Hi everyone! For the unit operations lab, each group has to perform 5 randomly selected labs. One of the five that our group did was the Filtration experiment. The filtration experiment is a very interesting one and it can get very messy physically if not careful. Basically, in this experiment, the goal is to filter out the Calcium Carbonate in water; so it’s like liquid chalk in a sense. The filtered out CaCO3 will be collected on filter papers. The filter papers were squeezed between metal filter plates, and they are not sealed tightly, they can splash and white slurry can go anywhere. So it was jokingly recommended by our lab professor that you should wear clothing that you don’t care about being splashed on.
To start the experiment, the pressurized tank was filled, secured and pressurized. Before pressurizing, the top of the tank was off to add 4 kg CaCO3 and 40 L of water for 10% weight volume, and mixed with a long rod. Next, the lid was bolted and air sent to the bottom of the vessel from the air valve on the wall to pressurize and keep slurry mixed. A pressure relief valve on the top of the tank allowed air to flow out to maintain a desired pressure. When ready, a plate was pressed between two filter papers and valves were open in accordance with Figure 1 so the cake and filtrate volume could be collected in 100 mL intervals, where the time at each interval was also be recorded. The slurry entered the filter press and CaCO3 was collected on the filter as the remaining water filtrate exited and collected into a cylinder. Once 1 L of filtrate had been collected all valves were closed and the filter press was loosened to remove the plate and filter paper, as seen in Figure 2. The weight of the cake on the filter paper was taken while wet, then dried and weighed again to determine the percent recovery of CaCO3 for the process. This was repeated four times using one filter plate and five time using two filter plate. When the latter trials were run, an additional plate and filter paper that acted as a gasket to the back end of the press were placed with the original set up so that the slurry could pass through one filter then another, both collecting CaCO3, before exiting.