The Preparation And Their Adsorption On Phosphoric Acid Root And N－(Phosphonomethyl) Iminodiacetic Acid Of Starch Microspheres

Over the years, as science and technology prosper, the frequent use of artificialpolymer materials had caused an increasing harzard to the environment. Therefore, it isof vital importance to develop a type of biodegradable, environment-friendly polymer.In this study, we employed the ‘water in water （W/W）’ emulsion crosslinking method tosynthesize N-CSM by using soluble starch as the raw material, sodium hydrogensulfite（NaHSO₃） and potassium sulfate （K₂S₂O₈） as the initiator, and N, N-methylene doubleacrylamide （MBAA） as crosslinking agent. Then, we used GTA as etherifying agent tosynthesize C-CSM from N-CSM. Finally, we chosed the potassium dihydrogenphosphate （KH2PO3） and N－（Phosphono-Methyl） Imino-Diacetic Acid （PMIDA） asabsorption subjects in order to study the absorption performance of N-CSM andC-CSM.The detections by microscope and electron microscope scanning （SEM） showedthat N-CSM spheres were rough surface of certain pore size. The cationic poly-acryl ofN-CSM had not damaged the whole spherical structure of N-CSM, making theirsurfaces rougher and pore diameter lessened. According to infrared spectrum analysis,we can conclude that acylamino groups was incorporated into N-CSM and C-CSM,representing that N-CSM and C-CSM were such cross-linked as having introduced-CH_2-N⁺（CH₃）₃groups. Swelling performance results showed that the swellability ofsoluble starch was weak, being151%; N-CSM, after having more acylamino groups,had a swellability up to277%; C-CSM with-CH_2-N⁺（CH₃）₃had a swellability as highas1484%. The analysis of specific surface area and porosity determination showed thatthe BET specific surface area and Langmuir specific surface area of N-CSM were aslarge as29.5917m²/g and41.1075m²/g, respectively. The differential thermal analysisshowed that thermal stability was N-CSM> C-CSM> starch.The study of N-CSM absorption to phospate ions （calculated as phosphorus）,indicated that absorption effect was considerable. The absorption process reached anequilibrium absorption in120min. The increase of ultrasonic intensity would suppressthe effect, however. While at the same temperature, absorption increased as the initialconcentration of the PO₄^-nincreased. While at the same initial concentration, theabsorption quantity declined with the temperature rise. The absorption rate equation forthe processes was described as Q=1.4625t^0.3632. The isothermal equations for absorptionprocesses at313K Langmuir and323K was described as Ce/qe=7.79Ce–615.46（R²= 0.9990） and Ce/qe=7.28Ce–760.67（R²=0.9990）. This adsorption is mainly physicaladsorption.The study of C-CSM absorption to PMIDA indicated that absorption effect wasconsiderable. The results of the single factor analysis showed that quality concentration,pH value, temperature, ultrasonic strength had more effects on the absorption comparedwith other factors. The optimal experiment through orthogonal experimental and rangeanalysis was that concentration of9g/L, pH value of8, ambient reaction temperature of298K, ultrasonic strength of90Hz. Based on the absorption isotherm equation, weindicated that both Langmuir and Freundlich isothermal absorption equations can befitted to the absorption behavior at298K, but displayed Langmuir equaltion bettercorrelation than Freundlich equation. This adsorption is mainly chemical adsorption.