Evaporation Step Research Articles

Total-recycling partial-discard strategy for improved performance of simulated moving-bed chromatography

Simulated moving-bed (SMB) chromatography has become one of the most useful techniques for difficult separations, such as enantiomer separations. We propose a novel “total-recycling partial-discard” (TR-PD) SMB operation strategy in which a portion of the product is temporarily stored or treated and then totally recycled as an additional feed. This new strategy can attain high purities with minimal recovery losses by varying the discard amount and discard length through changes in the effluent flow rates within a switching period. Remarkably, this method can achieve considerably higher extract purity and raffinate recovery. By using varied effluent flow rates during a switching period and intermittent evaporation steps for concentrating discarded portions, the TR-PD operation can overcome the limitations of the previously suggested fractionation and feedback SMB and recycling partial-discard operations, which have difficulties in recycling all of the discarded portions.

Structure of Nonsolvent‐Quenched Block Copolymer Solutions after Exposure to Electric Fields during Solvent Evaporation

AbstractIn this work, an electric field is incorporated during the solvent evaporation step of the block copolymer self‐assembly and nonsolvent induced phase separation (SNIPS) process. This study investigates the structure of nonsolvent‐quenched polystyrene‐block‐poly(2‐vinylpyridine) (PS‐b‐P2VP) and polystyrene‐block‐poly(4‐vinylpyridine) (PS‐b‐P4VP) diblock copolymer solutions after exposure to electric fields during solvent evaporation. The results indicate an emphasizing effect of the electric field, enhancing self‐assembly and compensating mediocre experimental parameters to a certain degree. However, the impact is found to be different for the two diblock copolymer membranes depending on the selection of experimental parameters as well as the segregation strength of the systems. In addition, an increasing length of the vertically aligned cylindrical pores by the electric field is observed for both membranes, scaling with the applied voltage. This effect is primarily attributed to the suppression of defects and ill‐alignment of polymer domains in the course of structure formation during SNIPS by the electric field. Scanning electron microscopy is used to image the surface and cross‐sectional morphology of the integral asymmetric membranes.

Ag/Au Alloyed Nanoislands for Wafer-Level Plasmonic Color Filter Arrays

Alloyed metals in nanoscale exhibit some intriguing features that are absent in mono-metallic nanostructures. Here we report silver and gold alloyed nanoislands with high tunability of localized surface plasmon resonance (LSPR) wavelength in the visible range for wafer-level plasmonic color filter arrays. The nanofabrication includes two simple steps of concurrent thermal evaporation of Ag and Au grains and solid-state dewetting of the as-deposited nanocomposite thin film. The alloy ratio during the evaporation precisely tunes the LSPR wavelengths within 415–609 nm spectrum range. The elemental composition map reveals that alloyed nanoislands are completely miscible while preserving uniform size, regardless of the alloy ratio. Besides, the multiple lift-off processes and thermal dewetting of Ag/Au nanocomposite thin films successfully demonstrate the wafer-level nanofabrication of plasmonic color filter mosaic. Each plasmonic color pixel comprises different alloy ratio and efficiently transmits colors ranging from cyan, yellow, and magenta. The transmission spectra transposed onto a CIE 1931 color map show comparable color diversity to the plasmonic color filters fabricated by conventional e-beam lithographic techniques. This novel method provides a new direction for large-scale and visible plasmonic color filter arrays in advanced display or imaging applications.

Molecularly imprinted graphite spray ionization-ion mobility spectrometry: application to trace analysis of the pesticide propoxur.

A porous graphite sheet modified by a molecularly imprinted polymer (MIP) was directly used as the spray ionization source for ion mobility spectrometry (IMS). Therefore, it was possible to selectively analyze samples extracted by the molecularly imprinted polymer. This obviates the need for the steps of elution, solvent evaporation, dissolution and injection. To prepare the sheet, the graphite surface was first modified by electrodeposition of a molecularly imprinted polypyrrole film. This polypyrrole film was fabricated in a three-electrode electrochemical system using cyclic voltammetry. The electropolymerization of the graphite sheet was carried out with LiClO4 as a supporting electrolyte in the reaction solution. The effects of the amount of monomer, the level of template concentrations, and the time of polymerization on the extraction efficiency of the MIP film were evaluated. The extraction conditions including extraction time, the extraction temperature, the pH values, the salt concentrations, and the stirring rate were also studied. Methanol was selected as the most suitable solvent for both desorption and ionization which occur simultaneously. The pesticide propoxur (acting as a test compound) was extracted from water samples and directly analyzed using IMS. The analytical parameters (working range: 1.0 to 250ng·mL-1; detection limit: 0.3ng·mL-1) indicated that the direct coupling of MIP and IMS has a great potential in terms of reproducibility, and speed of the analysis, while maintaining acceptable sensitivity. Graphical abstract Schematic presentation of molecularly imprinted graphite spray ionization coupled with ion mobility spectrometry (IMS) for rapid/selective extraction and ionization: Application to the pre-concentration of propoxur prior to its quantification by IMS.

A paper-based analytical device coupled with electrochemical detection for the determination of dexamethasone and prednisolone in adulterated traditional medicines

The adulteration of herbal medicines by dexamethasone or prednisolone is regarded as a serious problem in many communities. Herein, a novel platform for the separation and quantification of both target steroids in herbal medicines based on electrochemical paper-based analytical devices (ePADs) has been created. The ePAD was composed of Whatman SG81 chromatography paper, 3D-printed devices and a commercial screen-printed electrode. Whatman SG81 silica-coated paper was used for the separation of dexamethasone and prednisolone based on the difference in their partition coefficients during the flow of the mobile phase. The optimal mobile phase was composed of 60% ethyl acetate in cyclohexane and required 7 min for separation. The separated steroids on the paper were then quantified by electrochemical detection using differential pulse voltammetry, in which the 3D-printed devices facilitated the measurement. Analytical detection ranges of 10–500 μg mL−1 were obtained for both dexamethasone and prednisolone (r2 = 0.988 and 0.994, respectively). The limits of detection for dexamethasone and prednisolone were 3.59 and 11.98 μg mL−1, respectively, whereas the limits of quantification were 6.00 and 20.02 μg mL−1, respectively. The amounts of both target steroids derived from real herbal medicine samples determined by the proposed method were comparable to those obtained with assays using standard high-performance liquid chromatography. In addition, a simple evaporation step can be used to increase the concentration of the samples before analysis. These ePADs are simple, low-cost, rapid, and very promising for on-site quantitative detection.

Fabric phase sorptive extraction for simultaneous observation of four penicillin antibiotics from human blood serum prior to high performance liquid chromatography and photo-diode array detection

Fabric phase sorptive extraction (FPSE), a current and up-to-date technique of solid sorbent-based microextraction, is regarded to be the basis of the development and advancement of an environmentally friendly, simple, sensitive, trustworthy, and fast analytical method by making use of high performance liquid chromatography and photo-diode array detection (HPLC-PDA) for the concurrent determination of four penicillin antibiotics residues (benzylpenicillin, cloxacillin, dicloxacillin and oxacillin) in human blood serum. By means of FPSE, the sophisticated material properties of sol-gel derived extraction and microextraction sorbents and the rich surface chemistry of an inherent porous and hydrophilic cellulose fabric substrate are successfully combined, leading to a flexible microextraction device which is characterized by high efficiency in extracting target analytes directly from complex sample matrices. Solvent evaporation and reconstitution steps, which are considered to be rather time-consuming, were eradicated successfully from the sample preparation workflow, organic solvent consumption was brought to a minimum while protein precipitation was assessed as impractical. Thus, FPSE complies with all green analytical chemistry (GAC) criteria. The microextraction device is characterized by a very high chemical and solvent stability owing to the strong chemical bonds formed between the sol–gel sorbent and the substrate. Thus, any organic solvent/solvent mixture can serve as the eluent/back-extraction solvent. Herein, sol-gel poly(tetrahydrofuran) coated FPSE membrane provided optimum extraction sensitivity for the selected penicillin antibiotics, which were analyzed using an RP-HPLC method, validated in terms of sensitivity, linearity, accuracy, precision, and selectivity. For all four penicillin antibiotics, the limit of detection and the limit of quantitation were 0.15 ng/μL and 0.5 ng/μL, respectively.

Development of a Surfactant/Platinum Composite for Sensitive Cardio‐selective Beta Blocker Detection and their Theoretical Studies

AbstractAn electrooxidative behavior of beta‐blocker drug esmolol was thoroughly investigated by using glassy carbon electrode modified with sodium dodecyl sulfate‐based platinum nanoparticles. The designed nanosensor exhibited remarkable electro‐catalytic effect by dramatically boosting the signal of the esmolol as compared to the bare electrode with detection limit up to picomolar. The effects of pH, scan rate, temperature, deposition potential, deposition time, effect of electrolyte and interfering agents were investigated to optimize conditions for getting intense signal of the analyte. Under optimized experimental conditions, a linear calibration plot for esmolol with a detection limit of 60 pM was obtained. The analyte sensing ability of the modified electrode was supported by the application of theoretical studies that showed favorable interaction between sodium dodecyl sulfate/platinum nanoparticles composite and esmolol. In this study, our aim was to developed a nanosensor for the sensitive detection of esmolol by electrochemical assay. We tried a lot of different modification style and modifiers for creating a sensitive nanosensor for esmolol. This nanosensor can be applied to the esmolol in serum sample without using any further separation, evaporation or precipitation steps. Application could apply in serum sample to test accuracy of our sensor and method. The high recovery results were observed in serum study.

Pengaruh Temperatur dan Tekanan Evaporasi dalam Proses Isolasi Kristal Asam 6-Aminopenisilinat

6-aminopenicillinic acid (6-APA) is the raw materials for producing semi-synthetic penicillin. In commercial scale, penicillin G is conversed into 6-APA enzymatically by penicillin acylase. Due to the nature of equilibrium reaction, the products are in mixture solution of penicillin G, 6-APA, and phenil acetic acid (PAA). In order to purify the targetted 6-APA, steps of evaporation, crystallisation, and drying are thereby compulsory. In this research, the optimum operation conditions for model solution evaporation were observed. Operation variables, like temperature was varied in the range between 30-65°C at -100mmHg, and pressure was also set between -300 and -50mmHg at constant temperature of 50°C. The results showed that temperature is a dominant factor determining the yield of 6-APA, compared to vacuum pressure from -300 mmHg to -50 mmHg that provided similar yield value. This fact was supported by interpretation of the crystal’s purity for the pressure variation that overall was more than 90% (suggested the homogeneity and higher 6-APA content); hence, operation in each pressure for that range is feasible. To conclude, at 50°C and evaporation pressure of -100mmHg, the highest 6-APA yield and total yield of 97.46% and 91.76%, respectively, were attained.

Electrodialysis-based zero liquid discharge in industrial wastewater treatment.

Over the past few decades, reverse osmosis (RO) has been the dominant technology employed in zero liquid discharge (ZLD) systems for industrial wastewater treatment (WWT). However, RO is limited to a maximum operating salinity of about 75 g kg-1. Electrodialysis (ED) is a potentially attractive option as it can achieve much higher concentrations, thereby reducing the capacity and energy demand of the subsequent evaporation step. Feed-and-bleed experiments were undertaken on a laboratory-scale ED stack using a series of model solutions based on the most common inorganic salts with the aim of determining maximum achievable concentrations. The maximum salt concentration achievable via ED ranged between 104.2 and 267.6 g kg-1, with levels predominantly limited by water transport. In addition, a straightforward review of how ED incorporation can affect ZLD process economics is presented. The operational cost of an ED-based ZLD system for processing RO retentate was almost 20% lower than comparable processes employing high-efficiency RO and disc tubular RO. As the ED-based ZLD system appears economically preferable, and as maximum achievable concentrations greatly exceeded RO operating limits, it would appear to be a promising approach for bridging the gap between RO and evaporation, and may even eliminate the evaporation step altogether.

Solvent-Free and Scalable Procedure to Prepare PYR13TFSI/LiTFSI/PVDF⁻HFP Thermoplastic Electrolytes with Controlled Phase Separation and Enhanced Li Ion Diffusion.

Solid electrolytes for Li transport have been prepared by melt-compounding in one single step. Electrolytes are composed of polyvinylidene fluoride–hexafluoropropylene (PVDF–HFP) with PYR13TFSI on its own or with varying concentration of LiTFSI. While the extrusion of PVDF–HFP with PYR13TFSI is possible up to relatively high liquid fractions, the compatibility of PVDF–HFP with LiTFSI/PYR13TFSI solutions is much lower. An organo-modified sepiolite with D-α-tocopherol polyethylene glycol 1000 succinate (TPGS-S) can be used to enhance the compatibility of these blends and allows to prepare homogeneous PYR13TFSI/LiTFSI/PVDF–HFP electrolytes with controlled microphase separations by melt-compounding. The structure and morphology of the electrolytes has been studied by FTIR, differential scanning calorimetry (DSC), SEM, and AFM. Their mechanical properties have been studied by classical strain–stress experiments. Finally, ionic conductivity has been studied in the −50 to 90 °C temperature range and in diffusivity at 25 °C by PFG-NMR. These electrolytes prove to have a microphase-separated morphology and ionic conductivity which depends mainly on their composition, and a mechanical behavior typical of common thermoplastic polymers, which makes them very easy to handle. Then, in this solvent-free and scalable fashion, it is possible to prepare electrolytes like those prepared by solvent casting, but in few minutes instead of several hours or days, without solvent evaporation steps, and with ionic conductivities, which are very similar for the same compositions, above 0.1 mS·cm−1 at 25 °C. In addition, some of the electrolytes have been prepared with high concentration of Li ion, what has allowed the anion exchange Li transport mechanism to contribute significantly to the overall Li diffusivity, making DLi become similar and even clearly greater than DTFSI.

Reliability of the direct ICP-MS analysis of volcanic ash nanoparticles

ABSTRACTIn the present work, major and trace element concentrations in suspensions of volcanic ash nanoparticles were determined by ICP-MS after either the acid digestion of the suspensions or the direct analysis of these suspensions. The results obtained were compared. Since the acid digestion can be accompanied by an important dilution or can consist in different steps of evaporation and dilution, the determination of some trace element concentrations became limited because of the limit of detection of the analytical instrument. Therefore, analysis after acid digestion of suspensions and direct analysis after acidification of these suspensions were carried out and compared. The concentration of Al, Fe, Y, La, Ce, Pr, Gd, Ho, Cu, Tl and Pb determined by both preparation procedures were in agreement. The values of relative standard deviation are in the range from 1% to 14%. These results prove the reliability of the direct ICP-MS analysis and the possibility of its further application in hyphenated systems for the dimensional and elemental characterisation of natural mineral nanoparticles.

Determination of Trace Zearalenone and Its Metabolites in Human Serum by a High-Throughput UPLC-MS/MS Analysis

This paper described an improved method for high-throughput and sensitive determination of zearalenone and its five metabolites (zearalanone, α-zearalenol, β-zearalenol, α-zearalanol and β-zearalanol) in human serum. Serum samples were measured both before and after enzyme hydrolysis to assess the free and total amount of each compound by ultra-performance liquid chromatography–tandem mass spectrometry (UPLC-MS/MS) in multi reaction monitoring (MRM) mode following off-line 96-well μElution solid-phase extraction (SPE). All the analytes were completely separated on a C18 column within 6 min. It enabled multi-sample preparation at the same time eliminating tedious evaporation and reconstitution steps, allowing 96 (one plate) samples to be processed and analyzed within 24 h. Using an isotope labelled internal standard (13C-ZEN), high recoveries were achieved for all the compounds in the range 91.6%–119.5%, with intra-day and inter-day relative standard deviations (RSDs) of less than 8%. The limits of detection (LOD) and the limits of quantification (LOQ) were 0.02–0.06 ng mL−1 (0.6–2 fmol) and 0.1–0.2 ng mL−1 (3–6 fmol), respectively, demonstrating a notable enhancement in sensitivity compared to the existing methods. The validated method was applied to the analysis of paired urine and serum samples collected from 125 healthy individuals in Henan Province, locating in the middle area of China. ZEN metabolites in human serum were significantly lower than those in urine. Only one serum sample was positive for ZEN after enzyme digestion, whereas at least one of ZEN biomarkers was detected in 75.2% of the paired urine samples. Some comparison and discussion were also included in this paper.

Thermogravimetry coupled to an atmospheric pressure photo ionization quadrupole mass spectrometry for the product control of pharmaceutical formulations and the analysis of plasticizers in polymers

The development of a thermogravimetry coupled to an atmospheric pressure photoionization mass spectrometry (TG-APPI-MS) with a high temperature and flexible transfer line is presented. A method was developed to analyze plasticizers in solution which consist of a solvent evaporation step and subsequent evaporation of the analyte. These solutions of dibutyl phthalate (DBP) in hexane were used to investigate the repeatability (RSD: 3.6%) and linearity (R2: 0.9995) of the new developed system. With the new device the detection of different phthalates in a standardized PVC (polyvinyl chloride) polymer is shown. On the example of ASA, the degradation of a pharmaceutical drug is investigated. The dimerization and the possible trimerization of ASA during the thermal degradation is shown. Ten tablets of different ASA manufacturers were analyzed with the new developed analysis platform. The active substance was found in every tablet. Differences in mass spectral data as well as the studying of the pack insert were used to assign the tablets to companies and their subsidiaries. A unique formulation of ASA was found to have a different mass pattern when analyzed with TG-APPI-qMS. The developed device is a promising tool for the product control and the identification of falsified drugs.

Water Diffusion in the Semi-Liquid State during Industrial Candy Preparation

In the domain of production of flavor delivery systems based on carbohydrate matrices, Hot Melt Extrusion (HME) is one of the processes used which implies a relatively slow water evaporation step compared to Spray Drying or other common processes. The HME process of generating liquid syrup is stable only at industrial scales. The drying kinetic associated to the syrup formation is followed by collecting the vapored water. This experiment is exploited to estimate the diffusion coefficient of liquid water in a continuously concentrating carbohydrate melt ranging from 30.4 to 10.2%w/w water content and at temperatures ranging from 100 to 116 °C. A combination of Fick, Arnold and Vogel-Tammann-Fulcher models was used to derive the viscosity of the solution, the gradient thickness at the surface of the stirred solution and the diffusion coefficient of water in the liquid under boiling conditions. It is here demonstrated that under continuous boiling conditions, the water concentration gradient depth from the surface of the solution has a dimension that is comparable to the size of the hydrated carbohydrate molecules and the diffusion coefficient of water in boiling carbohydrate solutions ranges from 5.10−9 cm.s−2 for low temperature and high water content to 10−11 cm.s−2 for high temperature and low water content.

Miniaturized, rapid separation of neodymium from ultramafic and chondritic samples prior to high precision measurements of 142,143Nd/144Nd isotope ratios by TIMS

An improved method is described for isolating Nd from challenging silicate materials. This scheme does not involve evaporation steps and can be performed in about 12 hours, allowing the separation of Nd from Sm, Ce and Pr with good yields.

Micro-solid phase extraction and LC–MS3 for the determination of triptorelin in rat plasma and application to a pharmacokinetic study

Triptorelin is a synthetic decapeptide used for the treatment of prostate cancer. Attempts to determine triptorelin in clinical use by liquid chromatography-tandem mass spectrometry with multiple reaction monitoring have encountered problems due to its low concentration in plasma (pg/mL) and interference from endogenous peptides. We have overcome these issues using micro-solid phase extraction (μ-SPE) on Oasis® HLB 96-well μElution plates followed by LC–MS3. Sample preparation by μ-SPE achieved sample concentration without the need for evaporation and reconstitution steps. Detection by LC–MS3 showed no significant matrix interference at the retention time of analyte and achieved high sensitivity (lower limit of quantitation 10 pg/mL) and good linearity in the range 10–3000 pg/mL. The method was successfully applied to a pharmacokinetic study in rat involving a single intramuscular injection of a formulation of triptorelin acetate biodegradable microspheres.

Determination of benzo(a)pyrene in fried and baked foods by HPLC combined with vesicular coacervative supramolecular solvent extraction.

A simple, rapid and low-cost determination method of benzo(a)pyrene in fried and baked foods was proposed by high performance liquid chromatography combined with vesicular coacervative supramolecular solvent (SUPRAS) extraction. The vesicular coacervate was composed of 1-octanol and tetrabutylammonium bromide. 200mg of dried samples with 600μL SUPRAS could be mixed to extract benzo(a)pyrene. Neither evaporation nor further clean-up steps for the extracts were needed. The overall sample treatment took approximately 30min, and several samples could be simultaneously treated using conventional lab equipment. Then, benzo(a)pyrene was analyzed via liquid chromatography-fluorescence detection. Parameters affecting the extraction efficiency were investigated and optimized. The results showed good linearity of benzo(a)pyrene with the coefficients of determination (R 2) of more than 0.9999 in the range of 0.1-50.0µg/kg. The limit of detection of the method was 0.11µg/kg. Recoveries for spiked samples in the range of 1-10µg/kg were between 89.86 and 100.01%, with relative standard deviations from 1.20 to 3.20%. Benzo(a)pyrene was present in food samples (including instant noodles, biscuits, rice crust and fried bread stick) at concentrations in the range of 0.08-0.39µg/kg according to the proposed method. The proposed pretreatment method significantly reduces the analysis time. Furthermore, the solventless approach is in accordance with the green chemistry development trend and has significant application prospects.

Simultaneous determination of selected estrogenic endocrine disrupting chemicals and bisphenol A residues in whole milk using fabric phase sorptive extraction coupled to HPLC-UV detection and LC-MS/MS.

A simple and sensitive analytical methodology is developed for rapid screening and quantification of selected estrogenic endocrine disrupting chemicals and bisphenol A from intact milk using fabric phase sorptive extraction in combination with high-performance liquid chromatography coupled to ultraviolet detection/tandem mass spectrometry. The new approach eliminates protein precipitation and defatting step from the sample preparation workflow. In addition, the error prone and time-consuming solvent evaporation and sample reconstitution step used as the sample post-treatment has been eliminated. Parameters with most significant impact on the extraction efficiency of fabric phase sorptive extraction including sorbent chemistry, sample volume, extraction time have been thoroughly studied and optimized. Separation of the selected estrogenic endocrine disrupting chemicals including α-estradiol, hexestrol, estrone, 17α-ethinyl estradiol, diethylstilboestrol, and bisphenol A were achieved using a Zorbax Extend-C18 high-performance liquid chromatography column (15cm×4.6mm, 5μm particle size). The limit of detection values obtained in fabric phase sorptive extraction with high-performance liquid chromatography with ultraviolet detection ranged from 25.0to 50.0ng/mL. The method repeatability values were 3.6-13.9 (relative standard deviation, %) and intermediate precision values were 4.6-12.7 (relative standard deviation, %). The fabric phase sorptive extraction method was also coupled to liquid chromatography with tandem mass spectrometry for identifying each endocrine disrupting chemical at 10ng/mL.

Influence of smear matrix types on detection behaviors and efficiencies of polycyclic aromatic hydrocarbons using ion mobility spectrometry

Influence of smear matrix types on detection behaviors and efficiencies of polycyclic aromatic hydrocarbons (PAHs) with different molecular weights in ion mobility spectrometry (IMS) were investigated. Various smear matrices of stainless steel mesh (SM), cellulose paper (CP), and cotton fabric (CF) were employed. Anisole was used as the solvent and IMS analysis was performed without evaporation step of the solvent to apply charge transfer reactions between PAH molecules and the molecular ions of solvent. Shapes of reactant ion peaks (RIPs) were varied according to the smear matrix types. At the beginning of the sample inlet, intensity of RIPs of air and moisture notably decreased due to the lots of solvent vapor. The SM with good gas permeability showed relatively strong RIPs of air and moisture, whereas the CP with no gas permeability showed weak ones. Detection times and efficiencies of PAH ions were varied according to the smear matrix types as well as the kinds of PAHs. PAHs were on the whole detected well in 1–3 s after the sample inlet. Detection limits of PAHs measured using the SM were slightly better than those measured using the CP, while those measured using the CP were much better than those measured using the CF. The experimental results could be explained by structures of the smear matrices and evaporation behaviors of the PAH solutions.

Recovery of Inorganic Compounds from Spent Alkaline Pulping Liquor by Eutectic Freeze Crystallization and Supporting Unit Operations: A Review

After the kraft or soda pulping of lignocellulosic materials to produce pulp suitable for papermaking, the spent pulping liquor typically has been recovered by multi-effect evaporation, followed by incineration in a recovery boiler. This review article considers one unit operation, eutectic freeze crystallization (EFC), that may have potential to save some of the energy that is presently consumed in the evaporation step during recovery of inorganic chemicals from spent pulping liquor. Based on a review of the literature it appears that EFC can be employed to obtain relatively pure sodium sulfate and sodium carbonate, along with relatively pure water (in the form of ice) from the spent liquor, under the assumption that lignin previously has been removed by acidification and precipitation. Issues of inorganic scale formation, during the operation of an EFC process applied to lignin-free black liquor, will require research attention. The chemical reactions to regenerate the active pulping chemicals sodium hydroxide and sodium sulfide from sodium carbonate, sodium sulfate, and other compounds isolated by EFC can be carried out either in a separate operation or by returning the materials to the feed of an existing recovery boiler.