Deposition of silica and silicate based foulants in industrial water systems (e.g., cooling,
desalination, geothermal) and in reverse osmosis systems continues to be one of most difficult
challenges for water technologists. The complexity of controlling silica stems from the limited
solubility of both amorphous (polymerized) silica and metal silicates in the feed waters. Once
formed, silica scale is extremely difficult to remove and often requires the use of mechanical
and/or chemical methods; fluoride-based chemicals which present environmental and safety
concerns. Therefore, industrial water systems using silica fouling prone feed waters typically
employ conservative operating criteria; e.g., cooling systems limit cycles of concentration and
desalination systems limit recovery. This paper and results presented herein:
• Compare the performance of polymeric additives as silica polymerization inhibitors.
• Show the impact of impurities (i.e., inorganic and organic coagulant/flocculant) on the
performance of silica inhibitors.
• Illustrate the effect of water chemistry (type and concentration of cations) on the
performance of silica inhibitors.
• Characterize the composition of silica precipitates formed during the experiments.
Keywords: silica polymerization, inhibitors, iron, aluminum, cationic polymer, water chemistry