Preparation And Study On The Mechanism Of Corrosion-scale Inhibition Of Environmentally Friendly Corrosion And Scale Inhibitor Without Phosphorus

To solve the corrosion and scaling problems in industrial circulating cooling water system, avoid water and environmental pollution caused by using phosphorus water treatment agent. A environmentally friendly composite corrosion and scale inhibitor without phosphate for circulating cooling water system was prepared. It consisting of polyepoxysuccinic acid (PESA), sodium polyacrylate (PAAS), sodium molybdate, sodium lignin sulphonate and zinc chloride.In this paper, taking maleic anhydride as raw materials. PESA was synthesized according to one-step polymerization method. And the orthogonal experimental was conducted to optimize the concentration of PESA. PAAS, sodium molybdate, sodium gluconate and zinc chloride, so as to obtained the best formula of the composite non-phosphate corrosion and scale inhibitor. Corrosion and scale inhibition performance of the composite non-phosphate corrosion and scale inhibitor were studied by rotary hanging-piece corrosion test and static anti-scaling method, and the environmental and economic benefits were analyzed. And the corrosion inhibition and scale inhibition mechanism were pilot studied by electrochemical experiment, X-ray diffraction and scanning electron microscope.The results showed that, in a certain water quality conditions, the scale inhibition could exceed80%and the corrosion rate could drop to0.06mm/a or so with PESA. When the dosage of the composite non-phosphate corrosion and scale inhibitor was30mg/L,10mg/L of PESA,8mg/L of PAAS,3mg/L of sodium molybdate,6mg/L of sodium lignin sulphonate and3mg/L of zinc chloride was the optimum component of the composite non-phosphate corrosion and scale inhibitor. And the maximum corrosion inhibition and scale inhibition exceeded91%and93%. respectively. According to the contrast of technical and economic indexes, the composite corrosion and scale inhibitor without phosphate has the considerably high performance-price ratio compared with the corrosion and scale inhibitor of phosphorous WT-304C. The mechanism of the composite non-phosphate corrosion and scale inhibitor was studied. The composite non-phosphate corrosion and scale inhibitor mainly inhibits the anode process of corrosion. And the composite non-phosphate corrosion and scale inhibitor adsorption on the carbon steel surface, forming a layer of protective film, inhibiting the corrosion of carbon steel effectively. The adsorption of the phosphate-free corrosion and scale inhibitor on A3metal surface obeys Langmuir adsorption isotherm equation. Besides, the composite non-phosphate corrosion and scale inhibitor destroyed the regular rhombohedral shape of CaCO3crystal and the degree of integrity of CaCO3crystal, so that inhibited the growth of CaCO3crystal with the composite non-phosphate corrosion and scale inhibitor.