Fig. 10 illustrates the percentage flocculation of silica as a function of pH in the absence and presence of different concentrations of XG. In the absence of the polymer, the percentage flocculation of silica particles decreases as the pH increases, which is in agreement with the electrokinetic behaviour, wherein the negative zeta potential values increased as the pH was increased. This can lead to the increase electrostatic repulsion between the particles, which reduces the aggregation of the particles. Consequently, the percentage flocculation values of silica are decreased with the increase in pH. There is no significant change in the percentage flocculation of silica with the addition of different concentrations of XG throughout the pH range investigated. These result are in agreement with both the adsorption and electrokinetic result