Confusion on Absorption Q3

[rosiekrasnoff]

Question from Lab Manual: Calculate the retardation coefficient (Radsorption) based on the time to breakthrough for the columns with and without activated carbon.

Should we have an answer for each individual column, both those with and without activated carbon? (It seems like the ratio for those without AC should be 1) OR do we calculate R for the columns with AC using the values from those without?

We are confused about how to do this with the data we have! We wanted to use the equation for R: R_ads=t_mtz/t_water, but it is not clear how to get t_mtz, since we didn't run the experiments until the concentration leveled out. Should we be using the 50% time we calculated for question 2? Also, we are unclear about how to calculate/know t_water. Would it be the time for the dye to travel through the column without any AC in it? How would we ascertain that the concentration had sufficiently leveled off to pick what time that would be?

Thanks in advance!!

[monroews]

The columns without carbon could be used to estimate the reactor volume including tubing and photometer based on the time at which the dye concentration reaches 0.5C0 and the flow rate for each column.

The replicates are going to have variability and so you could perhaps take the average reactor volume or you may have more insight into why there is a significant difference in the controls.

t_mtz is based on the time that it takes for the concentration at the effluent to reach 50% of the influent concentration. This is an approximation that works well if the mass transfer zone is short relative to the column length.

t_water is different for every column. I suggest estimating the volume of water in the column + an estimate of the water in the tubing and photometer. I'd assume those volumes are relatively constant across the experiments. That is, of course, a weak assumption!

Remember, you are using the 50% of C0 to estimate the t_mtz. Consider accounting for tubing volume!