Unit 7.5 Water Purification
The need for pure drinking water on earth has caused mankind
to develop methods for water purification, either by filtration
or by using disinfectants, such as chlorine. Students are
shown purifying water in a chemistry lab activity.
Video program cues: 31:45-40:05
Purifying water laboratory
Isoke Baptiste teaches the principles of filtration and
phase separation in purifying water.
Oughton, J., Xu, S., Battino, R. (2001)' The Purification
of Water by Freeze-Thaw or Zone Melting, 'Journal of
Chemical Education, Vol. 78, No. 10, pp: 1373-1374.
"What weve heard from the Indians
of the continent, Latin America, and parts of Asia, is that
the most important technology they need is safe drinking
water. In Bangladesh, the monsoon rains came and stayed
two months longer than usual, and literally flooded much
of the country. The irony of this is that people cant
drink this water. They cant drink it because of pathogens
in the drinking water. We had the problem in the U.S., and
we used a variety of technologies, the most significant
being using chlorine. The chlorine kills the pathogens,
and we can drink the water safely. But you cant really
take chlorine and the technology you need to work with it
into a small village in Bangladesh, because of the reactive
nature of the chemical. But you could take a bottle of hydrogen
peroxide, and Calais pills, which would attach themselves
to the pathogens. The hydrogen peroxide and the Calais would
then kill the pathogens, and you could drink the water safely.
It could be done very inexpensively. We havent solved
this problem, but thats our drinking problem. We started
with water disinfection 20 years ago, and we still want
to do it."
Dr. Terry Collins
Professor of Chemistry, Carnegie Mellon University
Hogue, C. (2001)' Chloroform and Cancer, 'Chemical and
Engineering News, Vol. 79, No. 44, pp: 11.
to Unit 7.6