(b) indicates that the capacity
of C4 to increase the solution pH was improved. Considering that
200 mL of fresh distilled water was replaced in every cycle, U4 and
C4 increased pH of 7 and 10 L of distilled water up to 10.5,
respectively. It implies that the capacity of the slag to increase the
solution pH has been enhanced by 42.8% through the coating
process.