Study On Biphasic Selective Adsorption Of Mult-Glucopyranose Microspheres

Mult-glucopyranose microsphere is a kind of derivation of starch. It has favorable channel, microcavity and micrometer size through crosslinking action to starch molecular. For coexisting of adsorption of channel and microcavity, mult-glucopyranose microsphere has special properties and performance, especially in the fields of adsorption, environmental protection, loading-drug, material exchange, and so on, it will show broad application prospect. The structure of the microcavity in the mult-glucopyranose microsphere could adsorb guest molecule with suitable size for the shielding of electron cloud to form certain higher electron cloud density center. Because of the inclusion adsorption, in the mult-glucopyranose microsphere has more excellent adsorption than general microsphere. The adsorption process of the microsphere toward guest was composed with the adsorption of "open interval" including of van der waals force, hydrogen-bonding force, dispersion force, and so on, and the adsorption of "close interval" of the action of host-guest matching in the microcavity. The excellent adsorption is called biphasic-selective adsorption.The mult-glucopyranose microsphere was prepared from starch as crude materials and N, N'-methylenebiacrylamide as crosslinking reagent in inverse suspension.30mL 15% (wt) starch solution and 0.2g N, N'-methylenebiacrylamide were added in the reaction vessel until dissolution completely, and then were dropped in the oil phase which was composed by 90mL cyclohexane,0.75g Tween 20 and 0.25g span80. After oil phase formed uniform droplet,0.04g K2S2O8-NaHSO3 was added to initiate the polymerization at 65℃with stiring and the reaction was remained two hours. After reaction, the centrifugation operation was used to separate the oil, and the polymer in the bottom was treated with distilled water, anhydrous alcohol, acetone in turn by ultrasonic washing. And then the polymer was dried at room temperature in vaccum for 20 hours, so we will obtain the mult-glucopyranose of white powder fully dispersed.The cross-linked copolymerization was prepared with starch and N, N'-methylenebiacrylamide as the rude materials. The force between different starch molecular chains enhances the structure more closely with the cross-linking degree of increase and eventually to form a spatial network structure microsphere precipitation from aqueous solution. Starch molecules gradually shrink due to cross-linked and the water is moistured out of them, a number of micro-channel left in the microspheres which constitutes a microsphere pore. The starch molecular structure has been redistributed in the cross-linking to form a new polymer.Starch molecules are formed by a number of glucopyranose, the second hydroxyl of lglucopyranose and the cross-linking play a role in the process of the cross-linking, which led directly to cross-linking process has a certain random nature under the laws. Two cases occurred in the cross-linking process accompanied by such a regulation under the effect of random, the one is a number of starch molecular chains did not form a "closed zone" after the adoption of cross-linking, that is, there is no a ring connected end to end formed by a number of glucopyranose; the other is the "closed zone" formed by the same starch chain, or a number of cross-linking of starch chains, that is,the ring connected end to end is formed by a number of glucopyranose, and the different sizes of the ring can be produced for the random nature of cross-linking, which is formed by a number of different glucopyranose, the random nature is as well as the size of the ring.and the micro-cavity structure inside of micro-ball is constituted by the ring composed of number of different glucopyranose.Obtained the optimum conditions of microsphere through the preparation of single-factor micro-structure and properties of the ball were characterized by scanning electron microscopy, polarizing microscopy, Fourier transform infrared spectroscopy, x-ray diffraction, a comprehensive thermodynamic analysis instrument and other equipment,which further measured microspheres point of zero charge, surface area, pore volume, surface chemical properties, particle size distribution, degree of swelling, solubility, water absorption and cell toxicity were discussed. Mult-glucopyranose microsphere cylindrical spherical structure, which composition of surface chemical functional groups are significantly different from that of soluble starch,and has many advatages such as good dispersion, no adhesion, uniform particle size and so on.Indicator of methylene blue is easily colored to signal the excellent adsorption properties of microspheres in water medium.The zero charge point of microspheres is pH 3.75, pore volume dVp/dDp is 0.219, the average pore size DBJH is 14.28nm, the total acidity of micro-ball is 11.81 mmol·g-1, a total alkalinity of microspheres on the surface is 2.83 mmol·g-1, hydroxyl groups content of Microsphere surface is 10.19 mmol·g-1, particle size mainly distributed in the 120μm150μm, micro-balls has no biological toxicity was found by the the cell toxicity test. The regularity of molecular chain is destructed by the cross-linking role of Starch molecular chain with N, N'-methylene bisacrylamide, which making intermolecular forces, hydrogen bond significantly weakened and resulting in the ability of starch crystallization reduced and stability of thermal increased.The adsorption properties to metal ions Cu2+, Co2+, Ni2+by the Mult-glucopyranose microsphere is discussesed firstly in the paper. At a low pH, the microsphere surface hydroxyl and acetyl-protonated by the protonation,,making an empty track on the proton is occupated by the oxygen atoms and lone pairs of electrons of nitrogen atoms, which reducing or lossing the coordination capacity of an empty track with the metal ion, especially the pH is lower than the point of zero charge on the microspheres surface, while, at a higher pH,, it is not easy to be adsorpted by be mult-glucopyranose microsphere hydrolysis because of the existing form of metal ions is changed by the strong of hydration The adsorption capacity of the three kinds of metal ions rapid by increased with the increasing concentration of metal ions in solution, but the adsorption rate of increase began to slow down as the concentration increased to a certain extent, and, adsorption capacity has no increase when reached a turning point, athletic ability of metal ions in aqueous solution enhanced, the polarization of coordination group on the Microsphere surface will increase as the temperature rising, which leading to relatively weakened the role of coordination and adsorption between Microsphere and metal ions, as well as adsorption capacity of Microsphere to metal ions declined; for another, the hydrolysis trend of metal ions is relatively more obvious as the temperature rise, which led to its being Microspheres Absorption capability is relatively weakened, the adsorption of metal ions by the Mult-glucopyranose microsphere decrease as the temperature increased,. at the beginning of the adsorption kinetics of metal ions by the microspheres, the metal ions are adsorbed rapidly on the outer surface of microspheres;, the metal ion concentration gradually decreased as the adsorption process, absorption rate is slower,which mainly controlled by diffusion,as the resistance is rising while metal ions spread to the internal pore along the micro-the ball; the adsorption has reached the equilibrium at the late phase reaction,in which adsorption mainly on the surface of the microspheres, and the drivers of concentration getting smaller and smaller. Langmuir isotherm equation and the Freundlich isotherm equation come up to the adsorption behavior of microspheres on the metal ions, it indicates that the adsorption of microspheres on metal ions is "preferential adsorption" process when the fitting of n is greater than 1 at different temperatures. Adsorption process is exothermic, lower temperatures favor adsorption, and the Mult-glucopyranose microsphere of metal ions mainly by physical adsorption enthalpy,ΔH is the main driving force for adsorption. The part impacted by the coordination of Microsphere is effected by the electron withdrawing of metal ions due to the impact of the coordination when metal ions is adsorpted, which resulting in cloud density of electron increases, so that the absorption peaks of vibrating infrared, crystal structure and thermal stability will change when metal ions is adsorpted by microsphere, and the linear relationship between change of the degree and adsorption capacity of the metal ions is proportional..After studying the Mult-glucopyranose microsphere on adsorption of metal ions, further studied the adsorption of the microspheres on organic compounds, such as phenol, tetrahydrofuran and pyridine. Mult-glucopyranose microsphere on the adsorption kinetics of organic compounds performance the characteristics of adsorption rate faster at the beginning, with the extension of adsorption time, adsorption rate was gradually reduced.The first-order adsorption kinetic equation and the second-order dynamic equations could fit all organisms in a Mult-glucopyra-nose microsphere on the adsorption kinetics, and had been relatively satisfied with the results, absorption was controlled by the film diffusion and particle during the process of proliferation. This also indicated that Mult-glucopyranose microsphere on the adsorption behavior of organic compounds existed in the physical factors and the chemical elements. Microspheres had good fitting on organic phenol, tetrahydrofuran, pyridine adsorption behavior and Langmuir equation and Freundlich equation.This noted that the Mult-glucopyranose microsphere on experimental adsorption behavior of three kinds of organic matter were consistented with Langmuir isotherm equation and the Freundlich isotherm equation, but comparised, the Freundlich equation has a better fitting degree for phenol and tetrahydrofuran, while the Langmuir equation for pyridine. And at different temperatures, the fitting of 1/n are less than 1, it indicated that microspheres on phenol, tetrahydrofuran, pyridine adsorption is a "preferential adsorption" process. And the adsorption was exothermic process, the lower of temperatures was favor for adsorption, and the Mult-glucopyranose microsphere on adsorption of organic compounds in order to envelope mainly. Enthalpy AH was the main driving force for adsorption. Microsphere adsorption of metal ions, due to the impact of the role of coordination, made Microsphere structure, the role of coordination occurred in part by the role of metal ions in electron impact, leading to electron cloud density increases, so that after Microsphere adsorption of metal ions the infrared absorption vibrations peaks, crystal structure and thermal stability will change,and the degree of change with the metal ions adsorption capacity was proportional to the linear relationship.It resulted that physical adsorption was major way of microspheres by adsorption behavior and thermodynamic function, the reasons of adsorption capacity of microspheres were higher specific surface area, higher pore volume and multi-glucopyranosyl ring structure. Microspheres absorded metal ions by pore, adsorbed organic by it' smicrocavity. Mult-glucopyranose used it's pore and microcavity to reach the aim of biphasic role of selective adsorption.