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Explain how microscopic membrane filters purify contaminated waters, in terms of their design and composition. - HSC - SSCE Chemistry - Question 26 - 2013 - Paper 1
Question 26
Explain how microscopic membrane filters purify contaminated waters, in terms of their design and composition.
Worked Solution & Example Answer:Explain how microscopic membrane filters purify contaminated waters, in terms of their design and composition. - HSC - SSCE Chemistry - Question 26 - 2013 - Paper 1
Step 1
Detailed description of the composition and design of microscopic membrane filters
Answer
Microscopic membrane filters are typically composed of a thin layer of polymer material, such as polypropylene or polyethersulfone, which is characterized by tiny pores usually measuring around 0.2 micrometers in diameter. These filters are designed in a tubular or flat configuration, allowing for mass production and efficient filtering processes. The polymer is rolled into thin sheets, with multiple filters often bundled together to enhance the surface area for filtration. This design maximizes the number of contaminants that can be trapped as water flows through the filter, significantly improving purification efficiency.
The composition of these membranes also influences their electrochemical properties, which allows these filters to interact with certain types of contaminants. For instance, the surface of the membranes can be modified to enhance the adsorption of certain ions, leading to effective removal of dissolved substances and small particles, including bacteria and protozoa. This additional functionality makes microscopic membrane filters particularly effective in purifying water.
Step 2
Explanation on how these filters purify contaminated water
Answer
The purification process begins when contaminated water is forced through the microscopic pores of the membrane under pressure. Smaller particles, including water molecules and ions, can pass through these pores, while larger particles, such as bacteria and protozoa, are physically trapped by the membrane. This mechanism ensures that the filtered water is significantly cleaner and safer for consumption or use. Furthermore, any contaminants that adhere to the filter surface can be periodically rinsed off to maintain filter efficacy, illustrating an efficient and sustainable approach to water purification.