene blue. The data showed that it was up to 94% efficient at removing this dye. The addition of the titanium dioxide layer resulted in good photo-degradation as well. This relates to the ability of the material to remove organic dyes from the environment.

Figure 2: New porous material, before (a) and 15 min after (b) the exposition to exhaust fume of a diesel car.2

The second evaluation was the removal of particulate matter from diesel exhaust. Once again, the data showed a clear absorbance of the particulate matter from the exhaust (figure 2). The results showed particular promise at removing the most damaging particulate size of <1 micron. Additional experiments are underway to more accurately determine the absorbance properties of this material specifically for particulate matter.

This new hybrid material does show excellent absorbance properties. I wonder about the scalability of this material. Can it be scaled large enough to become practical in the real world. The authors discuss turning it into some type of coating which can be applied to building. What would the cost be for such a project sounds expensive? Perhaps if it was incorporated into new buildings the cost would be lower, but still this would not have the same effect they are looking for in coverage within a city. In addition, how would this material hold up after time in an urban environment? They evaluate this very little, so this is another area to investigate. Still I find this an interesting new perspective to help reduce pollution levels within cities.

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