Avon High School
The effect of bubble size on the removal of ink
Recycling paper is an important process in today's society. However, in order to successfully recycle paper contaminants such as ink need to be removed. One such method is to bubble air through a mixture of newspaper, water, and soap. The purpose of this experiment was to look at the relationship between bubble size and the amount of ink removed. Using a blender, I ground up some used copier paper with a common dishwashing surfactant, water and then bubbled air through the mixture. A mixture of foam and ink would rise to the top, which was then collected and filtered. Using a stereomicroscope I then counted the number of ink specks that remained on the filter paper. I also massed this filter paper and compared it to the mass of filter paper for the control solution for which I had not bubbled air through. I then repeated this experiment for different sized bubbles. By comparing the number of ink specks and the difference in mass between the sample and the control filter paper I could determine which bubble size removed the most ink. The smallest bubble averaged 17 ink specks/ 0.5 mm2, and the largest bubble averaged 5 ink specks/ 0.5 mm2. The smallest bubble recorded an average mass of 0.39 grams, while the largest bubble had an average of 0.32 grams. I concluded that the smallest bubble size collected the most ink.
The benefits of my project were to create the most efficient method of removing contaminants, such as ink, from newspaper. This would save time, money, and energy for the recycling processor.