The development of a rapid and simplified primary capture step for the direct selective recovery of intracellular proteins from particulate-containing yeast disruptate in the circumvention of problems associated with conventional fluidised bed/expanded bed adsorption has been undertaken. A protoype pellicular adsorbent, designed for intensified fluidised bed adsorption processes, was assembled by the three-phase emulsification coating of porous agarose upon a zirconia-silica solid core. The adsorbent, designated ZSA, was subj ected to physical and biochemical comparison with the performance of two commercial adsorbents (Streamline and Macrosorb K4AX). Bed expansion qualities and hydrodynamic characteristics (N, Daxl and Bo) of ZSA demonstrated a marked robustness in the face of elevated velocities (up to 550 cm/h) and biomass loading (up to 30% ww/v) disrupted yeast cells. Cibracron Blue derivatives of the pellicular prototype (ZSA-CB), evaluated in the batch and fluidised bed recovery of glyceraldehyde 3-phosphate dehydrogenase (G3PDH) from unclarified yeast disruptates, exhibited superior capacities and adsortionldesorption performances to the commercial derivatives. These advanced physical and biochemical properties facilitated a demonstration of the direct coupling of bead-milling and fluidised bed adsorption in a fully integrated process for the accelerated recovery of G3PDH from yeast. The practical feasibility and generic applicability of the direct integration in the same time frame of cell disruption with the capture of intracellular products has been demonstrated. The application of a multi-fluidised bed system (MFBS), where each bed is sequentially operated on-line to the disrupter to achieve a repetitive operation of this cycle was proposed and studied. The generic application of such pellicular adsorbents and integrated processes to the recovery of labile, intracellular products has been assessed.

The research described in this thesis is to develop and validate a process system model for an electrothermal swing adsorption (ESA) process that incorporates novel activated carbon monoliths (ACMs) for the recovery of volatile organic compounds (VOCs). The process system comprises two columns one dedicated for adsorption and the other for desorption and works in a cyclic mode of operation. Two mathematical models have been developed to describe the process system, namely in one dimension (1D) and in three dimensions (3D). The developed models have been validated using experimental data at the bench and the pilot scale, at different operating conditions and for two VOCs. It has been concluded that the 1D model was sufficient to represent the experimental data of the current study without going through the trouble of using the 3D model which was more demanding in terms of formulation and computation. The linear driving force approximation (LDF) approximation adequately predicted the concentration of VOCs in the gas phase with no need for a fundamental diffusion study within the solid of the ACMs. The kinetics of adsorption and desorption was governed by the mass transfer coefficient which was found by parameter estimation and was directly related to the internal mass transfer coefficient controlled mainly by molecular diffusion inside the pore structure of the ACMs.

Tunable diode laser spectroscopy (TDLS) has become the preferred option for industrial gas monitoring. TDLS with direct detection provides absolute measurement of a rotational / vibrational gas absorption line transmission function, facilitating the extraction of gas concentration (from line strength measurement). TDLS with wavelength modulation spectroscopy (WMS) enables AC detection of absorption line derivatives at frequencies where laser and 1/f noise is reduced. Coupled with lock-in detection, this provides a sensitivity improvement of up to 2 orders of magnitude. At fixed temperature and pressure, calibration to signals measured on a known gas composition has been used successfully to determine system scaling factors. However, demand has grown for gas monitoring in environments where the gas pressure is constantly varying and unknown. This introduces significant errors in the analysis as the primary system scaling factor is a function of linewidth, which is varying with the unknown pressure. Errors also arise from the inaccuracies in determining a number of instrument scaling factors, including the AM and FM characterisation of the laser. Pressure measurements may be made and the errors in concentration corrected, if the gas absorption linewidth can be accurately measured from the recovered signals and the instrument scaling factors can be accurately determined. However, the lack of accurate in-situ wavelength referencing schemes for use in the field, make linewidth measurement extremely difficult. Add to this the fact that conventional TDLS/WMS measurements are prone to systematic interference and the errors accumulated from inaccurate instrument scaling (noted above) and linewidth measurement, could determine a large final error on the derived concentration and/or pressure. This work reports the proposal, development and validation of both an in-fibre wavelength referencing scheme and a new technique for measuring the absolute absorption line transmission function using TDLS with WMS. Measuring the absolute absorption line transmission profile, as a function of the laser's wavelength scan across the absorption line, facilitates the extraction of the gas concentration and pressure via comparisons to theory (based on HITRAN data). Through novel signal processing techniques, the approach is free from systematic distortion and is absolute without the need for calibration. This new approach provides many of the benefits of TDLS/WMS, whilst offering the simplicity and accuracy of TDLS with direct detection. The promising results show that we have significantly advanced TDLS technology towards realising a stand-alone instrument for determining accurate gas composition measurements in harsh industrial environments.

This thesis investigates methods for the rapid determination of suitable operating conditions for the primary recovery of antibody fragments from high cell density fermentation broths by two alternative processes: centrifugation and expanded bed adsorption. The methodologies applied involve the use of predictive tools, such as scale-down techniques and simulations, in order to ensure rapid prediction of large-scale process performance. This is followed by the visualisation of suitable processing conditions for recovery of the high cell density cultures investigated using Windows of Operation. Challenges related to protein recovery from high cell density expression systems were identified and addressed. Existing USD clarification approaches lead to an over-prediction of separation performance when tested with high cell density cultures of E. coli whole cells and periplasmically lysed E. coli cells. This was attributed to aggregation effects occurring in the low shear environment of a laboratory centrifuge, which would not be apparent in the settling region of a continuous-flow industrial centrifuge. A modified USD clarification methodology was developed, which resulted in accurate predictions of large-scale performance. This novel USD clarification method was applied to E. coli homogenates and P. pastoris cultures of varying solids concentrations. For these feedstocks, a laboratory-based protocol for the determination of centrifugal dewatering was developed and applied. Windows of Operation were generated, visualising the available operating conditions for a number of industrial centrifuges, when the process was constrained by pre-defined performance and operating criteria. The main challenge identified upon processing of E. coli homogenate by expanded bed adsorption relate to cell-cell and/or cell-adsorbent interactions. These interactions were more prominent in the 1.9 mm ID scale-down column than in the 25 mm ID column, probably as a result of the high particle to column diameter ratio in the scale-down bed. As a consequence, the behaviour of the beds differed in terms of level of expansion, breakthrough profiles, binding capacity and yield. Industrial-scale EBA process performance was investigated using the general rate model to predict the output. This formed the basis for the generation of a series of Windows of Operation, displaying the most suitable combinations of load volume and flow rate for the processing of E. coli homogenates of a range of solids concentrations by EBA. A comparative study was performed based on the identification of suitable operating conditions from the Windows of Operation generated for E. coli homogenate, and suggested that EBA provides higher yields, shorter processing times and greater throughput relative to a more conventional processing route, comprising centrifugation, filtration and packed bed chromatography.

Process intensification by integration of catalytic and adsorptive functionalities has tremendous potential in energy and biochemical systems. In-situ or integrated catalytic adsorption can lead to higher yield, purity and selectivity compared to conventional reaction processes. The aim of this work is to develop a) multi-scale methodologies to determine the optimal process variables for maximum performance, b) new tools for the design and decision making of high performance sorption enhanced reaction processes. In this work, a unified framework has been developed that integrates continuum model at bulk scale with particle level diffusion-reaction-sorption model for a fixed bed reactor with multifunctional particles. At bulk scale the system is sensitive to various operating parameters like wall temperature, bed voidage and feed compositions etc. Two important particle level characteristics are identified: distribution of catalyst and sorbent inside particles and geometry of particle pores such as the ratio of pore radius to tortuosity. It has been demonstrated that considering an effective diffusivity at particle pore level has a better control on intensification of sorption enhanced reaction processes. Theadsorption capacity of a sorption enhanced reaction bed is limited. The yield and purity from the fixed bed decreases once the adsorption capacity of the bed is exhausted. The regeneration of the used bed along with recycle of the products can lead to continuous production of high purity products. Simulated moving bed reactor is one such process for the production of high quality products by continuous regeneration of a series of fixed bed reactor-adsorbers. In this work, we have developed rigorous dynamic simulation frameworks to achieve efficient operation of industrially relevant energy generation processes, such as steam methane reforming (SMR) for hydrogen production and esterification reactions for biodiesel production. The effect of various operating conditions such as switching time, feed flow rate, eluent flow rate, and length of the unit on the purity and conversion was systematically investigated. Thus optimal operating conditions for high conversion and purity from these processes are achieved. Multi-scale simulation is an emerging discipline that spans over different scales varying from . surface level to continuum level. Multi-scale model can predict the properties of catalyst and adsorbent for optimum operation of the sorption enhanced reaction processes discussed above. In addition to the dynamic simulation methodology, two novel multi-scale methodologies have been proposed a) coarse graining method by wavelet transform of surface level Monte Carlo simulations b) hybrid methodology combining continuum equations at bulk scale and Monte Carlo simulations at surface scale. The coarse grained MC simulations are applied to example problems of CO oxidation on the surface of catalyst and to a generic sequential linear reactions with three components, while hybrid Monte Carlo mean field methodology is applied to the cell cycle data to study the activation of cancer by mitogen activated protein kinase pathway. Furthermore the latter methodology was applied to study the mechanisms of biodiesel transesterification reactions.

The synthesis of resorcinol formaldehyde xerogels was investigated by controlling its porosity for potential use as a precursor for activated carbon adsorbents for heavy metals removal from industrial wastewater. Resorcinol formaldehyde carbon xerogels were synthesised by sol-gel polymerization of resorcinol (R) with formaldehyde (F) in the presence of sodium carbonate (C) and then vacuum dried. Resorcinol formaldehyde (RF) gels were synthesised at same temperature conditions with varying resorcinol ! catalyst (R/C) and resorcinol/ water (R/W) ratios. The characterization of the resorcinol formaldehyde xerogels (RF), carbonized resorcinol formaldehyde xerogels (CRF) included: pore size distribution; surface area (BET); scanning electron microscopy (SEM!EDX); FTIR spectroscopy; and X-Ray diffraction (XRD). The ACRF was also analysed to determine its pHpzc , pHSolution , surface basicity and acidity. The resorcinol formaldehyde xerogels were carbonised and activated by physical activation with carbon dioxide. The surface areas of the carbonized resorcinol formaldehyde xerogels (CRF) and activated carbon resorcinol formaldehyde xerogels (ACRF) are 577.3 m2/g and 993.5 m2!g respectively. The increase in surface area is as a result of the development of microporosity with activation. In comparison the surface area of a commercial activated carbon (AC) obtained from Norit was found to be 884.4 m2/g. The adsorption of chromium metal ion in aqueous solutions by activated carbon resorcinol formaldehyde xerogels (ACRF) was investigated. The experimental data show that pore structure, surface area and the adsorbent surface chemistry are important factors that control the adsorption of metal ions. Equilibrium adsorption isotherms were analysed using the Langmuir, Freundlich and Sips models. Pseudo first order, pseudo second order, Elovich and intraparticle diffusion

No description available.

Periodic adsorption processes have been gaining increasing commercial acceptance as energy efficient alternatives to other separation processes. Such processes are distributed in nature, with properties exhibiting spatial as well as temporal variations. Therefore, they can be mathematically represented by systems of partial differential and algebraic equations (PDAEs).The periodic nature of periodic adsorption processes arises from an externally imposed cyclic variation of the flowrates and intensive properties (e.g. pressure, temperature or composition) of the process feed streams, and of the flowrates of the product streams. This variation leads the system to a "cyclic steady state" (CSS) at which the conditions in each bed at the start and end of each cycle are identical. The traditional approach to cyclic steady state determination has been to carry out a dynamic simulation of the system, starting from a given initial condition, over a large number of cycles. In this work, a novel method is proposed to directly determine a cyclic steady state of periodic adsorption processes by replacing the initial condition specification by a periodicity condition demanding that the system states at the end of each cycle be identical to those at its start. Additional constraints are introduced to characterise the interactions between multiple beds in the process. Detailed dynamic models taking account of the spatial variation of properties within the adsorption bed(s) are used. The resulting systems of partial differential and algebraic equations, and the corresponding boundary conditions, are reduced to sets of algebraic constraints by discretisation with respect to both spatial and temporal dimensions. The performance of periodic adsorption processes is intrinsically affected by various design and operating parameters. The appropriate selection of the values of these parameters may significantly enhances the entire profit of the processes. However, the number of interacting decisions and constraints is such that obtaining an optimal solution by carrying out several dynamic simulations is laborious, if not altogether impossible. A new approach to the optimisation of periodic adsorption processes using mathematical programming is presented. It is demonstrated that the optimal operating and/or design decisions can be determined by solving a single optimisation problem with constraints representing a single bed over a single cycle of operation, irrespective of the number of adsorption beds in the process. Examples of periodic adsorption processes involving different number of adsorption beds and operating cycles are presented to illustrate the approach.

No description available.

The concept of creating heterogeneous structures by nanocasting techniques from a combination of several homogeneous surfactant templated structures to model reservoir rock properties has not been approached prior to this research project, and will be used to test and provide better understanding of gas adsorption theories such as the pore blocking phenomenon (Seaton, 1991). Porous media with controlled pore sizes and geometry can be used to mimic a variety of reservoir rock structures, as it can be engineered to consist of a network of elements which, individually, could have either regular or irregular converging and diverging portions. The restrictions in these elements are called throats, and the bulges pores. Catalysts developed from a range of Nanotechnology applications could be used in down-hole catalytic upgrading of heavy oil. They could also be used as catalyst supports or to analyse the coking performance of catalysts. These studies will highlight the pore structure effects associated with capillary trapping mechanisms in rocks, and potentially allow the manipulation of transport rates of fluids within the pore structure of catalysts. Mercury-injection capillary pressure is typically favoured for geological applications such as inferring the size and sorting of pore throats. The difference between mercury injection and withdrawal curves will be used to provide information on recovery efficiency, and also to investigate pore level heterogeneity. Mercury porosimetry studies are carried out to provide a better understanding of the retraction curve and the mechanisms controlling the extrusion process and subsequently the entrapment of the non-wetting phase. The use of model porous media with controlled pore size and surface chemistry allows these two effects to be de-convolved and studied separately. The nanotechnology techniques employed mean that uncertainty regarding exact pore geometry is alleviated because tight control of pore geometry is possible. Trapping of oil and gas on a microscopic scale in a petroleum reservoir rock is affected by the geometric and topologic properties of the pores, by the properties of the fluids and by properties related to fluid-rock interaction such as wettability. Several distinct mechanisms of trapping may occur during displacement of one fluid by another in a porous media, however in strongly water-wet rocks with large aspect ratios, trapping in individual pores caused by associated restricting throats (may be/is) the most important mechanism of trapping. The results of the proposed research will be both relevant to the Irene Osagie Evbuomwan PhD. Thesis (2009) 9 oil and gas as well as the solid mineral sector for application as catalyst or catalyst supports. By providing a better understanding of the relationship between reservoir rock pore space geometry and surface chemistry on the residual oil levels, a more accurate assessment of the potential of a particular reservoir could be generated. The analysis of gas adsorption/desorption isotherms is widely used for the characterization of porous materials with regard to their surface area, pore size, pore size distribution and porosity, which is important for optimizing their use in many practical applications. Although nitrogen adsorption at liquid nitrogen temperature is considered to be the standard procedure, recent studies clearly reveal that the use of additional probe molecules (e.g. argon, butane, carbon dioxide, water, hydrogen, and hydrocarbons e.g. cyclohexane and ethane) allows not only to check for consistency, but also leads to a more comprehensive and accurate micro/mesopore size analysis of many adsorbents. Furthermore, significant progress has been achieved during recent years with regard to the understanding of the adsorption mechanism of fluids in materials with highly ordered pore structures (e.g., M41S materials, SBA-15). This has led to major improvements in the pore size analysis of nanoporous materials. However, there are still many open questions concerning the phase and sorption behaviour of fluids in more complex pore systems, such as materials of a heterogeneous nature/differing pore structures, which are of interest for practical applications in catalysis, separation, and adsorption. In order to address some of these open questions, we have performed systematic adsorption experiments on novel nanoporous materials with well defined pore structure synthesised within this research and also on commercial porous silicas. The results of this study and experiments allow understanding and separating in detail the influence of phenomena such as, pore blocking, advanced condensation and delayed condensation on adsorption hysteresis and consequently the shape of the adsorption isotherms. The consequences of these results for an accurate and comprehensive pore size analysis of nanomaterials consisting of more complex nanoporous pore networks are also investigated.