I'm currently investigating the adsorption of heavy metals from water matrices using bio-derived adsorbents. When investigating the effect of contact time, do you sample the solution at varying time intervals (e.g. 0.5, 1, 2, 3.. etc.) from the sample solution or do you run the batch adsorption separately at the different time intervals?

In other words, do you run one batch adsorption experiment for 0.5 hr? Thereafter, another separate experiment for 1 hr. Or, do you use one solution and remove aliquotes at the desired time intervals? So, one solution would give data points for all the time intervals you require. (?)

Literature reports using the formula: Q=(Co-Ct)xV/W where Q is the adsorption capacity, Co is the initial conc, Ct is the conc at a specific time, V is volume and W is weight of the adsorbent. When sampling the solution at the end of a desired time( e.g. at the end of 0.5 hr, at the end of 1 hr etc.) the V = volume of the original solution. However, if sampling at different time intervals using one solution only, does the V remain as the volume of the initial solution or does it become the volume of the aliquot removed/analysed?

Any assistance or guidance to specific literature would be appreciated.

Thank you