Study On Adsorption Performance Of Pecan Fruit Peel Waste To Simulated Uranium

Pecan as an economic forest species has rapidly expanded cultivation area in Anhui province.In order to seasonable use the pecan fruit peel waste,the paper modified biochar adsorbents at 100 ?,150 ? and 200 ? under phosphoric acid catalysis.The five adsorbents such as pecan endocarp,the pecan epicarp,pecan epicarp modified biochar at 100?,pecan epicarp modified biochar at 150? and pecan epicarp modified biochar at 200? were used to remove uranium,so as to explore the difference of adsorption performance.The effects of pH of aqueous solution,reaction temperature,initial concentration of uranium solution and adsorption time on the adsorbent of pecan fruit peel were studied.Finally,the adsorbent materials of pecan fruit peel were characterized by scanning electron microscopy,X-ray diffraction,infrared spectroscopy and thermogravimetric analysis.The main results were as follows.(1)Experiments of pecan fruit peel adsorbent materials for uranium ion adsorption ability according to the pecan epicarp modified biochar at 150 ? > pecan epicarp modified biochar at 200?> pecan epicarp modified biochar at 100?> pecan epicarp > pecan endocarp order from big to small,at 298 k,pH of 6 under the same conditions,the uranium ions of saturated adsorption capacity were 232.558 mg,217.392 mg/g and 188.679 mg/g and 142.857 mg/g and 100 mg/g.(2)It can be seen from the scanning electron microscope and infrared analysis spectrum that the modified material surface of pecan epicarp has more pore structures and more oxygen-containing groups.At the same time,phosphate groups are introduced through phosphoric acid,which can combine with uranium ions to increase the adsorption amount.According to the results of X-ray diffraction and thermogravimetric analysis,the cellulose peak crystal of modified epicarp disappeared,and the graphite microcrystal and amorphous carbon body appeared instead,indicating that the modified epicarp generated porous carbon structure,which was conducive to adsorption.Due to the dehydration and protection of phosphoric acid,the results of thermogravimetric analysis showed that the carbon yield of pecan epicarp modified biochar was 60%,which was higher than 40% of epicarp.(3)The results of the adsorption study on U(VI)by the adsorbent of pecan fruit peel showed that the pH value had the most significant influence on the adsorption,and the optimal pH value was 6.Temperature can promote adsorption but has little effect on adsorption effect.In the early stage of adsorption,the adsorption rate increases rapidly,and reaches the saturation adsorption amount with the passage of time.The increase of initial uranium concentration can promote the saturation adsorption of pecan fruit peel adsorbent,but the best way to improve the effect is to change the internal structure and surface properties of the material through modification.(4)According to adsorption model fitting correlation coefficient can be judged,pecan endocarp,pecan epicarp and modified biochar of pecan epicarp for uranium ion adsorption process is spontaneous endothermic reaction,and consistent with pseudo-second order kinetic model and the Langmuir adsorption isotherm model,it shows that the adsorption process is mainly controlled by the chemical action of monolayer adsorption...