Three-stage Extraction Research Articles

Recovery of volatile fatty acids from anaerobic fermentation broth of baker’s yeast industry effluent by liquid−liquid extraction

As metabolic intermediates, volatile fatty acids (VFAs) can be recovered by separation and purification and contribute to the economy. It was necessary, however, to investigate the optimization of liquid–liquid extraction (LLE) in this study because of the technical difficulties encountered during the recovery of VFAs. For this reason, the organic solvents diethyl ether, trioctylamine, and toluene were investigated as LLE solvents to extract VFAs from Baker’s yeast industry effluent, which contains high levels of organic matter. An optimal pH value of 3 was determined by a pH scan performed between pH 2.5 and pH 7.5. Principal component analysis (PCA) was used to determine the effects of organic solvents and pH on extraction efficiency. The extraction efficiency was evaluated using the optimal pH and multi-stage extraction experiments. In a three-stage extraction, diethyl ether recovered 82% of the VFAs, making it a promising organic solvent for extracting VFAs from anaerobic fermentation broth. PCA revealed that an opposite correlation between VFA recovery and pH for each organic solvent. Based on the results of the cost analysis, it was determined that the costs of recovering VFAs were reduced by 90% per kilogram.

Selective separation of rare earth, Sr, Mo, and Zr from simulated raffinate of uranium/plutonium co-purification process

Spent fuel contains many elements including those that are radioactive. Separation and recovery of these substances have been challenging. This paper presents an efficient strategy for stepwise separation of the rare earth, strontium, molybdenum, and zirconium from the simulated raffinate of a uranium/plutonium co-purification process. This strategy employed three extractants with different metal ion selectivity, and cyclohexanediamine tetraacetic acid (CDTA) was introduced as a complexing agent to inhibit the extraction of Zr(IV) and precious metals. The recovery efficiency of all the rare earth elements was more than 97 % through the three-stage extraction, with N,N,N′,N′-tetranoctyl-diglycolamide (TODGA) as the extractant and N,N-dibutyloctanamide (DBOA) as the phase modifiers. Sr(II) was selectively recovered using N,N,N′,N′-tetracyclohexyl-diglycolamide (TCHDGA). A bisphosphonic acid extractant, N,N-hexadecylamine bis (methylene phenylphosphonic acid) (HADMPPA), was designed and synthesized for the selective separation of Zr(IV) and Mo(VI). The separation conditions of the recovered elements from other elements in each step were systematically examined. Moreover, the mechanism of the extraction reaction was investigated using FTIR spectroscopy, the slope method, and the equimolar series method. To our knowledge, this is the first time that four groups of major elements have been sequencially separated from the simulated high-level waste liquid in one process. This work could contribute to nuclear fuel reprocessing as well as the sustainable development of nuclear energy.

Oxidation leaching of NiMoV alloy enriched from spent hydrogenation catalysts and solvent extraction of Mo and V

Spent hydrogenation catalysts are strategic resources due to the high contents of Ni, Mo, and V. These metals were reduced and enriched as NiMoV alloy through pyrometallurgical smelting. However, it is a technical bottleneck for the separation of Ni, Mo and V from the polymetallic alloy. Hence, this paper proposed the atmospheric oxidation leaching of NiMoV alloy and separation of Ni, Mo and V through solvent extraction. The mixed solution of HCl and HNO3 was employed as the leaching reagent for the dissolution of the alloy. The leaching efficiencies of Ni, Mo and V were all exceed 99.5% under the optimal conditions: c(HCl) of 3.0 mol/L, c(HNO3) of 2.5 mol/L, S/L of 1:10 (g/mL), temperature of 95 °C for 3.0 h. N235 was used as the extractant for the synergistic extraction of V and Mo, while TBP and sulfonated kerosene was used as modifier and diluent. The extraction efficiencies of V and Mo were 99.2% and 99.9% under three-stage extraction of the following conditions: pH of 1.2, c(N235) of 25 vol%, and O/A of 1:1. It was found that only 0.01% Ni and 9.7% Fe entered the organic phase and can be removed by washing, which showed excellent selectivity for V and Mo. Then, based on the principle of ion exchange, H2SO4 and NH3·H2O were used to selectively strip V and Mo. Finally, V2O5, MoO3 and Ni(OH)2 were obtained after precipitation and calcination.

Oxidative desulfurization of fuel oil and molecular characterization of the sulfone compound distribution in the different extractants

PMoA/G5 catalyst was synthesized, and its oxidative desulfurization (ODS) performance on model oil was studied. The catalyst and oxidation-extraction-adsorption system was used for the ODS of Arabian Extra light oil (AXL). Acetonitrile and methanol were chosen as different extractants for the extraction of sulfones (O2S and O2S4). The distribution of sulfone was first reported in detail at each of the three-stage extraction solvents at the molecular level analyzed by the Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS), proton, and 13C nuclear magnetic resonance (1H NMR,13C NMR). The FT-ICR MS results show that the extracted proportion of macromolecular sulfone compounds increases with the extraction stages. Acetonitrile exhibited better selectivity than methanol for polyaromatic sulfone with a high carbon number for the O2S species with double bond equivalent (DBE) = 12–15 and O2S2 species with DBE = 11–16. The NMR results reveal that polyaromatics with naphthenic rings and a low carbon number (<30) can be easily extracted due to their high polarity. The excellent performance of the PMoA/G5 catalyst makes it a promising candidate in the ODS reaction, and the research results give guidelines for ODS technology.

Comprehensive recovery process of impurities removal and valuable metals co-extraction from simulated leaching solution of spent LIBs with CA12-TBP system

Effective recycling of valuable metals from the spent lithium-ion batteries (LIBs) is of great importance from the perspective of resource recycling and environmental conservation. In this work, a comprehensive recovery process of impurities removal and valuable metals co-extraction from simulated leaching solution of spent LIBs with CA12-TBP system was investigated. Firstly, more than 99.7% of Al, Fe and Cu were removed by co-extraction with 30 vol% CA12 (25% saponification degree) and 20 vol% TBP after three-stage extraction. The Ni, Co and Mn lost in the organic phase were decreased to 0.18%, 0.09% and 0.06% by single-stage scrubbing. Then, Fe, Cu and Al loaded in organic phase were completely stripped by 0.5 mol/L H2SO4 and 0.01 mol/L Na2SO3 through a four-stage stripping. After impurities removal, more than 99.9% of Ni, Co and Mn in the raffinate solution were selectively co-extracted with 30 vol% CA12 (60% saponification degree) and 15 vol% TBP after a three-stage extraction, and 7.88% of Li was co-extracted. Then, after a four-stage scrubbing experiment, only 0.52% of Li was lost in the loaded organic phase, which demonstrated that our system possesses the potential of efficient recovery of Ni, Co and Mn from the spent LIBs. Further, Ni, Co and Mn loaded in the organic were completely stripped with 1 mol/L sulfuric acid, and could be directly used for the preparation of the recycled ternary material precursors. Finally, Li in the raffinate solution was recovered by precipitation using Na2CO3, with the yield and purity of 96.4% and 99.6%. Overall, this recycling process with high impurity removal efficiency and valuable metals recovery efficiency not only simplify the production process, but also greatly reduces production costs, which is helpful for the regeneration and utilization of spent LIBs.

Humic acid recovery from stabilized leachate: Characterization and interference with chemical oxygen demand-colour removal.

Heterogeneous combinations of organic compounds (humic acid (HA) and fulvic acid) are the prime factor for the high concentration of colour and chemical oxygen demand (COD) in semi-aerobic stabilized landfill leachate. These organics are less biodegradable and cause a severe threat to environmental elements. Microfiltration and centrifugation processes were applied in this study to investigate the HA removal from stabilized leachate samples and its corresponding interference with COD and colour. The three-stage extraction process recovered a maximum of 1412 ± 2.5 mg/L (Pulau Burung landfill site (PBLS) leachate), 1510 ± 1.5 mg/L (Alor Pongsu landfill site (APLS leachate) at pH 1.5 and 1371 ± 2.5 mg/L (PBLS) and 1451 ± 1.5 mg/L (APLS) of HA (about 42% of the total COD concentration) at pH 2.5, which eventually indicates the process efficiency. Comparative characteristics analysis of recovered HA by scanning electron microscopy, energy-dispersive X-ray, X-ray photoelectron spectroscopy, and Fourier transform infrared significantly indicate the existence of identical elements in the recovered HA compared with the previous studies. The higher reduction (around 37%) in ultraviolet (UV) absorbance values (UV254 and UV280) in the final effluent indicates the elimination of aromaticity and conjugated double-bond compounds from leachate. Moreover, 36 and 39% COD and 39 and 44% colour removal exhibit substantial interference.

Grape Pomace as a Natural Source of Phenolic Compounds: Solvent Screening and Extraction Optimization.

The optimization of extraction by using solvents of phenolic compounds (TPh) of grape pomace (GP) based on a central composite design was investigated. The GP was characterized, and preliminary assays were conducted with five different solvents (water, ethanol, acetone, methanol, and butanol) and the aqueous mixtures thereof. Ethanol and acetone were revealed to be the best solvents for TPh extraction. The main extraction parameters (temperature-T, time-t, solvent concentration, and liquid-solid ratio-L/S) were optimized by using a central composite design. The optimized conditions for the ethanol extraction (T = 60 °C, t = 1.5 h, L/S = 25 mL/gdryGP) and for acetone (T = 50 °C, t = 1.5 h, L/S = 25 mL/gdryGP) were determined. Single-stage extraction revealed a TPh of 45.18 ± 9.51 mgGAE/gdryGP for acetone and a TPh of 38.70 ± 3.64 mgGAE/gdryGP for ethanol. The characterization of the extracts revealed the presence of gallic acid, caffeic acid, syringic acid, vanillic acid, chlorogenic acid, and p-coumaric acid, where the concentration of the first three compounds stands out in all extracts. A three-stage extraction increased the yield of ethanol to 63.3 mg GAE/gdryGP and the yield of acetone to 59.2 mg GAE/gdryGP. Overall, both solvents allow the extraction of phenolic compounds of grape pomace, but ethanol is commonly considered a greener solvent for this purpose.

Selective Solvent Extraction of Vanadium Over Chromium from Alkaline Leaching Solution of Vanadium Slag by D2EHPA/TBP

ABSTRACT A selective extraction process for recovering vanadium (IV) over chromium was proposed with use of a mixed extractant consisting of di(2-ethylhexyl) phosphate (D2EHPA) and tri-n-butyl phosphate (TBP). The influence of various factors, which included the initial aqueous pH value, the concentration of leach solution and D2EHPA, phase ratio (O/A), extraction equilibrium time and extraction temperature in the extraction process on the separation of V and Cr was investigated. Under the condition of the optimum extraction, vanadium extraction was above 94.0%. Meanwhile, under the optimum stripping conditions, the vanadium stripping was above 93.0% utilizing 1.5 mol/L sulfuric acid as the effective stripping reagent. The regeneration and reusability of the loaded organic phases after stripping were discussed. In addition, continuous three-stage extraction and stripping strategy indicated that the aggregate loss of vanadium was 0.885% and that the purity of vanadium was more than 99.9%. Under the condition of the optimum precipitation, when the pH value of the stripping solution was adjusted to 7.0 with ammonia water, the precipitation efficiency reached 99.93%. The calcination conditions (above 680 °C in air) were finally determined by TG-DTA and TG-MS experiments, and the V2O5 obtained by calcination was characterized by XRD. Additionally, a method for detecting impurity elements in vanadium matrix without interference was established. The recovery technology has practical significance in enlarging production scale, reducing specific energy consumption and cost, and realizing automatic control in vanadium leaching process.

Recovery of vanadium and nickel from spent-residue oil hydrotreating catalyst by direct acid leaching-solvent extraction

A process for the selective extraction and separation of vanadium and nickel from spent-residue oil hydrotreating catalysts by a direct acid leaching−solvent extraction method was studied. The extraction and separation of vanadium(IV) and nickel(II) are divided into two stages: acid coleaching of vanadium and nickel and solvent extraction. In the acid coleaching stage, the leaching ratios of vanadium and nickel reach 88.07% and 75.58%, respectively, which can realize highly effective coleaching. In the solvent extraction stage, countercurrent experiments show that the extraction ratio of vanadium can reach 99.21% after a three-stage extraction with P204 as the high-efficiency extractant of vanadium in the acidic environment, while nickel and iron are not extracted. After the anti-extraction solution is pretreated by aluminum precipitation, the extraction ratio of nickel reaches 99.79% after a three-stage extraction with LIX84-I as a high-efficiency extractant of nickel in ammonia medium. A process flow for the recovery of vanadium and nickel is proposed, which not only can realize the separation and recovery of vanadium and nickel but also can realize the recycling of reagents.

Coordination extraction for separating vanadium and impurities from black shale HCl leachate at low pH using D2EHPA and EHEHPA mixture

Comprehensive study on the coordination behavior of vanadium ions and extractants is an important guide to the establishment of new efficient extraction systems. In this study, the synergistic effect and mechanism of D2EHPA and EHEHPA as combined extractants for separating vanadium and impurity ions were investigated in detail. The optimal extraction conditions were D2EHPA:EHEHPA ratio 7:3, feed solution pH 1.4, extractant concentration 20%, stirring time 8 min, and phase ratio (O/A) 1:2. Under these optimal conditions, the extraction percentages of V, Fe, Al, and Zn were 79.22%, 16.6%, 2.61%, and 4.29%, respectively. Under the optimal conditions of three-stage extraction and two-stage stripping, V2O5 product with 98.62% purity could be obtained after ammonia precipitation. FTIR spectroscopy and ESI-MS analysis results indicated that D2EHPA and EHEHPA could form HA·HB dimer under the action of hydrogen bonding, and this dimer exhibited excellent extraction performance and selectivity. The solution chemistry and quantum chemistry results showed the dissociation process of the coordination bond between chloride ions and VO2+ at the extraction interface; however, only VO2+ ions entered the organic phase to react with the extractant, and the final extractant appeared as VOA2·HB.

Stockwell transform and semi-supervised feature selection from deep features for classification of BCI signals

Over the past few years, the processing of motor imagery (MI) electroencephalography (EEG) signals has been attracted for developing brain-computer interface (BCI) applications, since feature extraction and classification of these signals are extremely difficult due to the inherent complexity and tendency to artifact properties of them. The BCI systems can provide a direct interaction pathway/channel between the brain and a peripheral device, hence the MI EEG-based BCI systems seem crucial to control external devices for patients suffering from motor disabilities. The current study presents a semi-supervised model based on three-stage feature extraction and machine learning algorithms for MI EEG signal classification in order to improve the classification accuracy with smaller number of deep features for distinguishing right- and left-hand MI tasks. Stockwell transform is employed at the first phase of the proposed feature extraction method to generate two-dimensional time–frequency maps (TFMs) from one-dimensional EEG signals. Next, the convolutional neural network (CNN) is applied to find deep feature sets from TFMs. Then, the semi-supervised discriminant analysis (SDA) is utilized to minimize the number of descriptors. Finally, the performance of five classifiers, including support vector machine, discriminant analysis, k-nearest neighbor, decision tree, random forest, and the fusion of them are compared. The hyperparameters of SDA and mentioned classifiers are optimized by Bayesian optimization to maximize the accuracy. The presented model is validated using BCI competition II dataset III and BCI competition IV dataset 2b. The performance metrics of the proposed method indicate its efficiency for classifying MI EEG signals.

Extraction of scandium from sulphuric acid-based red mud leach liquors

Equimolar mixtures of di-2-ethylhexylphosphoric acid (D2EHPA) with trin-butylphosphate (TBP) or trioctylamine (TOA) in kerosene were used for extracting scandium from sulphuric acid-based red mud leach liquor. The results showed that when using a D2EHPA-TOA mixture, the overall extraction of scandium (ЕSc) tends to rise from 37 to 68% as the concentration of sulphuric acid rises. At the same time, the extraction of concomitant elements tends to decrease and remains way below the Е Sc . When using a D2EHPATBP mixture, the rising acidity of the solution does not lead to any significant increase in scandium extraction so that the latter remains quite high (i.e. 82&ndash;85%) while the extraction of the concomitant elements is significantly lower. A five-stage countercurrent extraction process was performed using a mixture of 0.1 mol/L D2EHPA and 0.1 mol/L TBP with 2 mol/L sulphuric acid to recover scandium from the liquor with minimized amounts of concomitant metals. The results showed that a 96.8% of scandium can be recovered after a three-stage countercurrent extraction process with 97% aluminium, 95% iron, 87% titanium and 54% zirconium removed from the liquor. A 4.7 mol/L sulphuric acid solution with an organic to aqueous ratio of 1:1 was used to wash the organic phase after a three-stage extraction process. For reextraction, a solution containing 2.5% NaOH and 6.5% Na2CO3 was used at a 2:1 aqueous to organic phase ratio. The solution was filtered to separate the solid phase. The precipitate was washed and dried and a primary 3.42% concentrate was obtained. Based on the obtained data, the authors describe a scandium extraction process using sulphuric acid-based red mud leach liquor. The new scandium concentration by extraction process parameters were tested on an enlarged scale at the Intermix MET site. A 100 g experimental batch of primary scandium concentrate containing, %: 2.2 Sc; 21.8 Тi; 4.3 Na; 0.6 Al; 1.7 Fe; 5.0 Zr; 0.0056 Y, was obtained from a 260-litre red mud leach liquor. For this, a cascade of five centrifugal extractors was used at the extractant saturation stage. An 8-litre mixture of 0.1 mol/L D2EHPA and 0.1 mol/L TBP in Exxsol D100 was used. The organic phase was in recycle, and due to that its saturation was 340 mg of scandium per litre of extractant.

Rapid extraction of high- and low-density microplastics from soil using high-gradient magnetic separation

Microplastics (MPs) are present in all environments, and concerns over their possible detrimental effects on flora and fauna have arisen. Density separation (DS) is commonly used to separate MPs from soils to allow MP quantification; however, it frequently fails to extract high-density MPs sufficiently, resulting in under-estimation of MP abundances. In this proof-of-concept study, a novel three-stage extraction method was developed, involving high-gradient magnetic separation and removal of magnetic soil (Stage 1), magnetic tagging of MPs using surface modified iron nanoparticles (Stage 2), and high-gradient magnetic recovery of surface-modified MPs (Stage 3). The method was optimised for four different soil types (loam, high‑carbon loamy sand, sandy loam and high-clay sandy loam) spiked with different MP types (polyethylene, polyethylene terephthalate, and polytetrafluoroethylene) of different particle sizes (63 μm to 2 mm) as well as polyethylene fibres (2–4 mm). The optimised method achieved average recoveries of 96% for fibres and 92% for particles in loam, 91% for fibres and 87% for particles in high‑carbon loamy sand, 96% for fibres and 89% for particles in sandy loam, and 97% for fibres and 94% for particles in high-clay sandy loam. These were significantly higher than recoveries achieved by DS, particularly for fibres and high-density MPs (p < 0.05). To demonstrate the practical application of the HGMS method, it was applied to a farm soil sample, and high-density MP particles were only recovered by HGMS. Furthermore, this study showed that HGMS can recover fibre-aggregate complexes. This improved extraction method will provide better estimates of MP quantities in future studies focused on monitoring the prevalence of MPs in soils.

Hydrothermal Separation of Titanium Vanadium and Chromium from a Pregnant Oxalic Acid Leachate.

The separation of titanium, vanadium and chromium in vanadium slag (VS) is a difficult problem restricting the comprehensive utilization of VS. This paper presents the first study on the separation of titanium, vanadium and chromium from oxalic acid leachate of VS. Firstly, the separation of titanium from the leachate by hydrothermal method was studied. The results show that more than 99% of titanium in the leachate was precipitated in the form of spherical anatase TiO2 with the purity of 95.7%. Then, the extraction separation of vanadium and chromium from the titanium-free filtrate by three-stage extraction of acidified N235 extractant and four-stage stripping of HCl solution was investigated. The extraction mechanism was identified as the anion exchange reaction between acidified N235 extractant and vanadium and chromium complex anions, which were further stripped by HCl solution in the stripping process. After obtaining the concentrated and purified stripping solution containing vanadium and chromium, the separation of vanadium and chromium from the stripping solution by hydrothermal method was studied, and the product was mainly composed of VO2 and Cr2O3. This process provides an idea for the comprehensive utilization of titanium, vanadium and chromium in oxalic acid system.

Extraction of vanadium(V) from a vanadium-bearing shale leachate through bifunctional coordination in Mextral 984H extraction system

The sulfuric acid leachate from vanadium-bearing shale (SALV) has high acidity with pH around 0.5, and contains several different elements. The chelating extractant Mextral 984H was proposed to extract vanadium from said leachate. In this study, the effects of pH, temperature, extraction time, phase ratio and Mextral 984H concentration on the vanadium extraction efficiency were investigated. Moreover, this has been appraised as well in regards to other impurities such as iron, aluminum, magnesium, potassium, phosphorus, and calcium. The results show that 99.55% of vanadium was extracted through a three-stage extraction, while concentration of extracted impurities was lower than 3%. These experiments were carried out at pH = 0.53, temperature of 25℃, extraction time of 12 min, phase ratio (A/O) equal to 2:1, Mextral 984H concentration of 20 vol% and sulfonated kerosene as diluent. The extraction mechanism of vanadium was investigated using FT-IR, 1H NMR, ESI and quantitative calculations. It has been observed that the O atom on the phenolic hydroxyl and the N atom on the oximido were coordinated with V(V) to form an extraction complex composed of a six-membered ring with 1:1 (metal:ligand) mole ratio; interestingly, the H atom on the phenolic hydroxyl was dissociated. According to the reported results, the Mextral 984H extraction system can be used to extract vanadium from the SALV with no need to adjust pH, which can simplify the extraction process and reduce the consumption of chemicals.

A novel strategy of lithium recycling from spent lithium-ion batteries using imidazolium ionic liquid

In light of the increasing demand for environmental protection and energy conservation, the recovery of highly valuable metals, such as Li, Co, and Ni, from spent lithium-ion batteries (LIBs) has attracted widespread attention. Most conventional recycling strategies, however, suffer from a lack of lithium recycling, although they display high efficiency in the recovery of Co and Ni. In this work, we report an efficient extraction process of lithium from the spent LIBs by using a functional imidazolium ionic liquid. The extraction efficiency can be reached to 92.5% after a three-stage extraction, while the extraction efficiency of Ni-Co-Mn is less than 4.0%. The new process shows a high selectivity of lithium ion. FTIR spectroscopy and ultraviolet are utilized to characterize the variations in the functional groups during extraction to reveal that the possible extraction mechanism is cation exchange. The results of this work provide an effective and sustainable strategy of lithium recycling from spent LIBs.

Ionic liquid-based multi-stage sugaring-out extraction of lactic acid from simulated broth and actual lignocellulosic fermentation broth

In this study, ionic liquid-based sugaring-out extraction was developed to separate lactic acid from the synthetic solution and actual lignocellulosic fermentation broth. Except for [EOHmim]BF4, the ILs with BF4− and OTF− anion can form aqueous two-phase system (ATPS) with the aid of saccharides. With the same kind of saccharides, the ATPS formation ability of ILs could be promoted by increasing the side-chain length of ILs in the order of [Hmim]BF4 ≈ [Bmim]BF4 ˃ [Emim]BF4 due to the decrease in ILs’ kosmotropicity. On the other hand, for the same type of ILs, an ATPS was formed more easily with glucose than with xylose. When IL concentration varied from 35% (w/w) to 40% (w/w) at a low glucose concentration of 15% (w/w), an interesting phase reversal was observed. When lactic acid was undissociated at pH 2.0, 51.8% LA and 92.3% [Bmim]BF4 were partitioned to the top phase, and 97.0% glucose to the bottom phase using an ATPS consisting of 25% (w/w) glucose and 45% (w/w) IL. The total recovery of LA would increase to 89.0% in three-stage sugaring-out extraction from synthetic solution. In three-stage sugaring-out extraction from the filtered and unfiltered fermentation broth obtained via simultaneous saccharification and co-fermentation (SSCF) of acid-pretreated corn stover by the microbial consortium, the total recovery of LA was 89.5% and 89.8%, respectively. Furthermore, the total removal ratio of cells and pigments from the unfiltered broth was 68.4% and 65.4%, respectively. The results support IL-based sugaring-out extraction as a potential method for the recovery of lactic acid from actual fermentation broth.Graphical

A Novel Hybrid Method Based on Three-Stage Extraction and DEA-CCR Models for Selecting the Optimal Conditions for Citronella Oil Extraction

In citronella oil extraction process by steam distillation, inefficient use of steam is the main cause of excessive energy consumption that affects energy cost and oil yield. This research is aimed to reduce the energy cost and increase the oil yield by studying the steam used in the process. The proposed method is the three-stage extraction model combined with the Data Envelopment Analysis developed by Charnes, Cooper and Rhodes (DEA-CCR model). Although the three-stage extraction model has been widely used, there is no research integrate this model with DEA-CCR model. It is well known that DEA-CCR model is an effective tool to evaluate efficiency of decision making units/alternatives. The advantages of this research were presented as the calculation of the optimum distillation conditions, including the steam flow rate and the distillation time, were achieved as discussed in this article. The study was comprised of 3 parts. Firstly, the three-stage extraction model for citronella oil was formulated. Secondly, the results of the proposed model were calculated under different conditions, classified by steam flow rates from 5,000 to 60,000 cm3/min for the distillation period of 15–180 min. Finally, the DEA-CCR model was utilized to evaluate and rank alternatives. The results expressed that the best condition for producing citronella oil was at the steam flow rate of 40,000 cm3/min and the distillation time of 60 min. The optimal energy cost and percentage of oil yield were equal to 0.440 kWh/mL and 0.7%, respectively. When comparing to the experimental results, the percentage error of optimal energy cost and oil yield were slightly different, with a value of 0.98% and 0.85%, respectively. Moreover, the energy consumption was also reduced by 34.6% compared to the traditional operating conditions.

Acid recovering and iron recycling from pickling waste acid by extraction and spray pyrolysis techniques

Acid recovering and iron recycling from pickling waste acid are the desired goal of the steel mills for current ecological requirements and economic benefit. This study proposed a novel method to treatment the pickling waste acid using extraction separation of ferric chloride and hydrochloric acid, following by the spray pyrolysis of ferric chloride stripping liquor. Comparing the Ruthner method, the significant technical advantages of this method is the lower treatment load and operating costs for the spray pyrolysis process, attributing to the reuse of most hydrochloric acid without iron powder neutralizing. Different extractants (TBP, CYC, IA, OA, and PA) are compared to extract ferric ion from high-concentration hydrochloric acid solution and the optimum conditions are researched. Spectroscopic analysis is performed to characterize iron state in extractants. For the stripped solution, spray pyrolysis is employed to produce high-purity Fe2O3 fine particles, meanwhile hydrochloric acid is recovered for following pickling procedure. The results showed that the effect of CYC under lower O/A ratio was better than that of TBP, and the opposite occurred at higher ratios. Three-stage extraction efficiency can reach over 80% at O/A = 2:1. The final O/A ratio of 1:1 was chosen for the stripping of iron-loaded extractants. Raman and UV–visible found that it was [FeCl4]- anion that existed in Fe-loaded TBP and CYC. Spray pyrolysis at 1000 °C can obtain fine pure Fe2O3 and hydrochloric acid. Eventually, a feasible technological process was put forward to recycle all chemicals and achieve zero emission of water and solid waste in the whole process.

Mathematical Model Coupled to Neural Networks Calculates the Extraction Recovery of Polycyclic Aromatic Hydrocarbons in Problematic Matrix.

Unknown extraction recovery from solid matrix samples leads to meaningless chemical analysis results. It cannot always be determined, and it depends on the complexity of the matrix and properties of the extracted substances. This paper combines a mathematical model with the machine learning method—neural networks that predict liquid extraction recovery from solid matrices. The prediction of the three-stage extraction recovery of polycyclic aromatic hydrocarbons from a wooden railway sleeper matrix is demonstrated. Calculation of the extraction recovery requires the extract’s volume to be measured and the polycyclic aromatic hydrocarbons’ concentration to be determined for each stage. These data are used to calculate the input values for a neural network model. Lowest mean-squared error (0.014) and smallest retraining relative standard deviation (20.7%) were achieved with the neural network setup 6:5:5:4:1 (six inputs, three hidden layers with five, five, and four neurons in a layer, and one output). To train such a neural network, it took less than 8000 steps—less than a second––using an average-performance laptop. The relative standard deviation of the extraction recovery predictions ranged between 1.13 and 5.15%. The three-stage recovery of the extracted dry sample showed 104% of three different polycyclic aromatic hydrocarbons. The extracted wet sample recovery was 71, 98, and 55% for phenanthrene, anthracene, and pyrene, respectively. This method is applicable in the environmental, food processing, pharmaceutical, biochemical, biotechnology, and space research areas where extraction should be performed autonomously without human interference.