Raffinate Streams Research Articles

Formulation and testing of a high-tin borosilicate nuclear waste glass for in-can melting

Borosilicate waste glasses were successfully developed to immobilize two high-level waste raffinate streams via an in-can melter process with an Inconel 601 canister at 1050 °C. Measured viscosity and crystallinity thermal profiles were within the targeted processing constraints for the in-can melter process. Measured chemical durability of the glass by ASTM C1285–21 (Method A), ranged from normalized loss of boron, NL(B) = 1.44 – 2.65 g·m−2, and NL(B) decreased with increased waste loading, accompanied by increased SnO2 crystallinity. Measured corrosion of the in-can melter canister by a glass melt showed that Inconel 601 performed well at 1100 °C for up to 500 hr. Resistance polarization measurements versus time revealed that Inconel 601 corrosion rates in (and by) glass melts decreased from an initial rate of 63 mm·y−1 down to 10.2 mm·y−1 after 137 h with increased duration, which was attributed to formation of an oxide passivation layer (mainly Cr2O3) at the alloy-glass interface.

Study on the benefit of HLLW partitioning on the high-level waste glasses from the viewpoint of waste management

The volume and characteristics of heat-generating waste glasses produced through spent fuel reprocessing PUREX process + HLLW partitioning TRPO process are evaluated as a function of burn-up and cooling period of spent fuel in this study. The waste loading of glass is assumed to be restricted by the heat generation rate, MoO3 content, and noble metal content. The results show that: 1) For spent fuel of 8–20 years cooling, the volume of waste glasses after HLLW partitioning is 39%–25% of that before partitioning. 2) After removing >99.967% of α-nuclides in HLLW through TRPO process, the TRPO raffinate stream can be immobilized into waste glasses. After 95 years of decay storage, intermediate-depth disposal rather than geological disposal of TRPO raffinate waste glasses could be engineered. 3) Separation of Sr and Cs from TRPO raffinate hardly reduces the volume of waste glasses. SrCs separation before vitrification is unnecessary. 4) The insoluble residues generated during the shearing and dissolution of spent fuel may not be suitable for mixing with the TRPO raffinate stream, nor for immobilizing into a borosilicate glass matrix. Alternative solutions rather than vitrification are encouraged.

Supervisory system for automated simulated moving bed (SMB) liquid chromatography (LC)

Praziquantel (PZQ) is a racemic mixture prescribed for Schistosomiasis disease treatment. However, only the enantiomer (R)-PZQ presents demonstrated efficiency against infirmity; the (S)-PZQ causes sickness and vomiting due to its bitter taste. The simulated moving bed chromatography system (SMB) is a well-established separation process applied in many branches of the chemical industry from drug purification stages to food processing systems. In order to implement and operate an SMB for the PZQ separation, allowing the production of medication with proven efficiency and without side effects, a LabVIEW supervisory system was developed. The automated software remotely controlled all equipment in the operational unit, such as automatic pumps, multi-position valves for flow rate alignments, and a chiral detector. Two experiments were conducted to characterize the system’s operational properties and efficiency. The first set of results demonstrated that the data acquisition programming retrieved information constantly, evidencing a direct correlation between the internal liquid pressure and the valve system position, with mean pressure values of approximately 50 bar. The second set of results demonstrated the SMB efficiency, with the raffinate stream producing (R)-PZQ of 100% purity.

A novel optimization approach for material screening in the adsorption process separation context based on rigorous models: Separation of a mixture of N2 and CO2 in a Pressure Swing Adsorption Unit as a case study

Adsorption material screening simultaneously with optimizing an adsorption-based process is a challenging problem with increasing attention in the literature. This is usually done in an uncoupled way, separated into two separated steps. The first step focuses on the materials' properties, followed by an optimization step where the focus is on the process behavior given a pre-selected material. It is observed in the literature an increasing demand for systematic optimization approaches that make use of materials science databases in a process systems engineering context. Therefore, providing a synergy between these two disciplines. Hence, the present work proposes the design of a looped optimization problem where the material and process operating conditions are used as decision variables to optimize a Pressure Swing Adsorption. An inner loop is used to screen the best material among the 12 options. An outer optimization loop is used to optimize de process operating variables. A case study presents the separation of the raffinate stream produced in the gaseous Simulated Moving Bed process to separate CH4/N2 using CO2 as the desorbent gas. Thus, the SMB raffinate stream is composed of a mixture of N2 and CO2. The results demonstrate that the proposed methodology can efficiently perform both tasks, identify the most suitable material and optimize the Pressure Swing Adsorption unit.

Health-Promoting Properties of Borage Seed Oil Fractionated by Supercritical Carbon Dioxide Extraction.

Borage (Borago officinalis L.) seed oil is an important source of γ–linolenic acid, which is normally used as a treatment against different pathologies. Since the fractionation of this interesting seed oil has many environmental, economic and biological benefits, two borage fractionation techniques after extraction with CO2 under supercritical conditions have been studied: precipitation in two cyclone separators and countercurrent extraction column. Both techniques have successfully collected free fatty acids in one fraction: (i) two separators set up in series obtained the highest concentration of free fatty acids in separator 2 at 90 bar/40 °C; (ii) when countercurrent extraction column was used, the acidity index of the raffinate stream was independent from the operating conditions (2.6 ± 0.5%). Furthermore, the composition of the fatty acids, as well as their antioxidant and cytotoxic activities, were determined. The profile of the fatty acids obtained by either of these two methods remained unaltered, so that the crude oil exhibited improved antioxidant and cytotoxic properties. All the extracts obtained in the two cyclone separators at the same pressure/temperature conditions displayed high tumouricidal activity against HL 60 promyelocytic leukaemia cells, even if the extracts at 50% concentration from separator 2 presented a lower inhibitory activity (IC50). The extracts from separator 2 at 90 bar/40 °C exhibited the highest anti-proliferative activity at low doses (IC50 of 0.3 μL/mL for the trypan blue exclusion test). To reach the lethal dose—IC50—with the product obtained through countercurrent column fractionation, a concentration of 2 μL/mL of crude borage oil raffinate was required.

Single‐component‐at‐a‐time variation study for glass‐ceramic waste forms

AbstractA 51‐sample composition variation study was performed on glass‐ceramic waste forms for a raffinate waste stream from aqueous reprocessing of used nuclear fuel containing high fractions of Mo, alkalis, alkaline earths (AEs), and rare earths (REs). The study was designed with a single‐component‐at‐a‐time variation approach off a centroid composition. The components that were varied included Al, B, Ca, Li, Mo, Na, REs, Si, Zr, and Others (containing minor components). Data analysis included crystallization curves, microstructure, and phase compositions. A number of components (i.e., Li2O, B2O3, REOx, MoO3, Na2O, and ZrO2) significantly impacted the concentration and chemistry of phases, especially the primary phases of oxyapatite [i.e., Ca2RE8(SiO4)6O2] and powellite (i.e., AEMoO4), precipitated in the slow‐cool heat‐treated waste forms; minor phases included cerianite [i.e., CexZr(1‐x)O2], Ba‐molybdate [i.e., Ba(Gd0.67Mo0.33O3], noble metals, pollucite (i.e., CsAlSiO4), and RE‐borosilicate (i.e., RE3BSi2O10).

Reversed-phase chromatographic separation and downstream precipitation of lupane- and oleanane-type triterpenoids: Experiments and modeling based on the method of moments

The reversed-phase chromatographic separation of two triterpenic acids (TTAs), betulinic and oleanolic acids, using a triacontyl (C30) stationary phase was addressed in this work. Methanol, water, acetonitrile, ethanol, isopropanol, ethyl acetate, acetone and mixtures thereof were tested, and the best mobile phase to conduct the separation was found to be methanol/acetonitrile 50/50 (%, v/v) at 23 °C, taking into account parameters like selectivity, resolution and TTAs solubility. The method of moments was used to determine the equilibrium constants of isotherms, the axial dispersion coefficients and the global linear driving force coefficients of pure betulinic and pure oleanolic acids. These parameters were then successfully validated by modeling unary and binary breakthrough curves. Simulated moving bed calculations showed that betulinic and oleanolic acids can be both obtained with purity of 99.2 % and productivity of 56.2 kg/(m3adsorbent day) using the packing material of an Acclaim C30 column with a 1-1-1-1 configuration with columns of 7.5 cm long. Finally, in order to recover the two TTAs from the SMB extract and raffinate streams, water was envisioned as a precipitation agent. Accordingly, the solubility of each TTA was measured in methanol/acetonitrile 70/30, 50/50, and 30/70 (%, v/v) modified with water. The obtained results showed that adding 65 % (%, v/v) of water it is possible to precipitate 98 % of the dissolved TTAs in all the tested methanol/acetonitrile mixtures.

Bovine serum albumin and myoglobin separation by size exclusion SMB.

The separation of the proteins Bovine Serum Albumin (BSA) and Myoglobin (Mb) was achieved by Size-Exclusion Simulated Moving Bed (SE-SMB) and performed experimentally in the FlexSMB® unit, an SMB unit designed and built in the Laboratory of Separation and Reaction Engineering. Before accomplishing the separation experiments in the mentioned unit, separation regions were computed by simulation based on a phenomenological mathematical model to determine appropriate operating conditions. The developed model was validated in advance, against fixed-bed dynamic adsorption experimental results, for pure component and binary mixtures. Then the SMB experiments were carried out, and purities of the Mb on the extract and BSA on the raffinate streams were 98% and 96%, respectively. The achieved recoveries were 80% of Mb on the extract and 94% of BSA on the raffinate. Lastly, productivities of 6.4 gprotein⋅lads-1⋅day-1 for the extract and 28.8 gprotein⋅lads-1⋅day-1 for the raffinate were obtained.

Recovery and purification of acetic acid from aqueous mixtures by simulated moving bed adsorption with methanol and water as desorbents

The objective of this work is to study the recovery of acetic acid from aqueous mixtures by adsorption using a commercial polyvinylpyridine (PVP) resin (Reillex® 425) as adsorbent, and methanol or water as desorbents. A theoretical model has been developed to describe the adsorption/desorption dynamics of acetic acid from aqueous mixtures in a fixed bed of the commercial resin. The model has been used to design and optimize a cyclic process based on simulated moving bed (SMB) technology for the recovery of acetic acid from a 10% w/w acetic acid/water mixture. The Triangle Theory and the volume separation method have been used, and an acetic acid with recovery ≥95% is obtained, and purity ≥99%. Productivities of 47.3 kg msolid−3 h−1 and 52.0 kg msolid−3 h−1, with desorbent consumptions of 0.0316 m3 kg−1 and 0.0205 m3 kg−1 have been achieved with methanol and water as desorbents, respectively. The recovery process of methanol from extract and raffinate streams has been simulated with Aspenplus®, calculating the energy requirement (0.0135 MJ/kgacetic acid).

Chromatographic separation of betulinic and oleanolic acids

In this work, a simulated moving bed unit (SMB) was designed for the separation of betulinic and oleanolic acids, two naturally occurring triterpenic acids that exhibit key pharmacological properties. Preliminary impulse experiments were conducted to select appropriate mobile and stationary phases, from which methanol/acetonitrile 50/50 (%, v/v) and an Apollo C18 column emerged as the most favorable option. Breakthrough experiments were conducted with the pure compounds to determine the equilibrium and mass transfer coefficients necessary for SMB simulations. These parameters were then validated through the successful prediction of breakthrough experiments of two binary mixtures of betulinic and oleanolic acids.Optimum SMB operating conditions were determined via an optimization strategy combining the design of experiments and response surface methodologies (DoE-RSM) with phenomenological computer simulations. It was demonstrated that an SMB unit consisting of two columns per section allows the recovery of betulinic acid in its raffinate stream with a purity of 99.0 % and oleanolic acid in the extract stream with 99.4 % purity. Moreover, it was also demonstrated that the addition of acetonitrile to methanol is translated into a gain of 16.1 % in terms of productivity when compared to other mobile phase such as methanol/water 95/5 (%, v/v).

Cloud point extractive spectrophotometric method for determination of uranium in raffinate streams during spent nuclear fuel reprocessing

A cloud point extractive spectrophotometric method was developed for the determination of uranium in raffinate streams. Uranium was extracted to a tri n-octyl phosphine oxide in o-Xylene from raffinate. Uranium present in organic phase was analyzed by spectrophotometry after cloud point extraction of U-PAR (4-(2-Pyridylazo) resorcinol) complex to cetyl trimethyl ammonium bromide—Triton-X-100 medium. The molar absorption coefficient for uranium complex was found to be 2.2 × 104 l mol−1 cm−1. The relative standard deviation for the determination of uranium was found to be 3.9% and with a minimum detection limit of 2 µg uranium per aliquot.

Process evaluation of swing strategies to recover N-ethylbutylamine after wet lipid extraction from microalgae

N-ethylbutyl amine (EBA) has been reported as switchable solvent for the extraction of lipids from microalgae. To properly assess the technical feasibility as well as the sustainability of the lipid extraction process with EBA, solvent recovery is an essential process consideration. In this paper, opportunities for solvent recovery from both the aqueous raffinate stream and the solid algal residue were investigated, and two approaches for solvent recovery from the extracted lipids were investigated. In the first approach, CO2 switching is applied, which switches EBA from a neutral molecule into an ionic liquid that phase splits from the lipids. In the second approach, the strong effect on water solubility of EBA due to its lower critical solution temperature (LCST) behavior is used in a temperature swing back-extraction. For both approaches, a conceptual process was designed, and for all unit operations where important information was missing, the missing information was obtained by experiment and/or using process simulation software (Aspen Plus V8.8). From the conceptual process evaluation, it was concluded that the process making use of CO2 switching suffers from large solvent losses due to the switching mechanism. With the temperature swing back-extraction, it was much better possible to recover the EBA, and design a feasible process that costs 12.4 MJ/kg lipids, which considering the energy content of 1 kg lipids, is net energy gain of 22.4 MJ/kg lipids.

Process integration for simulated moving bed reactor for the production of glycol ether acetate

This work designs and optimizes a simulated moving bed reactor (SMBR) within an overall process that includes two downstream units. The extract and raffinate streams are processed to improve product purity, and recycle streams leaving the downstream units are returned to the SMBR to reduce solvent consumption. Three different operating schemes are evaluated–the standard, limited superstructure, and full superstructure configuration.The proposed process flowsheet is optimized in a deterministic, nonlinear dynamic optimization scheme. The productivity of the target product, propylene glycol methyl ether acetate (PMA), is maximized while the minimum conversion is maintained between 70% and 99%, and the ratio of excess (solvent) reactant to the product is from 1.2 to 8. In addition to the standard configuration of SMBR, we found novel operating schemes through a superstructure formulation which allows feeding the recycle stream from downstream separation units. This work offers a realistic understanding of SMBR for implementation in an overall process flowsheet for industrial applications.

Separation of tartronic and glyceric acids by simulated moving bed chromatography

The SMB unit developed by the Laboratory of Separation and Reaction Engineering (FlexSMB-LSRE®) was used to perform tartronic acid (TTA) and glyceric acid (GCA) separation and to validate the mathematical model in order to determine the optimum operating parameters of an industrial unit. The purity of the raffinate and extract streams in the experiments performed were 80% and 100%, respectively. The TTA and GCA productivities were 79 and 115 kg per liter of adsorbent per day, respectively and only 0.50 cubic meters of desorbent were required per kilogram of products. Under the optimum operating conditions, which were determined through an extensive simulation study based on the mathematical model developed to predict the performance of a real SMB unit, it was possible to achieve a productivity of 86 kg of TTA and 176 kg of GCA per cubic meter of adsorbent per day (considering the typical commercial purity value of 97% for both compounds) with an eluent consumption of 0.30 cubic meters per kilogram of products.

Modeling of the separation of lactic acid from an aqueous mixture by adsorption on polyvinylpyridine resin and desorption with methanol

Abstract The main objectives of this work are to model the separation of lactic acid from an aqueous mixture by adsorption on a polyvinylpyridine resin (Reillex® 425), and to model the desorption of adsorbed lactic acid with methanol. The adsorption equilibrium isotherm of lactic acid in aqueous mixtures in Reillex® 425 has been measured. A theoretical model describing the column adsorption dynamics of lactic acid from an aqueous solution and its desorption with methanol has been developed and validated with experimental data. The model has been employed to design and optimize a simulated moving bed (SMB) process for recovering lactic acid from a lactic acid/water mixture containing 5% w/w of lactic acid, using the triangle theory and the separation volume method. The simulation results show that it is possible to obtain concentrated lactic acid (80% in water) with high recovery (95%) from lactic acid/water mixtures by SMB. The feasibility of recovering methanol from the extract and raffinate streams of the designed SMB process by distillation has also been analysed.

Extraction and recovery process to selectively separate aromatics from naphtha feed to ethylene crackers using 1-ethyl-3-methylimidazolium thiocyanate ionic liquid

Naphtha feed to ethylene crackers is an industrial stream of interest to form part of the habitual main sources of aromatics, pyrolysis and reformer gasolines, in order to reduce the costs caused by the non-converted aromatics in the ethylene crackers. Nonetheless, its lower aromatic concentration (10–25wt. %) in comparison with gasolines (over 50wt.%) has limited the implementation of the now-used technologies. Ionic liquids (ILs) arise as alternative solvents to current-used organic solvents, since the ILs are capable to selectively extract aromatic from a low-concentrated stream as is the naphtha feed to ethylene crackers. Accordingly, 1-ethyl-3-methylimidazolium thiocyanate ([emim][SCN]) has been selected to conceptually design the liquid–liquid extraction alternative process to separate BTEX from a naphtha model since this IL has shown the highest values of aromatic/aliphatic selectivity. The process simulation was based on experimental liquid–liquid equilibria (LLE) and vapor–liquid equilibria (VLE) data, the latter destined to plan the hydrocarbon recovery from the extract stream. Kremser method for extraction and a new algorithm for flash distillation units were used to simulate the process and select the most favorable working conditions to increase the purity of aliphatics in the raffinate stream and the purity in the aromatic stream obtained.

Enantioseparation of racemic aminoglutethimide using asynchronous simulated moving bed chromatography

The separation of aminoglutethimide enantiomers by the continuous multicolumn chromatographic processes were investigated experimentally and theoretically, where the columns were packed with cellulose tris 3,5-dimethylphenyl-carbamate stationary phase (brand name Chiralcel OD) and mobile phase was a mixture of n-hexane and ethanol with monoethanolamine additive. The continuous enantioseparation processes included a synchronous shifting process (SMB) and an asynchronous shifting process (VARICOL), which allowed reducing the column number (here from six-column SMB to five-column VARICOL process). Transport-dispersive model with the consideration of both intraparticle mass transfer resistance and axial dispersion was adopted to design and optimize the operation conditions for the separation of aminoglutethimide enantiomers by SMB process and VARICOL process. According to the optimized operation conditions, experiments were carried out on VARICOL-Micro unit using five-column VARICOL process with 1/1.5/1.5/1 configuration and six-column SMB process with 1/2/2/1 configuration. Products of R-aminoglutethimide (R-AG) enantiomer and S-aminoglutethimide (S-AG) enantiomer with more than 99.0% purity were obtained continuously from extract stream and raffinate stream, respectively. Furthermore, the experiemntal data obtained from five-column VARICOL process were compared with that from six-column SMB process, the feasibility and efficiency for the separation of guaifenesin enantiomers by VARICOL processes were evaluated.

Center-cut separation of intermediately adsorbing target component by 8-zone simulated moving bed chromatography with internal recycle

An 8-zone simulated moving bed chromatography with internal recycle (8ZSMB-IR) has been designed for center-cut separation, that is, for isolating an intermediately adsorbed component out of a multicomponent mixture. The system consists of two integrated subunits and operates in a fully continuous manner. In the first subunit the feed mixture is split into two fractions containing either a single component or a binary mixture. The binary mixture is recycled through the internal raffinate or extract port into the second subunit, where the target product is isolated. Additionally, the solvent is also recycled internally. For a case study, the separation of a ternary mixture of cycloketones as a model system under weakly non-linear isotherm conditions has been investigated. A few novel configurations of the 8ZSMB-IR unit including the arrangement of the internal recycle of extract, raffinate and solvent streams between two subunits have been examined with respect to various performance indicators for the process realization. The unit performed best with the developed configuration when the internal raffinate stream was recycled and the solvent recycling loop was closed between the last and the first zone of the first subunit. That configuration has further been analyzed experimentally and numerically. On the basis of the results a strategy for determining reliable operating conditions for the 8ZSMB-IR process has been developed. The procedure exploited a model of the process dynamics, which was implemented to refine the isotherm coefficients and to quantify the mixing effect of the liquid stream inside the recycling loops. The upgraded model with the adjusted parameters has been validated based on experimental data and successfully applied for optimizing the operating conditions of the separation.

Recovery of Hf and Zr from slurry waste of zirconium purification plant using solvent extraction

Hafnium is a very important valuable metal with numerous applications in electronics, refractory and nuclear industry. Its source is the secondary waste streams of zirconium purification plant. The waste raffinate stream generated from Zr extraction plant contains about 4kg of Hf per ton of zircon sand processed. The conventional solvent extraction process with Tri Butyl Phosphate (TBP) as extractant is not suitable to recover Hf value lost in this low acidic lean stream. Presence of high concentration of silica, about 2g/L poses additional challenge for application in solvent economic continuous contactors. A novel alkyl phosphine oxide based ligand having high separation factor for Zr over Hf, Mixed Alkyl Phosphine Oxide (MAPO) has been synthesised indigenously which is applicable for this lean stream. Batch equilibrium data were generated for this novel solvent to optimise the process conditions for application in continuous contactor. The developed process was successfully applied in five stage mixer settler set up in counter current mode with MAPO in mixed diluents as extractant, zirconium nitrate as the scrubbing agent and oxalic acid as the strippant. Recycle of extractant, scrub and strippant with concentration make up has been attempted to increase metal concentration in product stream and to reduce plant waste volume. The work has been successful in achieving not only complete extraction of the Hf value from the plant stream but also recovery of the metal as a concentrated solution ~10g/L with 95% purity which was efficiently converted to oxide. The Zr value is also recovered from the waste stream completely during stripping. Studies were also conducted on the characteristics of silica present in the waste stream and a technique comprising of flocculation followed by ultrafiltration was applied to make the slurry feed solid-free to achieve trouble free operation. The present studies show the potential of the developed process for application to Zr purification plant for recovery of the Hf as well as the Zr value from its raffinate waste.

CHROMATOGRAPHIC SEPARATION OF VERAPAMIL RACEMATE USING A VARICOL CONTINUOUS MULTICOLUMN PROCESS

Verapamil is a chiral drug that is marketed in its racemic form, but because of the pharmacological effects due to molecule’s chirality, one of the enantiomers is more potent, and the other exhibits different activities of therapeutic interest. The preparative separation of the verapamil enantiomers was performed using a continuous Varicol unit operated on a scale of 1 g/day. Amylose tris(3,5-dimethylphenylcarbamate) functioned as the stationary phase, and n-hexane/isopropanol/ethanol mixtures were used as the mobile phase. Diethylamine was used as the additive. The enantiomeric purities were 93.0% for S-(-)-verapamil and 92.0% for R-(+)-verapamil in the raffinate and extract streams, respectively. The unit provided productivities of 0.18 kg of raffinate per day per kg of adsorbent and 0.20 kg of extract per day per kg of adsorbent when using a feed concentration of 12.5 g L-1.