Research On Activated Carbon Preparated By Mechanochemical Process

In this thesis,we developed novel activated carbon with high performance by introducing mechanochemical process (MCP) into traditional ways for activated carbon preparation include phosphoric acid activation, zinc chloride activation and phosphoric acid-potassium nitrate activation. Plackett-Burman design (PBD), Box-Behnken design (BBD) and central composite design (CCD) were applied using Desgn-Expert software to optimize the conditions of preparation according RSM.Fitting of the data to various models (linear, two factorial, quadratic and cubic) and their subsequent ANOVA showed that iodine adsorption for MCP/phosphoric acid preparation was most suitably described with a quadratic polynomial model. A suitable coefficient of determination (R2= 0.9866) and similar adjusted R2 (adj-R2=0.9731) also showed that the quadratic polynomial model was highly significant and sufficient to represent the actual relationship between the response and the significant variables. Results showed that highest iodine adsorption (1331.23 mg/g) could be got under the following conditions:ratio of acid/sawdust 2.00, milling time 22.00 min, activation temperature 406.00℃, and concentration of phosphoric acid 20%. The same analysis also been done for methylene blue adsorption. A suitable coefficient of determination (R2= 0.9910) and similar adjusted R2 (adj-R2=0.9820) showed a good fit of the quadratic polynomial models with experimental data. Results showed that highest methylene blue adsorption (21.50 ml/0.1g) could be got under the following conditions:ratio of acid/sawdust 2.60, milling time 29.00 min, activation temperature 390.00℃, and concentration of phosphoric acid 22.5%.We also used the same analysis to work out the best mathematic model for MCP/zinc chloride preparation and MCP/phosphoric acid-potassium nitrate activation. These results also indicated that quadratic polynomial models sufficient to represent the actual relationship between the response and the significant variables. The optimum conditions of iodine adsorption for both activations were (1) ratio of zinc chloride/sawdust 2.7, milling time 34.00 min, activation temperature 593.00℃, activation time 1.90 h; and (2) ratio off activation reagent/sawdust 2.6, dosage of activation regent 14.00%, milling time 19.00 min, concentration of phosphoric acid 15.00%, activation temperature 400.00℃, activation time 60 min respectively. For methylene blue adsorption, the optimum conditions were (1) ratio of zinc chloride/sawdust 1.8, milling time 22.00 min, activation temperature 672.00℃, activation time 1.22 h; and (2) ratio off activation reagent/sawdust 2.6, dosage of activation regent 9.00%, milling time 40.00 min, concentration of phosphoric acid 23.00%, activation temperature 400.00℃, activation time 60 min respectively for MCP/zinc chloride preparation and MCP/phosphoric acid-potassium nitrate activation. Compare with MCP/zinc chloride preparation and MCP/phosphoric acid-potassium nitrate activation, MCP/phosphoric acid preparation showed highest iodine adsorption; and the MCP/zinc chloride preparation showed highest methylene blue adsorption.Furthermore, the activated carbons regenerated under the optimum condition for MCP/phosphoric acid preparation, MCP/zinc chloride preparation, and MCP/phosphoric acid-p otassium nitrate activation preparation were characterized by BET, SEM and FTIR.