The thermodynamics equilibrium principle was used to construct the diagrams for the concentration of complex ions(pc) vs pH,the distribution ratio of lead hydroxyl complex ions(αn) vs pH,and the conditional solubilit...The thermodynamics equilibrium principle was used to construct the diagrams for the concentration of complex ions(pc) vs pH,the distribution ratio of lead hydroxyl complex ions(αn) vs pH,and the conditional solubility product of Pb(OH)2 vs pH in the Pb2+-H2O system. The relationship between the equilibrium concentration of each kind of lead hydroxyl complex ions in equilibrium with Pb(OH)2(s) and pH value was shown in the system. The minimum solubility of lead is at the pH value of 10.096-10.997. The distribution ratio of each kind of the lead hydroxyl complex ions is determined as a function of the pH value and the total lead concentration([Pb]T). The diagram for the conditional solubility product,pKSP vs pH,shows that each kind of lead hydroxyl complex ions existing in the system is dependent upon an optimized pH value at the established concentration of [Pb]T,and that pKSP reaches the minimum at the pH value of 10.3-11.2. The results can provide a theoretical basis for removing lead ions from wastewater by the neutralization and hydrolyzation technology.展开更多
The effect of thermal oxidation of activated carbon surface on its adsorption of dibenzothiophene was investigated.The surface oxidation of the activated carbon was carried out by heating at different temperatures in ...The effect of thermal oxidation of activated carbon surface on its adsorption of dibenzothiophene was investigated.The surface oxidation of the activated carbon was carried out by heating at different temperatures in the air.Static equilibrium adsorption experiments were conducted to determine the isotherms of dibenzothiophene on the original and oxidized activated carbons.The type and concentration of oxygen functional groups on the activated carbons were determined by diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)and Boehm titration respectively.The influence of the surface chemistry of the activated carbons on the adsorption capacity for dibenzothiophene was discussed.The results showed that the acid oxygen-containing groups of the activated carbon surfaces played an important role in enhancing the adsorption of dibenzothiophene.It was shown that the use of thermal oxidation could increase the concentration of oxygen-containing groups on the activated carbon surfaces,and consequently increase its adsorption capacity for dibenzothiophene.It was also found that the higher the oxidation temperature,the more the oxygen-containing groups on activated carbon surface,which enhanced the adsorption capacity of dibenzothiophene on its surfaces.The Langmuir equation was shown to fit well these isotherms.展开更多
基金Project(2007BAC25B01) supported by the National Key Project of Scientific and Technical Supporting Programs Funded by Ministry of Science and Technology of China during the 11th Five-Year PlanProject(308019) supported by the Key Scientific and Technical Project of Ministry of Education of ChinaProject(08JJ3020) supported by the Natural Science Foundation of Hunan Province, China
文摘The thermodynamics equilibrium principle was used to construct the diagrams for the concentration of complex ions(pc) vs pH,the distribution ratio of lead hydroxyl complex ions(αn) vs pH,and the conditional solubility product of Pb(OH)2 vs pH in the Pb2+-H2O system. The relationship between the equilibrium concentration of each kind of lead hydroxyl complex ions in equilibrium with Pb(OH)2(s) and pH value was shown in the system. The minimum solubility of lead is at the pH value of 10.096-10.997. The distribution ratio of each kind of the lead hydroxyl complex ions is determined as a function of the pH value and the total lead concentration([Pb]T). The diagram for the conditional solubility product,pKSP vs pH,shows that each kind of lead hydroxyl complex ions existing in the system is dependent upon an optimized pH value at the established concentration of [Pb]T,and that pKSP reaches the minimum at the pH value of 10.3-11.2. The results can provide a theoretical basis for removing lead ions from wastewater by the neutralization and hydrolyzation technology.
文摘The effect of thermal oxidation of activated carbon surface on its adsorption of dibenzothiophene was investigated.The surface oxidation of the activated carbon was carried out by heating at different temperatures in the air.Static equilibrium adsorption experiments were conducted to determine the isotherms of dibenzothiophene on the original and oxidized activated carbons.The type and concentration of oxygen functional groups on the activated carbons were determined by diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS)and Boehm titration respectively.The influence of the surface chemistry of the activated carbons on the adsorption capacity for dibenzothiophene was discussed.The results showed that the acid oxygen-containing groups of the activated carbon surfaces played an important role in enhancing the adsorption of dibenzothiophene.It was shown that the use of thermal oxidation could increase the concentration of oxygen-containing groups on the activated carbon surfaces,and consequently increase its adsorption capacity for dibenzothiophene.It was also found that the higher the oxidation temperature,the more the oxygen-containing groups on activated carbon surface,which enhanced the adsorption capacity of dibenzothiophene on its surfaces.The Langmuir equation was shown to fit well these isotherms.
