| Rosin acid starch(RAS)with degree of substitution(DS)ranging from 0.031 to 0.056 were prepared by enzymatic esterification reaction,starch was used as substrate directly for the synthesis of RAS catalyzed by liquid lipase in tert-amyl alcohol solvent systems.The main contents and conclusions were as followed:In order to improve the efficiency of the enzymatic reaction,native cassava starch(NCS)was microporously pretreated by enzymatic treatment to increase its specific surface area,and the effects of the ratio of rosin acid to starch,reaction time,reaction temperature and amount of lipase on DS were studied by single factor experiment.The optimum reaction conditions were determined.The results showed that the mass ratio of rosin to starch was 4: 1,the reaction temperature was 55 ?,the reaction time was 12 h,the amount of immobilized lipase was 1%(the volume of reaction system),and the theoretical DS of RAS was 0.056.The structure of RAS was characterized by RAS infrared(FT-IR),1H NMR(NMR),scanning electron microscopy(SEM),X-ray diffraction(XRD)and other characterization methods.And the physical and chemical properties of RAS(DS = 0.031,DS = 0.047 and DS = 0.056)of different DS were studied.The results of characterization analysis showed that FT-IR indicated that RAS produced a new characteristic absorption peak at 1725 cm-1.1H NMR analysis showed that the esterification reaction of rosin acid and starch was catalyzed by liquid lipase SEM analysis showed that the surface of the microporous starch granules had many holes and the surface became rough and the specific surface area increased.XRD analysis showed that the crystal structure of the starch was not destroyed after the microporosity,but the crystal structure was enhanced.The results of physicochemical properties show that the introduction of rosin hydrophobic groups makes the starch molecules have a certain hydrophobicity and lipophilicity,so that the introduction of rosin acid hydrophobic groups compared RAS with the original starch effectively inhibited the starch molecules And the ability to bind to water,so that the solubility of the starch,swelling,viscosity,transparency and oil absorption and some other characteristics have changed,and with the RAS DS changes.The adsorption characteristics of RAS on phenol were studied.The results show that the initial concentration of phenol and the decrease of temperature are favorable for the adsorption.The adsorption of phenol by RAS is in accordance with the quasi-second order kinetic model.From the adsorption thermodynamics,adsorption kinetics and adsorption isotherm,adsorption is a spontaneous and the process of adsorption of phenol on RAS has the properties of monolayer adsorption.In this paper,the adsorption of benzopyrene in n-octane solution was studied by using RAS as adsorbent.The effects of adsorption time,temperature,initial concentration of benzopyrene and DS on the adsorption capacity of RAS were analyzed.The thermodynamics,the dynamics were analyzed.The results showed that the adsorption temperature,the concentration of benzopyrene and the DS of adsorbent could increase the adsorption capacity.RAS with DS of 0.12 was used as adsorbent,and the adsorption time was 120 min,the adsorption temperature was 50 ?,the concentration of benzopyrene The adsorption capacity of benzopyrene was 20.76 ?g / g under the condition of 10 mg / L.The Langmuir isotherm model could fit the adsorption process well.The thermodynamic parameters indicated that adsorption was a spontaneous and endothermic process.The kinetic data show that the quasi-second order kinetic model is suitable for describing the adsorption process of RAS to benzopyrene. |
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