Study On The Preparation Of Activated Carbon From Textile Wastes And Application

This paper proposes a chemically activated method to utilize the textile wastes to prepare activated carbon. Study on the process condition, characteristics, kinetics and thermodynamics of adsorption of dyes and application of activated carbon prepared from textile wastes.Phosphoric acid was the activation agent. With orthogonal experiments, based on the iodine value and the methylene blue value, the optimum process condition was obtained: the concentration of activation agent was 40%, the impregnation time was 24h, the activation temperature was 500℃, and the activation time was 30min. On this condition, the iodine value was 967mg/g, the methylene blue value was 112mL/g, and the rate of production was 37.96%. The thermogravimetry (TG) showed that the role of activator H3PO4 is dehydration and condensation, so that separate the H and O of the raw material in the form of water and remain more of C in the activated carbon.The characteristics of activated carbon prepared from the optimum process condition was determined with scanning electron (SEM), N₂ adsorption isotherm, FTIR analysis and Boehm titration. Comparison SEM picture of activated carbon with SEM picture of prolysis sample that obtained from prolysis of raw material, showed that phosphoric acid play a role of pore-forming. BET surface area was up to 1107.509m²/g, total pore volume was about 1.239cm³/g and the activated carbon was with a more open pore structure and suitable for the adsorption of the dye molecular. The results of the infrared spectroscopy and Boehm titration were that the surface of activated carbon may contained hydroxyl groups, carbonyl groups, lactonic groups, phosphorus-containing groups and so on, and the major oxygen groups-acid group, phenolic hydroxyl group, lactonic group and carboxyl group levels were: 0.847mmol/g, 0.951mmol/g, 0.444mmol/g,0.522mmol/g, 0.847mmol/g.Kinetics and thermodynamics of activated carbon adsorbing two dyes (acid blue 62 and reactive blue KN-R) were studied. The kinetics results showed that the adsorption of each dye by activated carbon followed pseudo second-order kinetic model, and the amount of each dye adsorbed at equilibrium approximated the amount from experiment. The thermodynamics results indicated that acid blue 62 adsorption by activated carbon accorded with both Langumir and Freundlich adsorption isotherm, and reactive blue KN-R adsorption belonged to Langumir adsorption isotherm. The adsorption of two dyes on the activated carbon was endothermic (enthalpy>0), spontaneous (free energy<0) and accompanied by an increase in entropy (entropy>0).The activated carbon from optimum condition was applied on the advanced treatment of dye waste water and compared with the commercial activated carbon. The removal of CODcr was 88% under the condition that pH value was 2, the appropriate dosage was 2g/L, and adsorption time was 60min. It's better than commercial activated carbon. The polluted activated carbon was regenerated by thermal regeneration and solvent regeneration, and the two regeneration process could be used together to achieve better result.The above results indicate that the activated carbon can be employed as an effective, safe and economically adsorption material in treatment of waster that contains large molecular pollutant such as dye and that provided an effective way to make the waste textile an resources.