Questions about dye adsorption and kinetics
I am investigating the effects of dye uptake on various different activated carbon samples. I have currently used three different amounts of activated carbon and I want to compare the differences in uptake ability.
* I had a sample of thionin acetate salt (CAS 78338-22-4) which I dissolved in water to form a solution. I know thionine is different to thionine acetate salt, but what form does the thionin acetate salt exist in water when it enters the activated carbon?
* If I use UV-Vis to monitor the changes in absorbance as the dye is adsorbed into the actvated carbon, what is the best way to make a comparison on the initial uptake? I am currently taking a UV-Vis spectrum at specific time intervals after mixing the activated carbon with the dye solution (The initial concentration remains constant) so that I can observe a decreasing maximum peak over time as the solution becomes less concentrated. I am thinking about then plotting absorbance on the y-axis and time on the x-axis to track the maximum peak to see how much it changes with time. If I then take the gradient of this graph to find the rate of uptake, how could I use this value from each activated carbon sample to make a valid comparison?
* Does the dye dimerise or react with water? I have tried to find information but I can find nothing about this dye
* Using UV-Vis only, what other methods can I look at to compare the dye adsorption ability of the activated carbon at different amounts?