Refined carbon(RC) derived from coal fly ash(CFA) as well as powdered activated carbon(PAC) was investigated as adsorbent to remove residual amine collector HAY from aqueous solution.The RC and PAC were characterized ...Refined carbon(RC) derived from coal fly ash(CFA) as well as powdered activated carbon(PAC) was investigated as adsorbent to remove residual amine collector HAY from aqueous solution.The RC and PAC were characterized by scanning electron microscopy(SEM),surface area measurement,Zeta potential measurement and Fourier transform infrared(FTIR) spectroscopy.The effect factors and mechanisms of HAY adsorption onto RC and PAC were studied in detail.The results show that the experimental kinetic data agree well with the pseudo second-order equation,and the Langmuir isotherm model is found to be more appropriate to explicate the experimental equilibrium isotherm results than the Freundlich model.The adsorption capacities of PAC and RC increase with pH.It is found that alkaline condition is conducive to the adsorption of HAY onto PAC and RC and the adsorption efficiency of RC is close to PAC at pH near 11.Zeta potential variation of adsorbents suggests that HAY generates electrostatic adsorption onto RC and PAC.FTIR analysis shows that the adsorption is dominantly of a physical process.The Box-Behnken design optimization conditions of process are RC 1 g/L,pH 11,temperature 302 K and initial HAY concentration 100 mg/L.Under these conditions,the measured adsorption ratio and adsorption capacity are 87.91%and 87.91 mg/g,respectively.Thus,the RC is considered to be a potential adsorbent for the removal of residual amine from aqueous solution.展开更多
The adsorption capacity for vapor-phase elemental mercury(Hg0) of residual carbon separated from fly ash was studied in an attempt for the control of elemental mercury emissions from combustion processes. At low mercu...The adsorption capacity for vapor-phase elemental mercury(Hg0) of residual carbon separated from fly ash was studied in an attempt for the control of elemental mercury emissions from combustion processes. At low mercury concentrations(<200 μg/m3), unburned carbon had higher adsorption capacity than commercial activated carbon. The adsorbality of unburned carbon was also found to be source dependent. Isotherms of FS carbon(separated from fly ash of a power plant of Shishi in Fujian Province) were similar to those classified as typeⅡ. Isotherms of XJ carbon(separated from fly ash of a power plant of Jingcheng in Shanxi Province) were more like those classified as type Ⅲ. Due to the relatively low production costs, these residual carbons would likely be considerably more cost-effective for the full-scale removal of mercury from combustion flue gases than other technology.展开更多
A model was developed to describe the adsorption characteristic of mercury in flue gas based on one residual carbon sample and one activated carbon sample. The differential equations were established with mass balance...A model was developed to describe the adsorption characteristic of mercury in flue gas based on one residual carbon sample and one activated carbon sample. The differential equations were established with mass balance of mercury in the gas phase and in the solid phase. Then the model was solved using a Matlab program with a Runge-Kutta process. The mercury adsorption isotherms of these two adsorbents were obtained by breakthrough column experiments. The results show that at low gas phase mercury concentrations （ 〈 0. 3 mg/ m^3）, the adsorption equilibrium of residual carbon is in accord with the case of a type Ⅱ isotherm of the Freundich theory. Whereas the data of activated carbon falls into the Langmuir relationship, it is the case of a type Ⅲ isotherm. The experimental data were fitted to the Freundlich model by Matlab software. The variances of mercury concentration are smaller than 0. 81 which implies the agreement between measurements and simulation is quite agreeable considering the wide scatter of the measurements. This model is useful for forecasting mercury removal efficiency and is helpful to the mechanism analysis of mercury adsorption on carbon-based adsorbent.展开更多
基金Projects(2013BAB07B03,2013BAC15B01)supported by the National Key Technology Research and Development Program of the Ministry of Science and Technology of ChinaProject(51264005)supported by the National Natural Science Foundation of China+1 种基金Project(Qiankehejz[2014]2009)supported by the Key Foundation of Science and Technology of Guizhou Province,ChinaProject([2013]019)supported by“125”Major Special Project of Guizhou Province,China
文摘Refined carbon(RC) derived from coal fly ash(CFA) as well as powdered activated carbon(PAC) was investigated as adsorbent to remove residual amine collector HAY from aqueous solution.The RC and PAC were characterized by scanning electron microscopy(SEM),surface area measurement,Zeta potential measurement and Fourier transform infrared(FTIR) spectroscopy.The effect factors and mechanisms of HAY adsorption onto RC and PAC were studied in detail.The results show that the experimental kinetic data agree well with the pseudo second-order equation,and the Langmuir isotherm model is found to be more appropriate to explicate the experimental equilibrium isotherm results than the Freundlich model.The adsorption capacities of PAC and RC increase with pH.It is found that alkaline condition is conducive to the adsorption of HAY onto PAC and RC and the adsorption efficiency of RC is close to PAC at pH near 11.Zeta potential variation of adsorbents suggests that HAY generates electrostatic adsorption onto RC and PAC.FTIR analysis shows that the adsorption is dominantly of a physical process.The Box-Behnken design optimization conditions of process are RC 1 g/L,pH 11,temperature 302 K and initial HAY concentration 100 mg/L.Under these conditions,the measured adsorption ratio and adsorption capacity are 87.91%and 87.91 mg/g,respectively.Thus,the RC is considered to be a potential adsorbent for the removal of residual amine from aqueous solution.
基金The National Natural Science Foundation of China(No. 50306010) and the National Basic Research Program(973) of China(No. G1999022200)
文摘The adsorption capacity for vapor-phase elemental mercury(Hg0) of residual carbon separated from fly ash was studied in an attempt for the control of elemental mercury emissions from combustion processes. At low mercury concentrations(<200 μg/m3), unburned carbon had higher adsorption capacity than commercial activated carbon. The adsorbality of unburned carbon was also found to be source dependent. Isotherms of FS carbon(separated from fly ash of a power plant of Shishi in Fujian Province) were similar to those classified as typeⅡ. Isotherms of XJ carbon(separated from fly ash of a power plant of Jingcheng in Shanxi Province) were more like those classified as type Ⅲ. Due to the relatively low production costs, these residual carbons would likely be considerably more cost-effective for the full-scale removal of mercury from combustion flue gases than other technology.
文摘A model was developed to describe the adsorption characteristic of mercury in flue gas based on one residual carbon sample and one activated carbon sample. The differential equations were established with mass balance of mercury in the gas phase and in the solid phase. Then the model was solved using a Matlab program with a Runge-Kutta process. The mercury adsorption isotherms of these two adsorbents were obtained by breakthrough column experiments. The results show that at low gas phase mercury concentrations （ 〈 0. 3 mg/ m^3）, the adsorption equilibrium of residual carbon is in accord with the case of a type Ⅱ isotherm of the Freundich theory. Whereas the data of activated carbon falls into the Langmuir relationship, it is the case of a type Ⅲ isotherm. The experimental data were fitted to the Freundlich model by Matlab software. The variances of mercury concentration are smaller than 0. 81 which implies the agreement between measurements and simulation is quite agreeable considering the wide scatter of the measurements. This model is useful for forecasting mercury removal efficiency and is helpful to the mechanism analysis of mercury adsorption on carbon-based adsorbent.
