Question B1 (50 marks). Dissolved Methylene Blue (MB) is adsorbed on a CaO photocatalyst under sun light. The results of a series of laboratory experiments using different amounts of the photocatalyst

(indicated in grams in the graph) for a MB concentration of 10 mg/L are reported in figure 1. Removal (%) 100 80 60 40 20 200 400 600 == qt Time (min) Q1) comment the above results in view of potentially proposing a scale-up of the process. Make your own choice of catalyst concentration and briefly explain your decision. (you may choose any of the quantities represented in the plot providing your reasons are clearly explained). [20 Marks] 800 Q2) for your chosen concentration of the catalyst, make an estimate of the order of adsorption kinetics using the Lagergren model between the linearised equations below: k₁t 1st order: In(qe qt) = ln(qe) - 2.303 1 2nd order: k₂qć + - 0.05 g CaO/ 20 ml MB 0.2 g CaO/ 20 ml MB -0.4 g CaO/ 20 ml MB -0.6 g CaO/ 20 ml MB 1000 1200 1400 1600 qe Where qe and q are the amounts (mgMB Bat¹) of MB adsorbed on the catalyst at equilibrium and at time t (minutes), respectively, and k₁ and k₂ are the 1st and 2nd order kinetic constants, respectively. Take values from the above plotted results. Assume a 95% adsorption at equilibrium for all cases. [30 Marks]