| 2013 China environment bulletin shows that the heavy metals and organic chemicals had been two kinds of main pollutants material in surface water pollution.Finding an effect way to control and remove the heavy metals and organic pollutants in the surface water is more and more urgent. Using agriculture and forestry waste materials as adsorption material to reduce heavy metals and organic pollutants concentration and deal with basin pollution load has become a new scheme. Applying this scheme can reduce the treatment cost and realize waste recycling which has important practical significance.Sawdust, pine needles, loose skin, wheat bran, rice husk, straw, corn straw, corn cobs, coconut shells, walnut shell,10 kinds of agriculture and forestry waste material,had been selected as original materials in this study. Cu(â…¡) and nitrobenzene had been chosed as model pollutants. This research aims at conducting material selection and using optimal material to absorb Cu( â…¡) and nitrobenzene. By the means of Characterization and adsorption, three kinds of materials was selected to be modified by acid, alkali and high temperature methods. Finally, the optimal material was selected and absorption conditions was studied to find the opitimal condition. Besides, the adsorption isotherm and adsorption kinetics are speculated to study the adsorption characteristic and the mechanism. The main results were as follows:Material surface characteristics analysis results showed that among 10 kinds of materials, coconut shells, sawdust, rice husk had a larger specific surface area, which were 184.36, 121.87, 86.68 m2/g. Boehm titration method showed that selecting materials were alkaline. Adsorption efficiency of the experiment results showed that the sawdust, rice husk, coconut shell got better effect for romovel of Cu(â…¡), removal rate could reach 70.46%, 66.56%, 66.38%. sawdust, loose skin, rice husk, straw, corn straw,corn cob got better effect for romovel of nitrobenzene, removal rate were 62.23%,82.39%, 68.32%, 82.39%, 78.21%, 70.21%, but the straw, wheat bran, corn straw,walnut shell etc exist precipitation of organic compounds. Characteristics of 9 kinds of modified materials analysis showed that high temperature modification of materials got larger specific surface area and porosity, acid and alkali modified cause changes in the material surface functional groups, modified adsorption material adsorption efficiencyshowed that high-temperature modification made to the Cu(â…¡) adsorption efficiency greatly improved, the high temperature modified coconut shell, sawdust, rice husk of Cu(â…¡) removal rate could reach 98.52%, 82.15%, 98.58%. High-temperature modification made to the nitrobenzene adsorption slightly ascending, removal rate of 56.19%,79.14% and 87.64% respectively.Single factor variable experimental results showed that pH, adsorbent dosage,concentration of the pollutants, adsorption time, temperature, water contact conditions have effects on adsorption efficiency of pollutants, the optimum adsorption conditions were determined according to the result of the experiment.Adsorption kinetics and adsorption isotherm studies showed that, the process of high-temperature modified rice husk adsorption Cu( â…¡) and nitrobenzene was exothermic reaction, and had a rapid speed of adsorption. Modified rice husk achieve stability in 30 min with the absorption of Cu(â…¡), achieve stability in 60 min with the adsorption of nitrobenzene. Adsorption dynamics are composite quasi secondary dynamics equation. High-temperature modified rice husk absorbing Cu(â…¡) was more in line with the Freundlich adsorption isothermal adsorption model, of which the fitting correlation coefficient is 0.9583, the largest adsorption capacity is 2.32 mg/g.High-temperature modified rice husk absorbing nitrobenzene was more accord with the Langmuir adsorption isothermal adsorption model, of which the fitting correlation coefficient is 0.9959, the largest adsorption capacity of 0.026 mg/g. |
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