Preparation Of Polyphenol Macroporous Adsorption Resins And Its Adsorption Mechanism

The present paper selects the condensed tannin (larix tannin and the tannin of black chaste tree) chemically to synthesize the high polymer for the first time. By solidifying tannin on a kind of high polymer, which is the chloromethyl polystyrene resin, the author synthesized a new macroporous adsorption resins containing the polyphenol hydroxyl, and researched systematically its adsorption performance and the adsorption mechanism using the phenol and the alkaline dye as the simulated waste water, and carried out practically the adsorption recycling to actual wastewater of the phenol and natural product baicalin. The main conclusions of this research are as the following:1) The polyphenol macroporous adsorption resin has successfully been prepared by three chosen crafts process of synthesis. Through the influence factor experiment and the orthogonal experiment, the best synthesis conditions of the resins are determined, for the resin Ⅰ it is that: the using amount of sodium nitrite is 1.0g, the density of the hydrochloric acid is 3.0mol/L, larix tannin is used 1.0g, and the synthesis temperature is 20 ℃. The best synthesis conditions of resin Ⅱ are that: amino resin is used 2g, 5ml the dissolving-distending agent is put in to dissolve and distend 2h, then 25ml water and 1ml watery solution of methanol is put in to react 30min;then put in 25ml of 1% tannin watery solution to reacts above 7 hours under pH value 6.4～6.7 and 99～100℃. The best preparation conditions of resin Ⅲ are: the NaOH density 1mol/L, the reaction time 1 hour, the tannin density 5%, does not adjust the pH value of solidifying.2) The static state adsorption conditions of resin Ⅰ are: the alkaline dye solution of pH3.0, the resin charge of 0.5g, the adsorption temperature of 30 ℃. The best conditions of the dynamic adsorption experiment are that the flow speed is 20ml/min, and pH is 3.0. The best static state adsorption conditions of Resin Ⅱ are: the phenol solution of pH value 3, the adsorption temperature of 30 ℃. The best dynamic adsorption conditions are: the room temperature, the phenol of pH value 6, and flow speed 1BV/h;The best static state adsorption conditions of adsorption resin Ⅲ are: the alkaline dye solution of pH value 5.0;the adsorption temperature of 25 ℃, dye initial density of 100mg/L. The dynamic adsorption conditions of adsorption resin Ⅲis the flow speed of 2BV/h.3) The dynamics research of the adsorption resin. Using Langmuir and Freundlich separately, the analysis finds that the adsorption process basically conforms to the Langmuir adsorption isotherm and the Freundlich adsorption isotherm. The adsorption of the adsorption resin have two forms, i.e. the outside surface adsorption and the internal adsorption. The internal adsorption has a larger influence to the adsorption process than the outside surface adsorption. The adsorption mass transfer process mainly is influenced and controlled by the proliferating in the fluid film and inside the grains. The all resin adsorptive capacity increases along with the increases of the equilibrium concentration. The lower temperature is advantageous to the adsorption.4) The best static state desorption condition of the modified resin I are that: the desorption agent is NaOH solution of 1.5 mol/L, the desorption temperature is 50 °C. After 3 times circulation uses, the rate of the modified resin I absorbing the alkaline dye is above 80%. The best static state desorption conditions of the modified resin II are that: the desorption agent is alcohol solution, the desorption temperature is the room temperature. After 5 times circulation uses, the adsorption capacity of resin II nearly do not reduce. Especially in the adsorption recycling to actual phenol waste water and natural products baicalin, the adsorption resin II also displays the good adsorption characteristic. The static state desorption conditions of the adsorption resin Illare that: the desorption agent is the NaOH solution of 0.5mol/L, the desorption temperature is 45 °C. After 5 times desorption under 45 °C, the adsorption capacity of the resin nearly do not dropped.By the above-mentioned experiment, we found that resin II showed the good property in both synthesis and adorption.5) The thermodynamical parameter analysis of the adsorption resin II indicated that the adsorption is an exothermic process, temperature increment does go against the adsorption. It tallies with the experimental result. At the same time, AG<0, AH<() and AS<0 indicates that the adsorption is a spontaneous physisorption process;all the adsorption enthalpy is in 29~39kJ/mol, and basically in the bond energy scope of hydrogen bond (8~50kJ/mol). From this it can be deduced that hydrogen bond function is one of the main propelling forces of the resin II adsorbing phenol. The competition adsorption of phenol farther testifies that the adsorption process of the resin mainly is the hydrogen bond adsorption. The 4 electric potential measure of the resin proves that the electric charge on surface of the resin has an effect on adsorption.The innovation part of the study is successfully to synthesize a high efficient, secure and atoxic new macroporous adsorption resin by Mannich reaction etc., using the plant tannin of the natural macromolecule for the first time. This polyphenol adsorption resin takes the hydrogen bond function as the main propelling force, and has a good performance and industrial application prospect. This paper is an outcome of the creative thinking and practice, and has the important theoretical significance and application worth.