Synthesis Of An Environment-friendly Reverse Osmosis Menbrane Terpolymer Scale Inhibitor And Researches On Its Properties

The development of environmental protection copolymer scale inhibitor of reverse osmosis membrane fouling control system has become a hot research topic in domestic water treatment chemicals.In this study,the formula is no phosphorus and cheap.The efficient and environment-friendly terpolymer scale inhibitor was synthesized by aqueous solution free radical polymerization method.Three monomers are acrylic acid(AA),hydroxyethyl methylacrylate(HEMA)and 2-acrylamido-2-methylpropane sulfonic acid(AMPS),the initiator used in this reaction is ammonium persulfate,and the isopropyl alcohol as molecular weight regulator.The optimum conditions for the synthesis of copolymers were determined by orthogonal experiment.The monomer ratio(AA:AMPS:HEMA)was 1 :0.8: 0.4,the dosage of ammonium persulfate and isopropyl alcohol accounted for 14% and 10% of the total mass of monomer,the polymerization tempetature,dropwise tim and holding time are 85℃,2.5h and2 h,respectively.The terpolymer is a kind of water soluble polymer,its scale inhibition rate was over 89%,the conversion rate was 99.23%,and the relative viscosity was 1.9863.The structure of gel chromatography showed that the molecular weight of the copolymer was normal distribution,and it was a polymer with narrow molecular weight distribution.The infrared spectrum results show that the functional groups such as carboxyl group,hydroxyl group and sulfonic acid group were present in the copolymer molecules.The multiple functional groups cooperate with each other,which promoted the scale inhibition,dispersion performance and calcium tolerance.The results of static and dynamic experiments showed that the copolymer has better scale inhibition performance to calcium carbonate and calcium sulfate.When the constant temperature was 25℃,the constant temperature time was 10 h,the hardness and alkalinity were 500mg/L,and the pH value was 7.Just adding the dosage of 4mg/L,the scale inhibition rate reached 98.46%.Its scale inhibition effect is superior to PESA,PASP,PBTCA,PAA four kinds of contrast scale inhibitors.The scanning electron microscopy shows that the copolymer has strong crystal lattice distortion and complex solubilization of calcium carbonate and calcium sulfate crystal.The copolymer has better scale inhibition and dispersion performance,it is specially appropriate for the reverse osmosis membrane with middle and low temperature,medium and high hardness alkalinity.The corrosion inhibition performance of the copolymer was determined by the weight loss method,The experimental results show that corrosion inhibition rate is up to 97.87%,when additive amount of terpolymer was 4mg/L,water temperature was 25℃ and pH value was controlled at 8 seperately.The inhibition effect was significantly better than PASP,sodium gluconate,sodium tungstate,sodium molybdate four kinds of traditional inhibitor.The scanning electron microscope tests that the copolymer formed a compact protective film on the surface of the carbon steel,the coupon was protected from the corrosive medium,it can effectively prevent the reverse osmosis membrane system from being corroded.The biodegradation rate of the copolymer reached 65% in twentieth days,it belongs to the organic matter which is easy to be degraded.It is a kind of environmental friendly scale inhibitor,in line with the requirements of the development of the green water treatment agent.This paper has a total of 29 pictures,11 charts and 96 references.