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Nanochemistry Activity 1

Scale of Particles through Filtration

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Introduction

Filtration is a laboratory technique used to remove impurities from solutions. One method of filtration is through the use of a filtration column which contains materials that remove unwanted substances from the liquid as it passes through them. The pore sizes of the materials used in a filtration column help determine which substances will pass through the column and into a collection cup.

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Activated charcoal can be used during filtration processes to remove impurities by attracting and gathering molecules on its surface . This process is called adsorption and is dependent on the surface structure and pore size of the charcoal used . Varying methods of the preparation of activated charcoal used in filtration processes result in varying pore sizes.

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The chemical formula for talcum powder is H2Mg3O12Si4 and can be used as a body powder that is generally made from 200-mesh talc   . This means that 95-99% of the talc particles can pass through a 74μm mesh screen when dispersed in water . Talc is insoluble in water . Brilliant Blue FCF is well known for its blue colouring and is often used as a food dye. Its chemical formula is C37H34N2Na2O9S3 .

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For the following activity students can work in groups of 2-3. In this experiment, talcum powder and food dye will be mixed with water then filtered using pebbles, sand and filter paper. A second mixture will be filtered using the same materials as well as a fourth material, activated charcoal. Completing two filtration processes will allow students to compare the results and effectiveness of the materials used. If the talc particles and food dye molecules have been successfully removed from the solution, then the resulting liquid will be clear.

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Materials:

  • 10g of talcum powder

  • Blue food dye

  • 150ml beaker

  • Glass rod

  • 8g of powdered activated charcoal

  • Water filtration kit

  • Qualitative Filter paper circles; with a defined pore size of 11μm.
    - 2 x Filter paper with a diameter of ≈ 30mm
    - 2 x Filter paper with a diameter of ≈ 125mm.

  • ≈ 40g of clean pebbles around 0.5cm3

  • ≈ 30g of clean sand

Method:

  1. Place 10g of talcum powder and 4 drops of food dye into a 150ml beaker. Fill the beaker with water to create a 100ml mixture.
     

  2. Stir the mixture for 30 seconds or until all of the talcum powder is evenly dispersed.
     

  3. Construct the water filtration apparatus with pebbles in the first (top) tube, sand in the second tube, 30mm filtration paper at the bottom of the third column and ≈125mm filter paper in the shape of a cone in the fourth (bottom) column of the apparatus.

    To create the cone shape, fold the large filter paper in half. Fold the paper in half again to make a flattened cone shape before folding the paper in half once more to make a thinner cone shape. Pull out one fold of the paper from the inside of the flattened cone to create the cone shape.
     

  4. Carefully pour the 100ml mixture into the water filtration apparatus and collect the filtered liquid.
     

  5. Repeat step 4 with the solution collected and with 8g of powdered activated charcoal placed on top of the 30mm filtration paper in the third column of the filtration apparatus.

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Figure 1: Water Filtration Apparatus.
Filtration apparatus set up for second filtration with pebbles in the first (top) tube, sand in the second tube, powdered activated charcoal placed on top of 30mm filtration paper in the third column and ≈125mm filter paper in the shape of a cone in the fourth (bottom) column of the apparatus.
 

Questions

  1. Analyse the resulting filtrates from the two filtrations and provide a description of them in comparison to your starting mixture.
     

  2. Provide an explanation for your observations stated above in relation to the pore size and surface structure of the activated charcoal powder.
     

  3. Draw diagrams of A. talcum powder and B. talcum powder dispersed in water.
     

  4. Nanoparticles are materials between 1 and 100nm in size . There are 1000000 nanometres in 1 millimetre. Nanoparticles are too small to be seen with a light microscope and require a higher powered microscope such as the scanning electron microscope to be viewed .

    Do you think molecules of this size can have negative effects on the environment? Explain why?
     

  5. Research the use of activated charcoal in treating drug overdoses. What property
    of activated charcoal makes it desirable as a treatment for a drug overdose?

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   References:​

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  1. Nuffield Foundation and Royal Society of Chemistry, Carbon filtration, <http://www.rsc.org/learn-chemistry/resource/res00000412/
    carbon-filtration?cmpid=CMP00005004>, 2015 (accessed 2 September 2018).
     

  2. M. O. IIomuanya, B. Nashiru, N. D. Ifudu and C. I. Igwilo, J Microsc Ultrastruct, 2017, 5 (1) 32-38.
     

  3. PubChem, Dioxosilane; Oxomagnesium; Hydrate, <https://pubchem.ncbi.nlm.nih.gov/compound/talc#section=Top>, n.d. (accessed 20 October 2018).
     

  4. R. Zazenski, W. H. Ashton, D. Briggs, M. Chudkowski, J. W. Kelse, L. MacEachern, E. F. McCarthy, M. Nordhauser, M. T. Roddy, N. M. Teetsel, A. B. Wells and S. D. Gettings, Regul Toxicol Pharmacol, 1995, 21 (2) 218-229.
     

  5. The National Institute for Occupational Safety and Health, Talc (containing no asbestos and less than 1% quartz), <https://www.cdc.gov/niosh/npg/npgd0584.html>, 2016, (accessed 21 October 2018).
     

  6. PubChem, Brilliant Blue FCF, <https://pubchem.ncbi.nlm.nih.gov/compound/Acid_Blue_9#section=Top>, n.d. (accessed 21 October 2018).
     

  7. S. M. Taghavi, M. Momenpour, M. Azarian, M. Ahmadian, F. Souri, S. A. Taghavi, M. Sadeghain and M. Karchani, Electron Physician, 2013, 5 (4) 702-712.
     

  8. United States National Nanotechnology Initiative, Seeing at the Nanoscale, <https://www.nano.gov/nanotech-101/what/seeing-nano>, n.d. (accessed 7 September 2018).

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