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Rapid Production of a Porous Cellulose Acetate Membrane for Water Filtration using Readily Available Chemicals

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journal contribution
posted on 30.03.2017, 12:04 by Adrian Kaiser, Wendelin J. Stark, Robert N. Grass
A chemistry laboratory experiment using everyday items and readily available chemicals is described to introduce advanced high school students and undergraduate college students to porous polymer membranes. In a three-step manufacturing process, a membrane is produced at room temperature. The filtration principle of the membrane is then illustrated by filtering solutions containing pigmentary watercolor or food coloring. A comparison of the filtration results shows that insoluble watercolor pigments are too large to pass the pores of the membrane and are successfully rejected by the membrane, whereas the food coloring is completely soluble in water and easily passes the membrane. The laboratory experiment can be performed in a 2 h activity and serves the purpose of (1) exposing students to a new and interesting field of material science. It (2) makes them familiar with porous membranes for the production of safe drinking water and (3) introduces them to a template-removal technique utilizing acid/base theory. There were 52 advanced high school students and 55 high school teachers in Switzerland who already successfully performed the laboratory experiment and found the activity engaging and motivating.