Multistage Column Research Articles

Recovery of Li from seawater using Li1.33Mn1.67O4 immobilized multi-stage column system

The securing of lithium (Li) from resources containing low concentrations of Li+, such as brines and seawater, is receiving a lot of attention due to the rapid increase in demand for lithium-ion batteries. In this respect, the adsorption process is regarded as the most appropriate method for the direct extraction of Li+ from low-concentration solutions. However, for practical application, the adsorbent materials need to be shaped into granules, spheres, or foams using binding materials, which can reduce the adsorption performance by blocking adsorption sites. To overcome this drawback, an alternative method is proposed herein whereby the adsorbent lithium manganese oxide (LMO) powder is loaded into a multi-stage column (MSC) system equipped with a fabric filter. The optimum conditions for the fabrication of the LMO powder are found to be an Li/Mn molar ratio of 0.8 with a heating temperature of 500 °C for 4 h, and its delithiated product giving a maximum adsorption capacity of 23.9 mg g−1 from Li-spiked seawater (2–60 ppm). By comparison, stirring the adsorbent powder in solution for the same adsorption time yielded 22.8 mg g−1. The MSC adsorption process fits well with the Langmuir isotherm and pseudo second-order kinetics. To confirm the feasibility of the proposed method, its performance is also evaluated in the extraction of Li+ from natural seawater, giving Li+ recoveries ranging from 4 to 4.9 mg g−1 during repeated adsorption/desorption runs. Thus, the proposed method provides a practical Li+ extraction approach that can recover Li+ with a good adsorption performance.

Experimental Study and Correlation for Mass Transfer Coefficient in the Pilot Plant Multistage Column with the Presence of Molybdenum

In the present work, multistage extraction column performance for reactive separation of molybdenum from the leach aqueous phase by using D2EHPA and TBP in kerosene was investigated by using axial diffusion model. Initially, the values of initial pH and extractant concentration were optimized on the batch experiments. The variation of volumetric overall mass transfer coefficients based on continuous phase at various operating conditions was obtained. By considering the chemical reaction conditions, the experimental data indicate that the volumetric overall mass transfer coefficients increase with an enhancement in rotor speed and continuous and dispersed phase flow rates. According to the sensitivity analysis, the rotor speed and flow rate of dispersed phase have more influence on column performance. Also, the continuous flow rate has little effect on volumetric overall mass transfer coefficients. After the steady-state condition was established, the concentration profile for the extraction of molybdenum along the column was obtained. The experimental data were studied and compared with the previous models. A new model based on dimensionless numbers was derived from the evaluation of overall mass transfer coefficients with consideration of the reactive extraction system.

Theoretical study of industrial scale closed-loop recycling counter-current chromatography separations

Industrial separation technologies can be improved and greatly simplified by using the methods of counter-current chromatography (CCC). We have previously proposed the use of currently available solvent extraction equipment (a series of multistage columns, a cascade of centrifugal mixer-settler extractors) as large-scale CCC devices. For industrial separations, the application of closed-loop recycling counter-current chromatography (CLR CCC) methods seems to be the most promising. To improve the performance of the CLR CCC separations, semi-continuous three-stage processes (1 – continuous loading of the mixture solution over a definite time; 2 – separation of solutes in recycling closed-loop; 3 – elution of the fractions of the separated solutes with the mobile phase) can be used. The purpose of this study is to present a simple and easy to use mathematical model allowing the simulation and design of various options for implementing such separation processes and analyze the influence of its main parameters on separation efficiency.

Studying the Effect of Recycling on the Semibatch Process of the Extraction Separation of Components in a Multistage Loop

The results of an experimental study on the effect of regime parameters and recycling on the efficiency of the continuous process of the chromatographic extraction separation of a binary caffeine–coumarin mixture in a closed cascade of multistage columns are presented.

Improved Flotation Recovery and Selectivity of an Ultra-Fine Brazilian Phosphate Ore Using Eriez’ Column Flotation Technology

Eriez Flotation Division recently completed column flotation testing of two igneous phosphate ore samples from the Tres Estradas deposit as part of Aguia Resources’ bankable feasibility study for the greenfield project. Due to fine dissemination of the phosphate and associated grinding requirements, column flotation was selected for the metallurgical test program to address the inherent limitations of fine particle flotation using conventional mechanical flotation cells. Eriez’ column flotation cells with Cavitation-Tube spargers are a commercially-mature and efficient technology for flotation of fine particles that may otherwise not be feasible using conventional flotation machines. Accordingly, continuous column flotation pilot tests were conducted by Eriez on two ultra-fine (212x0 µm) samples of Tres Estradas carbonatite ore (fresh and oxidized) to determine flotation responses and develop an industrial circuit design. Using Eriez’ automated multi-stage column flotation circuit, the fresh carbonatite ore was upgraded from 3.6-4.1% P2O5 to 30-32% P2O5 at a P2O5 recovery of 71-80% using a rougher-scavenger-cleaner-cleaner circuit configuration. Similarly, the oxidized (saprolite) carbonatite ore was upgraded from 10.0-11.5% P2O5 to 32-33% P2O5 at a P2O5 recovery of 85-90% using a rougher-cleaner column circuit configuration. The benefits of Eriez’ column flotation technology realized from this test work include a higher degree of selectivity, increased recovery, and reduced collector dosage as compared to bench-scale mechanical flotation. Specifically, the recovery of fresh carbonatite and oxidized (saprolite) carbonatite ore by column floatation increased 2-3% and 5% respectively, while collector dosage was reduced by 20-40% and the required number of cleaning stages to achieve the target concentrate grade was reduced.

Analysis of Extraction Chromatographic Separation of a Binary Mixture in a Series of Multistage Columns

Two processes of multistage extraction chromatographic separation of components (with and without recycling) are theoretically studied under various conditions of loading of a mixture to be separated to the apparatus. A mathematical description of the separation processes is presented. It is shown that the separation of components in the process with recycling requires an order of magnitude fewer equilibrium stages than separation in the process without recycling. Moreover, the productivity of the process with recycling, which is determined by the duration of loading to the apparatus, is an order of magnitude higher.

Investigation into the Extraction–Chromatographic Separation of a Binary Mixture in a Series of Multistage Columns

The semibatch multistage extraction chromatographic separation of a binary system of components has been experimentally studied under various conditions of loading of the mixture to the apparatus. An acceptable fit of the previously developed mathematical model of the process to the experimental results is determined.

Cytotoxic polyphenolic compounds from Lespedeza bicolor stem bark

Four new pterocarpans (6aR,11aR)-6a,11a-dihydrolespedezol A2 (2), (6aR,11aR)-2-isoprenyl-6a,11a-dihydrolespedezol A2 (3), (6aR,11aR,3′R)-6a,11a-dihydrolespedezol A3 (4), (6aR,11aR,3′S)-6a,11a-dihydrolespedezol A3 (5) and one new stilbenoid with 1,2-diketone fragment named bicoloketone (6) along with one previously known pterocarpen lespedezol A2 (1) have been isolated from Lespedeza bicolor stem bark using multistage column chromatography on polyamide and silica gel. The structures of the isolated polyphenolic compounds were determined by spectroscopic methods. The absolute configurations of 4 and 5 were determined by comparison of their electronic circular dichroism (ECD) spectra obtained experimentally and the spectra calculated using time-dependent density functional theory (TDDFT). The isolated compounds exhibited a moderate DPPH scavenging effect and ferric reducing power compared to the reference antioxidant quercetin. The cytotoxicity of compounds against three human cancer cell lines, HTB-19, Kyse-30, and HEPG-2, and two normal cell lines, RPE-1 and HEK-293, was tested using the MTT assay. Compound 3 showed the strongest cytotoxic activity against all cell lines (IC50 6.0–19.1 μM) compared with the positive control cisplatin. The other tested compounds possessed moderate cytotoxic activity against cancer cells.

Purification and characterisation of antimicrobial agents isolated from a member of the Paenibacillus genus

Antimicrobial resistance (AMR) poses an ever-increasing threat to public health; the prevalence of resistant bacterial strains has reduced the clinical efficacy of many existing therapeutics and is therefore contributing to rising mortality rates due to difficult to treat bacterial infections. Two key approaches used to mitigate the threat of AMR are the discovery of novel therapeutics with activity against these resistant strains, and educating the wider public about the impact of AMR, and steps that can be taken to reduce the development of resistance. We are combining both approaches to enhance the impact of our public engagement activities. During a recent event at the University of Plymouth, a member of the public isolated the bacterial strain ‘36A’ from the button of a lift control panel. Simultaneous antagonistic screening identified antimicrobial activity against a range of both Gram-positive and Gram-negative bacteria. 36A was then subjected to draft genome sequence determination via the MinION platform (Oxford Nanopore). Growth media were optimised to enhance antimicrobial activity, with fermentation in LB broth and subsequent purification of the culture supernatant via multi-stage column chromatography resulting in the isolation of four putative antimicrobial compounds. Initial characterisation has shown that each compound has a peptidic component, all showing stability and potency at a relatively low concentration against MRSA, E. coli, Klebsiella pneumoniae and Pseudomonas aeruginosa. Structural characterisation has been carried out using mass spectrometry, with further characterisation and cell toxicity studies ongoing. The producing strain has been identified as a member of the Paenibacillus genus.

Novel multistage solid–liquid circulating fluidized bed: liquid phase mixing characteristics

Liquid phase axial mixing studies have been carried out in the novel solid–liquid circulating fluidized bed (SLCFB). The SLCFB primarily consists of a single multistage column (having an inner diameter of 100 mm i.d. and length of 1.40 m) which is divided into two sections wherein both the steps of utilization, namely loading (e.g., adsorption and catalytic reaction) and regeneration of solid phase, can be carried out simultaneously in continuous mode. Weak base anion exchange resin was used as the solid phase, whereas water as the fluidizing medium. The effects of physical properties of solid phase, superficial liquid velocity, and solid circulation rate on liquid phase axial dispersion coefficient were investigated. The dispersion coefficient increases monotonically with an increase in the size of solid particle, superficial liquid velocity, and solid circulation rate. The axial dispersion model (ADM) was used to model experimental residence time distribution (RTD) data. A good agreement was found between ADM predictions and the experimental measurements. A unified correlation has also been proposed to determine dispersion coefficient as a function of physical properties of solid and liquid phases, superficial liquid velocity, and solid circulation rate based on all previous and present experimental data on multistage SLCFB.

Effect of Contact Time of Gaseous Phase in Multi-Stage Contact Columns in Intermediate Ozonation Process on Reduction of Bromate Concentration

This article describes research on the application of ozone technology for the purification of surface water in the presence of bromides. The pilot system used multistage contact columns for water-ozonation processes with stabilized contact time. The research has shown that the basis for limiting the formation of bromates is the optimum amount of residual ozone after the ozonation process and the constant time of ozone contact with the water. This solution allows us to reduce the formation of harmful compounds and apply ozone technology with water containing carcinogenic precursors.

Process simulation of organic liquid products fractionation in countercurrent multistage columns using CO2 as solvent with Aspen-Hysys

Fractionation of liquid phase products (OLP), obtained by thermal catalytic cracking of palm oil, simulated in multistage countercurrent absorber/stripping columns using SC-CO2 as solvent with Aspen-Hysys, at 333 K, 140 and 180 bar, and (S/F) = 12, 15, 17, 25, 30, 38. RK-Aspen EOS applied to correlate equilibrium data of binary systems (OLP)-i/CO2. Composition of OLP used to predict thermophysical properties and acentric factor of OLP compounds by group-contribution methods. The effect of pressure and (S/F) on process performance evaluated by computing the yield and recoveries of hydrocarbons, olefins, oxygenates, carboxylic acids. The regressions show that RK-Aspen EOS describe well phase equilibrium data, showing AAD between 0.8% and 1.25% and 0.01%– 0.66% for the liquid and gaseous phases. The best deacidifying conditions obtained at 333 K, 140 bar, and (S/F) = 17. Simulations show that SC-CO2 was able to deacidify OLP and to obtain fractions with lower olefins content.

Solid-liquid circulating fluidized bed: a way forward

Abstract Solid-liquid circulating fluidized beds (SLCFBs) offer several attractive features over conventional solid-liquid fluidized beds such as efficient liquid-solid contact, favorable mass and heat transfer, reduced back-mixing of phases, and integrated reactor and regenerator design. These unique features have stimulated theoretical and experimental investigations over the past two decades on transport phenomena in SLCFBs. However, there is a need to compile and analyze the published information with a coherent theme to design and develop SLCFB with sufficient degree of confidence for commercial application. Therefore, the present work reviews and analyzes the literature on hydrodynamic, mixing, heat transfer, and mass transfer characteristics of SLCFBs comprehensively. Suitable recommendations have also been made for future work in concise manner based on the knowledge gaps identified in the literature. Furthermore, a novel multistage SLCFB has been proposed to overcome the limitations of existing SLCFBs. The proposed model of SLCFB primarily consists of a single multistage column which is divided into two sections wherein both the steps of utilization viz. loading (adsorption, catalytic reaction, etc.) and regeneration of solid phase could be carried out simultaneously on a continuous mode.

Novel multistage solid–liquid circulating fluidized bed: Hydrodynamic characteristics

The present work proposes a novel radially cross-flow multistage solid–liquid circulating fluidized bed (SLCFB). The SLCFB primarily consists of a single multistage column (having an inner diameter of 100mm and length of 1.40m), which is divided into two sections wherein both the steps of utilization or loading (e.g., adsorption and catalytic reaction) and regeneration of the solid phase can be carried out simultaneously in continuous mode. The hydrodynamic characteristics were studied using ion exchange resin as the solid phase and water as the fluidizing medium. The loading and flooding states were determined for three particle sizes; i.e., 0.30, 0.42, and 0.61mm. The effects of the superficial liquid velocity and solid feed rate on the solid hold-up were investigated under loading and flooding conditions. The solid hold-up increases with an increase in the solid feed rate and decreases with an increase in the superficial liquid velocity. An artificial-intelligence formalism, namely the multilayer perceptron neural network (MLPNN), was employed for the prediction of the solid hold-up. The input space of MLPNN-based model consists of four parameters, representing operating and system parameters of the proposed SLCFB. The developed MLPNN-based model has excellent prediction accuracy and generalization capability.

In Situ Magnetite Formation and Long-Term Arsenic Immobilization under Advective Flow Conditions.

In situ precipitation of magnetite and other minerals potentially sequesters dissolved arsenic (As) in contaminated aquifers. This study examines As retention and transport in aquifer sediments using a multistage column experiment in which magnetite and other minerals formed from added nitrate and ferrous iron (Fe). Sediments were collected from the Dover Municipal Landfill Superfund site. Prior to nitrate-Fe(II) addition, As was not effectively retained within the sediments in the column. The combination of nitrate (10 mM) and Fe(II) (4 mM), resulted in mineral precipitation and rapidly decreased effluent As concentrations to <10 μg L(-1). Mineralogical analyses of sectioned replicate columns using sequential extractions, magnetic susceptibility and X-ray absorption spectroscopy indicate that magnetite and ferrihydrite formed in the column following nitrate-Fe(II) addition. This magnetite persisted in the column even as conditions became reducing, whereas ferrihydrite was transformed to more stable Fe oxides. This magnetite incorporated As into its structure during precipitation and subsequently adsorbed As. Adsorption to the minerals kept effluent As concentrations <10 μg L(-1) for more than 100 pore volumes despite considerable Fe reduction. The results indicate that it should be feasible to produce an in situ reactive filter by nitrate-Fe(II) injection.

Removal of motor oil by continuous multistage froth flotation: Effect of operational parameters

ABSTRACTA continuous multistage froth flotation column was employed to remove motor oil from water at a low concentration (500 mg/L) using an extended surfactant – branched alcohol propoxylate sulphate sodium salt (C14-15–8PO–SO4–Na) – as a frother. The highest separation efficiency (97% motor oil removal with the enrichment ratio of 16 for motor oil) was obtained at a foam height of 60 cm, an air flow rate of 40 L/min, a feed flow rate of 60 mL/min, a surfactant concentration of 0.3% (w/v), and an NaCl concentration of 1.5% (w/v). The process performance increased with increasing tray number but beyond 4 trays, the system could only offer lower concentrations of motor oil and surfactant in the effluent.

Experimental mass transfer coefficients in a pilot plant multistage column extractor

The volumetric overall mass transfer coefficients in a multistage column have been measured using axial dispersion model for toluene–acetone–water system. The effect of operating parameters on the volumetric overall mass transfer coefficients has been investigated for both mass transfer directions. The results show that the mass transfer performance is strongly dependent on rotor speed and mass transfer direction, although only slightly dependent on phase flow rates. In addition, empirical correlations to predict the overall mass transfer coefficients have been developed. The proposed correlations based on dimensionless numbers can be considered as a useful tool for the possible scale up of the multistage column extractor.

Experimental investigation of dispersed phase holdup and flooding characteristics in a multistage column extractor

In this research work, liquid–liquid extraction via three different systems has been investigated for determination of holdup, flooding velocities and holdup at the flooding points in a multistage column extractor. The effects of various parameters including rotor speed and dispersed and continuous phase velocities were studied. The results showed that the enhancement of rotor speed and dispersed and continuous phase velocities would enhance the dispersed phased holdup. There was a significant increase in the holdup at the flooding points with an increase in the rotor speed because of the smaller drops formation. New correlations were also developed for prediction of the flooding velocities, holdup at flooding points and dispersed phase holdup in the multistage column extractor. The results of the proposed correlation were compared with the experimental data obtained from the literature and the present investigation. Findings of this study demonstrated that the proposed correlations give accurate predictions for flooding characteristics.

Development of multi-stage column for lithium recovery from an aqueous solution

Spinel lithium manganese oxides (LMOs) are the most effective lithium adsorbent for the recovery of lithium from an aqueous solution with high selectivity. Developing a systematic method to apply LMOs powder will have a profound impact on the effective and practical process of lithium recovery. We previously fabricated a reservoir system in which the LMO powder was packed in the inside of fabric membrane and then tested by dipping it in an aqueous solution. However, this method exhibited lower adsorption capacity compared with that of LMO powder by stirring in an aqueous solution. Here, we demonstrate a new method to selectively recover lithium from an aqueous solution through an integration of several columns filled with LMO powder. Briefly, our system comprises a series of columns equipped with fabric filters that accumulate LMO powder onto the fabric membrane in which the aqueous solution containing Li+ ion is introduced into the system by applying pressure. We report that the multi-stage column (MSC) uniformly packed with LMOs exhibited higher adsorption capacity (30.7mg·g−1) compared with that (12.3mg·g−1) of a reservoir system at a lithium concentration of 30mg·L−1. To confirm the feasibility of the multi-stage column (MSC), we also tested it to the recovery of lithium from Salt Lake, which was artificially manufactured.

Process study for stripping components in absorption–desorption processes for CO2-removal from power plant flue gases

In this work the influence of adding an organic stripping component which is immiscible with water to the desorber of a Post-Combustion-Capture absorption–desorption process is examined. For that purpose a model for a three-phase equilibrium was developed: aqueous liquid phase with monoethanolamine (MEA), organic liquid phase and gas. In the aqueous liquid phase chemical reactions of dissolved CO2 have to be considered. Based on this model for the phase equilibrium, a multistage column model representing the desorber was set up. With this model for the desorber and a two-phase equilibrium model for the absorber, both implemented in MATLAB, the overall absorption–desorption process can be simulated. Moreover, a power plant model was set up in the commercially available process simulator UniSim Design in order to investigate the overall performance of a coal fired power plant with Post-Combustion-Capture of CO2.The results show that depending on the choice of the organic component added to the desorber, the boiling temperature of the reboiler of the desorber can be lowered significantly. However, the overall penalty for power plant including CO2 separation is in favor of the conventional two-phase regeneration. The physical effects for this behavior are presented in detail.