Reactor For Purification Research Articles

Synergistically interface networked organic–inorganic photocatalytic membrane for highly stable Cr(VI) reduction and hydrogen production

Artificial conversion technology based on solar energy is one of most strategic artificial technologies for addressing environmental hazards and energy crisis. However, micro/nano-sized particulate catalysts mostly have the drawbacks of unstable microstructure and difficult recovery, which inevitably limits the practical application of photocatalysis technology. In order to overcome the defects of most inorganic particulate photocatalysts, a novel organic–inorganic photocatalytic membrane based on highly active Bi4Ti3O12/CdS composite and polyvinylidene fluoride (PVDF) was processed for simulated sunlight (SSL)-driven Cr(VI)-to-Cr(III) (CTC) reduction and H2O-to-H2 (HTH) conversion. Due to the maximum light harvesting capacity and synergistically electronic interaction of this synergistically interface networked organic–inorganic membrane, it possesses accelerated dynamics for separating/transferring photoexcitons and restraining photoexciton recombination, thereby outstanding CTC reduction rate (1.25 × 10-2 min−1) and HTH conversion rate (7.45 mmol∙m−2∙h−1) were achieved under SSL-irradiation, and highly stable photoactivity was maintained even being recycled for dozens of times owing to the convenient separation/recovery performance and stable organic–inorganic matrix. Subsequently, a panel reactor for wastewater purification was constructed to achieve 6.5 × 10-3 min−1 of CTC reduction rate under SSL-irradiation. This study provides a prospective insight for application of photocatalysis technology based on the membrane materials.

3D printed photocatalytic reactor for air purification

A 3D printed plastic sinusoidal reactor with a 3D printed photocatalytic lining is prepared and used to purify air, containing the test pollutants, NO2, NO, acetaldehyde and ozone. This 3D printed, air-purifying photocatalytic reactor, 3D APPR, is first UVA pre-conditioned (168 h, 1.5 mW cm−2), to render its P25 TiO2 containing photocatalytic lining active, through the destruction of the thin layer of polymer that covers the photocatalytic particles at, or near, to the surface. When testing for pollution removal, unless stated otherwise, the typical reaction conditions are, [pollutant] = ca. 1000 ppb, flow rate = 0.26 L min−1, relative humidity = 50%, UVA irradiance (352 nm) 1 mW cm−2 and irradiation time, t, = 5 h. Under these conditions the 3D APPR removes 27% of the NO2, 25.3% of the NO, but simultaneously generates 17.3% NO2 so %NOx removed is only ca. 8%. With acetaldehyde, [pollutant] = ca. 5000 ppb; 3 h irradiation, 34.2% is removed. Finally, with ozone, [pollutant] = ca. 420 ppb; 1 h irradiation; 2.8 mW cm−2 368 nm, 99% is removed. Indeed, the latter process is so effective that the small amount (47 μW cm−2) of UV in cool white fluorescent tubes is able to effect the removal of 70 % of the ozone. In all cases, the 3D APPR is more effective at removing the test pollutant than Activ™ self-cleaning glass, even though the latter has nearly 3 times the irradiated surface area and over 12 times the residence time. Long term (5 day) irradiations of the same systems produces very similar, if not enhanced, % removal values for all the pollutants tested. The potential of this type of disposable, plastic film photocatalytic reactor, made using a biodegradable plastic, polylactic acid, PLA, is discussed briefly.

Влияние параметров разрядной камеры на эффективность наработки озона импульсным коронным разрядом

The article discusses ways to increase the efficiency of ozone production in a coaxial chamber using a pulsed corona discharge. The effect of the discharge gap and the diameter of the potential electrode on the energy efficiency of ozone production using a pulsed corona discharge of negative polarity with a duration of 40 ns and a voltage of about 100 kV was investigated. It is shown that with an increase in the discharge gap, the productivity of the installation decreases, and the energy efficiency increases. The optimal diameter of the potential electrode has a value of about 0.64 mm. This information will be useful in the development of highly efficient ozonators and in optimizing the parameters of plasma chemical reactors for air purification by electro-discharge methods

Influence of discharge chamber parameters on the efficiency of ozone generation by pulsed corona discharge

The article discusses ways to increase the efficiency of ozone production in a coaxial chamber using a pulsed corona discharge. The effect of the discharge gap and the diameter of the potential electrode on the energy efficiency of ozone production using a pulsed corona discharge of negative polarity with duration of 40 ns and voltage of about 100 kV was investigated. It is shown that with an increase in the discharge gap, the productivity of the installation decreases, and the energy efficiency increases. The optimal diameter of the potential electrode has a value of about 0.64 mm. This information will be useful in the development of highly efficient ozonators and in optimizing the parameters of plasma-chemical reactors for air purification by electro-discharge methods. Keywords: pulsed corona discharge, ozone, non-equilibrium plasma, ozonator.

Petroleum Hydrocarbon Removal from Wastewaters: A Review

Oil pollutants, due to their toxicity, mutagenicity, and carcinogenicity, are considered a serious threat to human health and the environment. Petroleum hydrocarbons compounds, for instance, benzene, toluene, ethylbenzene, xylene, are among the natural compounds of crude oil and petrol and are often found in surface and underground water as a result of industrial activities, especially the handling of petrochemicals, reservoir leakage or inappropriate waste disposal processes. Methods based on the conventional wastewater treatment processes are not able to effectively eliminate oil compounds, and the high concentrations of these pollutants, as well as active sludge, may affect the activities and normal efficiency of the refinery. The methods of removal should not involve the production of harmful secondary pollutants in addition to wastewater at the level allowed for discharge into the environment. The output of sewage filtration by coagulation and dissolved air flotation (DAF) flocculation can be transferred to a biological reactor for further purification. Advanced coagulation methods such as electrocoagulation and flocculation are more advanced than conventional physical and chemical methods, but the major disadvantages are the production of large quantities of dangerous sludge that is unrecoverable and often repelled. Physical separation methods can be used to isolate large quantities of petroleum compounds, and, in some cases, these compounds can be recycled with a number of processes. The great disadvantage of these methods is the high demand for energy and the high number of blockages and clogging of a number of tools and equipment used in this process. Third-party refinement can further meet the objective of water reuse using methods such as nano-filtration, reverse osmosis, and advanced oxidation. Adsorption is an emergency technology that can be applied using minerals and excellent materials using low-cost materials and adsorbents. By combining the adsorption process with one of the advanced methods, in addition to lower sludge production, the process cost can also be reduced.

Progress in Modeling of Silica-Based Membranes and Membrane Reactors for Hydrogen Production and Purification

Hydrogen is seen as the new energy carrier for sustainable energy systems of the future. Meanwhile, proton exchange membrane fuel cell (PEMFC) stacks are considered the most promising alternative to the internal combustion engines for a number of transportation applications. Nevertheless, PEMFCs need high-grade hydrogen, which is difficultly stored and transported. To solve these issues, generating hydrogen using membrane reactor (MR) systems has gained great attention. In recent years, the role of silica membranes and MRs for hydrogen production and separation attracted particular interest, and a consistent literature is addressed in this field. Although most of the scientific publications focus on silica MRs from an experimental point of view, this review describes the progress done in the last two decades in terms of the theoretical approach to simulate silica MR performances in the field of hydrogen generation. Furthermore, future trends and current challenges about silica membrane and MR applications are also discussed.

Investigation and Modeling of Ozone Penetration in a Fixed Bed Reactor for Purification of Soil Contaminated with Anthracin

ABSTRACTIn this research, the influence of effective parameters on ozone penetration in the soil contaminated with anthracin has been investigated. The soil was then contaminated with anthracin, a polycyclic aromatic hydrocarbon, after washing and moisture removal stored in a dark environment for one week in closed containers. The parameters studied are as follows: the soil height, the soil particle size, contaminant concentration, ozonation time, and moisture percent. The maximum removal efficiency was 92%. In this study, it was observed that by changing the size of the soil particles, there are significant changes in the penetration rate. Also, the pollutant concentration, the height of the soil column, and moisture affect penetration rate. It was also observed that the highest penetration rate occurred in the first 10 min of the ozonation process. In the next step, by obtaining the governing equations for the decomposition of ozone by contaminate, organic and inorganic materials, soil active sites and spontaneous ozone decomposition, a model for ozone penetration in the soil was presented, and by comparing experimental data and modeling results, the coefficients of reaction rate of ozone kinetic reactions with pollutant, organic matter and inorganic soil, soil active sites and spontaneous ozone decomposition were obtained approximately.

The Efficiency Simulation of the Performance of a Sequencing Batch Biofilm Reactor for Purification of Domestic Sewage based on the Artificial Neural Network

The Efficiency Simulation of the Performance of a Sequencing Batch Biofilm Reactor for Purification of Domestic Sewage based on the Artificial Neural Network

Hydrogen and Deuterium Solubility in Commercial Pd–Ag Alloys for Hydrogen Purification

Pd–Ag alloys with compositions close to 23–25% Ag are considered as a benchmark for hydrogen permeability. They are used in small scale reactors for hydrogen separation and purification. Permeability and solubility are strictly mathematically correlated, and the temperature dependence of solubility can provide useful information about the physical state of the material, the hydrogenation enthalpy, and the occurrence of different thermodynamic states. While the permeability of Pd–Ag alloys has been largely investigated, solubility measurements are available only in a restricted temperature range. In this paper, we extend solubility measurements up to 7 bar for Pd77Ag23 in the temperature range between 25 °C and 400 °C and for Pd30Ag70 for temperatures between 190 °C and 300 °C. The occurrence of solid solutions or hydride phases is discussed, and the hydrogenation enthalpy is calculated.

Influence of the autonomous oscillations and the CO concentration on the performance of an ECPrOx reactor

In this contribution a well-mixed electrochemical preferential oxidation (ECPrOx) reactor for hydrogen purification is considered and the influence of the CO concentration on the polarization curve, the conversion, the selectivity and the specific energy required is investigated. For that, a wide range of CO concentrations are studied and two different control modes are evaluated: voltage and current control. It was established that the oscillations, which arise during current control, enhance the reactor performance. They decrease the specific energy required and increase, as does the CO concentration, the selectivity and the conversion. Furthermore, it was found that the bifurcation current and potential vary nonlinearly with the CO concentration.

Palladium based membranes and membrane reactors for hydrogen production and purification: An overview of research activities at Tecnalia and TU/e

In this paper, the main achievements of several European research projects on Pd based membranes and Pd membrane reactors for hydrogen production are reported. Pd-based membranes have received an increasing interest for separation and purification of hydrogen. In addition, the integration of such membranes in membrane reactors has been widely studied for enhancing the efficiency of several dehydrogenation reactions. The integration of reaction and separation in one multifunctional reactor allows obtaining higher conversion degrees, smaller reactor volumes and higher efficiencies compared with conventional systems. In the last decade, much thinner dense Pd-based membranes have been produced that can be used in membrane reactors. However, the thinner the membranes the higher the flux and the higher the effect of concentration polarization in packed bed membrane reactors. A reactor concept that can circumvent (or at least strongly reduce) concentration polarization is the fluidized bed membrane reactor configuration, which improves the heat transfer as well. Tecnalia and TU/e are involved in several European projects that are related to development of fluidized bed membrane reactors for hydrogen production using thin Pd-based (<5 μm) supported membranes for different application: In DEMCAMER project a water gas shift (WGS) membrane reactor was developed for high purity hydrogen production. ReforCELL aims at developing a high efficient heat and power micro-cogeneration system (m-CHP) using a methane reforming fluidized membrane reactor. The main objective of FERRET is the development of a flexible natural gas membrane reformer directly linked to the fuel processor of the micro-CHP system. FluidCELL aims the Proof-of-Concept of a m-CHP system for decentralized off-grid using a bioethanol reforming membrane reactor. BIONICO aims at applying membrane reactors for biogas conversion to hydrogen. The fluidized bed system allows operating at a virtually uniform temperature which is beneficial in terms of both membrane stability and durability and for the reaction selectivity and yield.

Study of plasma off-gas treatment from spent ion exchange resin pyrolysis

Polystyrene divinylbenzene-based ion exchange resins are employed extensively within nuclear power plants (NPPs) and research reactors for purification and chemical control of the cooling water system. To maintain the highest possible water quality, the resins are regularly replaced as they become contaminated with a range of isotopes derived from compromised fuel elements as well as corrosion and activation products including 14C, 60Co, 90Sr, 129I, and 137Cs. Such spent resins constitute a major proportion (in volume terms) of the solid radioactive waste generated by the nuclear industry. Several treatment and conditioning techniques have been developed with a view toward reducing the spent resin volume and generating a stable waste product suitable for long-term storage and disposal. Between them, pyrolysis emerges as an attractive option. Previous work of our group suggests that the pyrolysis treatment of the resins at low temperatures between 300 and 350°C resulted in a stable waste product with a significant volume reduction (>50%) and characteristics suitable for long-term storage and/or disposal. However, another important issue to take into account is the complexity of the off-gas generated during the process and the different technical alternatives for its conditioning. Ongoing work addresses the characterization of the ion exchange resin treatment's off-gas. Additionally, the application of plasma technology for the treatment of the off-gas current was studied as an alternative to more conventional processes utilizing oil- or gas-fired post-combustion chambers operating at temperatures in excess of 1000°C. A laboratory-scale flow reactor, using inductively coupled plasma, operating under sub-atmospheric conditions was developed. Fundamental experiments using model compounds have been performed, demonstrating a high destruction and removal ratio (>99.99%) for different reaction media, at low reactor temperatures and moderate power consumption. The role of H2O as an important participant of the oxidation mechanisms in plasma conditions was established. The combination of both processes could represent a simple, safe, and effective alternative for treating spent ion exchange resins with a large reduction of generated gaseous byproducts in fuel cycle facilities where processes that utilize open flames are undesirable.

Anatase TiO2 nanotube arrays and titania films on titanium mesh for photocatalytic NOX removal and water cleaning

An anodization method was developed for the preparation of highly photoactive titania nanotube arrays (TiNTs) on commercially available titanium mesh. The prepared material was characterized from the point of view of its structure and possible photocatalytic applications and was compared with titania films deposited on the Ti-mesh by liquid deposition (TiO2-LD) and sol-gel methods (TiO2-SG). The photoactivity was determined in gas phase using NOX decomposition according to the ISO standard no. 22 197-1 (2007) as well as in liquid phase by decolorization of organic dyes e.g. methylene blue (MB) and rhodamine B (RhB). The investigated anatase nanotube arrays on Ti mesh showed the highest photoactivity in both gaseous and liquid phases and are promising for applications in photocatalytic reactors for environmental purification.

CO-PrOx over nano-Au/TiO2: Monolithic catalyst performance and empirical kinetic model fitting

In this work, the performance of ceramic monoliths washcoated with Au/TiO2 is studied on CO preferential oxidation (CO-PrOx) reaction in H2-rich environments under a wide range of operating conditions of practical interest. The parameter estimation of a nonlinear kinetic empirical model representing this system is made via genetic algorithms by fitting the model predictions against our laboratory observations. Parameter uncertainty leading to inaccurate predictions is often present when kinetic models with nonlinear rate equations are considered. Here, after the fitting was concluded, a statistical study was conducted to determine the accuracy of the parameter estimation. Activation energies of ca. 30 kJ/mol and 55 kJ/mol were adjusted for CO and H2 oxidations, respectively. The catalyst showed appropriate activity and selectivity values on the CO oxidation on a H2-rich environment. After ca. 45 h on stream the catalyst showed no deactivation. Results show that the model is suitable for reproducing the behavior of the CO-PrOx reactions and it can be used in the design of reactors for hydrogen purification.

Integrated system for extraction, purification, and digestion of membrane proteins.

An integrated system was developed for directly processing living cells into peptides of membrane proteins. Living cells were directly injected into the system and cracked in a capillary column by ultrasonic treatment. Owing to hydrophilicity for broken pieces of the cell membrane, the obtained membranes were retained in a well-designed bi-filter. While cytoplasm proteins were eluted from the bi-filter, the membranes were dissolved and protein released by flushing 4% SDS buffer through the bi-filter. The membrane proteins were subsequently transferred into a micro-reactor and covalently bound in the reactor for purification and digestion. As the system greatly simplified the whole pretreatment processes and minimized both sample loss and contamination, it could be used to analyze the membrane proteome samples of thousand-cell-scales with acceptable reliability and stability. We totally identified 1348 proteins from 5000 HepG2 cells, 615 of which were annotated as membrane proteins. In contrast, with conventional method, only 233 membrane proteins were identified. It is adequately demonstrated that the integrated system shows promising practicability for the membrane proteome analysis of small amount of cells.

Numerical study of heat and mass transfer processes in a metal hydride reactor for hydrogen purification

The present paper describes a numerical study of heat and mass transfer processes in a metal hydride reactor for hydrogen purification with aluminium foam. A numerical simulation was done with the help of the mathematical model, which had been used previously for a numerical simulation of heat and mass transfer processes in different types of metal hydride reactors during sorption/desorption processes. The results illustrate that the major factors that reduce the rate of sorption, and consequently the efficiency of the system, are increasing the temperature of the reactor and the pressure drop, which is due to filtering the mixture through a metal hydride bed with low permeability. It is shown that the use of aluminium foam allows us to realise a more effective system for hydrogen purification from impurities, compared to a case without aluminium foam, while the volumetric capacity of the system is reduced slightly (9%). Increasing pressure at the reactor inlet also increases the efficiency of the system.

Evaluation of a tubular nano-composite ceramic membrane for hydrogen separation in methane steam reforming reaction

Nano-composite ceramic membranes are successfully applied in a membrane reactor for simultaneous production and purification of hydrogen in the MSR reaction.

Numerical study of hydrogen purification using metal hydride reactor with aluminium foam

The present paper describes a numerical study of heat and mass transfer processes in a metal hydride reactor for hydrogen purification with aluminium foam. The mathematical model, which was used previously for numerical simulation of heat and mass transfer processes in different types of metal hydride reactors, was modified for a reactor with aluminium foam. To validate the thermal equilibrium between the aluminium foam and metal hydride, pore-scale modelling was performed. In the case of pure hydrogen sorption, the model was validated by a comparison with experimental data; good agreement for sorption dynamics was obtained. The effects of various parameters of the pressure swing absorption method on the effectiveness of metal hydride systems for hydrogen purification were studied. The obtained results show that the use of aluminium foam enhances intensity of heat and mass transfer and consequently decreases the time required for hydrogen purification (up to two times) compared to a case without aluminium foam, while the volumetric capacity of the system is reduced slightly (9%). It is shown that pressure swing absorption method with fixed time interval between purges and the method with fixed interval of the fraction changing of the transformed material between purges provide a similar performance; in the second case the hydrogen recovery ratio remains constant during the hydrogen purification process.

Preparation and characterization of mixed-mode magnetic adsorbent with p-amino-benzamidine ligand: Operated in a magnetically stabilized fluidized bed reactor for purification of trypsin from bovine pancreas

The magnetic beads were synthesized using glycidylmethacrylate (GMA) and methylmethacrylate (MMA) monomers. A multimodal ligand (i.e., p-amino-benzamidine) was covalently immobilized onto magnetic beads after glutaraldehyde activation, and consequently used for purification of the trypsin from bovine pancreas. The p-amino-benzamidine ligand immobilized magnetic beads were characterized by FTIR, VSM, SEM, and analytical methods. Trypsin adsorption experiments were investigated under different experimental conditions (i.e., medium pH, initial trypsin concentration, temperature, and ionic strength) in a batch system. Maximum trypsin adsorption capacity was found to be 75.9±2.6mg/g beads. Adsorbed trypsin was eluted by using (0.1M acetate buffer, pH 3.0) with a 97% recovery. The purification factor of trypsin from crude pancreas extract was 8.7 folds. The purity of the eluted trypsin from p-amino-benzamidine functionalized magnetic beads was determined as 86% by HPLC. The method developed in this report was successfully applied for purification of the trypsin from crude pancreas extract in a magnetically stabilized fluidized bed reactor.

Numerical simulation of sorption/desorption processes in metal-hydride systems for hydrogen storage and purification. Part II: Verification of the mathematical model

A numerical simulation of heat and mass transfer in metal-hydride reactors for hydrogen storage and purification was performed. Hydrogen desorption and hydrogen sorption from gaseous mixtures were analysed. The calculated results are compared with experimental data obtained in the Joint Institute of High Temperatures of the Russian Academy of Science. The agreement between the calculated results and the experimental data is demonstrated to be satisfactory. It is indicated that to increase the efficiency of hydrogen purification in a metal-hydride reactor, the thickness of the porous bed cooled by external water must be no more than 6–8mm.