A correct mathematical treatment is given for calculation of the light absorption of the individual components of a multi-absorbent reaction mixture.
On the basis of the literature data and die present results, a probable chemical and reaction kinetic model was proposed to characterize the investigated reaction systems. Reaction kinetic simulations demonstrated that the model predicts a good fit to the measured data with the preferred literature rate constants, except that for the HO3 radical decomposition reaction. A reasonable reduction of this rate coefficient value is in accordance with the latest published results. 相似文献
Experimental measurement of carbon dioxide absorption from mixture with air was performed in a pilot-plant column with expanded metal sheet packing irrigated with sodium hydroxide solution.
Resulting liquid and gas-side mass transfer coefficients are compared with values obtained from physical Absorption measurement of carbon dioxide into water and with measurement of gas-side mass transfer coefficient for sulphur dioxide in the same column.
The differences between determined values are discussed. 相似文献
It has been indicated that the removal of the five species of aromatic nitro compounds by ozonation can well be expressed mathematically by first order reaction equations. Besides, the reaction constants and half-life periods for various species of the tested nitro compounds were calculated at different temperatures and pH.
An ozonation effect index (OI) was developed in the study to express the degree of degradation of substrates by ozonation, by means of which the five aromatic nitro hydrocarbons were compared with each other and finally ranked in the following order from greatest to smallest degrees of degradation:
p-nitroaniline > nitrobenzene > p-dinitrobenzene > p-nitrotoluene > m-dinitrobenzene
It has also found that the CODm/M ratio increases with ozone doses. This means that some easily degradable intermediates are produced, and increase in concentration with increase of ozone dose in the ozonation process.
The mechanisms of removing the five aromatic nitro hydrocarbons are discussed from the viewpoint of orienting effects of substituent groups on the aromatic rings. 相似文献
The paper also evaluates the influence of white and nonwhite noise on the behavior of an oscillating system and illustrates it by considering two case examples. One example indicates the conflicting role of white and nonwhite noise in bringing about the transitions from the oscillatory behavior while the second example shows no influence of white and nonwhite noise on the oscillating solution
The implications of the role of noise in analysing bistable and oscillatory systems is discussed. 相似文献
Predicted products fell into one of permanent gases, tight liquids, phenolics and carbonaceous residue fractions. Product yields were more dependent on lignin type than on reaction environment.
Comparison of simulation predictions with experimental pyrolyses of actual lignins, accomplished in terms of both product identities and yields, is encouraging. It is noteworthy that the simulations are strictly a priori and incorporate no actual lignin pyrolysis information. 相似文献
The dilute H2SO4/O2 lixiviant was effective in leaching uranium from the ore samples tested. The leaching process was chemical reaction rate limited and can be represented using pseudo first-order kinetics. The leaching rate constant is proportional to the proton concentration of the lixiviant.
Much of the uranium was leached from the ore before decomposition of carbonate minerals by the acid was complete. Acid consumption per pound of U3O8 increased sharply as the uranium recovery level exceeded 70%. There appears to be a minimum oxygen pressure for effective uranium leaching. A pressure of 2758 KPa was adequate for the ore samples tested 相似文献
Nb2O5(s) + 3Cl2 (g) + 3CO(g) = 2NbOCl3 (g) + 3CO2(g).
Up to 60% conversion, the amount of volatilized product was found to be directly proportional to the time of reaction. The external surface area of the pellets remains unchanged up to this stage while the intergranular morphology changes.
These results were compared with reaction rates of commercial pyrochlore concentrate in order to establish the fundamental reaction stages of the process of extraction of Nb2O5 from pyrochlore. 相似文献
Two factors appear to control the rate of this catalytic reaction process: (1) the size and dispersion of the silver crystals and surface area of the supporting bed; and (2) the volume of oxygen in solution. The source of the oxygen can be atmospheric oxygen dissolved in the water or, for a greatly enhanced reaction rate, dissolved ozone produced by an ozone generator. In this process, oxygen molecules absorbed onto the catalyst surface are subsequently transferred to other oxidizable substrates including bacteria and viruses.
These catalytic oxidizing reactions exhibit two properties of significance in the sanitation of water. First, because oxygen on the catalyst surface reacts with both living and nonliving substrates, bacteria or viruses which are in the water flowing over the catalyst-containing medium are killed or inactivated on contact by the oxidizing reactions (i.e., without requiring the release of metals into water). Second, oxygen also is transferred to oxidizable inorganics (such as bromide ion) to generate readily measurable and relatively stable “residual” oxidizers/disinfectants that continue to sanitize water downstream.
Results of this Author's experiments have been independently replicated by sources from the University of Arizona, and at Herbert V. Shuster, Inc. Laboratories in Massachusetts. 相似文献
Methods: Occlusal surfaces of 48 extracted human molars were ground to expose flat superficial dentin surfaces. Specimens were randomly divided into two main groups according to the tested self-etch adhesive system either: One-step self-etch (AdperTM easy-one) or two-step self-etch (AdperTM SE Plus). Each adhesive system was applied on the prepared dentin surfaces followed one of these techniques: (1) Passive application of a single layer, (2) Active application of single layer, (3) Passive application of double adhesive layer (with light curing in between), and (4) Active application of double adhesive layers. Resin composite was packed inside micro-tubes fixed on the bonded dentin surfaces and light cured for 40 s. All specimens were stored in artificial saliva either for 24 h or 3 months before testing. Microshear bond strength test was employed using a universal testing machine at a crosshead speed of 0.5 mm/min.
Results: AdperTM SE Plus showed higher significant microshear bond strength in compared with AdperTM easy-one. For both adhesive systems active application showed higher significant microshear bond strength to dentin than passive application. Double application of adhesive systems showed lower microshear bond strength than single application.
Conclusion: Active application of self-etch adhesives could improve the dentin microshear bond strength. Double application with curing in between the layers did not improve the bond strength to the tested adhesive. 相似文献
Further developments are expected in the field of lamp construction and also improvement of reactor geometry. A better knowledge of the aging of the lamps is required, as well as of the photochemical reactions of oxygen in the technologies applied.
Systems presently available are most promising for application on small scale or in areas of public water distribution which have no developed structure.
- oxido-flocculation, using Fe2+, H2O2
- inter-oxidation, using O3, H2O2 and eventually an heterogeneous catalyst.
- disinfection, using UV, O3 and H2O2 combinations.
Results show that triazines can be removed by all these processes with different efficiencies. At full scale, the O3/H2O2 process presents the best performances from an economical and technical point of view. 相似文献
Introduction of new technological achievements and development in the field of flame retardancy (FR)
Review of the current state of science and technology in FR
Review of applications and markets for FR products
Presentation of recent developments in local and global standardization and in testing technology
Discussion of toxicity and environmental issues
Provision of a unique opportunity for newcomers to FR research technology and marketing to become acquainted with the FR field in all its aspects
Discussion of halogen-based and non-halogen-based flame retardant chemicals, syngergism, intumescence, FR mechanisms, modeling, flame parameters, inherently FR polymers, and polymer blends 相似文献
1. Surface irregularities caused by melt flow phenomena
2. Crystallization behavior
3. Melt drawing phenomena in certain types of polyethylene 相似文献
Highlights:
Mathematical model of cascade for separation of multicomponent isotope mixture has been developed.
The model verification has been done.
The isotope transient regularities into cascade during nonstationary processes has been identified. 相似文献
The only variable parameter used in all simulations is the choice of the amount of acid initially in the system to establish a certain pH value. An initial pH of 5.9 to 6.25 (i.e. the baseline scenarios) allows for replicating the nicotine deposition rate and total deposition in the lower tube sections. For the same simulation, ammonia deposition rate and total deposition are of the order of the experimental data. For the simulation featuring the initially lower pH value, the deposition of ammonia is lower than the experimental data – in the other case it is higher. Increasing the molality of alkaline substances initially in the system by roughly 20% drastically reduces the differences between simulated and measured nicotine deposition rate.
The present model describes some aspects of the dynamics of the complex cigarette smoke in a simplified manner; however, since it is independent of experiment specific parameters it may be applied to other environments such as deposition in the respiratory tract. 相似文献
In the pH range of 7 to 9, the TNT destruction rate increases with the hydrogen peroxide and hydroxyl ion concentrations with exponents of 0.104 and 0.15 respectively. It is technically feasible to treat toluene and TNT contaminated waters by the peroxone oxidation process to achieve the residual level of a few parts per billion in treated waters to meet environmental requirements. 相似文献
Material and methods: Flattened dentine surfaces from 30 bovine incisors were bonded with five one-step one-bottle self-etch adhesives (iBond, Clearfil S3 Bond, AdheSE One F, G-Bond, Optibond all-in-one) and one two-step self-etching adhesive (Clearfil SE Bond). Composite buildups were done with microhybrid resin composite. Bonded samples were sectioned into resin–dentine sticks of 0.8 mm2 cross section. Randomly selected 20 sticks were tested directly by microtensile bond strength testing machine, whereas another randomly selected 20 sticks were tested after being stored in solution of 10% NaOCl for 5 h. Data were analyzed by two-way analysis of variance (ANOVA) and Tukey’s honest significant difference (HSD) tests (p < 0.05).
Results: All adhesives exhibited similar dentine bond strength with exception of G-Bond. After NaOCl storage, μTBS reduced in all groups significantly. The lowest μTBS were found for G-Bond. Rest of one-step self-etch adhesives presented similar μTBS with two-step self-etch adhesive.
Conclusion: Interfaces of resin–dentine bonding are susceptible to NaOCl degradation. The amount of the destruction depends on adhesive system. NaOCl degradation of the nonresin encapsulated collagen fibers might decrease long-term stability of resin bonding with dentine. 相似文献
A commonly proposed method for controlling .VOC emissions is filtration of the off-gas through adsorption of the stripped organics in the off-gas by granular activated carbon. The high incremental cost of this alternative has produced an interest in alternative control technologies.
One alternative currently available is based on short wavelength ultraviolet (UV) radiation. This technique combines the effects of ozone generation, free radical formation and photolysis of the contaminants to effectively control the VOC emissions. This technique is known as Advanced Photo Oxidation (APO)R.
The cost for APO is $0.27/m3 for a 3.8 m3/hr contaminated water system. A system of this size is adequate for a groundwater decontamination project where a moderate length of time is available for restoration of the site. The cost of a conventional air stripping tower with Granular Activated Carbon (GAC) adsorption emissions control in this size range would be $0.40 to $0.45/m3 (J.M. Montgomery, 1986).
Additional testing will be required to fully develop design guidelines for different contaminants and larger systems. Another area for additional technical documentation is the application of this technique to the liquid phase oxidation of VOCs. 相似文献
The authors, here report three dimensional air velocity distributions within the inside drum of model Sturtevant-type air classifier measured by a spherical five-holed Pitot-lube, and also two dimensional particle ejecting velocities on a model distributor determined by photography.
Using those results, the cut size calculated from particle trajectories in the classifier is compared with the experimental results and theoretical values. 相似文献