Investigating the Bio-corrosion Inhibition Effect of Enzymes in Circulating Cooling Water System

To avoid the secondary pollution that inorganic corrosion inhibitor may cause in circulating cooling water, the bio-corrosion inhibition effect of lysozyme, catalase, lipase, and laccase, as the biologic inhibitors without the above problem, and the increased bio-corrosion inhibition effect of Ca+2 and Mg+2 are studied. An enzyme with corrosion properties was selected by rotary coupon test. The inhibition rate test and the inhibition rate of ultraviolet test of lysozyme as well as lipase’s SEM analysis and elemental analysis were used to explore its inhibition mechanism. Aiming to decrease enzyme’s usage cost, the rotary coupon test was performed to study the effect of different ion mass concentrations on enzyme activity; its inhibition effect was first analyzed, and the complex formulation of enzyme with ion and polyaspartate was then investigated. The experiment showed that among all single enzymatic reagents, lysozyme and lipase had the best corrosion inhibition effect, and when Ca+2 mass concentration range was 107.75-182.57 mg/L, enzyme activity, microbial resistance, and corrosion inhibition properties were improved; a sample compound showed the best corrosion inhibition effect when 10 mg/L, 50 mg/L, and 50 mg/L of lysozyme, lipase, and poly-aspartic acid respectively were used. When the corrosion speed was controlled at 0.005 mm/a, the inhibition efficiency was above 95%.