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The main purpose of this research is to use aluminum oxide nanoparticles in order to manipulate the formation mechanism of poly acrylonitrile (PAN) UF membranes with the aim of improving their performance in separating biological macromolecules including sodium alginate, humic acid, bovine serum albumin (BSA). For this purpose, alumina nanoparticles with the approximate size of 40 nm and high hydrophilicity properties were placed within the structure of the PAN membrane to engineering design of pores. Viscometry analysis and determination of cloud point were performed in order to investigate the formation mechanism of the nanocomposite membrane. Chemical, surface, and morphological variations of the nanocomposite membrane were evaluated using FTIR, zeta potential, contact angle, DLS, porosity metering, SEM, and AFM analyses. Eventually, investigation of the filtration performance of the nanocomposite membranes showed that the membranes containing 1 wt% of alumina nanoparticles have a water flux 57% more than that of raw membrane. Further, in terms of flux recovery parameter, this membrane indicated 22, 9, and 14% increase for sodium alginate, humic acid, and BSA, respectively. Regarding extent of dye separation, sodium alginate separation, humic acid separation, and BSA separation, 12, 7, 9, and 7% increase was observed for the nanocomposite membrane containing 3 wt% of alumina nanoparticles. [ABSTRACT FROM AUTHOR]

A laboratory stirred tank bioreactor with six single and dual-impeller configurations was tested to obtain the optimum operating conditions for future biological processes. Six impeller combinations consisting of three basic impeller types, namely Rushton turbine (RT), pitched 4blade (P4B) and pitched 2blade (P2B) downward flow were investigated in 1.77 L bioreactor working volume. Power consumption and gas holdup measurements were taken over a range of 100-1000 rpm of stirring speed and 1-5 Lmin-1 of air flowrates, for all the six combinations consisting of any single and dual impellers. Using predicted data some empirical correlations were derived which present relations in estimation of power consumption in stirred tanks with various impeller configurations. Electrical measurement method was use to determine the power drown in the stirred bioreactor. Gas hold-up increased with an increase in stirring speed and superficial gas velocity for all the impellers employed. The number and type of impellers in stirred bioreactor had considerable influence on gas hold-up behavior of the stirred bioreactor. Besides, Rushton turbine-dual Impeller gave comparably maximum gas hold-up, but at significantly higher power consumption levels. The proposed correlations offered good agreement with the experimental data. [ABSTRACT FROM AUTHOR]

Bubble size distribution was modelled by employing the population balance equation (PBE). All three bubble coalescence mechanisms (turbulence, buoyancy and laminar shear) and the main bubble breakup mechanism (breakup due to turbulent eddies) were considered in the model. Local bubble size distributions at the top and bottom of the column were obtained by solving this PBE. The results were compared with the experimental data for seven independent multiphase systems (water/air, isomax diesel/air, kerosene/air and four other liquid mixture/air) at two diverse gas velocities. The experimental adjustable constant in the coalescence efficiency function was determined by fitting the population balance to the experimental bubble size distributions. An empirical correlation was proposed for the coalescence efficiency by the dimensional analysis, which includes Reynolds and Weber numbers. © 2011 Canadian Society for Chemical Engineering [ABSTRACT FROM AUTHOR]

Oxidation of glucose by homogeneous glucose oxidase was performed in rectangular bubble column reactor at 40 °C, ambient pressure and pH of 5.5 while superficial gas (oxygen) velocity was varied in the homogeneous and transition regime in the range of 0.0014-0.0112 m s-1. Effect of superficial gas (oxygen) velocity on the apparent reaction rate and its parameters was determined and it was observed that the apparent reaction rate on the basis of volume of the liquid increased with increasing the superficial gas (oxygen) velocity. The apparent reaction rate was assumed to be in the form of Michaelis-Menten equation and its apparent kinetic parameters were evaluated by the nonlinear regression method. [ABSTRACT FROM AUTHOR]