| As a new composite material,core-shell materials is made up of the same or different substance with its core and shell,and the new properties and functions of core-shell materials are endowed with the interaction between components.In this thesis,core-shell technology is applied to the field of formed activated carbon.Using powdered activated carbon as raw material,Carboxymethyl cellulose(CMC)and CMC/silica sol were used as adhesive to prepare core-shell forming activated carbon,which was coated with powder activated carbon in hard porous shell.The effects of adhesive dosage,heat treatment temperature and time on the strength and iodine adsorption value of core-shell formed activated carbon bonded by different adhesives were studied in this thesis.The optimized preparation conditions were obtained,and surface morphology and pore structure characteristics of core-shell activated carbon were characterized by many modern instrument analysis methods.Morphology characteristics and pore structure characteristics of core-shell formed activated carbon were characterized specific surface area and pore size analyzer(ASAP)and scanning electron microscope(SEM),and the thermal stability of core-shell formed activated carbon was characterized by comprehensive thermal analysis instrument(TGA).On this basis,the thesis further investigate the adsorption properties of the core-shell formed activated carbon in gas-phase adsorption(adsorption for benzene)and liquid-phase(adsorption for Pb2+)to providing basic experimental data and theoretical reference for the industrial application of core-shell formed activated carbon.The main contents and significant results in this thesis are as follows:(1)The core-shell formed activated carbon was prepared with using powdered activated carbon as raw material and CMC as adhesive.The preparation conditions of the powder of core carbon and the effects on strength and iodine adsorption value of core-shell formed activated carbon by heat treatment.The results show that the core carbon can be powdered,which is obtained by 0.5wt%CMC addition are treated at 200 ? for 90min.The optimized preparation process of core-shell formed activated carbon is obtained:the CMC addition is 10wt%,shell/core mass ratio of is 3:1,heat treatment temperature is 200?,heat treatment time is 120min.Under this preparation process,strength,iodine adsorption value,specific surface area and total pore volume of core-shell formed activated carbon was 99.94%,986mg·g-1,1375m2·g-1,1.07cm3·g-1,respectively.Adsorption capacity and pore volume and the specific surface area of the core-shell formed activated carbon are between powdered activated carbon and shell-carbon,which indicates that core-shell formed activated carbon combines the structure and properties of powdered carbon and ordinary formed activated carbon.In addition,through the benzene adsorption test,it is found that the adsorption capacity of the saturated benzene on the core-shell formed activated carbon is 426.3mg g'1,and the adsorption process of benzene conforms to pseudo-second-order kinetic model.(2)The core-shell formed activated carbon was prepared with using powdered activated carbon as raw material and CMC/silica sol as adhesive.By investigating the effects of CMC/silica sol addition and heat treatment process on the strength and iodine adsorption value of core-shell formed activated carbon,the optimized preparation process is obtained:the CMC/silica sol addition is 20wt%,heat treatment temperature is 200?,heat treatment time is 120min.Under this preparation condition,strength,iodine adsorption value,specific surface area and total pore volume of core-shell formed activated carbon was 99.96%,922mg·g-1,1139m2·g-1,1.04cm3·g-1,respectively.Adsorption capacity and pore volume and the specific surface area of the core-shell formed activated carbon are between powdered activated carbon and shell-carbon,which indicates that core-shell formed activated carbon combines the structure and properties of powdered carbon and ordinary formed activated carbon.Compared to the core-shell formed activated carbon bonded by CMC,the core-shell formed activated carbon bonded by CMC/silica sol has strong water resistance.In addition,through the Pb2+ adsorption test,it is found that the adsorption capacity of the saturated Pb2+ on core-shell formed activated carbon is 24.8mg·g-1,removal rate is 99.53%,and the adsorption process of Pb2+ conforms to pseudo-second-order kinetic model.(3)The core-shell formed activated carbon was prepared with using powdered activated carbon as raw material,porous material(such as sepiolite)as additive and CMC/silica sol as adhesive.The effect of sepiolite addition on the structure properties of core-shell formed activated carbon was investigated.The results show that with the increase of sepiolite addition,the mesoporous rate of core-shell formed activated carbon increases.It is found that sepiolite is embedded in the middle of the shell observed by scanning electron microscope,which is beneficial to strengthening the strength and water resistance of core-shell formed activated carbon,but the iodine adsorption value of the sepiolite is greatly reduced. |
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