Electrogeneration of aluminium to remove silica in water

Abstract

This paper presents the results of a study on electrogeneration of aluminium, as a coagulant to remove silica in make-up water for cooling towers. Three electrochemical systems were tested, two with aluminium electrodes (one with polarity change and another without it), and a third one with aluminium anodes and cathodes of stainless steel. From the obtained results it was concluded that under the studied conditions, the most advantageous system to produce aluminium and remove silica is the one with both electrodes of aluminium working with direct current. Due to chemical production of aluminium at the cathode, the concentration of aluminium in the water at the outlet of the electrochemical reactor is much higher than the one calculated according to Faraday's law. Under the tested conditions it was possible to remove up to 66% of silica from water containing around 50 mg L(-1).

Removal of Silica from Cooling Water by Electrocoagulation: A Comprehensive and Systematic Study Using Response Surface Methodology

“…Walter Den and Chia-Jung Wang 11 used electrocoagulation as a pretreatment process to treat the source brackish water containing 100 mg/L silica for reverse osmosis process and the extent of flux decline was markedly improved. Gelover-Santiago et al 18 tested three electrochemical systems to remove silica in makeup water for cooling tower and the most advantageous system is the one with both aluminium electrodes working with direct current. Liao et al 19 reported the effectiveness of electrocoagulation using iron and aluminium electrodes for treating cooling tower blowdown water containing dissolved silica, Ca 2+ and Mg 2+ with different initial pH values and additives.…”