Research On Synthesis And Applications Of Phosphate-free Scale Inhibitor On Water Treatment

Amount of organic and inorganic phosphorus scale inhibitor used in industrial recycling water damaged water resources and polluted environment. This attracts people attention increasingly. On the basis of prohibition of phosphorus-containing detergent, many cities in China started restricting the use of phosphorus-containing scale inhibitor. Developing and applying phosphate-free scale water treatment technology is the direction of water treatment industry.In this paper, two kinds of phosphate-free scale water treatments was researched and developed. One is polyaspartic acid synthesized using L-aspartic acid as the main raw material; the other is AA/MA/MAc copolymers synthesized by aqueous solution polymerization process, meanwhile their structures were characterized and the molecular weight distribution was tested. We finished the scales of static water samples testing in simulation water and in five domestic large-scale thermal power recycling water basing on scale of standardized test performance. The results showed that both using these two scale inhibitors, the inhibition rate of CaCO3 is at or near 100%, and the amount is less than phosphorus-containing. The research pave the way to promote the industrialization.The optimum reaction conditions of polyaspartic acid were found as follows: Reaction temperature ranges from 180～220℃.Reaction time duration is about 2 hs. Consumption amount of catalyzer is 5 % of the amount of L-aspartic acid,it need 30ml 2mol / L NaOH solution to hydrolyze 5g polysuccinimide. The temperature of hydrolyzable reaction ranges from 50～60℃and the reaction time is 1.0 h. The Consumption amount of HC1 to neutralize the remanent NaOH is about 0.08mol/L. the white low-density powder of the the sodium salt of polyaspartic acid are got by dropping the hydrolyzable solution to carbinol that its Consumption amount is 3～6 times to the amount of solution. the powder's density is about 0.35g/ml.The optimum reaction conditions of acrylic copolymers were found as follows:In oxidation - reduction system, MA/AA/MAc = 3:2.5:4.5. Consumption amount of initiator is 8%.Reaction temperature ranges from 60～70℃, and reaction time duration is about 5 hs.