Experimental Setup
In this experiment, we filled three 1 liter graduated cylinders with varying concentrations of Calcium Hypochlorite. The graduated cylinders consisted of a 10g/L, 20g/L, and 30g/L solution of Calcium Hypochlorite solution. The solutions were mixed well and allowed to sit for 3 days in order to observe the height and weight of precipitate forming in the bottom of each cylinder after each day.
The weight of precipitate in each solution was found using vacuum filtration. The contents of each cylinder were poured through a filter and the liquid was vacuumed out. The precipitate left on the filter paper was then weighed.
Observations
After allowing the cylinders to stand for a three days, most of the precipitate settled to the bottom, but some did float as a film on the very top of the solution. Some flocs of precipitate could be seen floating throughout the solution. After three days the amount of precipitate settling to the bottom of the cylinders did not increase.
Small bubbles were observed floating to the top of the cylinder, which sometimes would attach to flocs of the precipitant. These flocs would either float to the top or stay suspended somewhere between the bottom and the top of the graduated cylinder depending on the floc size.
Results & Discussion
For the first three days, the height of precipitate in the bottom of each cylinder increased. At day four, the amount of precipitate did not increase from day three.
In the future, the 50 gallon drums that hold the Calcium Hypochlorite solution should have exit flow valves installed at a height high enough from the bottom, so that any precipitant formed and settled does not flow out of the tank at this valve.
Measuring the height from the bottom of a container, to the top of the settled precipitant that forms, will help us determine the height to place the exit valve.
The fact that after 3 days no more precipitate settles out, gives a good estimate of time to wait before sending the calcium hypochlorite solution into the plant. Waiting 3 days to use the solution and pouring out only the liquid at the top of the precipitant and bellow the film formed at the top of the container should decrease the amount of precipitate in the system and help to eliminate clogging. Further we would recommend some type of filtration of the solution to remove the flocs of precipitant that are levitating in the middle of the holding container.