Common activations of sulfite(S(Ⅳ))-based advanced oxidation processes(AOPs)utilized metal ions and oxides as catalysts,which are constrained by challenges in catalyst recovery,inadequate stability,and susceptibility...Common activations of sulfite(S(Ⅳ))-based advanced oxidation processes(AOPs)utilized metal ions and oxides as catalysts,which are constrained by challenges in catalyst recovery,inadequate stability,and susceptibility to secondary pollution in application.Calcium sulfite(CaSO_(3)),one of the byproducts of flue gas desulfurization,is of interest in AOPs because of its ability to slowly release S(Ⅳ),low toxicity,and costeffectiveness.Therefore,a heterogenous activator,molybdenum carbide(Mo_(2)C)was selected to stimulate Ca SO3for typical antibiotic elimination.Benefiting from the dissociation form of HSO_(3^(-))from CaSO_(3)and improved electron transfer of Mo_(2)C at pH 6,the simulated target metronidazole(MTZ)can be removed by 85.65%with rate constant of 0.02424 min^(-1)under near-neutral circumstance.The combining determinations of quenching test,electron spin resonance spectrum,and reactive species probe demonstrated singlet oxygen(^(1)O_(2))and sulfate radicals played leading role for MTZ decontamination.Characterization and theoretical calculation suggested the alteration of Mo valence state drove the activation of S(Ⅳ),and revealed that dissolved oxygen promoted the adsorption of HSO_(3^(-))on the surface of Mo_(2)C,then facilitating production of^(1)O_(2).The favorable stability and applicability for Mo_(2)C/CaSO_(3)process indicated an applied prospect in actual pharmaceutical wastewater.展开更多
Constant load tests in NS4 solution purged with N2-5%CO2 gas mixture were conducted on American Petroleum Institute （API） X80 pipeline steel applied in the 2nd West-East （;as Pipeline project with and without prelo...Constant load tests in NS4 solution purged with N2-5%CO2 gas mixture were conducted on American Petroleum Institute （API） X80 pipeline steel applied in the 2nd West-East （;as Pipeline project with and without preload. The results show that cracks could initiate and propagate in X80 pipeline steel in near-neutral pH environment under a constant load condition. The life of crack initiation and propagation increased with decreasing applied stress. Preload did not change its corrosion behavior obviously. However, preload reduced the time for crack initiation.展开更多
The stress corrosion cracking (SCC) behaviour of X-70 pipeline steel in near-neutral pH solutions was studied via slow strain rate testing (SSRT). The results showed that the cracking mode of X-70 pipeline steel in ne...The stress corrosion cracking (SCC) behaviour of X-70 pipeline steel in near-neutral pH solutions was studied via slow strain rate testing (SSRT). The results showed that the cracking mode of X-70 pipeline steel in near-neutral pH solutions was transgranular at different temperatures and applied potentials with the feature of quasi-cleavage. The pH value of the solution decreased with increasing the addition of CO2, which increased the susceptibility to SCC. SCC susceptibility increased as the applied potential moved towards the cathodic direction, suggesting that hydrogen induced cracking (HIC) dominated the cracking process at cathodic potentials. The slight decrease of pH values with decreasing temperature of the solution increased the susceptibility to SCC, which attributed to the change of solubility of CO2 in the solution at different temperatures. The propagating directions of SCC cracks were different at different potentials. At rather negative cathodic potentials, the cracks were almost perpendicular to the tensile axis, while at free corrosion potential and near anodic potentials, cracks were nearly at 45 degree, and in the range of moderate cathodic potentials both propagating directions could be observed.展开更多
The cracking behaviour of X-70 pipeline steel in near-neutral pH solutions was studied under different modes of cyclic loading. The crack propagation process of X-70 pipeline steel under low frequency cyclic loading c...The cracking behaviour of X-70 pipeline steel in near-neutral pH solutions was studied under different modes of cyclic loading. The crack propagation process of X-70 pipeline steel under low frequency cyclic loading condition was controlled mainly by stress corrosion cracking （SCC） mechanism. Under mixed-mode cyclic loading, both higher tensile stress and shear stress made cracks easier to propagate. Applied cathodic potentials and high content of carbon dioxide in solutions also promoted the propagation of cracks. The propagation directions of cracks were different under different cyclic loading conditions. Under mode I （pure tensile stress） cyclic loading condition, cracks were straight and perpendicular to the tensile stress axis, while under mixed-mode 1/111 （tensile/shear stress） cyclic loading,cracks were sinuous and did not propagate in the direction perpendicular to the main tensile stress axis. Under the mixed-mode cyclic loading, cracks were much easier to propagate, suggesting that shear stress intensified the role of tensile stress. In addition, shear stress promoted the interaction between cracks, resulting in easier coalescence of cracks.展开更多
基金the support received from the National Natural Science Foundation of China(No.51908485)the Central Guidance on Local Science and Technology Development Fund of Hebei Province(Nos.246Z3603G and 226Z3603G)。
文摘Common activations of sulfite(S(Ⅳ))-based advanced oxidation processes(AOPs)utilized metal ions and oxides as catalysts,which are constrained by challenges in catalyst recovery,inadequate stability,and susceptibility to secondary pollution in application.Calcium sulfite(CaSO_(3)),one of the byproducts of flue gas desulfurization,is of interest in AOPs because of its ability to slowly release S(Ⅳ),low toxicity,and costeffectiveness.Therefore,a heterogenous activator,molybdenum carbide(Mo_(2)C)was selected to stimulate Ca SO3for typical antibiotic elimination.Benefiting from the dissociation form of HSO_(3^(-))from CaSO_(3)and improved electron transfer of Mo_(2)C at pH 6,the simulated target metronidazole(MTZ)can be removed by 85.65%with rate constant of 0.02424 min^(-1)under near-neutral circumstance.The combining determinations of quenching test,electron spin resonance spectrum,and reactive species probe demonstrated singlet oxygen(^(1)O_(2))and sulfate radicals played leading role for MTZ decontamination.Characterization and theoretical calculation suggested the alteration of Mo valence state drove the activation of S(Ⅳ),and revealed that dissolved oxygen promoted the adsorption of HSO_(3^(-))on the surface of Mo_(2)C,then facilitating production of^(1)O_(2).The favorable stability and applicability for Mo_(2)C/CaSO_(3)process indicated an applied prospect in actual pharmaceutical wastewater.
基金supported by the National Natural Science Foundation of China (Grant No. 51025104)
文摘Constant load tests in NS4 solution purged with N2-5%CO2 gas mixture were conducted on American Petroleum Institute （API） X80 pipeline steel applied in the 2nd West-East （;as Pipeline project with and without preload. The results show that cracks could initiate and propagate in X80 pipeline steel in near-neutral pH environment under a constant load condition. The life of crack initiation and propagation increased with decreasing applied stress. Preload did not change its corrosion behavior obviously. However, preload reduced the time for crack initiation.
基金This work was supported by the Special Funds for the Major State Basic Research Projects G19990650 in China,also supported by the Science and Technology Commission of Shanghai Municipality via projects 025258036 and 02ZE14031.
文摘The stress corrosion cracking (SCC) behaviour of X-70 pipeline steel in near-neutral pH solutions was studied via slow strain rate testing (SSRT). The results showed that the cracking mode of X-70 pipeline steel in near-neutral pH solutions was transgranular at different temperatures and applied potentials with the feature of quasi-cleavage. The pH value of the solution decreased with increasing the addition of CO2, which increased the susceptibility to SCC. SCC susceptibility increased as the applied potential moved towards the cathodic direction, suggesting that hydrogen induced cracking (HIC) dominated the cracking process at cathodic potentials. The slight decrease of pH values with decreasing temperature of the solution increased the susceptibility to SCC, which attributed to the change of solubility of CO2 in the solution at different temperatures. The propagating directions of SCC cracks were different at different potentials. At rather negative cathodic potentials, the cracks were almost perpendicular to the tensile axis, while at free corrosion potential and near anodic potentials, cracks were nearly at 45 degree, and in the range of moderate cathodic potentials both propagating directions could be observed.
基金This work was supported by the Special Funds for the Major State Basic Research Projects in China(No.G19990650)also supported by the Science and Technology Comm is—sion of Shanghai Municipality(Projects Nos.025258036 and 02ZE14031
文摘The cracking behaviour of X-70 pipeline steel in near-neutral pH solutions was studied under different modes of cyclic loading. The crack propagation process of X-70 pipeline steel under low frequency cyclic loading condition was controlled mainly by stress corrosion cracking （SCC） mechanism. Under mixed-mode cyclic loading, both higher tensile stress and shear stress made cracks easier to propagate. Applied cathodic potentials and high content of carbon dioxide in solutions also promoted the propagation of cracks. The propagation directions of cracks were different under different cyclic loading conditions. Under mode I （pure tensile stress） cyclic loading condition, cracks were straight and perpendicular to the tensile stress axis, while under mixed-mode 1/111 （tensile/shear stress） cyclic loading,cracks were sinuous and did not propagate in the direction perpendicular to the main tensile stress axis. Under the mixed-mode cyclic loading, cracks were much easier to propagate, suggesting that shear stress intensified the role of tensile stress. In addition, shear stress promoted the interaction between cracks, resulting in easier coalescence of cracks.
