| In order to control scale and corrosion in industrial cooling water systems for the purpose ofefficient and equipments truning normally in a long time, water treatment agents was usually added tocirculating water. All kinds of water treatment agents were developed over the past decades. Since then,inorganic scale-corrosion inhibitor, polyphosphate salts scale-corrosion inhibitor, phosphate–basedwater-treatment agent and so on have been successfully developed. However, these water treatment agentswas falled into disuse or restricted, because these agents easily produced secondary scaling, which causedenvironmental pollution. So, green, efficient and environment-friendly water trentment agents have drawnwide attention, for example, bamboo leaf extract, garlic extract and areca nut extract. In addition,polyaspartic acid and its derivatives receives much concern because of high performance on scaleinhibition, non-phosphorus, non-toxic and good biodegradability. The main contents of the present thesisare as follows:1. Carrot extract was prepared by immersing powdered carrot in water at80°C for3hours inassociation with cooling and follow-up filtration. The inhibition performance of as-prepared carrot extractagainst CaCO3scale was evaluated based on static scale inhibition test, where the morphologies of theCaCO3scales formed under different inhibition test conditions were observed using a field emissionscanning electron microscope. The corrosion inhibition performance of as-prepared carrot extract forcarbon steel was evaluated by measuring the weight loss of the rotating hung steel slices tested in salinewater. Moreover, the transmittance of the supernatant of as-prepared carrot extract was measured to evaluate its dispersion ability for ferric oxide. The results show that when the powdered carrot-watermixture is heated at80°C for3h and the concentration of resultant carrot extract is fixed at10ml/L, theinhibition efficiency against CaCO3scale can reach as high as99.99%. Besides, when50ml/L of carrotextract is introduced into the to-be-tested solution, the best dispersion capacity for Fe2O3is reached,corresponding to a light transmittance of43.7%of the solution. Further, the maximum corrosion inhibitionefficiency, as high as99.99%, is reached at a carrot extract concentration of30mg/L, and the corrosioninhibition rate of the carrot extract at various tested concentrations is all above50%.2. A graft copolymer PASP/6-amino-1-naphthol-3-sulfonic acid (abridged as PASPJ) wassynthesized by using polysuccinimide and6-amino-1-naphthol-3-sulfonic acid, which was characterized byIR. The influences of PASPJ concentration, Ca2+concentration, temperature and pH value of the system onthe inhibition efficiency are investigated. The result shows that PASPJ grafted copolymer obtained atan PSI to6-amino-1-naphthol-3-sulfonic acid molar ratio of1:0.8had the best inhibitionefficiency against CaCO3scale, and an inhibition rate of as high as100%was reached when the1.5mg/Lof PASPJ grafted copolymer; When the concentration of Ca2+was500mg/L, the inhibition efficiencyagainst CaCO3scale can reach as high as95%; The inhibition efficiency against CaCO3scale can reach ashigh as100%when the pH<3.7and temperature over60℃. So the PASPJ was a goos temperaturewithstanding water treatment agent.3. The carrot extract, PASPJ and bactericide NaClO were compounded and the optimum ratiowas found. At the same time, Their synergistic effect was studied. The results shows that when the volumeratio of carrot extract, PASPJ and NaClO at10:0.4:5, the inhibition efficiency against CaCO3scale canreach as high as100%for circulating water of dong da Corporation; when the volume ratio of carrot extract,PASPJ and NaClO at30:4.2:5, the maximum corrosion inhibition efficiency, as high as98.79%. It was proved that they have certain synergistic effect. |
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