Study And Application Of Carboxymethyl Inulin,A Green Scale Inhibitor

With the development of society and the concept of"green chemistry",it is important to research and develop green environmental protection scale inhibitors.Inulin,as a kind of natural oligosaccharide,contains abundant hydroxyl group which can be used as the modified active site.Inulin after carboxymethyl modification of the form of carboxymethyl inulin,which retains inulin green environmental protection,non-toxic and harmless,degradable and other advantages,but also has good metal ion chelating ability,it can be used as a scale inhibitor,washing aid and food additives in food,daily chemical,biomedicine,water treatment and other industries.In this study,starting from the optimization of the synthesis process,carboxymethyl inulin with a high degree of substitution was prepared,and the samples were comprehensively characterized.The performance of carboxymethyl inulin in inhibiting calcium carbonate scale was investigated,and its scale inhibition mechanism was analyzed.Finally,the biological toxicity was studied.The main research results were as follows:In this paper,95%ethanol as solvent,using orthogonal experiment and single factor experiment to fully consider the synthesis reaction conditions,using atomic absorption method to determine the degree of substitution of carboxymethyl inulin,explore the best process of solvent preparation of high substitution carboxymethyl inulin,through the experiment found that when n（sodium hydroxide）:n（HSI inulin）=4:1;n（chloroacetic acid）:n（HSI inulin）=2:1;Alkalization temperature:40℃;Alkalization time:40 min;Etherification temperature:50℃;Etherification time 4 h;Solid mass:When solvent=20%,carboxymethyl inulin with the highest degree of substitution of 1.65 can be prepared.Through infrared spectrum test,scanning electron microscopy test,X-ray diffraction test and gel permeation chromatography test,it was found that the group,micro morphology and molecular weight of the product were changed,indicating that inulin was successfully carboxymethylated.The scale inhibition test of the modified carboxymethyl inulin was carried out,and the scale inhibition rate of carboxymethyl inulin with a substitution degree of 1.65 was determined by calcium carbonate deposition method.The influence of external conditions on the scale inhibition rate of carboxymethyl inulin was explored,and the scale inhibition mechanism of carboxymethyl inulin was explored by means of conductivity test,scanning electron microscope and X-ray diffraction.The results showed that the scale inhibition rate of carboxymethyl inulin with a degree of substitution of 1.65 was 78%when the dosage was 40 mg/L.The inhibition rate of Ca CO₃ by carboxymethyl inulin is closely related to degree of substitution,dosage,system temperature,time,Ca²⁺concentration and p H of the system.The conductivity of scale saturated solution and crystal morphology of calcium scale were measured by experiments.It was concluded that the inhibition mechanism of carboxymethyl inulin mainly includes chelation solubilization,lattice distortion and dispersion adsorption.The biotoxicity of carboxymethyl inulin was determined by luminescent bacteria method.The results showed that carboxymethyl inulin did not have biotoxicity.