Kinetic parameters of the decomposition of hazardous chemicals can be applied for the estimation of their thermal behavior under any temperature profile.Presented paper describes the application of the advanced kineti...Kinetic parameters of the decomposition of hazardous chemicals can be applied for the estimation of their thermal behavior under any temperature profile.Presented paper describes the application of the advanced kinetic approach for the determination of the thermal behavior also under adiabatic conditions occurring e.g.in batch reactors in case of cooling failure.The kinetics of the decomposition of different samples(different manufacturers and batches) of 3-methyl-4-nitrophenol were investigated by conventional DSC in non-isothermal(few heating rates varying from 0.25 to 8.0K/min) and isothermal(range of 200~260℃) modes.The kinetic parameters obtained with AKTS-Thermokinetics Software were applied for calculating reaction rate and progress under different heating rates and temperatures and verified by comparing simulated and experimental signals.After application of the heat balance to compare the amount of heat generated during reaction and its removal from the system,the knowledge of reaction rate at any temperature profiles allowed the determination of the temperature increase due to the self-heating in adiabatic and pseudo-adiabatic conditions.Applied advanced kinetic approach allowed simulation the course of the Heat-Wait-Search(HWS) mode of operation of adiabatic calorimeters.The thermal safety diagram depicting dependence of Time to Maximum Rate(TMR) on the initial temperature was calculated and compared with the results of HWS experiments carried out in the system with Ф-factor amounting to 3.2.The influence of the Ф-factor and reaction progress reached at the end of the HWS monitoring on the TMR is discussed.Presented calculations clearly indicate that even very minor reaction progress reduces the TMRad of 24h characteristic for a sample with initial reaction progress amounting to zero.Described estimation method can be verified by just one HWS-ARC,or by one correctly chosen ISO-ARC run of reasonable duration by knowing in advance the dependence of the TMR on the initial temperature for any Ф-factor.Proposed procedure results in significant shortening of the measuring time compared to a safety hazard approach based on series of ARC experiments carried out at the beginning of a process safety evaluation.展开更多
Removal of nitrophenols （NPs） from aqueous solutions through the adsorption process by using cationic β-cyclodextrin （CCD） modified zeolite （CCDMZ） was investigated. The effects of particle size, contact time, ...Removal of nitrophenols （NPs） from aqueous solutions through the adsorption process by using cationic β-cyclodextrin （CCD） modified zeolite （CCDMZ） was investigated. The effects of particle size, contact time, solution pH values and sodium chloride content in the aqueous on adsorption capacity were evaluated through a series of batch experiments. The results showed that CCDMZ had a higher adsorption capacity for removing NPs at a size fraction of 0.45-0.9 mm while adsorption of NPs on CCDMZ reached equilibrium within 60 min. The adsorption process was apparently influenced by pH values and sodium chloride content in aqueous solution. To ascertain the mechanisms of sorption, the experimental data were modeled by using the pseudo-first and pseudo-second order kinetic equations, and the results indicated that the adsorption kinetics of NPs on CCDMZ well-matched with the pseudo-second order rate expression.展开更多
The adsorption of phenol and nitrophenols on hypercrosslinked polymeric adsorbent was studied as a function of the solution concentration and temperature. Adsorption isotherms of phenol and nitrophenols on hypercrossl...The adsorption of phenol and nitrophenols on hypercrosslinked polymeric adsorbent was studied as a function of the solution concentration and temperature. Adsorption isotherms of phenol and nitrophenols on hypercrosslinked resin were determined. These isotherms were modeled according to the Freundlich adsorption isotherm. The isotherms for phenol and nitrophenols on hypercrosslinked resin were assigned as L curves. Thermodynamic parameters were calculated for all phenol and nitrophenols. The kinetics experiment results showed that the adsorption rates were of the first-order kinetics. The rate constants at 303K were calculated.展开更多
文摘Kinetic parameters of the decomposition of hazardous chemicals can be applied for the estimation of their thermal behavior under any temperature profile.Presented paper describes the application of the advanced kinetic approach for the determination of the thermal behavior also under adiabatic conditions occurring e.g.in batch reactors in case of cooling failure.The kinetics of the decomposition of different samples(different manufacturers and batches) of 3-methyl-4-nitrophenol were investigated by conventional DSC in non-isothermal(few heating rates varying from 0.25 to 8.0K/min) and isothermal(range of 200~260℃) modes.The kinetic parameters obtained with AKTS-Thermokinetics Software were applied for calculating reaction rate and progress under different heating rates and temperatures and verified by comparing simulated and experimental signals.After application of the heat balance to compare the amount of heat generated during reaction and its removal from the system,the knowledge of reaction rate at any temperature profiles allowed the determination of the temperature increase due to the self-heating in adiabatic and pseudo-adiabatic conditions.Applied advanced kinetic approach allowed simulation the course of the Heat-Wait-Search(HWS) mode of operation of adiabatic calorimeters.The thermal safety diagram depicting dependence of Time to Maximum Rate(TMR) on the initial temperature was calculated and compared with the results of HWS experiments carried out in the system with Ф-factor amounting to 3.2.The influence of the Ф-factor and reaction progress reached at the end of the HWS monitoring on the TMR is discussed.Presented calculations clearly indicate that even very minor reaction progress reduces the TMRad of 24h characteristic for a sample with initial reaction progress amounting to zero.Described estimation method can be verified by just one HWS-ARC,or by one correctly chosen ISO-ARC run of reasonable duration by knowing in advance the dependence of the TMR on the initial temperature for any Ф-factor.Proposed procedure results in significant shortening of the measuring time compared to a safety hazard approach based on series of ARC experiments carried out at the beginning of a process safety evaluation.
基金Supported by the National Natural Science Foundation of China （NEPCP 200809098） and the Natural Science Foundation ot Gansu Province （0803RJZA003）.
文摘Removal of nitrophenols （NPs） from aqueous solutions through the adsorption process by using cationic β-cyclodextrin （CCD） modified zeolite （CCDMZ） was investigated. The effects of particle size, contact time, solution pH values and sodium chloride content in the aqueous on adsorption capacity were evaluated through a series of batch experiments. The results showed that CCDMZ had a higher adsorption capacity for removing NPs at a size fraction of 0.45-0.9 mm while adsorption of NPs on CCDMZ reached equilibrium within 60 min. The adsorption process was apparently influenced by pH values and sodium chloride content in aqueous solution. To ascertain the mechanisms of sorption, the experimental data were modeled by using the pseudo-first and pseudo-second order kinetic equations, and the results indicated that the adsorption kinetics of NPs on CCDMZ well-matched with the pseudo-second order rate expression.
文摘The adsorption of phenol and nitrophenols on hypercrosslinked polymeric adsorbent was studied as a function of the solution concentration and temperature. Adsorption isotherms of phenol and nitrophenols on hypercrosslinked resin were determined. These isotherms were modeled according to the Freundlich adsorption isotherm. The isotherms for phenol and nitrophenols on hypercrosslinked resin were assigned as L curves. Thermodynamic parameters were calculated for all phenol and nitrophenols. The kinetics experiment results showed that the adsorption rates were of the first-order kinetics. The rate constants at 303K were calculated.
