Organic Phase Ratio Research Articles

Furfural production from xylan using a Pueraria Residues carbon-based solid-acid catalyst.

The conversion of biomass into high value-added platform compounds is an important method of biomass utilization. The conversion of hemicellulose represented by xylan into furfural can not only reduce the consumption of fossil fuels, but also promotes the development and utilization of non-edible biomass resources. In this study, a bifunctional solid-acid catalyst prepared from agricultural and forestry waste Pueraria (P. eduli) Residues was used to convert xylan into furfural in a biphasic system. In this study, P. eduli Residues was used as raw material to prepare a P. eduli Residues-based carbon solid-acid catalyst (PR/C-SO3H-Fe) by one-step sulfonation carbonization and impregnation. The catalyst catalyzes the conversion of xylan to furfural in a biphasic system (2-methyltetrahydrofuran/water). The physicochemical properties of the catalysts were characterized by X-ray powder diffraction, scanning electron microscopy, differential thermogravimetric analysis, Brunauer-Emmett-Teller surface area, Fourier transform infrared spectroscopy and ammonia temperature-programmed desorption. Subsequently, the experimental conditions were studied and optimized, such as metal species, iron ion concentration, reaction time and temperature, volume ratio of organic phase to water phase and ratio of substrate to catalyst. The results showed that under conditions of 160 °C, 50 mg catalyst, 100 mg xylan and 7 mL reaction solvent, the yield of furfural could reach 78.94% after 3 h of reaction. This study provides an effective research method for the conversion of xylan into furfural, and provides a reference for the catalytic conversion and utilization of hemicellulose in agricultural and forestry biomass. It also provides a feasible method for the resource utilization of agricultural and forestry waste. © 2024 Society of Chemical Industry.

Sustainable and efficient recovery of lithium from rubidium raffinate via solvent extraction

In recent years, with the increasing prevalence of rechargeable lithium-ion batteries in the burgeoning markets of electric vehicles and portable electronic devices, the consumption of lithium batteries has significantly surged. Hence, the efficient development and utilization of associated lithium resources bear paramount significance. This study aims to recover lithium from rubidium raffinate via solvent extraction. A systematic investigation was conducted to examine the effects of various parameters such as organic phase concentration, contact time, and phase ratio (O/A) during the separation process. The results indicated that the organic phase composed of 0.1 mol/L 4,4,4-Trifluoro-1-phenyl-1,3-butanedione (HBTA) and 0.1 mol/L Trioctylphosphine oxide (TOPO) could efficiently extract lithium from the rubidium raffinate. The optimal conditions were observed at a temperature of 20℃, O/A=1, and a contact time of 5 min. After three-stage countercurrent extraction, a lithium extraction rate of 99.24 % could be achieved, with over 95 % of the sodium easily scrubbed by 0.1 mol/L HCl at an O/A=10. With the use of 3 mol/L HCl, stripping efficiency exceeding 99 % could be attained at an O/A=10, consequently a successful preparation of battery-grade lithium carbonate product was achieved. Regeneration experiments confirmed the organic phase's excellent reproducibility efficiency. Slope analysis and density function theory (DFT) simulations indicated that optimal lithium extraction is achieved when HBTA and TOPO are at equal molar concentrations. The proposed process is expected to provide a green and sustainable route for the recovery of associated lithium resources.

Optimization of thorium solvent extraction process from feed solution with Cyanex 272 by response surface methodology (RSM)

Due to the limited reserves of uranium, the abundance of thorium compared to it and other advantages, the development of the thorium fuel cycle is of interest in different countries. The optimization of thorium extraction from a feed solution produced by Saghand ore with bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex 272) on a laboratory scale was evaluated by response surface method. The operating variables include Cyanex 272 concentration of 0.001 to 0.2 mol/L, pH of 0 to 2, equilibrium time of 5 to 60 min and aqueous to organic phase ratio of 0.5 to 2.5 were conducted. The value of R2 = 0.9695 and an error of less than 4% indicate the validity of the model. Therefore, the model is in good agreement with the experimental results. It can be said that there are significant interactions between operational parameters, which vindicate different feedbacks of the system in different operational conditions. The results showed that the 4 mol/L sulfuric acid was a suitable agent for recovering thorium ions from the loaded organic phase. In optimum conditions, the thorium purity percentage and thorium stripping efficiency were obtained 98.99 and 94.12%, respectively.

From waste to added-value product: A case of efficient separation and recovery of zinc and iron from spent galvanizing acid

Spent galvanizing acid solution contains high concentrations of zinc salts, ferrous salts, and residual acids, exhibiting extremely high value-added recovery potential. However, achieving the efficient extraction and separation of Zn over Fe becomes particularly challenging under elevated Zn ion concentration. Here, the key extraction parameters, such as modifier ratio, Cyanex 923 concentration and ratio of organic phase to aqueous phase (O/A), are investigated. The stripping and regeneration of extractant, extraction mechanism, as well as high-value recovery of Zn and Fe resources are also comprehensively expounded. After the two-stage extraction, the extraction efficiency of Zn and Fe is 98.92 ​% and 2.09 ​%, respectively. Moreover, the stripping efficiency of Zn reaches 92.3 ​% with O/A ratio of 1 : 2, using oxalic acid as stripping agent. The predominant extracted species is confirmed to be ZnCl3−, resulting in the formation of HZnCl3∙R3PO complex. More importantly, the regenerated extractant can be recycled back into the extraction process, and the reproduced HCl, high-value recovered ZnO and Fe2O3 can be used for different industrial fields. These findings lay a solid foundation for the efficient separation and comprehensive recovery of high-concentration spent galvanizing acid solution.

Prediction of mass spectrometry ionization efficiency based on COSMO-RS and machine learning algorithms.

Non-targeted analysis of high-resolution mass spectrometry (MS) can identify thousands of compounds, which also gives a huge challenge to their quantification. The aim of this study is to investigate the impact of mass spectrometry ionization efficiency on various compounds in food at different solvent ratios and to develop a predictive model for mass spectrometry ionization efficiency to enable non-targeted quantitative prediction of unknown compounds. This study covered 70 compounds in 14 different mobile phase ratio environments in positive ion mode to analyze the rules of the matrix effect. With the organic phase ratio from low to high, most compounds changed by 1.0 log units in log IE. The addition of formic acid enhanced the signal but also promoted the matrix effect, which often occurred in compounds with strong ionization capacity. It was speculated that the matrix effect was mainly in the form of competitive charge and charged droplet' gasification sites during MS detection. Subsequently, we present a log IE prediction method built using the COSMO-RS software and the artificial neural network (ANN) algorithm to address this difficulty and overcome the shortcomings of previous models, which always ignore the matrix effect. This model was developed following the principles of QSAR modeling recommended by the Organization for Economic Cooperation and Development (OECD). Furthermore, we validated this approach by predicting the log IE of 70 compounds, including those not involved in the log IE model development. The results presented demonstrate that the method we put forward has an excellent prediction accuracy for log IE (R2pred = 0.880), which means that it has the potential to predict the log IE of new compounds without authentic standards.

Optimizing Process Parameters for Controlled Drug Delivery: A Quality by Design (QbD) Approach in Naltrexone Microspheres.

The formulation of microspheres involves a complex manufacturing process with multiple steps. Identifying the appropriate process parameters to achieve the desired quality attributes poses a significant challenge. This study aims to optimize the critical process parameters (CPPs) involved in the preparation of naltrexone microspheres using a Quality by Design (QbD) methodology. Additionally, the research aims to assess the drug release profiles of these microspheres under both in vivo and in vitro conditions. Critical process parameters (CPPs) and critical quality attributes (CQAs) were identified, and a Box-Behnken design was utilized to delineate the design space, ensuring alignment with the desired Quality Target Product Profile (QTPP). The investigated CPPs comprised polymer concentration, aqueous phase ratio to organic phase ratio, and quench volume. The microspheres were fabricated using the oil-in-water emulsion solvent extraction technique. Analysis revealed that increased polymer concentration was correlated with decreased particle size, reduced quench volume resulted in decreased burst release, and a heightened aqueous phase ratio to organic phase ratio improved drug entrapment. Upon analyzing the results, an optimal formulation was determined. In conclusion, the study conducted in vivo drug release testing on both the commercially available innovator product and the optimized test product utilizing an animal model. The integration of in vitro dissolution data with in vivo assessments presents a holistic understanding of drug release dynamics. The QbD approach-based optimization of CPPs furnishes informed guidance for the development of generic pharmaceutical formulations.

Lithium extraction from aqueous medium using hydrophobic deep eutectic solvents

Because lithium resources are becoming increasingly scarce, their recovery is an urgent problem that needs to be solved. In this paper, an environmentally friendly process for the recovery of lithium ions from water resources by liquid-liquid extraction (LLE) is proposed. Menthol (DLM) was used as a hydrogen bond acceptor (HBA), and octanoic acid, decanoic acid, and lauric acid (LA) were used as hydrogen bond donors (HBDs) to form nine hydrophobic deep eutectic solvents (HDESs). The HDESs synthesized using DLM and LA had the best effect and thus were selected for the lithium extraction experiment. The single extraction efficiency of lithium ions was 80.69 %, with optimized rotational speed, equilibrium time, pH, molar ratio of organic phase to inorganic phase (O/L), and initial concentration of different lithium complexes of 660 rpm, 30 min, 12, 3:1, and 0.5 g/L, respectively. In addition, the regeneration cycle experiment of the HDES was further investigated. The possible extraction mechanism was demonstrated by Fourier-transform infrared spectroscopy and slope method. The separation factor (β) of Li/Na and Li/K obtained from the experimental results was 18.72 and 84.25, showing that 2DLM/LA can selectively extract lithium ions from systems containing Li, Na and K. This will be beneficial to design potential green HDESs for recovering lithium resources from aqueous solutions.

Fabrication and optimization of itraconazole-loaded zein-based nanoparticles in coated capsules as a promising colon-targeting approach pursuing opportunistic fungal infections

Itraconazole (ITZ), a broad-spectrum antifungal drug, was formulated into colon-targeting system aiming to treat opportunistic colonic fungal infections that commonly infect chronic inflammatory bowel diseases (IBD) patients due to immunosuppressive therapy. Antisolvent precipitation technique was employed to formulate ITZ-loaded zein nanoparticles (ITZ-ZNPs) using various zein: drug and aqueous:organic phase ratios. Central composite face-centered design (CCFD) was used for statistical analysis and optimization. The optimized formulation was composed of 5.5:1 zein:drug ratio and 9.5:1 aqueous:organic phase ratio with its observed particle size, polydispersity index, zeta potential, and entrapment efficiency of 208 ± 4.29 nm, 0.35 ± 0.04, 35.7 ± 1.65 mV, and 66.78 ± 3.89%, respectively. ITZ-ZNPs were imaged by TEM that revealed spherical core–shell structure, and DSC proved ITZ transformation from crystalline to amorphous form. FT-IR showed coupling of zein NH group with ITZ carbonyl group without affecting ITZ antifungal activity as confirmed by antifungal activity test that showed enhanced activity of ITZ-ZNPs over the pure drug. Histopathological examination and cytotoxicity tests ensured biosafety and tolerance of ITZ-ZNPs to the colon tissue. The optimized formulation was then loaded into Eudragit S100-coated capsules and both in vitro release and in vivo X-ray imaging confirmed the success of such coated capsules in protecting ITZ from the release in stomach and intestine while targeting ITZ to the colon. The study proved that ITZ-ZNPs is promising and safe nanoparticulate system that can protect ITZ throughout the GIT and targeting its release to the colon with effectual focused local action for the treatment of colon fungal infections.Graphical

Spectrophotometric Determination of Diphenhydramine hydrochloride and Application to Pharmaceutical Preparations

The research involves the use of analytical method for determination of the diphenhydramine hydrochloride (DPH) drug in some pharmaceutical preparations using molecular absorption technique (UV-Vis.) in addition to the investigating of complexes obtained. The optimum analytical data obtained throughout of study could be summarized as follows: order of addition (DPH + 2% CS2 in CHCl3+Ag(I), pH(11),volume of ammonia solution (1ml), concentration of Ag(I) (8µg/ml), aqueous : organic phase ratio 1:1, reaction time (4 minutes), extraction time (8minutes), reaction temperature 25oC, one extraction process, extraction ratio (E%=99.82) chloroform proved to be the best solvent for extraction of DPH-Ag complex without interferences, λmax.=363nm. The analytical figures obtained were: linear dynamic range (0.25-80µg/ml)for DPH , RSD% (0.396), D.L (0.29µg/ml), Erel% (0.125), recovery (99.87%).This method was applied for determination of DPH in pharmaceutical preparation (syrup) using direct and standard addition methods, recovery's was found to be (97.8%, 98.2 %).

Machine learning for predicting the dynamic extraction of multiple substances by emulsion liquid membranes

As of now, the models are only able to predict emulsion liquid membranes (ELM) for a single contaminant. In this study, to develop models for predicting the extraction efficiency of ELM for multiple substances, we used the linear model, random forest model, extreme gradient boosting model (XGB), and artificial neural network model. A total of 1010 data points were collected, which contained two main types of input features, the preparation conditions and operating parameters of ELM. Among these models, XGB showed excellent prediction accuracy (R2: 0.942, RMSE: 6.478, MAPE: 1.587). These evaluations showed that this model had a powerful ability to predict the extraction efficiency of ELM, and the results show that the predicted extraction efficiency was very close to the real ones. By quantifying the weightiness and marginal effect of the parameters, the models were interpreted using the Shapley additive explanation method. This work showed that the extraction time, volume ratio of organic phase to internal phase, emulsification time and feed concentration had important effects on the extraction efficiency of ELM, and the results indicated that the extraction efficiency can be promoted by increasing the values of the parameters before the optimum value, while it was inhibited after the optimum value. Our work suggested that the proposed model can be helpful for making more rational decisions in determining the preparation conditions and operating parameters of ELM.

Comparative investigation of artificial neural network and response surface approach in the optimization of indium recovery from discarded LCD screen with the presence of ionic liquids

This paper aimed to predict the solvent extraction conditions to maximize indium recovery from discarded LCD screens. Two approaches, including the response surface methodology (RSM) and the artificial neural network (ANN), were utilized to predict the efficiency of indium recovery. The main parameters, such as aqueous phase acidity (A), indium concentration (B), ionic liquid concentration (C), and aqueous to organic phase ratio (D), were investigated by using CyphosIL 101 diluted in kerosene as the organic phase. The experimental results were used to train a multilayer perceptron for creating an ANN model with the structure of one, eight, and three for input, hidden, and output layers, respectively. The optimum conditions by the RSM approach to provide the maximum efficiency of indium recovery were.4 mol/L A, 197.79 ppm of B, 0.009 mol/L of C, and 1.58 mol/L of D. By contrast, the ANN approaches illustrated the optimal A, B, C and D equal to 4.2, 194.32, 0.0085, and 1.52 %, respectively. Two statistical approaches described the satisfactory data, and the superior data was obtained with the ANN approaches. The use of two ionic liquids verified the indium recovery from the discarded LCD screen, and 99.7 % of indium ions were separated and extracted into the stripping solution.

Developing an improved UHPLC method for impurity profile analysis of ceftriaxone using analytical quality by design.

In this study, we developed a new reversed-phase ultra-high-performance liquid chromatography (UHPLC) method for comprehensively measuring impurities in ceftriaxone. The method was developed based on the Chinese Pharmacopoeia (ChP) HPLC method, which is limited by the lack of selectivity to potential impurities and a long running time. Screening experiments showed that octylamine concentration, mobile phase pH, and organic phase ratio were critical method parameters. Further optimisation and Monte-Carlo simulations were performed to map out the design space. The selected working conditions resulted in a complete separation of the impurity profile in approximately 10 min. A multivariate approach confirmed that the method was robust, and the proportion of acetonitrile should be carefully controlled. Additionally, the developed UHPLC method could be transferred back to HPLC in a single step using a Columns Calculator, providing a new approach for the rapid and effective development of the HPLC method. Our findings could serve as a reference for developing the next version of the ChP.

Estimation of terbinafine HCL by spectophotometric analysis with Tpooo, Nb12br and WFB

One simple and sensitive procedure (simple spectrophotometric method) for the assay of drug Terbinafine HCl in pure form and formulations. This method involves the formation of ion-association complex between TRB and the TPOOO, NB12BR and WFB. In order to establish the optimum conditions necessary for rapid and quantitative formation of coloured product with maximum stability and sensitivity, the author performed experiments by measuring the absorbance at λmax 480nm,420nm and580nm of respective series of solutions, varying one and fixing the other parameters in each case such as type, volume and concentration of acid, organic solvent used for extraction, ratio of organic phase to aqueous phase during extraction, shaking time and temperature. The variable parameters were optimized. The results were statistically validated.

Testing Thymol-Based DES for the Elimination of 11 Textile Dyes from Water

Textile industries release dangerous wastewater that contain dyes into the environment. Due to their toxic, carcinogenic and mutagenic nature, they must be removed before the discharge. Liquid–liquid extraction has proven to be an efficient method for the removal of these dyes. As extractants, deep eutectic solvents (DESs) have shown excellent results in recent years, as well as presenting several green properties. Therefore, four different hydrophobic DESs based on natural components were prepared thymol:decanoic acid (T:D (1:1)), thymol:DL-menthol (T:M (1:1)), thymol:DL-menthol (T:M (1:2)) and thymol:coumarin (T:C (2:1)) for the extraction of Malachite Green (MG), Brilliant Blue G (BBG), Acid Yellow 73 (AY73), Reactive Red 29 (RR29), Acid Blue 113 (AB113), Reactive Black 5 (RB5), Remazol Brilliant Blue (RBB), Direct Yellow 27 (DY27), Acid Blue 80 (AB80), Direct Blue 15 (DB15) and Acid Violet 43 (AV43) dyes from water. The operational parameters of the liquid–liquid extraction were selected in order to save time and materials, resulting in 30 min of stirring, 15 min of centrifugation and an aqueous:organic ratio of 5:1. In these conditions, the highest values of extraction obtained were 99% for MG, 89% for BBG and 94% for AY73. Based on these results, the influence of the aqueous:organic phase ratio and the number of necessary stages to achieve water decolorization was studied.

Increasing the circularity of the copper metallurgical industry: Recovery of Sb(III) and Bi(III) from hydrochloric solutions by integration of solvating organophosphorous extractants and selective precipitation

The lack of high-purity ores has made the copper industry exploit low-impurity ores containing As, Sb and Bi which can affect the final product quality due to the floating insoluble arsenates. This is usually solved by treating the electrorefining electrolyte in a polishing stage devoted to removing Sb and Bi using aminophosphonic resins. Once the resin is saturated, it is regenerated using 6 M HCl, and the eluate produced is treated with CaO(s) to precipitate both Sb and Bi. However, this stream is of interest due to the inclusion of both elements in the Critical Raw Material list from the European Union. Therefore, the linear management option must be substituted by a circular approach. This work aims to develop such approach by the selective separation and recovery of Sb and Bi from HCl stream polluted with As. The method presented was based on the use of using a solvating mixture of alkylphosphine oxides commercialized as Cyanex 923 dissolved in kerosene and 1-decanol (10 %) as phase modifier. The separation factors of Sb(III) and Bi(III) from As(V) were evaluated and optimized as function of both extractant concentration and the aqueous to organic phase ratio. Results showed that at the lowest Cyanex 923 concentration (0.15 mol/L) and working at an A/O ratio of 1/3, it could be possible to extract 39 % Bi and 78 % Sb with As co-extraction below 2.5 %. Both Sb and Bi were easily recovered (>90 %) using 8 M HNO3 as stripping agent. Following a treatment using NaOH/NaCl or NaOH, both elements could be recovered either as oxychlorides (SbOCl(s) and BiOCl(s)) or oxides (Sb2O3(s) and BisO3(s)).

Development, optimization, and evaluation of Cisplatin-loaded PLGA nanoparticles

Nanoparticle drug delivery systems are engineered technologies that use nanoparticles for the targeted delivery and controlled release of therapeutic agents. Cisplatin-loaded nanoparticle formulations were optimized utilizing response surface methods and the central composite rotating design model. This study employed a central composite rotatable design with a three-factored factorial design with three tiers. Three independent variables namely drug polymer ratio, aqueous organic phase ration, and stabilizer concentration were used to examine the particle size, entrapment efficiency, and drug loading of cisplatin PLGA nanoparticles as responses. The results revealed that this response surface approach might be able to be used to find the best formulation for the cisplatin PLGA nanoparticles. A polymer ratio of 1:8.27, organic phase ratio of 1:6, and stabilizer concentration of 0.15 were found to be optimum for cisplatin PLGA nanoparticles. Nanoparticles made under the optimal conditions found yielded a 112 nm particle size and a 95.4 percent entrapment efficiency, as well as a drug loading of 9 percent. The cisplatin PLGA nanoparticles tailored for scanning electon microscopy displayed a spherical form. A series of in vitro tests showed that the nanoparticle delivered cisplatin progressively over time. According to this work, the Response Surface Methodology (RSM) employing the central composite rotatable design may be successfully used to simulate cisplatin-PLGA nanoparticles.

DEVELOPMENT AND OPTIMIZATION OF ASTRAGALIN-LOADED POLYMERIC NANOPARTICLES USING CENTRAL COMPOSITE FACTORIAL DESIGN

Objective: The objective of the present study was to develop and optimize Astragalin-loaded polymeric nanoparticles (AST-NPs) using a central composite factorial design (CCD). Methods: AST-NPs were prepared by the dialysis method. CCD was employed to study the influence of formulation factors, polymer concentration, aqueous organic phase ratio, and process parameter stirring time on dependent physicochemical characteristics, particle size, zeta potential, and percentage entrapment efficiency (%EE) of the drugs. The optimized formulation was evaluated for in vitro release studies and subjected to stability studies. Results: Polymer concentration and process parameters were optimized to produce nanoparticles with desired parameters. The prepared NPs were characterized by Fourier transmission infrared (FT-IR), differential scanning calorimetry (DSC), drug loading, entrapment efficiency, particle size, zeta potential, and in vitro studies. FT-IR and DSC studies indicated that there was no interaction between the drug and polymer. The optimized NPs exhibits stability. Optimized NPs exhibited spherical and porous surfaces with a mean PS of 118 nm, the zeta potential of-25 mV, and %EE of 89%. Conclusion: Astragalin-loaded nanoparticles prepared with optimized formulation composition and process parameters.

Formulation and Evaluation of Eudragit L- 100 based Nanoparticles of Senna for Treatment of Constipation

Background: The pharmaceutical industries are keen in development of new herbal bioactive molecules with an improved effect and less toxicity in order to replace synthetic drugs. Constipation is the most prevalent medical concerns. It’s estimated that one in five adults worldwide suffers from constipation. Hence, the demand of herbal laxatives is increasing worldwide. The purpose of this research work was to develop Senna nanoparticles with the help of Eudragit L100 an enteric coating polymer to provide site specific activity and to prevent degradation of Senna in acidic environment. Materials and Methods: Senna loaded nanoparticles were prepared by using emulsion solvent evaporation method. Different formulation has been formulated with varying concentration of Eudragit L-100 and constant aqueous and organic phase ratio (1:9). Drug and polymer compatibility study was analysed by FTIR. The prepared formulation was characterized by melting point, particle size, zeta potential, polydispersity index, vesical morphology and in-vitro drug release. Results: All the formulation batches shows particle size between 380.61 - 1061.71nm. The zeta of optimized batch (F5) was found to be -23.75mV. Entrapment efficiency of the entire prepared formulation batch in between 3.16±0.31- 55.18±0.35%. The in-vitro drug release shows maximum drug release i.e. 61.03% in 8 hrs which shows that release of drug prolonged and site specific due to use of enteric coated polymer Eudragit L100. Conclusion: The developed Senna loaded nanoparticles can provide site specific drug delivery. The polymer used in Senna Nanoparticles formulations shows efficient and targeted drug release as well as reduction in dose, dosing frequency and side effects

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. 82–85%) 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.

Hydrolysis of tri-butyl phosphate in n-dodecane using sodium hydroxide: Factors affecting the hydrolysis process

Alkaline hydrolysis of tri-n-butyl phosphate (TBP) in n-dodecane (n-DD) using sodium hydroxide was studied for the treatment and disposal of spent organic waste generated from nuclear reprocessing plants. Experiments were performed in a stainless steel autoclave with a process volume of about 1 L to investigate the effect of agitator speed, temperature, organic to aqueous phase ratio, and concentration of sodium hydroxide on the kinetics of TBP hydrolysis. The concentration of TBP gradually decreased with increase in the duration of hydrolysis followed by a sharp fall in the concentration of TBP due to autocatalytic hydrolysis of TBP. The diluent does not take part in the hydrolysis reaction which was evident from the third phase formation during the course of hydrolysis. The present study confirms the complete conversion of TBP to its aqueous soluble products during hydrolysis. The results showed that among the various parameters studied, the concentration of NaOH and temperature were the key factors in determining the rate of hydrolysis of TBP. By using 12.5 M NaOH, aqueous phase to organic phase ratio above 1/3, temperature above 353 K, at an agitation speed of 1000 rpm, nearly complete hydrolysis of 1.1 M TBP was achieved in less than 3 h.