1. In theory, for freeze concentration, water freezes out as "pure ice" leaving all other non-aqueous material in solution. However, some solids always seem to be "caught" in the ice crystals when they are removed.

   In a highly fictitious process, a processor wants to concentrate some low molecular weight material present in a particular plant extract. It is believed to have some health benefits due to its bio-activity. Since this material is considered too delicate to concentrate by heat treatment, the processor decides to use freeze concentration to concentrate the solids in solution to about 5% by weight. The remaining concentrated solution will then undergo further processing to produce a final powdered product.

   The processor starts off with 1,225 kg of solution containing 1.5% of the low molecular weight molecules. Following freeze concentration, 322.1 kg of concentrated solution are obtained containing 5.3% of the desired solids by weight.

   It is suspected that some of the solids are being lost in the ice during the concentration process. 

   1. Calculate the weight of solids lost during the freeze concentration process (if any are indeed lost). Express your answer in kg to two decimal places. 

   2. Express the weight of solids lost as a percentage of the total ice removed in the process. Give your answer to two decimal places. 

   3. Express the weight of solids lost as a percentage of the initial weight of solids entering the process. Give your answer to one decimal place. 

   4. Do you think that this process is functioning in a satisfactory manner? The processor is willing to accept small losses of product (i.e., solids) as long as they are less than 0.5% of the total weight of the ice. 

   5. What limits the extent of concentration which can be achieved through freeze-concentration processes? Why (or how)?