| Thesis work mainly studied the modification of microcrystalline cellulose(MCC) as adsorbents toward the removal of heavy metal ions for water clarification. Three types of modified MCC were successfully prepared, including maleic anhydride modified adsorbent(Cell-MA)? TEMPOmodified adsorbent(Cell-O2)and the MCC modified with glycine catalysed by EDC/NHS( Cell-O-Gly) The resulting adsorbents were mainly assessed based on the adsorption behavior of Cu2+?Cr(?) and the removal efficiency.The optimum conditions for the syntheses of Cell-MA?Cell-O2?Cell-O-Gly were obtained through an orthogonal test. For Cell-MA, the best synthesis conditions showed that, the dosage of MA was 14 g, reaction time was 3 hours, reaction temperature was 100°C, which led to the grafting rate at 4.42%(wt). Since that Cell-O2 oxidation needs two steps, the best synthesis conditions are as follows: for the first step of oxidation, reaction time was 10 hours, reaction temperature was 40°C, and then the carboxyl content reached was 0.425mmol/g; for the second step of oxidation, the highest carboxyl content of Cell-O2 at 0.593mmol/g was obtained at the 1% concentration of NaClO2, 24 h of reaction time and reaction temperature at 30°C. For Cell-O-Gly, the best synthesis conditions showed that, EDS/NHS activation time was 2 hours, the dose of amino acid was 16 g, reaction time was 24 hours, then the nitrogen content was 4.71‰.The industrial simulation wastewater was prepared by dissolving elementary Cu powder in nitric acid, and the concentration of Cu2+ before and after adsorption was determined using the ICP-OES. Furthermore, adsorption capacity of modified cellulose was calculated according to a formula. By changing the temperature?pH and the dose of adsorbent,ascertain the influence of adsorption conditions on the adsorption capacity, besides, the corresponding adsorption rate and the maximum static adsorption capacity were calculated. The experimental data were fitted with the pseudo-first order kinetic model and the secondary kinetic model, as well as two kinds of isothermal adsorption models. The results demonstrated that, the adsorption capacity of three kinds of adsorbent toward Cu2+ was increased with the increase of temperature, and the adsorption amount was decreased with the increase of the adsorbent dosage. Regarding the pH effect, the adsorption capacity of Cell-MA andCell-O-Gly to Cu2+ was increased with the increase of pH; and Cell-O2 adsorption capacity reached the maximum at pH 4.02. Cell-MA adsorption behavior fitted the pseudo-first order kinetics model; whereas Cell-O2?Cell-O-Gly adsorption behavior fitted the secondary kinetics model. The results from fitting adsorption isotherml models indicated that that all three kinds of adsorbent fit the Langmuir model well. The desorption behavior of Cell-O2 in 0.5mol/L HCl solution was studied. Results showed that desorption- adsorption behavior was completed for 3 times in 120 min and desorption efficiency was 57.6%.Through dissolving potassium dichromate to configure the industrial wastewater containing chromium(?),The adsorption behavior of Cell-O-Gly was studied. By changing the temperature and pH ascertain the influence of adsorption conditions on the adsorption capacity, besides, the corresponding the static adsorption capacity were calculated. The experimental data were fitted with the pseudo-first order kinetic model and the secondary kinetic model, as well astwo kinds of isothermal adsorption models. Results showed that the Cr(?) adsorption capacity of Cell-O-Gly was increased first and then decreased with increasing temperature. The adsorption capacity reached minimum at pH about 4. Cell-O-Gly adsorption behavior was fitted the pseudo- secondary order kinetics model and the results from fitting adsorption isotherml models indicated that fit the Langmuir model well. |
PDF Full Text Request