Study On The Synthesis Of New Type Green Scale Inhibitors And Their Antiscaling Performances

Chitosan is highly deacetylated derivative of chitin ,one of the most abundant natural and biodegradable ploymers.It has both reactive amione and hydroxyl groups that can be chemically alter its properties under mild reaction condition.Carboxymethyl chitosan,O-hydroxypropyl chitosan ,maleicanhydride chitosan, acrylic chitosan were prepared and characreried by FT-IR spectrum,XRD spectrum and 1H NMR spectrum in this paper.Their anti-scaling performances were evaluated by static scaling inhibition experiment.The recommendation for modified chitosan application in antiscaling treatment are as the followings: (1) the dosage of carboxymethyl chitosan is 16 mg/L,pH value ranges from 6.8 to 7.2, [Ca²⁺]≤480mg/L;(2) the dosage of hydroxypropyl chitosan is 20mg/L,pH value ranges from 6.7 to 6.9, [Ca²⁺]≤365mg/L;(3) the dosage of maleicanhydride chitosan is16mg/L,pH value ranges from 6.7 to 7.2, [Ca²⁺]≤600mg/L;(4) the dosage of acrylic chitosan is 20mg/L,pH value ranges from 6.7 to 7.2 ,[Ca²⁺]≤300mg/L.Based on the conditions of experiment, operation facilities and the performance of scale inhibition , carboxymethyl chitosan was chozened for further study.A new approach to chemically modification of carboxymethyl chitosan(CMCTS) was reported,where CMCTS was prepared from chitosan with ion liquids asreactive and catalystic reagent,the degree of substitution of carboxymethyl was up to 1.67;the scaling inhibition rate of CMCTS reached to 97%.Then N-quaternary ammonium group was introduced by the reaction of CMCTS with 2,3-epoxypropyl trimethyl ammonium chloride.The structures of the derivatives were confirmed by FT-IRspectrum,XRD spectrum and ¹H NMR spectrum,¹³C NMR spectrum.The static scaling inhibition assesement of the quaternized carboxymethyl chitosan(QCMCTS)showed that it is possessed antiscaling performances and its scaling inhibition rate could be to 99% .Chitosan and the chemical modified chitosan were one kind of new type green water treatment agents,but need further improvement their antiscaling mechmism and application.