Fabrication and characterization of micro-porous ceramic membrane based on kaolin and alumina

Kaolin and α-alumina powders are used to synthesise microporous ceramics using starch as an organic pore-former, and phosphoric acid as an inorganic binder. This work has been carried out to further develop microporous ceramic materials based on alumina-kaolin for filtration purposes. The membranes are characterized using SEM, XRD, permeability, porosity, density, average pore size, chemical stability, shrinkage, and solvent permeation. The ceramics sintered at 1200°C, after being compacted at 14.7 MPa, exhibit porosity of about 32.2±3%. These ceramics show reasonably good permeability as well as mechanical strength. The average pore sizes of these supports found to be approximately between 0.5–1.5 µm and are hydrophilic in nature

Fabrication and characterization of micro-porous ceramic membrane based on kaolin and alumina

367-373Kaolin and α-alumina powders are used to synthesise microporous ceramics using starch as an organic pore-former, and phosphoric acid as an inorganic binder. This work has been carried out to further develop microporous ceramic materials based on alumina-kaolin for filtration purposes. The membranes are characterized using SEM, XRD, permeability, porosity, density, average pore size, chemical stability, shrinkage, and solvent permeation. The ceramics sintered at 1200°C, after being compacted at 14.7 MPa, exhibit porosity of about 32.2±3%. These ceramics show reasonably good permeability as well as mechanical strength. The average pore sizes of these supports found to be approximately between 0.5–1.5 µm and are hydrophilic in nature

Carboxylic acids separation using hollow fiber supported liquid membrane

20-31The experimental and modeling studies for extraction of different carboxylic acids using hollow fiber supported liquid membrane operated in a recycle mode has been described here. Characterization of membrane has been carried out to find the pore size. Tri-n-butyl phosphate (TBP), tri-n-octylamine (TOA) and tri-n-octylphosphine oxide (TOPO) are used as extractants for extraction studies. A generalized methodology for the extraction of carboxylic acids has been proposed. The extraction equilibrium studies for carboxylic acids are carried out to find the distribution coefficient (kd) and the equilibrium constant (Kex). A mathematical model has been developed by considering the mass transfer as well as the complexation and de-complexation reactions. The equilibrium results show that the extractants plays an important role in extraction of carboxylic acids, and thus influence the extraction of carboxylic acids. Almost 99% extraction of carboxylic acids has been achieved using 1% TOPO as an extractant. Effect on transport of carboxylic acids under various conditions, including acid concentrations, extractant concentrations, feed/strip flow rate, feed volume, scale up etc. has been investigated. Scale-up experiment show that flux obtained at both scales is the same and hence the rate of extraction is significantly faster in a module with high surface area

Relation between flow pattern and blending in stirred tanks

In the present work, the relationship between the flow pattern and blending has been investigated. The flow patterns generated by around 40 axial flow impellers have been examined. The impellers differed in blade angle, blade twist, blade width, impeller diameter, impeller location, and pumping direction. The mean-flow and turbulence characteristics generated by all of the impellers have been measured using laser doppler velocimetry (LDV). On the basis of available LDV data, the flow pattern throughout the vessel was established by employing computational fluid dynamics (CFD) and subsequently used for the simulation of the blending process. The predicted mixing times were found to be in excellent agreement with the experimental measurements. It has been shown that the dimensionless mixing time (θ ) varies inversely with the secondary flow number of the impeller. Comparison of the impellers on the basis of equal power consumption per unit mass has shown that θ<SUB>mix</SUB> ∝ N<SUB>P</SUB><SUP>1/3</SUP>T<SUP>2/3</SUP>/N<SUB>QS</SUB>. The present CFD model has shown the possibility of reducing the eddy diffusivity to about 20% of the actual value and still achieving the same mixing time. This reduction in eddy viscosity represents substantial savings in operating costs

Hydrodynamics of a stirred vessel equipped with a gas-inducing impeller

Hydrodynamic characteristics of a gas-liquid reactor equipped with a gas-inducing impeller were investigated. Four different impeller designs and two different ring spargers were used. The effects of superficial gas velocity, liquid submergence, and the interimpeller clearance on the critical impeller speed for gas induction, the rate of gas induction, and the fractional gas hold-up were investigated. The critical impeller speed was found to increase with an increase in the superficial velocity of the sparged gas. It was also affected by the lower impeller design and the sparger size. The rate of gas induction was found to decrease with an increase in the superficial gas velocity. It also depends on the lower impeller design and the sparger size. The liquid submergence had an optimum value at which the rate of gas induction was a maximum. The data obtained could be successfully correlated on the basis of mathematical models developed earlier