Synergistic inhibition effect of polyaminoamide dendrimers and polyepoxysuccinic acid on silica polymerization

Colloidal silica (SiO2) is probably the most undesirable inorganic deposit formed in industrial water treatment systems, either in bulk or on surfaces. Several reports have shown that generations 1 and 2 NH2-terminated polyaminoamide dendrimers (PAMAMs 1G and 2G) can efficiently inhibit colloid silica formation. PAMAM-1G is a more effective inhibitor compared with PAMAM-2. The present paper tests the effects of NH2-terminated PAMAMs (0G–2G) on colloid silica formation. The results show that PAMAM-0G is a most efficient inhibitor compared with PAMAMs 1G and 2G. However, polyepoxysuccinic acid (PESA) is introduced because a small amount of silica–PAMAM white insoluble floc precipitates appeared in the solution. PESA alone cannot inhibit silica polymerization. However, combined PESA and PAMAM can prevent white floc and improve the inhibition performance of PAMAM. The underlying mechanism for this phenomenon is investigated using zeta potentials and atomic force microscopy topography.