Simple separation method of Zn(Ⅱ) and Cd(Ⅱ) from brine solution of zinc plant residue and synthetic chloride media using solvent extraction

In this work, the possibility of separation of Zn~(2+) and Cd~(2+) metal ions from chloride(brine) solutions was examined. For this purpose, simple solvent extraction(SX) experiments by di-2-ethylhexyl phosphoric acid(D2EHPA)in kerosene as a diluent was performed on synthetic and industrial chloride solution obtained from brine leaching of zinc filter cakes(by-product of zinc hydrometallurgical processing). The optimal conditions for separation were determined. The zinc extraction efficiency was 99% with negligible co-extraction of cadmium.Therefore, a high ΔpH_(0.5) value for Zn(Ⅱ) and Cd(Ⅱ) was achieved. FT-IR and slope analysis indicated that ZnClA·3HA and CdClA·3HA species were probably extracted.     

Extraction of p-coumaric acid from agricultural residues and separation using ‘sugaring out’

We investigated the extraction of para-coumaric acid (pCA) from different agriculture residues (corn stover, sugarcane bagasse, sorghum stalk, pearl millet stalk, green gram shell, groundnut shell, sesame shell) using sugarcane bagasse alkaline hydrolysis and separation of pCA using sugaring out - a new phase separation method. Primary screening of different feed stocks was by alkaline hydrolysis with 2M NaOH for 6 h at room temperature. Sugarcane baggase resulted into significant amount of pCA (1.1 g/L) and small amount of ferulic acid (FA) (0.23 g/L). The optimized alkaline hydrolysis conditions (2 M NaOH and 16 h) resulted into maximum pCA release of 2.0 g/L. The pCA was separated from alkaline hydrolysate using sugaring out, a two phase separation method that results in aqueous phase and the organic solvent (acetonitrile) phase. Sugaring-out separated more than 90% of the pCA from the alkaline hydrolysate. Results of HPLC using standard pCA and FA showed that the main component of the separated top (organic solvent) phase was pCA rather than FA.     

Performance and mechanism of the separation of C8 α-olefin from F-T synthesis products using novel Ag-DES

As an attractive alternative technology for the separation of long chain olefin and paraffin, a novel silver-based deep eutectic solvent (Ag-DES) was prepared and utilized for 1-octene/n-octane separations. Comprehensive reactive extraction separation experiments were performed to highlight the Ag-DES concentration and operating temperature discriminations using compounds with different ratio of 1-octene/n-octane. The novel Ag-DES showed optimal separation performance regarding 1-octene/n-octane and possessed the highest levels separation selectivity in the range 3.57–16.11 with excellent circulation stability in our best knowledge. Furthermore, FT-Raman measurements and quantum chemistry calculation were performed to elucidate the interaction mechanism of Ag-DES in the separation of 1-octene and n-octane, which revealed that both chemical complexation and strong physical attraction existed in the complex of Ag-DES and 1-octene rather than n-octane. A practical process was proposed for the separation of olefin and paraffin, which indicates that an advanced separation technology could largely reduce the energy consumption. This study lends important insight for the development of Ag-DES reactive extraction separation process for the energy-efficient long chain α-olefins purification from F-T synthesis products.     

Solvent extraction of praseodymium using different extractants – a synergistic study

The extraction of praseodymium was investigated from chloride media using different extractants such as D2EHPA, PC88A, Cyanex 272, Cyanex 921, Cyanex 923, Cyanex 301, Cyanex 302, LIX 84I, LIX 622N, Alamine 336, Aliquat 336 and their mixtures. The synergistic effect of Cyanex 272, Cyanex 921, Cyanex 923, Cyanex 301 and Cyanex 302 were studied with each other. Among all the combinations, the mixtures of Cyanex 921-Cyanex 301 and Cyanex 923-Cyanex 301 showed the synergistic effect on the extraction of praseodymium. Solvent extraction of Pr was carried out with the mixture of 0.5 M Cyanex 301 and 0.5 M Cyanex 923. The McCabe-Thiele diagram indicated the quantitative extraction of Pr in two counter-current stages at an A:O phase ratio of 1:2. The two-stage counter-current simulation study showed 94% of extraction efficiency.     

Reaction kinetics in reactive extraction for chiral separation of α-cyclohexyl-mandelic acid enantiomers with hydroxypropyl-β-cyclodextrin

This paper reports on determination of the intrinsic reaction kinetics in reactive extraction of α-cyclohexyl-mandelic acid (α-CHMA) enantiomers with hydroxypropyl-β-cyclodextrin (HP-β-CD) in a modified Lewis cell, in which HP-β-CD dissolved in 0.1 mol/l NaH₂PO₄/H₃PO₄ buffer solution was selected as chiral extractant. α-CHMA enantiomers were extracted from an organic phase to an aqueous phase in the extraction module. The theory of extraction accompanied by chemical reactions has been used to obtain the intrinsic kinetics of this extraction module. The different factors affecting the extraction rate, such as agitation speed, interfacial area, initial enantiomers concentration in an organic phase as well as HP-β-CD concentration in an aqueous phase were separately studied. The experimental results demonstrate that the extraction reaction kinetics is fast. The reactions between α-CHMA enantiomers and HP-β-CD in a stirred cell fall in regime 3 and are first order with respect to α-CHMA enantiomers and second order with respect to HP-β-CD with forward rate constants of 6.9×10⁻² m⁶/(mol² s) and 2.5×10⁻² m⁶/(mol² s) for S-α-CHMA and R-α-CHMA, respectively. These data will be useful in the design of the extraction process.     

Selective extraction of In(Ⅲ),Ga(Ⅲ) and Zn(Ⅱ) using a novel extractant with phenylphosphinic acid

A new extractant,[N,N-di(2-ethylhexyl)amino]methylphenylphosphinic acid(DEAPP),was synthesized to develop the mutual separation techniques of In(III),Ga(III) and Zn(II).The extraction selectivity for In(III),Ga(III)and Zn(II) with DEAPP was higher than that of the commercial phosphorus acid extractants such as D2 EHPA and PC-88 A.The extraction selectivity for metal ions in 1 mol·L-1aqueous ammonium nitrate solution with DEAPP was in the following order:In(III) N Ga(III) N Zn(II).These selective extraction behaviors indicate that the amino moiety of DEAPP plays an important role in the mutual separation of In(III),Ga(III) and Zn(II).The extraction equilibria of In(III),Ga(III) and Zn(II) with DEAPP(=HR) were expressed by the following reactions:In3++ 2HRT2In R3HRT + 3H+,Ga3++ 1.5HRT-2+ NO3 GaR 2eHRT N O3T + 2H+,and Zn2++ 2HRT2 Zn R2HRT2+ 2H+.The extraction equilibrium constants of In(III),Ga(III) and Zn(II) with DEAPP were determined to be Kex,M= 1.7 × 104[dm3·mol-1],4.17 [(dm3·mol-1)0.5],and 1.55 x 10-2[–],respectively.     

Production of no-carrier-added 97Ru from 11B-activated natural yttrium target and its subsequent separation using liquid–liquid extraction

Production of no-carrier-added (NCA) ⁹⁷Ru was investigated from the ¹¹B-induced reaction on the natural Y target. Bombardment of 40 MeV B-beam on the ^natY foil (2.8 mg/cm²) produced 17.4 kBq activity of ⁹⁷Ru in 7.5 h along with the minute production of ⁹⁶Tc and ^93mMo. Separation of NCA ⁹⁷Ru from the bulk was performed by liquid–liquid extraction (LLX). Liquid cation exchanger di-(2-ethylhexyl)phosphoric acid (HDEHP) dissolved in cyclohexane was used in combination with the aqueous solution of HNO₃. Optimum separation of NCA ⁹⁷Ru from the bulk Y was achieved at 1% HDEHP and 10^?5 M HNO₃ that led to a high separation factor of ~10⁵.     

Selective separation of benzene from hydrocarbon mixtures via liquid–liquid extraction method using aqueous solutions of substituted cyclodextrins

The selective separation of benzene from hydrocarbon mixtures was investigated by way of liquid–liquid extraction using aqueous solutions of unsubstituted α-cyclodextrin (αCD), βCD and seven kinds of substituted CDs. Separation factor for benzene to cyclohexane was evaluated from the extraction of an equimolar mixture of benzene and cyclohexane. Hydroxypropyl-αCD showed the highest selectivity followed by 2,6-di-O-methyl-αCD, hydroxyethyl-βCD, hydroxypropyl-βCD and 2,6-di-O-methyl-βCD. Then, separation selectivity for benzene was compared among the nine kinds of CDs carrying out the extraction from an equimolar mixture of 3-methylpentane, n-hexane, benzene and cyclohexane. Finally, the extraction method was applied to reformate using the aqueous solutions of hydroxypropyl-αCD and hydroxypropyl-βCD. The results suggest that this method is effective for reducing the benzene content in reformate.     

Process-intensified extraction of phycocyanin followed by β-carotene from Spirulina platensis using ultrasound-assisted extraction

ABSTRACT

The development of sustainable technology for the extraction of value-added products from the ecological feedstock is gaining importance. The present work focuses on the intensification of extraction of different metabolites such as phycocyanin and β carotene from microalgae (Spirulina platensis) and also presents the optimum extraction parameters using an ultrasound-assisted approach. Initially, phycocyanin was extracted from lyophilized biomass of Spirulina platensis using an ultrasound-assisted approach, and then the extract was centrifuged and the supernatant was treated by using the sugaring-out method to separate phycocyanin from chlorophyll. The remaining biomass was further used for the extraction of β-carotene using the same ultrasound-assisted approach. Various operating parameters such as amplitude, duty cycle, sonication time, and depth of horn immersed into the solution have been investigated for intensified extraction. Moreover, Taguchi design of experiments was used to evaluate the yield of β-carotene using the L₉ orthogonal array based on the effect of probe length, amplitude, duty cycle, and sonication time. On the basis of results and signal-to-noise (S/N) ratio analysis, a ranking of the parameters was performed. It can be noted here that the order of ranking was amplitude > sonication time > duty cycle > depth of horn immersing into the solution. Overall, it has been observed that maximum extraction of phycocyanin and β-carotene was 67 mg/g of dry biomass and 4.66 mg/g of dry weight, which was obtained at optimal amplitudes of 80% and 66% of the duty cycle and 0.5 cm depth of horn immersing into the solution in 4 min and 10 min, respectively. The present study clearly demonstrated that significant intensification benefits can be obtained in terms of the extraction of metabolites at optimal conditions using the ultrasound-assisted approach.     

Synthesis of pinonic acid esters from ozonolysis of α-pinene

以天然产物松节油的主要成分α-蒎烯和醇为原料,二氯甲烷为溶剂,经臭氧氧化制得α-蒎烯臭氧化物,臭氧化物不加分离直接在三乙胺（TEA）催化下经乙酸酐重排（AA）裂解,一锅法合成了6种蒎酮酸酯类化合物。考察了乙酸酐用量、三乙胺用量、反应时间和反应温度等条件对蒎酮酸酯收率的影响,并通过正交试验对合成条件进行了优化。优化的实验条件为：nAA/nα-蒎烯 = 3.0∶1,nTEA/nα-蒎烯 = 0.75∶1,反应时间为60 min,反应温度为30 ℃,在该条件下合成的6种蒎酮酸酯收率均在60%以上,并采用1H NMR、13C NMR、IR、MS对6种化合物的结构进行了表征。该方法操作简便,条件温和,且收率高,是合成蒎酮酸酯类化合物的一种简易可行的方法。     

Separation of α-ketoglutaric acid by salting-out extraction coupled with solar-driven distillation

Alpha-ketoglutaric acid (α-KG), as an essential intermediate in biosynthesis and drug synthesis, has a broad application prospect. However, the lower product concentration and impurities in the α-KG production make the downstream separation more complex and costly. In this study, α-KG was separated from biotransformation broth by salting-out extraction (SOE) combined with solar-driven distillation. First, the aqueous two-phase system (ATPS) consisting of acetone/(NH₄)₂SO₄ was selected by comparison. The effects of acetone/(NH₄)₂SO₄ concentration, temperature, α-KG concentration, and pH on the distribution behavior of α-KG in ATPS were investigated. Under the optimized conditions, higher extraction efficiency and purity of α-KG were obtained in the actual biotransformation broth. In addition, solar evaporation was used to achieve preconcentration of the organic phase and salt recovery, significantly reducing energy consumption. The method is environmentally friendly and easy to operate, providing a new idea for separating low concentration products in biosynthesis.     

Supercritical fluid extraction of α- and β-acids from hops compared to cyclically pressurized solid–liquid extraction

In this paper, two solid–liquid extraction techniques, supercritical fluid extraction (SFE) with and without modifiers and cyclically pressurized solid–liquid extraction with a Naviglio Extractor, were compared on the basis of extraction of acidic compounds contained in hops flowers. The hops extracts were analyzed by electro-kinetic capillary chromatography (MECK). The results showed that the technique using supercritical carbon dioxide was more effective for the isolation of β acids; the use of ethanol as a co-solvent, as reported in the literature, produced a heterogeneous extract, while cyclically pressurized solid–liquid extraction showed a greater extraction capacity for α acids. Consequently, both techniques are valid for the extraction of α and β acids from hops. By suitably varying the parameters of the two extractive procedures, it will be possible to obtain extracts for use in the production of beer and dietary supplements and drugs. Furthermore, based on the SFE CO₂ extraction process, a mathematical model was applied to the examined process, and a numerical simulation was performed, leading to a model that provides direction for the optimization of further experiments.     

Electrochemical studies of Zn–Ni alloy coatings from acid chloride bath

The electrodeposition of Zn–Ni alloy from chloride bath was carried out in presence of condensation product (CP) formed between vanillin and hexamine. The investigation of electrodeposition and nucleation process was carried out on glassy carbon electrode using cyclic voltammetric and chronoamperometric techniques. During the anodic scan of cyclic voltammetry, three anodic peaks were observed corresponding to the dissolution of zinc and nickel from different phases of Zn–Ni alloy. The model of Scharifker and Hills was used to analyze the current transients and it revealed that Zn–Ni electrocrystallization process in the presence of CP, under the studied conditions, is governed by three-dimensional nucleation process controlled by diffusion. In presence of CP, the results indicated that nucleation process changes from progressive to instantaneous when the deposition potential becomes more negative. The phase structure and surface morphology of the deposits were characterized by means of X-ray diffraction analysis and Scanning electron microscopy, respectively.     

Efficient extraction of impurities from phosphogypsum during crystal regulation of α-hemihydrate gypsum

Phosphogypsum (PG) is a solid waste generated during the “wet phosphoric acid process.” The phosphorus (P) impurities and low-value-added recycling products seriously constrain PG re-utilization, which results in its massive accumulation and thus occupies large land areas and poses a severe pollution threat to the environment. In this study, by regulating gypsum crystal and P species in CaCl₂–HCl solutions under mild conditions, efficient removal of P impurities (leaching efficiency of 97.78%) and synchronous preparation of high-strength α-CaSO₄·0.5H₂O (α-HH) (compressive strength of 35.2 MPa) from PG were achieved during the phase transition from CaSO₄·2H₂O (DH) to α-HH, which was a reaction of DH dissolution, followed by α-HH crystallization. The co-crystalline P was fully released during the dissolution process, which was necessary to efficiently eliminate P impurities. HCl dissolved the released P and transformed them into the protonated specie (H₃PO₄) with less similarity to SO₄²⁻, which prevented the recombination of the released P with gypsum during the crystallization process. Furthermore, α-HH morphology and size were controlled by seeding in the mixed solutions. The formation of regular large α-HH crystals with a low-specific surface area significantly weakened the surface adsorption of P in solutions and further increased the P leaching efficiency. More importantly, the large stumpy α-HH was identified as high-strength gypsum with high added value. This work would provide innovative guidance to efficiently remove impurities from gypsum and pioneer a cost-effective approach for clean and high-value utilization of industrial gypsum residues.     

Modeling of the α-lactalbumin and β-lactoglobulin protein separation

This work used the General Rate Model (GRM) to evaluate the experimental data of α-lactalbumin (α-la) and β-lactoglobulin (β-lg) mass transfer using size exclusion chromatography (SEC). The chromatographic simulation has become necessary in large scale production processes. Mathematical models have been used for the optimization and control of different operating conditions of the process, as well as providing calculations for the process scale-up. For the SEC experiments, the aqueous biphasic system was composed of polyethylene glycol 1500 g/mol, potassium phosphate and whey protein isolate. The polymeric phase was enriched with α-la and the saline phase with β-lg. The experiments were conducted using a glass column packed with the Sephadex G-25^® gel. Both proteins were quantified by reverse phase liquid chromatography. The experimental data were fitted by non-linear regression, using the successive quadratic programming algorithm. The mass transfer model utilized represented adequately the SEC experimental results.     

Synthesis,characterization and controlled release behaviour of adducts from chloroacetylated cellulose and α-naphthylacetic acid

Celluloses partially functionalized with chloroacetate groups were obtained by reaction of cellulose with chloroacetyl chloride using pyridine as catalyst and the dimethylacetamide/LiCl system as solvent. ¹³C NMR spectra at 75.4 MHz of partially modified cellulose with chloroacetate groups were studied in order to evaluate the selectivity of the reaction of cellulose with chloroacetyl chloride in the homogeneous phase. Analysis of the spectra of ring carbons in the anhydroglucose units shows that the reactivity of the individual hydroxyl groups decreases in the order C-6>C-3>C-2. The coupling of α-naphthylacetic acid to cellulose functionalized with chloroacetate groups was carried out by reaction with their potassium salts or directly in the presence of 1.8-diazabicyclo[5.4.0]-7-undecene. High degrees of modification were obtained by both methods. However, the esterification reaction is somewhat more efficient in the case of the potassium salt. The kinetic results were consistent with a second-order reaction. The hydrolysis in the heterogeneous phase of cellulose–α-naphthylacetic acid adducts showed that the release of the bioactive compound is dependent on the hydrophilic character of the adduct as well as on the pH value of the medium.     

Response surface optimization of supercritical CO2 extraction of α-tocopherol from gel and skin of Aloe vera and almond leaves

Supercritical fluid extraction (SFE) was studied as an alternative technology in the pharmaceutical industry for the separation of α-tocopherol from gel and skin of Aloe vera and almond leaves. The influence of operating conditions was investigated on the recovery of supercritical carbon dioxide (SC-CO₂) extraction of α-tocopherol from three-year old Aloe vera (Aloe barbadensis Miller) leaf gel. The obtained results were compared with the conventional Soxhlet extraction. Response surface methodology (RSM) was applied to optimize effective variables on the extracted recovery of α-tocopherol. The maximum α-tocopherol recovery of 53.41% from Aloe vera gel was obtained with employing RSM predicted optimal operating conditions of 32 MPa, 45.91 °C, 0.84 ml SC-CO₂/min and 140 min for extraction. The α-tocopherol extraction yield for gel and skin of Aloe vera and almond leaves at these optimal operating conditions were obtained 1.53, 16.29 and 2.61 mg/100 g dry sample, respectively.     

Development of novel grafted hybrid PVA membranes using glycidyltrimethylammonium chloride for pervaporation separation of water–isopropanol mixtures

Tetraethylorthosilicate incorporated hybrid poly(vinyl alcohol) membranes were grafted with glycidyltrimethylammonium chloride (GTMAC) in different mass%. The resulting membranes were subjected to physico-chemical investigations using Fourier transform infrared (FTIR) spectroscopy, wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), thermogravimetry analysis (TGA) and scanning electron microscopy (SEM). The effects of grafting and feed composition on pervaporation performance of the membranes were systematically investigated. The membrane containing 30 mass% of GTMAC exhibited the highest separation selectivity of 1570 with a flux of 1.92 × 10^?2 kg/m² h at 30 °C for 10 mass% of water in the feed. The total flux and flux of water are almost overlapping each other, manifesting that these membranes could be used effectively to break the azeotropic point of water–isopropanol mixtures. From the temperature dependent diffusion and permeation values, the Arrhenius activation parameters were estimated. The activation energy values obtained for water permeation (E_pw) are two to three times lower than those of isopropanol permeation (E_pIPA), suggesting that the developed membranes have higher separation ability for water–isopropanol system. The E_p and E_D values ranged between 63.73 and 33.07, and 62.78 and 32.75 kJ/mol, respectively. The positive heat of sorption (ΔH_s) values was obtained for all the membranes, suggesting that Henry's mode of sorption is predominant in the process.     

Effect of Ba and rare earths cations on the properties and dehydrocyclization activity of Pt/K‐LTL catalysts

Several Pt/L‐zeolite catalysts were prepared by the impregnation method from L‐zeolite samples previously exchanged with Ba²⁺, La³⁺, Pr³⁺, Nd³⁺ and Sm³⁺. Lanthanides (Ln³⁺) increase the overall dispersion of platinum, measured by H₂–O₂ titration. TPR and CO/FTIR measurements indicate that these ions modify the distribution of Pt in the zeolite lattice, increasing the fraction of metal on the external surface. Additionally, both CO/FTIR and competitive hydrogenation of toluene–benzene mixtures indicate that, in the presence of Ln³⁺, the electron density of the platinum decreases in comparison with Pt/KL‐zeolite. On the other hand, Ba²⁺ does not substantially modify neither the distribution nor the electronic state of Pt. The reactivity measurements in the hydroconversion of n‐heptane show that Pt/BaKL and Pt/KL exhibit similar catalytic behaviour with a high dehydrocyclization activity. However, the exchange of K⁺ by Ln³⁺ increases the production of heptane isomers, while selectivities to aromatic and terminal hydrogenolysis products significantly decrease. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effect of pH on separation of Pb (II) and NO3− from aqueous solutions using electrodialysis

Pb²⁺ and NO₃^? are major water pollutants with severe environmental effects. Several methods were used for treating them, but most of the intended solutions failed to treat these ions simultaneously. Electrodialysis (ED) may be able to treat them, particularly after the recent progress in membrane manufacture that has led to significant improvements in the performance. In this paper, we investigated the effect of pH on ED separation of Pb²⁺ and NO₃^? in terms of concentration ratio (CR), concentration polarization (i_lim), current efficiency (η), and energy consumption (EC). The results showed that, pH between 3 and 5 was the most effective for removal of these ions. Additionally, the distribution of ions among the charged sites on the membrane surfaces was governed by pH. At low electric potentials (< 10 V), ion exchange/adsorption was the prevalent phenomenon occurring on the membrane surfaces, while at voltages over 25 V the membranes were regenerated. Consequently, cation and anion exchange membranes could be used for water treatment at low voltages, then regenerated at higher voltages.