Preparation And Evaluation Of Multifunctional Corrosion And Scale Inhibitors

In the industrial circulating cooling water system,the water continuously evaporates and concentrates in the process of circulation,and the concentration of corrosive ions and easily scaling ions in the water gradually increases,which aggravates the scaling corrosion phenomenon of the circulating water system.At present,adding scale inhibitor is the most commonly used method to inhibit scaling.In this paper,a multifunctional copolymer HEMA/AA/SAS was synthesized by free radical polymerization with water as solvent,AA,HEMA and SAS as monomers,tert butanol as molecular weight regulator and ammonium persulfate as initiator.In the static experiment,the influence of monomer proportion,initiator dosage and other factors on the scale inhibition performance of the copolymer was discussed.The optimum conditions for the synthesis of the copolymer were: the ratio of monomer HEMA:AA:SAS was 1:8:1,the ratio of Tert butanol to the total mass of the monomer was12%,the ratio of ammonium persulfate to the total mass of the monomer was 8%,the polymerization temperature was 90℃,and the synthesis time was 3 hours.The physicochemical properties of copolymer HEMA/AA/SAS were analyzed.The solid content of copolymer was 25.94% by differential weight method.The free monomer content of copolymer was 2.589% by using sodium thiosulfate standard solution titration method.The hydrolysis resistance,gel resistance,viscosity and water solubility of copolymer were investigated.The structure of the copolymers was characterized by infrared spectroscopy FI-IR,scanning electron microscopy SEM and thermogravimetry TGA.The infrared spectra showed that the copolymers contained target functional groups such as hydroxyl,carboxyl and sulfonic groups.The scanning electron microscopy showed that the copolymers with larger specific surface area were more likely to inhibit calcium carbonate scale.Thermogravimetry showed that the copolymers had good thermal stability.The scale inhibition,corrosion inhibition and dispersion performance of the copolymer HEMA/AA/SAS were evaluated.The static scale inhibition method was used to determine the scale inhibition performance of the copolymer on calcium carbonate and other factors,such as temperature,concentration and metal ions.When the concentration of copolymer is6mg/L,the scale inhibition effect of calcium carbonate is the best.Compared with PAA,PESA and PASP,the results showed that the copolymer had obvious scale inhibition effect Potential.The dispersibility of copolymer to iron and silicon was determined by turbidimetric method.When the concentration was 7.5mg/L,the transmittance of copolymer to iron oxide was about 50%,and that to silicon was about 55%.The corrosion inhibition performance of the copolymer was determined by the rotating hanging plate method,and the influence of p H,the concentration of the copolymer and other factors on the corrosion inhibition performance was investigated.When the concentration of the copolymer was 7.5mg/L,the corrosion inhibition effect on the carbon steel test piece reached 88.12%.Compared with the commercial scale inhibitor,the copolymer HEMA/AA/SAS has good scale inhibition,corrosion inhibition and dispersion performance.The mechanism of scale and corrosion inhibition of the copolymer was studied.The results of crystal dynamics show that the crystallization induction time will be prolonged,the surface energy of crystal will be increased,the nucleation rate of crystal will be reduced,the critical free energy of crystal will be increased,and the radius of critical crystal nucleus will be increased,which indicates that the growth of crystal will be inhibited by adding copolymer.The morphology and crystal form of calcium carbonate were studied by scanning electron microscope,X-ray diffraction（XRD）and infrared spectrum.The results show that the addition of copolymer destroys the morphology of calcium carbonate crystal,crystal lattice distortion occurs,crystallinity decreases,and the copolymer has a good inhibition effect on calcium carbonate.Corrosion kinetics and adsorption thermodynamics were used to study the corrosion inhibition mechanism of the copolymer.The copolymer molecules formed a protective film on the surface of carbon steel mainly by chemical adsorption,which increased the activation energy of the reaction,increased the difficulty of corrosion reaction and inhibited the corrosion reaction on the surface of carbon steel.This paper has a total of 52 pictures,11 charts and 107 references.