Study On The Synthesis And Inhibiting Properties Of Polyaether Scale Inhibitor And Dispersant

The water-soluble copolymer P(AA/MPEGAA) of acrylic acid (AA) andmethoxy polyethylene glycol acrylate (MPEGAA) containing aether groups in theside chains were synthesized by radical aqueous solution copolymerization. Theeffects of the reaction conditions such as ratio of monomer, dosage of initiator,dosage of chain transfer agent, reaction temperature and reaction time on theanti-scaling performance of the copolymer were studied. The effects of thecopolymer concentration, calcium concentration, pH value, inhibiting temperatureand inhibiting time on the anti-scaling rate of calcium carbonate, calcium phosphateand calcium sulphate were investigated. The performances of copolymer ofdispersing ferric oxide, anti-corrosing and influencing the turbidity were studied too.The copolymer structure and heat resistance were respectively characterized by IRSpectrum and Tg. The crystal morphology of CaCO₃ phase was characterized bySEM and XRD.The results show that the influence of reaction conditions on the performanceof the copolymer mainly depends on the molecular weigh of the copolymer whichhas more effect on inhibiting calcium carbonate than inhibiting calcium phosphate.The copolymer has excellent performances of inhibiting calcium phosphate, calciumsulphate and very good performance of inhibiting calcium carbonate. Theanti-scaling performances of copolymer become bad a little with the calciumconcentration increasing or inhibiting temperature rising or the pH value increasingor inhibiting time prolonging, but the copolymer can be still used in cooling watersystem of much high cycle of concentration. The carboxyl group is the primary factor of inhibiting calcium carbonate scale,while mechanism of inhibiting calcium phosphate and calcium sulfate is dispersionby contrasting the inhibiting performance of PAA, P(AA/AMPS) withP(AA/MPEGAA). The copolymer can reduce the turbidity of the cycle system bycongregating the small particles such as calcium scales which form biggish congeriesand are easily mechanically separated because aether groups endow the copolymerwith inhibiting, dispersing and flocculating fuctions.SEM micrographs further approve that the copolymer changes the crystalmorphology of calcium carbonate. The morphology of calcium carbonate scale withthe presence of the PAA is not in order any more, but can be still observed the shapeof cubic structure. The crystal morphology of calcium carbonate scale with addingP(AA/MPEGAA) is completely destroyed, and XRD spectrums show the quantity ofcalcite reduces, so the scales become loose, spongy, floccular and amorphous.