coagulation is the process by which the dispersed phase of a colloid is made to aggregate and thereby separate from the continuous phase. The minimum concentration of an electrolyte in mili-moles per litre of the electrolyte solution which required to cause the coagulation of colloidal sol is called coagulation value . therefore higher is the coagulating power of effective ion, smaller will be the coagulation value of the electrolyte. the coagulation of colloidal particles to the sol can be caused by :
heating,
adding electrolyte,
adding oppositely charged sol,
all of these.