Synthesis And Evaluation Of Biodegradable Polyether Copolymer As A Water Treatment Agent

Scaling and corrosion will bring great challenges in circulating cooling water systems,which will decrease the efficiency of heat transfer equipment,hinders the normal heat transfer process and even causes the equipment lay-off.The commonly occurring scales,such as calcium carbonate,calcium sulfate and calcium phosphate,have a strong appeal to the researchers and they have worked on various solutions to inhibit scale formation and precipitation for many years.While the addition of scale inhibitors is one of the most common applied chemical methods to prevent or control scale deposition and corrosion.Therefore,considering the environmental pollution and ecological imbalance in water,it's extremely urgent to develop ecologically benign scale and corrosion inhibitors,which will gradually replace the application of high levels of phosphonates in water treatment systems.?1?In the present work,a modified and new polyepoxysuccinic acid inhibitor ESA-APEM was synthysized with epoxysuccinic acid and oxalic acid-allypolyethoxy carboxylate as monomers,water as solvent and ammonium persulfate as initiator by the free-radical polymerization.Also,a terpolymer ESA-APES-AMPS was synthesized with the same method.Among them,epoxysuccinic acid was prepared from maleic anhydride.?2?According to the scale inhibition effect of polymers against CaCO₃ and CaSO₄,the best synthesis process for ESA-APEM was as following:monomer ratio m?ESA?:m?APEM?=2:1,6%initiator amount,reaction temperature at 70?and reaction time for 3 h,while for ESA-APES-AMPS was:monomer ratio m?ESA?:m?APES?:m?AMPS?=2:0.5:0.5,6%initiator amount,reaction temperature at 70?and reaction time for 3 h.?3?The scale inhibition effect of ESA-APEM polymer against CaCO₃,CaSO₄,Ca₃?PO₄?₂ scales and the ability to disperse Fe₂O₃ was studied through the method of static scale inhibition test.The inhibition efficiency for CaCO₃ and Ca₃?PO₄?₂ was best,while ratio of CaCO₃ was 89.6%and ratio of Ca₃?PO₄?₂ was 99.5%at the dosage of 8mg/L,while the inhibition efficiency for CaSO₄ was 98.2%at the dosage of 4 mg/L.The inhibition efficiency was also studied with different dosages,solution temperature,pH,and concentration of Ca²⁺,HCO₃^-,SO₄^2-and PO₄^3-.Under the conditions of the best synthesis process,the best dispersion efficiency was reached to 22%?transmittance?when 14 mg/L of ESA-APEM was added into the tested solution.?4?The corrosion inhibition performance by ESA-APEM was examined through weight loss measurements and the biodegradability was studied with shaking-bottle incubating test.The maximum corrosion inhibitory power was 80%at the dosage of70 mg/L.Its corrosion ability was better than EDTMP and less than HEDP and POCA.ESA-APEM was easily degradable,because all rates were more than 50%on day 10and above 88%on day 28.The polyethers,ester groups and carboxylic groups could attributed to its ability of biodegradability.?5?The environmental friendly terpolymer,ESA-APES-AMPS,exhibited excellent scale inhibition property against calcium scales,such as calcium carbonate and calcium sulfate.The inhibition efficiency for CaCO₃ was 90%at the dosage of 16mg/L,while the efficiency for CaSO₄ was 93%at the dosage of 9 mg/L.?6?SEM?TEM?XRD and FT-IR indicated that morphology of calcium scales were completely changed or the crystal structure was changed in the presence of ESA-APEM and ESA-APES-AMPS.When polymer solutions were added into the cooling water system,carboxyl groups in polymer matrix could recognize and encapsulate or react with positively charged calcium ions.Encapsulation or interaction,between Ca²⁺and carboxly groups,leaded to the spontaneous formation of COO-Ca complexes?Encapsulation zone?.Therefore,nucleation and crystal growth processes were retarded,the tenacity of the scale was weakened and its crystal structure was distorted.With the piece form,the deposition would be easily removed from flowing water with enough shear force.