Preparation And Application Of Chestnut And Walnut Shell Adsorbent

Agricultural and forestry waste is agricultural, forestry production and processingprocess byproducts, variety, with large output, renewable, easy to biodegradable,environmental friendly, They are important biomass resources. The agricultural andforestry waste and other biomass materials by Regeneration treatment used in the field ofenvironmental governance is one of the major trends in contemporary environmentalengineering of new materials. In this study, the chestnut shell and walnut shell in theselection of forestry waste as raw material for preparing efficient water treatment adsorbent.Through chemical modification to enhance the adsorption performance, study theunmodified and modificatied adsorption on the Cr(VI). Based on the preparation andexploration process conditions, to explore the methods andconditions of preparation of thebest. Provide basic reference data for theindustrialization of the adsorbent.By microwave irradiation, walnut shell and malic acid were prepared modified walnut,chestnut shell adsorbent by reactions, the best preparation conditions were obtained bysingle factor and orthogonal experiments: the optimal scheme of microwave irradiation,malic acid modified walnut shell preparation of adsorbent for liquid material ratio is1:7,microwave irradiation time is8min,microwave power is600W, the concentration of malicacidsolution is1mol/L. Cr(VI) simulated water before and after the modification of walnutshell adsorbent is20mg/L, when the temperature is25℃, walnut shell adsorbent dosage is25g/L,pH value is medium fornatural value, speed of150r/min, the adsorption time is120min,the removal rate of Cr(VI) can reach85.82%,54.24higher than unmodified. Theremoval rate of Cr(VI) by modified walnut shell adsorbent recycling after10to canmaintain above75%. Modified walnut shell adsorbent in the adsorption of Cr(VI)adsorption isothermal curve for the I type, and can be well fitted by Langmuir isothermadsorption equation. Modified walnut shell adsorbent for Cr(VI) adsorption process is aspontaneous endothermic process, temperature was beneficial to adsorption. Thecorrelation coefficient of modified walnut shell adsorbent to fit two order kinetic equationswere ln(Qe-Qt)=-0.0204t–1.1091,R2=0.9873, higher than the pseudo first order kineticsequation correlation coefficient. That used to describe the adsorption reaction process tobetter two order kinetics equation.The optimal scheme of microwave irradiation,malic aci dmodified chestnut shelladsorbents are prepared by solid-liquid ratio is1:4, microwave time is5min, microwavepower is500W, the concentration of malic acid solution is0.8mol/L. The concentration of Cr(VI) simulated water by before and after the modification of chestnut shell adsorbent is50mg/L, when the temperatureis is25℃, chestnut shell adsorbent dosage is12.5g/L, pHvalue is medium fornatural value, speed of150r/min,the adsorption time is300min,theremoval rate of Cr(VI) can reach90.3%,39.64%higher than unmodified The removal rateof Cr(VI) by modified chestnut shell adsorbent recycling after10to can maintain morethan76%, the adsorption capacity of adsorbents by regenerating modified chestnut shell isbetter than the walnut shell. Modified chestnut shell adsorbent in the adsorption of Cr(VI)adsorption isothermal curve for the I type, and can be well fitted by Langmuir isothermadsorption equation. Modified chestnut shell adsorbent for Cr(VI) adsorption process is apontaneous endothermic process, temperature was beneficial to adsorption. The correlationcoefficient of modified chestnut shell adsorbent to fit two order kinetic equations wereln(Qe-Qt)=-0.0152t+0.8429,R2=0.9838, higher than the pseudo first order kineticsequation correlation coefficient. That used to describe the adsorptionreaction process tobetter two order kinetics equation.By infrared spectrum analysis, in the infrared spectrum picture of the modified walnutshell and chestnut shell adsorbent can find C=O characteristic peaks with stretchingvibration in the ester bond, show that the walnut shell, chestnut shell and malic acid wereappleacid esterification under microwave irradiation. The surface of modified walnut,chestnut shell adsorbent was characterized by scanning electron microscopy(SEM) areroughness, appear large pores, loose structure of the porous adsorption is beneficial toimprove the adsorption performance of removing Cr(VI).