| With the rapid development of China's economy and the increase of urban sewage treatment plants,the output of sludge is increasing rapidly.At present,80%of the sludge is not stabilized treatment,which has brought serious environmental pollution.Activated carbon has an abundant pore structure and a huge specific surface area.It has been widely used in industry,national defense,transportation,medicine and health care,environmental protection and other fields.The preparation of activated carbon by using sewage sludge can not only reduce solid waste pollution,but also facilitate the resource utilization of sludge.Hence,the related research has become a hot issue.However,the activated carbon made by sewage sludge has some disadvantages such as low carbon content,relatively low surface area and high ash content.To improve the quality of activated carbon,peanut shell was added to sludge in this paper,and the magnetic sludge-peanut shell based composite activated carbon(MSPSAC)was prepared.The adsorption characteristics of azo dyes methyl orange and reactive brilliant red K-2BP onto MSPSAC were studied,and the related adsorption mechanisms were discussed.The main contents and conclusions of this paper are as follows:].Preparation of magnetic sludge-peanut shell based composite activated carbonWith two kinds of solid waste,sewage sludge and peanut shell,used as raw materials,MSPSAC was prepared in the existence of potassium carbonate K2CO3and Fe3O4.The influences of several operating parameters,such as the ratio of sludge to peanut shell,the dosage of K2CO3 and Fe3O4,contact time,adsorbent dose,activation temperature and activation time were investigated in batch mode.The results showed that the optimal conditions are 5g of raw material with 65%sludge,1.5g of K2CO3,0.5g of Fe304,activation temperature of 750 ? and activation time of 1h,.The obtained MSPSAC has an iodine value of 630.24 mg/g and a methylene blue value of 370.35 mg/g.2.Characterization of magnetic sludge-peanut shell based composite activated carbonThe obtained MSPSAC was characterized by using scanning electron microscope(SEM),(SEM),specific surface area and pore size distribution,X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR),Bohem titration method,X-ray diffraction(XRD),vibrating sample magnetometer,etc.The results show that MSPSAC has a loose and porosity structure.saturated magnetic intensity,and so on.The surface of magnetic sludge-peanut shell-based composite activated carbon Morphology,pore structure,phase,surface functional groups and magnetic properties were characterized.Its The results show that the structure of the composite activated carbon is fluffy and the porous structure is more developed.The specific surface area,total pore volume and average pore diameterare is 665.477m2/g,the total pore volume is 0.3617cm3/g and the average pore diameter is 2.306nm,respectively.There are rich acid functional groups including Its surface contains hydroxyl,carboxyl,lactone,phenolic hydroxyl and other acidic functional groups on the surface of MSPSAC,and,the total content amount is of 1.5358mmol/g.The magnetic additive agentaddition of Fe3O4 is finally converted to iron carbide with a saturation magnetizationmagnetic valuestrength of 2.67Am2/kg,which allows can be magnetically separated from a suspended system by using an external magnetic field.(3)Adsorption characteristics of magnetic sludge-based composite peanut shell activated carbon on methyl orange and reactive brilliant red K-2BPIn 2 kinds of azo dyes as adsorbent,self-made composite activated carbon as adsorbent.The influence of pH,adsorption time,adsorbent dose,methyl orange concentration and temperature of solution were investigated in batch mode.The related kinetic and equilibrium data were fitted with different models,and the thermodynamic data were calculated.The results show that.(a)the solution pH only has small effects on the adsorption of methyl orange on MSPSAC at pH 5-12.The adsorption time,methyl orange concentration and temperature were positively correlated with the amount of adsorption,while adsorbent dose was negatively correlated.The adsorption reached equilibrium at 2h.Pseudo-second-order kinetic model and Langmuir model can better describe the adsorption behavior of methyl orange on MSPDAC.The adsorption process is spontaneous,and the maximum monolayer adsorption capacity is 216.83mg/g at 40?.(b)the removal of reactive brilliant red K-2BP decreased rapidly and then tended the equilibrium with increasing solution pH from 2 to 9.The adsorption time,initial concentration of activated brilliant K-2BP and solution temperature were positively correlated with the amount of adsorption,while adsorbent dose was negatively correlated.The adsorption reached equilibrium at2h.Pseudo-second-order kinetic model and Langmuir model can better describe the adsorption behavior of reactive brilliant red K-2BP on MSPSAC.The adsorption process is spontaneous,and the maximum monolayer adsorption capacity is 2693.69mg/g at 40?... |
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