Coal fly ash(CFA)is composed of minerals containing some oxides in crystalline phase(i.e.,quartz and mullite),as well as unburned carbon as mesoporous material,thus enabling CFA to act as a dual-sites adsorbent with u...Coal fly ash(CFA)is composed of minerals containing some oxides in crystalline phase(i.e.,quartz and mullite),as well as unburned carbon as mesoporous material,thus enabling CFA to act as a dual-sites adsorbent with unique properties.This work focused on the adsorption of Pb(Ⅱ)and Zn(Ⅱ)from binary system,a mixture containing two metal ion solutions present simultaneously,onto NaOH-modified CFA(MCFA).Several adsorption tests were conducted to evaluate the effect of several parameters,including pH and contact times.The experiment results indicated that chemical treatment of CFA with NaOH increased pore volume from 0.021 to 0.223 cm^3·g^(-1).In addition,it could also enhance the availability of functional groups on both minerals and unburned carbon,resulting in almost 100%Pb(Ⅱ)and 97%Zn(Ⅱ)adsorbed.The optimum pH for adsorption system was pH=3 and quasi-equilibrium occurred in 240 minutes.Equilibrium data from the experimental results were analyzed using Modified Extended Langmuir(MEL)and Competitive Adsorption Langmuir-Langmuir(CALL)isotherm models.The analysis results showed that the CALL isotherm model could better describe the Pb(Ⅱ)and Zn(Ⅱ)adsorption process onto MCFA in binary system compared with MEL isotherm model.展开更多
Forming adsorbents FFA-R,FFA-A and FFA-B were prepared from different particle size coal fly ashes FA-R,FA-A and FA-B,their average particle sizes(d_(50)) were 15.75,3.61 and 1.73 μm respectively.The structure an...Forming adsorbents FFA-R,FFA-A and FFA-B were prepared from different particle size coal fly ashes FA-R,FA-A and FA-B,their average particle sizes(d_(50)) were 15.75,3.61 and 1.73 μm respectively.The structure and adsorption properties for Cr^(6+) of forming adsorbents from aqueous solution were studied.The results show that forming adsorbent prepared from the coal fly ash with smaller particle size exhibits higher specific surface area,higher pore volume and better adsorption properties for Cr^(6+).The adsorption kinetics of Cr^(6+) on FFA-R,FFA-A and FFA-B fitts the second order kinetic model and the second adsorption rate constants are 7.523,3.197 and 2.187 mg·g^(-1)·min^(-1/2),respectively.The adsorption of Cr^(6+) on FFA-R,FFA-A and FFA-B can be described in terms of Langmuir isotherms better,and the adsorption processes are spontaneous and exothermic.展开更多
This study aims to investigate the feasibility of using decoration waste powder(DWP)as a partial replacement for fly ash(FA)in the preparation of geopolymer masonry mortar,and to examine the effect of different DWP re...This study aims to investigate the feasibility of using decoration waste powder(DWP)as a partial replacement for fly ash(FA)in the preparation of geopolymer masonry mortar,and to examine the effect of different DWP replacement rates(0%-40%)on the fresh and mechanical properties of the mortar.The results showed that each group of geopolymer masonry mortar exhibited excellent water retention performance,with a water retention rate of 100%,which was due to the unique geopolymer mortar system and high viscosity of the alkaline activator solution.Compared to the control group,the flowability of the mortar containing lower contents of DWP(10%and 20%)was higher.However,as the DWP replacement rate further increased,the flowability gradually decreased.The DWP could absorb the free water in the reaction system of geopolymer mortar,thereby limiting the occurrence of geopolymerization reaction.The incorporation of DWP in the mortar resulted in a decrease in compressive strength compared to the mortar without DWP.However,even at a replacement rate of 40%,the compressive strength of the mortar still exceeded 15 MPa,which met the requirements of the masonry mortar.It was feasible to use DWP in the geopolymer masonry mortar.Although the addition of DWP caused some performance loss,it did not affect its usability.展开更多
The application of forced mercury oxidation technology would lead to an increase of Hg^(2+)concentration in the flue gas.Although Hg^(2+)can be easily removed in the WFGD,the mercury re-emission in the WFGD can decrea...The application of forced mercury oxidation technology would lead to an increase of Hg^(2+)concentration in the flue gas.Although Hg^(2+)can be easily removed in the WFGD,the mercury re-emission in the WFGD can decrease the total removal of mercury from coal-fired power plants.Hence,it is necessary to control Hg^(2+)concentration in the devices before the WFGD.Fly ash adsorbent is considered as a potential alternative for commercial activated carbon adsorbent.However,the adsorption efficiency of the original fly ash is low.Modification procedure is needed to enhance the adsorption performance.In this study,the adsorption of Hg^(2+)by brominated fly ash was studied.The fly ash was collected from the full-scale power plant utilizing bromide-blended coal combustion technology.The brominated fly ash exhibited excellent performance for Hg^(2+)removal.The flue gas component HBr and SO_(2)could improve adsorbent’s performance,while HCl would hinder its adsorption process.Also,it was demonstrated by Hg-TPD experiments that the adsorbed Hg^(2+)mainly existed on the fly ash surface in the form of HgBr_(2).In summary,the brominated fly ash has a broad application prospect for mercury control.展开更多
The geopolymer synthesized by alkali-activated fly ash was firstly used as a novel photocatalyst for degradation of methylene blue (MB) dye from wastewater. The geopolymer is composed of nanoparticulates with an ave...The geopolymer synthesized by alkali-activated fly ash was firstly used as a novel photocatalyst for degradation of methylene blue (MB) dye from wastewater. The geopolymer is composed of nanoparticulates with an average particle size of about 50 nm, More than 90% of pore volume in the fly ash-based geopolymet predominately centralized on the pore size in the range of 17-700 nm. The degradation efficiency of MB dye by fly ash-based geopolymer catalyst was up to 92.79% under UV irradiation due to the synergistic effect of adsorption and semiconductor photocatalysis. The pseudo-first-order and pseudo-second-order rate equations as well as intra-particle diffusion rate equation were employed to correlate analysis for the adsorption kinetics of MB dye, The experimental data agreed well with pseudo-second-order rate equation in both cases of with UV and without UV irradiations. The intra-particle diffusion process is not the rate determining step. The photocatalytic degradation of MB dye in solution obeys third-order reaction kinetics.展开更多
In the “Laguna” region of Coahuila state, Mexico like other places in the world, the groundwater needs to be treated to meet the quality required for human consumption. The study had probed that a Mexican fly ash ca...In the “Laguna” region of Coahuila state, Mexico like other places in the world, the groundwater needs to be treated to meet the quality required for human consumption. The study had probed that a Mexican fly ash can be used as a raw material to obtain effective low cost adsorbents for drinking water treatment, as well evaluated the effects of pH, ion coexistence, dose, arsenic (As) concentration and temperature on the As(V) uptake by using P and W modified zeolites (PMOD and WMOD) obtained from a Mexican fly ash. The As(V) adsorption capacity of the WMOD zeolite was not affected by pH and As(V) concentrations in aqueous solution was achieved 0.01 mg/L in the studied pH range;however, the As(V) removal by using PMOD zeolite decreased at high pH values. Carbonate concentration had a negative effect on the As(V) uptake of both zeolites but this effect was higher for the PMOD zeolite. The maximum adsorption capacities (Qmax) were 76.11 and 44.44 mg of As(V)/g of zeolite for the WMOD and the PMOD zeolites, respectively. The adsorption process was endothermic, spontaneous and occurred by chemical exchange. The experimental data were best interpreted by a pseudo-second order kinetic model. The WMOD zeolite showed a higher adsorption capacity and rate than the PMOD even at the highest evaluated As(V) concentration. The adsorption capacity of the regenerated WMOD zeolite was similar to the original zeolite. Because of the high As(V) adsorption capacity, chemical stability and regenerability, the WMOD zeolite is potentially useful as low-cost adsorbent for As(V) removal from aqueous effluents.展开更多
基金Deanship of Scientific Research(DSR)at King Saud University(KSU),Saudi Arabia for financially supporting this research project(No.RG-1435-078)。
文摘Coal fly ash(CFA)is composed of minerals containing some oxides in crystalline phase(i.e.,quartz and mullite),as well as unburned carbon as mesoporous material,thus enabling CFA to act as a dual-sites adsorbent with unique properties.This work focused on the adsorption of Pb(Ⅱ)and Zn(Ⅱ)from binary system,a mixture containing two metal ion solutions present simultaneously,onto NaOH-modified CFA(MCFA).Several adsorption tests were conducted to evaluate the effect of several parameters,including pH and contact times.The experiment results indicated that chemical treatment of CFA with NaOH increased pore volume from 0.021 to 0.223 cm^3·g^(-1).In addition,it could also enhance the availability of functional groups on both minerals and unburned carbon,resulting in almost 100%Pb(Ⅱ)and 97%Zn(Ⅱ)adsorbed.The optimum pH for adsorption system was pH=3 and quasi-equilibrium occurred in 240 minutes.Equilibrium data from the experimental results were analyzed using Modified Extended Langmuir(MEL)and Competitive Adsorption Langmuir-Langmuir(CALL)isotherm models.The analysis results showed that the CALL isotherm model could better describe the Pb(Ⅱ)and Zn(Ⅱ)adsorption process onto MCFA in binary system compared with MEL isotherm model.
基金Funded by the National Natural Science Foundation of China(No.51278418)the Natural Science Basic Research Plan in Shaanxi Province of China(No.2013K11-10)the Key Laboratory of Environmental Protection&Pollution and Remediation of Water and Soil of Shaanxi Province(Chang’an University)
文摘Forming adsorbents FFA-R,FFA-A and FFA-B were prepared from different particle size coal fly ashes FA-R,FA-A and FA-B,their average particle sizes(d_(50)) were 15.75,3.61 and 1.73 μm respectively.The structure and adsorption properties for Cr^(6+) of forming adsorbents from aqueous solution were studied.The results show that forming adsorbent prepared from the coal fly ash with smaller particle size exhibits higher specific surface area,higher pore volume and better adsorption properties for Cr^(6+).The adsorption kinetics of Cr^(6+) on FFA-R,FFA-A and FFA-B fitts the second order kinetic model and the second adsorption rate constants are 7.523,3.197 and 2.187 mg·g^(-1)·min^(-1/2),respectively.The adsorption of Cr^(6+) on FFA-R,FFA-A and FFA-B can be described in terms of Langmuir isotherms better,and the adsorption processes are spontaneous and exothermic.
基金Funded by the National Natural Science Foundation of China(No.52008046)Young Elite Scientists Sponsorship Program from JSAST(No.TJ-2023-024)Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX21_2848)。
文摘This study aims to investigate the feasibility of using decoration waste powder(DWP)as a partial replacement for fly ash(FA)in the preparation of geopolymer masonry mortar,and to examine the effect of different DWP replacement rates(0%-40%)on the fresh and mechanical properties of the mortar.The results showed that each group of geopolymer masonry mortar exhibited excellent water retention performance,with a water retention rate of 100%,which was due to the unique geopolymer mortar system and high viscosity of the alkaline activator solution.Compared to the control group,the flowability of the mortar containing lower contents of DWP(10%and 20%)was higher.However,as the DWP replacement rate further increased,the flowability gradually decreased.The DWP could absorb the free water in the reaction system of geopolymer mortar,thereby limiting the occurrence of geopolymerization reaction.The incorporation of DWP in the mortar resulted in a decrease in compressive strength compared to the mortar without DWP.However,even at a replacement rate of 40%,the compressive strength of the mortar still exceeded 15 MPa,which met the requirements of the masonry mortar.It was feasible to use DWP in the geopolymer masonry mortar.Although the addition of DWP caused some performance loss,it did not affect its usability.
基金financially supported by the National Key Research and Development Program of China(Grant No.2016YFB0600603)National Natural Science Foundation of China(Grant No.51776084)Shenzhen Science and Technology Innovation Committee(Grant No.JCYJ20190809095003718).
文摘The application of forced mercury oxidation technology would lead to an increase of Hg^(2+)concentration in the flue gas.Although Hg^(2+)can be easily removed in the WFGD,the mercury re-emission in the WFGD can decrease the total removal of mercury from coal-fired power plants.Hence,it is necessary to control Hg^(2+)concentration in the devices before the WFGD.Fly ash adsorbent is considered as a potential alternative for commercial activated carbon adsorbent.However,the adsorption efficiency of the original fly ash is low.Modification procedure is needed to enhance the adsorption performance.In this study,the adsorption of Hg^(2+)by brominated fly ash was studied.The fly ash was collected from the full-scale power plant utilizing bromide-blended coal combustion technology.The brominated fly ash exhibited excellent performance for Hg^(2+)removal.The flue gas component HBr and SO_(2)could improve adsorbent’s performance,while HCl would hinder its adsorption process.Also,it was demonstrated by Hg-TPD experiments that the adsorbed Hg^(2+)mainly existed on the fly ash surface in the form of HgBr_(2).In summary,the brominated fly ash has a broad application prospect for mercury control.
基金financially supported by Industrial Key Project of Shaanxi Province(No.2010K01-080)Open Fund of State Key Laboratory of Architecture Science and Technology in West China(XAUAT)+1 种基金Xi'an University of Architecture and Technology(No.10KF05)Scientific Research Program Funded by Shaanxi Provincial Education Department(No.12JK0579)
文摘The geopolymer synthesized by alkali-activated fly ash was firstly used as a novel photocatalyst for degradation of methylene blue (MB) dye from wastewater. The geopolymer is composed of nanoparticulates with an average particle size of about 50 nm, More than 90% of pore volume in the fly ash-based geopolymet predominately centralized on the pore size in the range of 17-700 nm. The degradation efficiency of MB dye by fly ash-based geopolymer catalyst was up to 92.79% under UV irradiation due to the synergistic effect of adsorption and semiconductor photocatalysis. The pseudo-first-order and pseudo-second-order rate equations as well as intra-particle diffusion rate equation were employed to correlate analysis for the adsorption kinetics of MB dye, The experimental data agreed well with pseudo-second-order rate equation in both cases of with UV and without UV irradiations. The intra-particle diffusion process is not the rate determining step. The photocatalytic degradation of MB dye in solution obeys third-order reaction kinetics.
文摘In the “Laguna” region of Coahuila state, Mexico like other places in the world, the groundwater needs to be treated to meet the quality required for human consumption. The study had probed that a Mexican fly ash can be used as a raw material to obtain effective low cost adsorbents for drinking water treatment, as well evaluated the effects of pH, ion coexistence, dose, arsenic (As) concentration and temperature on the As(V) uptake by using P and W modified zeolites (PMOD and WMOD) obtained from a Mexican fly ash. The As(V) adsorption capacity of the WMOD zeolite was not affected by pH and As(V) concentrations in aqueous solution was achieved 0.01 mg/L in the studied pH range;however, the As(V) removal by using PMOD zeolite decreased at high pH values. Carbonate concentration had a negative effect on the As(V) uptake of both zeolites but this effect was higher for the PMOD zeolite. The maximum adsorption capacities (Qmax) were 76.11 and 44.44 mg of As(V)/g of zeolite for the WMOD and the PMOD zeolites, respectively. The adsorption process was endothermic, spontaneous and occurred by chemical exchange. The experimental data were best interpreted by a pseudo-second order kinetic model. The WMOD zeolite showed a higher adsorption capacity and rate than the PMOD even at the highest evaluated As(V) concentration. The adsorption capacity of the regenerated WMOD zeolite was similar to the original zeolite. Because of the high As(V) adsorption capacity, chemical stability and regenerability, the WMOD zeolite is potentially useful as low-cost adsorbent for As(V) removal from aqueous effluents.