The degradation mechanism of Cationic Red X-GRL was investigated when the intermediates, the nitrate ion and the pH were analyzed in the ozonation. The degradation of the Cationic Red X-GRL includes the de-auxochrome...The degradation mechanism of Cationic Red X-GRL was investigated when the intermediates, the nitrate ion and the pH were analyzed in the ozonation. The degradation of the Cationic Red X-GRL includes the de-auxochrome stage, the decolour stage, and the decomposition of fragment stage. During the degradation process, among the six nitrogen atoms of Cationic Red X-GRL, one is transferred into a nitrate ion, one becomes the form of an amine compound, and the rest four are transformed into two molecules of nitrogen. In the course of the ozonation of Cationic Red X-GRL, the direct attack of ozone is the main decolour effect.展开更多
The ozonation of Cationic Red X-GRL in a semi-batch reactor was studied with variation of the gas flow rate, initial Cationic Red X-GRL concentration, temperature, and pH value. By the evaluation of the liquid mass tr...The ozonation of Cationic Red X-GRL in a semi-batch reactor was studied with variation of the gas flow rate, initial Cationic Red X-GRL concentration, temperature, and pH value. By the evaluation of the liquid mass transfer coefficient, the interfacial area, and the stoichiometric ratio between ozone and Cationic Red X-GRL, the rate constants and the kinetic regime of the reaction between ozone and Cationic Red X-GRL were investigated by applying the experimental data to a model based on the film mass transfer theory. The results obtained support a second order overall reaction, first order with respect to both ozone and dye, and the rate constants were correlated by a modified Arrhenius Equation of temperature and pH value with activation energy of 18.06kJ·mol-1. Hatta number of the reaction was found to be between 0.026 and 0.041, it indicates that the reaction occurs in the liquid bulk, corresponding to the slow kinetic regime.展开更多
As secondary mineral resources, diatomite tailings（DT） got from the Linjiang region of China were prepared and characterized by SEM, XRF and XRD. Mono-factor experiments were carried out to investigate the effects o...As secondary mineral resources, diatomite tailings（DT） got from the Linjiang region of China were prepared and characterized by SEM, XRF and XRD. Mono-factor experiments were carried out to investigate the effects of the operation factor, including contact time, adsorbent concentration, initial p H value of the dye solutions, adsorption temperature and initial concentration of cationic Red X-GRL（X-GRL） on the adsorption of X-GRL. The adsorption kinetics, isotherms, thermodynamics and mechanisms for X-GRL were also studied. It was efficient for DT to adsorb X-GRL from aqueous solutions, and it was even discovered to have higher adsorptivity for X-GRL than diatomite concentrate（DC） in our previous test. The adsorption processes fit very well with the pseudo-second-order model and the Langmuir isotherm equation. In addition, various thermodynamic parameters, such as standard Gibbs free energy（ΔG°）, standard enthalpy（ΔH°） and standard entropy（ΔS°） have been calculated. From thermodynamic studies, it was seen that the adsorption was spontaneous and endothermic. The main driving forces of the physical adsorption on DT are electrostatic attraction. The reason why DT showed higher adsorptivity for X-GRL than DC was that there were more clay mineral particles within, which has a remarkable ability of dye adsorption due to its high surface area. DT as a cheap absorbent for X-GRL removal would replace or partially replace the activated carbon.展开更多
Azo dye cationic blue X GRL, which is non biodegradable toxic organic compound, is decolorized and subsequently mineralized by UV/H 2O 2/N 2 or UV/H 2O 2/air (O 2) system. The effects of initial solution conce...Azo dye cationic blue X GRL, which is non biodegradable toxic organic compound, is decolorized and subsequently mineralized by UV/H 2O 2/N 2 or UV/H 2O 2/air (O 2) system. The effects of initial solution concentration, initial solution pH, and some ions produced during the degradation on the rate of decolorization of cationic blue X GRL were investigated. The photodegradation of cationic blue X GRL approximately follows first order kinetics. The regression curve of the natural logarithm of concentration verus reaction time becomes less linear with initial concentration increasing. Oxygen and appropriate OH\+· generator can accelerate reaction rate. The effect of reaction atmosphere, initial concentration, light intensity on the optimal dosage of H 2O 2 were studied. It was found that the optimal H 2O 2 dosage was determined by UV light intensity. These intermediates of cationic blue X GRL decolorization are biodegradable.展开更多
文摘The degradation mechanism of Cationic Red X-GRL was investigated when the intermediates, the nitrate ion and the pH were analyzed in the ozonation. The degradation of the Cationic Red X-GRL includes the de-auxochrome stage, the decolour stage, and the decomposition of fragment stage. During the degradation process, among the six nitrogen atoms of Cationic Red X-GRL, one is transferred into a nitrate ion, one becomes the form of an amine compound, and the rest four are transformed into two molecules of nitrogen. In the course of the ozonation of Cationic Red X-GRL, the direct attack of ozone is the main decolour effect.
基金Partly supported by Returnee Foundation of China Education Ministry (No. 2002-247).
文摘The ozonation of Cationic Red X-GRL in a semi-batch reactor was studied with variation of the gas flow rate, initial Cationic Red X-GRL concentration, temperature, and pH value. By the evaluation of the liquid mass transfer coefficient, the interfacial area, and the stoichiometric ratio between ozone and Cationic Red X-GRL, the rate constants and the kinetic regime of the reaction between ozone and Cationic Red X-GRL were investigated by applying the experimental data to a model based on the film mass transfer theory. The results obtained support a second order overall reaction, first order with respect to both ozone and dye, and the rate constants were correlated by a modified Arrhenius Equation of temperature and pH value with activation energy of 18.06kJ·mol-1. Hatta number of the reaction was found to be between 0.026 and 0.041, it indicates that the reaction occurs in the liquid bulk, corresponding to the slow kinetic regime.
基金Funded by the Key Science and Technology Support Programs(No.2011BAB03B07)of the Ministry of Science and Technology of China
文摘As secondary mineral resources, diatomite tailings（DT） got from the Linjiang region of China were prepared and characterized by SEM, XRF and XRD. Mono-factor experiments were carried out to investigate the effects of the operation factor, including contact time, adsorbent concentration, initial p H value of the dye solutions, adsorption temperature and initial concentration of cationic Red X-GRL（X-GRL） on the adsorption of X-GRL. The adsorption kinetics, isotherms, thermodynamics and mechanisms for X-GRL were also studied. It was efficient for DT to adsorb X-GRL from aqueous solutions, and it was even discovered to have higher adsorptivity for X-GRL than diatomite concentrate（DC） in our previous test. The adsorption processes fit very well with the pseudo-second-order model and the Langmuir isotherm equation. In addition, various thermodynamic parameters, such as standard Gibbs free energy（ΔG°）, standard enthalpy（ΔH°） and standard entropy（ΔS°） have been calculated. From thermodynamic studies, it was seen that the adsorption was spontaneous and endothermic. The main driving forces of the physical adsorption on DT are electrostatic attraction. The reason why DT showed higher adsorptivity for X-GRL than DC was that there were more clay mineral particles within, which has a remarkable ability of dye adsorption due to its high surface area. DT as a cheap absorbent for X-GRL removal would replace or partially replace the activated carbon.
文摘Azo dye cationic blue X GRL, which is non biodegradable toxic organic compound, is decolorized and subsequently mineralized by UV/H 2O 2/N 2 or UV/H 2O 2/air (O 2) system. The effects of initial solution concentration, initial solution pH, and some ions produced during the degradation on the rate of decolorization of cationic blue X GRL were investigated. The photodegradation of cationic blue X GRL approximately follows first order kinetics. The regression curve of the natural logarithm of concentration verus reaction time becomes less linear with initial concentration increasing. Oxygen and appropriate OH\+· generator can accelerate reaction rate. The effect of reaction atmosphere, initial concentration, light intensity on the optimal dosage of H 2O 2 were studied. It was found that the optimal H 2O 2 dosage was determined by UV light intensity. These intermediates of cationic blue X GRL decolorization are biodegradable.
