Preparation Of Sludge Activated Carbon And Adsorption Properties Of Phenol On It

The urban sewage treatment plants has been built on a large scale with the development of urbanization and the increasing demands of people on ecological environment.As the by-product of sewage treatment,the production of sludge has greatly increased.How to avoid the harm of sewage sludge and reasonable disposal of that has aroused people's urgent concern.The preparation of safe and cheap porous activated carbon from sewage sludge is expected to substitute expensive commercial activated carbon in some field,which is considered to be a potential method for sludge utilization,and some positive results have been achieved.Howeve,the preparation and application of sludge activated carbon remains to be further research,such as modification of sludge activated carbon,the development and utilization of new chemicals and efficiency problem of sludge activated carbon in practical application.In this paper,the residual sludge of urban sewage treatment plant is as the main raw material,and 25%of peanut shell powder is used as carbon source additive,and chemical activation method is adopted to prepare the sludge activated carbon?FSPAC?with FeCl₃·6H₂O as activating agent.The factors influencing the preparation of activated carbon from sludge were optimized by orthogonal test and single factor experiment.The best preparation conditions for sludge activated carbon is the terminal temperature 700?,the terminal temperature activator to add ratio 0.5 and residence time of 1.5 h.A porous activated sludge?FSPAC?was successfully prepared,which BET surface area is 780.56 m²/g,total pore volume is 0.859 cm³/g,and micropore volume is 0.293 cm³/g.Scanning electron microscopy?SEM?was used to observe FSPAC and which showed a developed pore structure.The thermal gravimetric analyzer?TGA?analysis showed that the activating agent promoted the deep decomposition of organic components in raw materials.The appropriate dose of activating agent is an important factor for preparation of FSPAC with high specific surface area and developed pore structure.The results of fourier transform infrared spectrometer?FT-IR?analysis showed that there were a lot of functional groups on FSPAC surface,including O-H,C-O,C=C and C=O,and the activating agent had a certain effect on the surface properties of FSPAC.The analysis results of heavy metal leaching of FSPAC showed that the FSPAC can be safely used within a certain range,because the heavy metals in FSPAC were effectively stabilized and became less solublized.Adsorption of phenol in water by FSPAC was studied.The effects of FSPAC dosage and pH on FSPAC adsorption on phenol were studied.The results showed that with the increase of FSPAC dosage,the adsorption capacity of FSPAC decreased,and the reasonable FSPAC dosage was 1mg/L.In the pH range of 4⁹,the adsorption capacity of phenol on FSPAC increased slightly with the increase of pH.When the pH>9,the adsorption capacity decreased,and the alkaline environment was not conducive to the phenol adsorption on FSPAC.The adsorption kinetics results showed that the adsorption of phenol on FSPAC conformed to the second-order dynamic adsorption equation,and physical adsorption and chemical adsorption occurred in the adsorption system.The results of isothermal experiments showed that the freundlich isothermal equation suitably described the adsorption behavior of phenol on FSPAC,and the adsorption of phenol belonged to endothermic reaction.The maximum equilibrium adsorption capacity of phenol in synthetic wastewater was 109.58 mg/g under 298 K,which was higher than that of other sludge activated carbon in many literatures.