| A novel adsorbent was prepared by the emulsion-congealedcrosslinking method, using the gelatine which is a kind of biologicalmacromolecules as raw material and glutaraldehyde as the crosslinkingagent. Using the particle size of microspheres as the reference index,the preparation conditions of gelatin microspheres were optimized bythe single factor experiments. The structure, morphology and otherperformances of gelatin microspheres were characterized by FT-IR,SEM, Particle Size Analyzer, AFM, XRD, TG, Zeta-Potential Locatorand so on. The adsorption performance of gelatin microspheres for thethree anionic dyes which are Acid Red B, Reactive Brilliant Red X-Band Direct Sky Blue6B was studied by the static adsorptionexperiments. The optimum applied conditions were also optimized. Atlast, the renewable capacity of gelatin microspheres was studied by thedesorption-second adsorption experiments.The single factor experimental result of prepared gelatinmicrospheres showed that the optimum prepared conditions follow asthe stirring speed for950~1150r/min, dosage of the gelatin for10%,water/oil volume rate, namely V(gelatin solution):V(atoleine)controlled for1:7~1:8and dosage of the emulsifier Span-80for2%. Thestructure and morphology of gelatin microspheres were characterized byFT-IR, SEM, Particle Size Analyzer and AFM. The result indicated thatthe gelatin was successfully crosslinked by the glutaraldehyde. Themorphology of the product was spherical and the average particle sizewas about17.46μm. They were in uniform distribution and not sticky. The expected products were got in the experiment, according to theexpected route. The crystalline state of the gelatin microspheres wascharacterized by XRD. The results indicated that the crystalline state ofthe gelatin had not been affected by crosslinking of the glutaraldehyde.The heat stability of gelatin microspheres was detected by TG. Theresult showed that the thermal decomposition form of gelatinmicrospheres was single and the heat stability was good. The weightloss rate was80%from starting to finishing of the decomposition. Inaddition, comparing TG curve of the gelatin with that of gelatinmicrospheres, the crosslinking mechanism of gelatin and glutaraldehydecould be determined initially to the Schiff Base mechanism. Theisoelectric point of the gelatin microspheres was got for3.2byZeta-Potential Locator. The morphology of gelatin microspheres whichwere treated under the acid and alkali conditions was observed by SEM.It was found that the performance of resisting acid and alkali of gelatinmicrospheres was very strong.The experiment results of the static adsorption showed theoptimum conditions follow as pH of the Acid Red B and ReactiveBrilliant Red X-B for3and pH of the Direct Sky Blue6B for5,temperature for30℃, treated time for60min, when the concentration ofthe treated of the simulative anionic dye wastewater including the AcidRed B, Reactive Brilliant Red X-B and Direct Sky Blue6B was0.5g/L.Under the experimental conditions treated, the initial concentration ofthe simulative wastewater of the three anionic dyes should not morethan0.5,0.3,0.2g/L. Their adsorption capacity got respectively to448,320and245.3mg/g and the decolouring rate was more than98%. Afteradsorbing the dyes, the morphology of gelatin microspheres was hardlyaffected. The experiment results of the desorption-second adsorptionshowed that the desorption rate of gelatin microsphere in the10g/L ofNaOH solution was higher than that in the distilled water. The optimumtemperature was30℃and getting to the desorption balance needed for80min. The one-time desorption rate can got to88%in the alkalisolution. The gelatin microspheres which were desorbed could be recycled and used for secondary adsorption. The saturated adsorptioncapacity was near to that of the first adsorption. So they can be recycledand reused. The gelatin microspheres which was used to treat the dyeswastewater as the adsorbent have the characteristics follow as the largerspecific surface area, high adsorption capacity, easy biodegradable,environment friendly, renewable, recycling and saving resources. |
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