Preparation Of α- Ketoglutarate Modified Chitosan And Its Adsorption Mechanism Of U (Ⅵ) In

Using chitosan as raw material, alpha-ketoglutarate as modifier, NaBH4asreductant, we prepared the alpha-ketoglutaric acid-modified chitosan by graftcopolymerization method; According to X-ray diffraction, infrared spectroscopy andother modern analytical techniques characterize the structural features of thesechemicals. The adsorption properties and the adsorption mechanism of uranium bythis new adsorbent were studied. The main results of this study are showed asfollowing:(1) The influencing factors of Schiff base reaction between chitosan andalpha-ketoglutarate was explored, then the optimum conditions for the preparation ofalpha-ketoglutaric acid-modified chitosan were determined. Namely, when pH is5.0,alpha ketone glutaric acid and chitosan mass ratio is1.6, and the reaction time is4h.(2) With the modern analytical techniques to characterize the alpha-ketoglutaratemodified chitosan, X-ray diffraction spectra analysis shows that intermolecular oforderly crystal structure in chitosan was destroyed after modified byalpha-ketoglutaric acid and NaBH4; Infrared spectroscopy analysis indicated thatchitosan active-NH2occurs Schiff base reaction which leads into the introduction ofthe-COOH at the same time.(3) By researching the adsorption properties of alpha-ketoglutaric acid-modifiedchitosan to uranium, the effects of adsorption properties of uranium was confirmed byinvestigating the initial pH, adsorbent dosage, reaction time, reaction temperature,coexisting ions and other factors. Experimental results show that, alpha-ketoglutaricacid-modified chitosan has a good adsorption performance to trace uranium insimulated wastewater, under the following conditions, the adsorbent dosage0.10g,reaction temperature of25°C, initial pH value of4.00, the removal efficiency toadsorption of uranium is up to99.5%.Moreover, the adsorption removal rate issignificantly higher than the chitosan before modified.(4)In addition, adsorption isotherms of processing in reaction is in line with theFreundlich and Langmuir isotherm equation, the dynamic model is in line with thefirst order and second-order kinetic equation.(5) Analysed by scanning electron microscopy and infrared spectroscopy andfound, after adsorption uranium, uneven porous structure in alpha-ketoglutaric acid-modified chitosan basically filled，besides, the characteristic absorption peaks inthe infrared spectra did not change significantly before and after adsorption,-OH inthe-COOH absorption peak, and the carbonyl group in the carboxylic acid saltabsorption peak occurs a slight offset, this results indicate that the introduction ofthe-COOH is the major binding sites of uranium in the process of modificatingchitosan.