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Minesweeper-problemsSorption experiments
You are conducting sorption experiments in order to measure the sorption coefficient of a pesticide between water and a specific soil. For these experiments 5 g soil are equilibrated with 100 ml of an aqueous solution of the pesticide with a known concentration.
The sorbed amount is to be determined via a mass balance approach i.e. it is the difference between the total amount of pesticide applied and the amount that stays in solution after equilibration. The equilibrium concentration in water can be determined with a Solid Phase MicroExtraction (SPME). To this end, a fiber coated with a sorbing polymer is equilibrated with the aqueous soil suspension. Afterwards the pesticide content in this fiber is analysed. Based on a calibration one can back calculate the concentration in water if the fraction that sorbs into the SPME fiber is so small (e.g. < 1%).
Calculate how much of the sorbing polymer coating (in mg) may be equilibrated with the soil suspension so that less than 1% of the pesticide will reside in the SPME fiber in equilibrium.
The partition constant water/SPME is: Kwater/SPME = 2.8 10-4 (kgSPME/ Lwater) and a preliminary estimation for the soil/water partition constant is Ksoil/water = 1200 (Lwater/kgsoil).
Assume that the air in in the partition system is neglegible.
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