The problem of water and sulfur poisoning in flue gas atmosphere remains a significant obstacle for low-temperature deNO_(x) catalysts.This study investigated the sulfation mechanism of the CoMn_(2)O_(4)/CeTiO_(x)(CMC...The problem of water and sulfur poisoning in flue gas atmosphere remains a significant obstacle for low-temperature deNO_(x) catalysts.This study investigated the sulfation mechanism of the CoMn_(2)O_(4)/CeTiO_(x)(CMCT)catalyst during the selective catalytic reduction of NO_(x) with NH3 under conditions containing H2O and SO_(2) at 150℃.Employing a comprehensive suite of time-resolved analysis and characterization techniques,the evolution of sulfate species was systematically categorized into three stages:initial rapid surface sulfate accumulation,the transformation of surface sulfates to bulk metal sulfates,and partial sulfates decomposition after the removal of H2O and SO_(2).These findings indicate that bulk metal sulfates irreversibly deactivate the catalyst by distorting active component lattices and consuming oxygen vacancies,whereas surface sulfates(including ammonium sulfates and surface-coordinated metal sulfates)cause reversible performance loss through decomposition.Furthermore,the competitive adsorption of H2O and SO_(2) significantly influences the catalytic efficiency,with H2O suppressing SO_(2) adsorption while simultaneously enhancing the formation of Brönsted acid sites.This research underscores the critical role of sulfate dynamics on catalyst performance,revealing the enhanced SO_(2) resistance of the Eley-Rideal mechanism facilitated by the Ce-Ti support relative to the Langmuir-Hinshelwood pathway.Collectively,the study unravels the complex interplay of sulfate dynamics influencing catalyst performance and provides potential approaches to mitigate deactivation in demanding atmospheric conditions.展开更多
The batch photodegradation reactor was used to investigate the influence of the common coexisting substances in wastewater,such as H+,anions (HCO3-,Cl-and NO3-) and organic compounds (methanol and bisphenol A),on the ...The batch photodegradation reactor was used to investigate the influence of the common coexisting substances in wastewater,such as H+,anions (HCO3-,Cl-and NO3-) and organic compounds (methanol and bisphenol A),on the photodegradation behaviors of EE2 in the UV/H2O2 process.The results indicated that the addition of coexisting substances can influence the photodegradation behaviors of EE2 and it also follows the first-order kinetics.The acidic (pH 2-4) and alkaline (pH 10-12) medium benefit the photodegradation of EE2,but the photodegradation rate constant of EE2 keeps almost constant in the pH value of 4-10.The addition of anions,such as HCO3-,Cl-and NO3-,can inhibit the photodegradation of EE2,and the rate constant has a negative linear relationship with the concentration of the anions.However,the reduction degrees vary with the anions kinds,and the inhibition effect of the three anions is in the order of HCO3->NO3->Cl-.Addition of 5 mg/L methanol and bisphenol A can reduce the photodegradation rate constant of EE2by 84.31% and 72%,respectively.By comparison,the retardant effect of methanol is much more evident.In the studied concentrations range,the photodegradation rate constant of EE2 is the unary quadratic function of the organic compounds concentrations.展开更多
Here we report that the presence of MgCO_(3) stimulates the extracellular polymeric substance (EPS) secretion of Microcystis Aeruginosa (M. Aeruginosa). This stimulation led to a significant reduction in the total con...Here we report that the presence of MgCO_(3) stimulates the extracellular polymeric substance (EPS) secretion of Microcystis Aeruginosa (M. Aeruginosa). This stimulation led to a significant reduction in the total concentration of NH_(4)^(+)‒N by more than 86%, and effective recovery of PO_(4)^(3-)‒P within three days from concentrated wastewater (WW), although the secreted EPS inhibited the conversion of MgCO_(3) to specific crystal forms (MgNH4PO4.6H2O or MgHPO4.7H2O). Moreover, with an increase in PO_(4)^(3-) concentration in WW, these crystals appeared, thus the removal of NH_(4)^(+)‒N and PO_(4)^(3-)‒P nutrients can be attributed to the combined effect of M. Aeruginosa and MgCO_(3). We used Surface-Enhanced Raman Spectroscopy (SERS) combined with X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy with Energy-Dispersive X-ray Spectroscopy (FESEM-EDS), and X-ray Photoelectron Spectroscopy (XPS) to investigate the mechanism for competitive interactions between M. Aeruginosa and MgCO_(3) in removing NH_(4)^(+)‒N and PO_(4)^(3-)‒P. We identified that the bound EPS accumulated amorphous Mg–P–O dense particles on M. Aeruginosa, while soluble EPS, containing –COOH groups of humic-like substances decreased the pH of the solution and coordinated with Mg^(2+) ions. Therefore, both secreted bound and soluble EPS play a vital role in hindering the transformation of Mg^(2+) ions or MgCO_(3) to MgNH4PO4.6H2O or MgHPO4.7H2O crystals within WW, and they enhanced M. Aeruginosa 's ability in absorbing nutrients of NH_(4)^(+)‒N and PO_(4)^(3-)‒P. This mechanism plays a crucial role in the efficient recovery of NH_(4)^(+)‒N and PO_(4)^(3-)‒P from concentrated wastewater sources such as aerobically or anaerobically digested effluent from various sources like agriculture, livestock, and domestic wastewaters.展开更多
A new inorganic-organic hybrid framework microporous material Cd 3(BDC) 0.5(BTC) 2·(DMF)(H 2O)·3DMF·H 3O·H 2O, in which two kinds of carboxylate ligands coordinate with cadmium ions synchronously, ...A new inorganic-organic hybrid framework microporous material Cd 3(BDC) 0.5(BTC) 2·(DMF)(H 2O)·3DMF·H 3O·H 2O, in which two kinds of carboxylate ligands coordinate with cadmium ions synchronously, was obtained under a mild synthesis condition. The titled compound is crystallized in a monoclinic system, space group P2(1)/c with a=1.584 7(7) nm, b=1.426 7(6) nm, c=1.936 3(6) nm, β=113.186(7)°, V=4.024 6(3) nm 3, Z=4, D X=1.947 mg/m 3, M r=1 179.92, μ=1.662 mm -1, F(000)=2 344, R=0.074 8, wR=0.215 1. Three cadmium centers link with each other through BDC or BTC ligand to form a 3-D open framework.展开更多
文摘The problem of water and sulfur poisoning in flue gas atmosphere remains a significant obstacle for low-temperature deNO_(x) catalysts.This study investigated the sulfation mechanism of the CoMn_(2)O_(4)/CeTiO_(x)(CMCT)catalyst during the selective catalytic reduction of NO_(x) with NH3 under conditions containing H2O and SO_(2) at 150℃.Employing a comprehensive suite of time-resolved analysis and characterization techniques,the evolution of sulfate species was systematically categorized into three stages:initial rapid surface sulfate accumulation,the transformation of surface sulfates to bulk metal sulfates,and partial sulfates decomposition after the removal of H2O and SO_(2).These findings indicate that bulk metal sulfates irreversibly deactivate the catalyst by distorting active component lattices and consuming oxygen vacancies,whereas surface sulfates(including ammonium sulfates and surface-coordinated metal sulfates)cause reversible performance loss through decomposition.Furthermore,the competitive adsorption of H2O and SO_(2) significantly influences the catalytic efficiency,with H2O suppressing SO_(2) adsorption while simultaneously enhancing the formation of Brönsted acid sites.This research underscores the critical role of sulfate dynamics on catalyst performance,revealing the enhanced SO_(2) resistance of the Eley-Rideal mechanism facilitated by the Ce-Ti support relative to the Langmuir-Hinshelwood pathway.Collectively,the study unravels the complex interplay of sulfate dynamics influencing catalyst performance and provides potential approaches to mitigate deactivation in demanding atmospheric conditions.
基金Sponsored by the Key Project of National Science Foundation of China (Grant NO.50638020)the National High Technology Research and Development Program of China (Grant No.2007AA06A411)the State Key Laboratory of Urban Water Resource & Environment (Grant No.2009TS04)
文摘The batch photodegradation reactor was used to investigate the influence of the common coexisting substances in wastewater,such as H+,anions (HCO3-,Cl-and NO3-) and organic compounds (methanol and bisphenol A),on the photodegradation behaviors of EE2 in the UV/H2O2 process.The results indicated that the addition of coexisting substances can influence the photodegradation behaviors of EE2 and it also follows the first-order kinetics.The acidic (pH 2-4) and alkaline (pH 10-12) medium benefit the photodegradation of EE2,but the photodegradation rate constant of EE2 keeps almost constant in the pH value of 4-10.The addition of anions,such as HCO3-,Cl-and NO3-,can inhibit the photodegradation of EE2,and the rate constant has a negative linear relationship with the concentration of the anions.However,the reduction degrees vary with the anions kinds,and the inhibition effect of the three anions is in the order of HCO3->NO3->Cl-.Addition of 5 mg/L methanol and bisphenol A can reduce the photodegradation rate constant of EE2by 84.31% and 72%,respectively.By comparison,the retardant effect of methanol is much more evident.In the studied concentrations range,the photodegradation rate constant of EE2 is the unary quadratic function of the organic compounds concentrations.
基金supported by Cultivating Fund Project of Hubei Hongshan Laboratory(2022hspy002).
文摘Here we report that the presence of MgCO_(3) stimulates the extracellular polymeric substance (EPS) secretion of Microcystis Aeruginosa (M. Aeruginosa). This stimulation led to a significant reduction in the total concentration of NH_(4)^(+)‒N by more than 86%, and effective recovery of PO_(4)^(3-)‒P within three days from concentrated wastewater (WW), although the secreted EPS inhibited the conversion of MgCO_(3) to specific crystal forms (MgNH4PO4.6H2O or MgHPO4.7H2O). Moreover, with an increase in PO_(4)^(3-) concentration in WW, these crystals appeared, thus the removal of NH_(4)^(+)‒N and PO_(4)^(3-)‒P nutrients can be attributed to the combined effect of M. Aeruginosa and MgCO_(3). We used Surface-Enhanced Raman Spectroscopy (SERS) combined with X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy with Energy-Dispersive X-ray Spectroscopy (FESEM-EDS), and X-ray Photoelectron Spectroscopy (XPS) to investigate the mechanism for competitive interactions between M. Aeruginosa and MgCO_(3) in removing NH_(4)^(+)‒N and PO_(4)^(3-)‒P. We identified that the bound EPS accumulated amorphous Mg–P–O dense particles on M. Aeruginosa, while soluble EPS, containing –COOH groups of humic-like substances decreased the pH of the solution and coordinated with Mg^(2+) ions. Therefore, both secreted bound and soluble EPS play a vital role in hindering the transformation of Mg^(2+) ions or MgCO_(3) to MgNH4PO4.6H2O or MgHPO4.7H2O crystals within WW, and they enhanced M. Aeruginosa 's ability in absorbing nutrients of NH_(4)^(+)‒N and PO_(4)^(3-)‒P. This mechanism plays a crucial role in the efficient recovery of NH_(4)^(+)‒N and PO_(4)^(3-)‒P from concentrated wastewater sources such as aerobically or anaerobically digested effluent from various sources like agriculture, livestock, and domestic wastewaters.
文摘A new inorganic-organic hybrid framework microporous material Cd 3(BDC) 0.5(BTC) 2·(DMF)(H 2O)·3DMF·H 3O·H 2O, in which two kinds of carboxylate ligands coordinate with cadmium ions synchronously, was obtained under a mild synthesis condition. The titled compound is crystallized in a monoclinic system, space group P2(1)/c with a=1.584 7(7) nm, b=1.426 7(6) nm, c=1.936 3(6) nm, β=113.186(7)°, V=4.024 6(3) nm 3, Z=4, D X=1.947 mg/m 3, M r=1 179.92, μ=1.662 mm -1, F(000)=2 344, R=0.074 8, wR=0.215 1. Three cadmium centers link with each other through BDC or BTC ligand to form a 3-D open framework.
