The Kinetics And Mechanisms Of Reaction Of Tooth Enamel In Buffered Solutions Of High Fluoride Concentrations.

PhDPharmacologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/186735/2/7123896.pd

Vehicular pollution control- removal of carbon monoxide through catalytic converters

219-222In an attempt to find a substitute to noble-metal based catalysts in the catalytic converters for the removal of CO from automotive exhaust, non-noble metal based catalysts of perovskite based oxides were tested. Perovskites of the structure ABO3, where A cation had La, Ba or Ca and B cation had Co or Fe were used for the reaction. Substituted perovskite of the form A1-xA'xBO3, where A' was Ce metal, was also used. The perovskite catalyst were tested in unsupported as well as supported forms. The supports used were zirconia, ceria or a mixture of the two in different proportions. The results indicate that among the unsupported catalysts, LaCoO3 is the best. Among the substituted catalysts, La0.3Ce0.7CoO3 gave the best performance showing 100% CO conversion at 200°C. The support, zirconia (20%) and ceria (80%) mixture was found to be the best combination. The durability runs up to 6 h show the activity pattern in the order: La0.3Ce0.7CoO3 > La0.6Ce0.4CoO3 >LaCoO3

A POTENTIAL OF BIOSORBENT DERIVED FROM BANANA PEEL FOR REMOVAL OF As (III) FROM CONTAMINATED WATER

ABSTRACT: The main aim of this work is to evaluate the potential of application of banana peel (BP) as a biosorbent for removal of As(III) ion from contaminated water. Characterization of biosorbent was analyzed with FTIR, EDX and SEM. Equilibrium isotherms and kinetics were obtained and the effects of solution pH, temperature, dosage and contact time were studied in batch experiments. Maximum percentage removal (82.23%) of As(III) ion was obtained at optimized pH 7, contact time (tc) of 90 min, dosage (d c ) of 8 g, temperature (t c ) of 35 o C and 10 mg/l As(III) ion concentration (C i ), respectively. Equilibrium was well described by Freundlich isotherm model (R 2 = 0.993). Moreover, it was also found that sorption kinetics favour pseudo-second order model with high linear regression coefficient (R 2 = 0.998)

Catalytic wet air oxidation of toxic nitrogen containing compounds (pyridine) from wastewater

757-759Cu-Co/C (heterogeneous) and CuSO4 (homogeneous) were used as catalysts for wet air oxidation to remove nitrogen containing toxic organic compounds from wastewater. For this purpose, a model compound, pyridine, was treated in a high-pressure batch autoclave at mild conditions of temperature and pressure. Copper and cobalt are relatively inexpensive catalytic material and have shown higher conversion efficiencies. Both CuSO4 and Cu-Co/C have optimum activity at an initial pH 4 of the pyridine solution. After 2 h of reaction time, % conversion with CuSO4 (75.1 %) was more in comparison to Cu-Co/C (71.8 %) using 5 mg/l catalyst concentration at 160 oC and 9 bar total pressure

Reactive extraction of propionic acid using Aliquat 336 in MIBK: Linear solvation energy relationship (LSER) modeling and kinetics study

708-713This study presents linear solvation energy relationship (LSER) modeling of reactive extraction of propionic acid using Aliquat 336 in MIBK as diluent. Reaction was slow in Aliquat 336 + MIBK with rate constant at 0.0079 (m3/kmol)0.55 s-1.Order of reaction with respect to acid and Aliquat 336 was 1 and 0.9 respectively. Modeling of reactive extraction equilibria using LSER was carried out and predicted a close resemblance of experimental data

Flow behavior in weakly permeable micro-tube with varying viscosity near the wall

Weakly permeable micro-tubes are employed in many applications involving heat and/or mass transfer. During these processes, either solute concentration builds up (mass transfer) or steep change in temperature (heat transfer) takes place near the permeable wall causing a change in the viscosity of the fluid. Results of the present work suggest that such change in viscosity leads to a considerable alteration in the flow behavior, and the commonly assumed parabolic velocity profile no longer exists. To solve the problem numerically, the equation of motion was simplified to represent permeation of incompressible, Newtonian fluid with changing viscosity through a micro-tube. Even after considerable simplification, the accuracy of the results was the same as that obtained by previously reported results for some specific cases using rigorous formulation. The algorithm developed in the present work is found to be numerically robust and simple so that it can be easily integrated with other simulations

Catalytic wet air oxidation of carboxylic acid present in wastewater

838-842Catalytic Wet Air Oxidation (CWAO) of acrylic acid, a representative of carboxylic acids, was carried out in a pressurized reactor at a partial pressure of air (4 kg/cm2) and temperature (140-180°C) to reduce the COD of wastewater containing acrylic acid. Catalysts tested include both homogeneous (CuSO4 and FeSO4) and heterogeneous [Co: Bi (5:1) and Mn: Ce (1:1)] catalysts. Catalytic activity of Mn: Ce (1:1) at 5g/l was best with 86% COD reduction at 180°C and air partial pressure 4 kg/cm2 in 6 h. Initial pH of the solution has strong effect on COD reduction. Reaction kinetics of wet air oxidation of acrylic acid fitted well a first order kinetics with respect to COD of acrylic acid. Catalysts activity was correlated in terms of the physical characteristics

Comparative Performance of Ion-exchanged ZSM-5 and Y -Zeolite Catalysts for Toluene Disproportionation Reaction

810-816The toluene disproportionation reaction was carried out using ZSM-5 as well as Y- zeolite catalysts after ion exchange with active metals Ni, Pb,and Cr. The reaction was carried out under atmospheric pressure. The effect of type of cation used for ion exchange, silica- alumina ratio, type of zeolite, and particle size were also studied. The percent p-xylene yield (which is the most desirable product), was found to increase after ion-exchange with active cations. A maximum p -xylene yield of 2.3 percent was obtained with Cr HZSM-5 (SAR-19) at 600C and 1 atmos pressure