Solvent Extraction Step Research Articles

The industrial process of solvent extraction of castor oil reduces the toxicity of the meal

Castor (Ricinus communis L.) oil is an important raw material for the chemical industry. The industrial process of castor oil extraction exposes the material to chemical, thermal, and mechanical treatments that influence the properties of the proteins in the meal. This study tested the hypothesis that the regular industrial process of castor oil extraction with solvent changes properties of the meal like the profile of proteins, the nematicide efficiency, and its toxicity. The changes made by the process of oil extraction create opportunities for adding value to this by-product. Samples of castor cake and meal were collected along the process of oil extraction under the regular operation of an industry. The samples were analyzed for chemical composition, hemagglutination activity, nematicide efficiency, and toxicity for feeding broilers and sheep. It was found that the step of solvent evaporation is responsible for the most relevant modifications in the meal, with significant changes in the protein profile, loss of hemagglutination capacity, and reduction of toxicity and nematicide efficiency. The castor meal produced just after the solvent evaporation has the toxicity reduced to a level that was tolerable to be used in the ration of small ruminants without detectable loss of performance or clinical signs of intoxication. The castor meal was toxic for broilers. The nematicide capacity of castor meal against larvae of Haemonchus contortus is reduced after the step of solvent extraction, but it is still significant and detected in doses as low as 5 mg/g. When castor meal was separated in fractions by sieving, the fine fraction (particles smaller than 0.5 mm) had high protein content (60.2%), low fiber content (6.0%), and high water holding capacity (164.2% of its dry weight).

An inimitable and ecological pleasant technique for the assessment of trace amount of copper (II) in tangible samples with new complexing reagent

A simple and rapid spectrophotometric technique has been designed for the trace copper analysis employing 1-(2-Thiazolylazo)-2-naphthol (TAN) reagent in aqueous micellar solution of cetyl trimethylammonium bromide (CTAB) as a surfactant. Copper complexed with 1-(2-Thiazolylazo)-2-naphthol to form bis[1-(2-Thiazolylazo)-2-naphthol]copper. The present spectrophotometric technique was very important since the micellar system was used in place of the toxic, high cost and time-consuming solvent extraction steps. The technique showed an enhanced detection efficiency, specificity, and molar absorptivity. It was found that the molar absorption coefficient and sensitivity of Sandel were ε 2.45 × 104 L mol−1cm−1 and 2.6 ngcm−2 at λmax 578.4 nm. A linear calibration plot in the range 0.12–5.0 μg mL−1 was obtained; a stoichiometric metal ligand ratio [M:L] of 1:2 was found for the formation of Cu-[TAN]2. The complex was formed at pH 9.5 and was stable up to 24 h. The proposed technique has been employed to study copper from different alloys, biological, environmental and pharmaceutical samples.

Determination of Glyphosate and AMPA in Food Samples Using Membrane Extraction Technique for Analytes Preconcentration.

The method for determining glyphosate (NPG) and its metabolite AMPA (aminomethyl phosphonic acid) in solid food samples using UAE-SLM-HPLC–PDA technique was developed. Firstly, ultrasonic-assisted solvent extraction (UAE) and protein precipitation step were used for the analyte isolation. Then, the supernatant was evaporated to dryness and redissolved in distilled water (100 mL). The obtained solution was alkalized to pH 11 (with 1 M NaOH) and used directly as donor phase in SLM (supported liquid membrane) extraction. The SLM extraction was performed using 2 M NaCl (5 mL) as an acceptor phase. The flow rate of both phases (donor and acceptor) was set at 0.2 mL/min. The membrane extraction took 24 h but did not require any additional workload. Finally, the SLM extracts were analyzed using the HPLC technique with photo-diode array detector (PDA) and an application of pre-column derivatization with p-toluenesulfonyl chloride. Glyphosate residues were determined in food samples of walnuts, soybeans, barley and lentil samples. The LOD values obtained for the studied food were 0.002 μg g−1 and 0.021 μg g−1 for NPG and AMPA, respectively. Recoveries values ranged from 32% to 69% for NPG, 29% to 56% for AMPA and depended on the type of sample matrix. In the case of buckwheat and rice flour samples, the content of NPG and AMPA was below the detection level of a used analytical method.

Partitioning of heat generating fission product (137Cs & 90Sr) from acidic medium by 1,3-dioctyloxy-calix[4]arenecrown-6 (CC6) & Octabenzyloxyoctakis[[[(N,N-diethylamino)carbonyl)]methyl]oxy]calix[8]arene (BOC8A) in nitro octane diluent: Batch scale study & process parameter optimization

Partitioning of heat emitting fission product 137Cs & 90Sr in a single solvent extraction step with nearly zero actinide and lanthanide contamination have been studied using a mixture of calixarene based ionophore 1,3-dioctyloxy-calix[4]arenecrown-6 (CC6) & Octabenzyloxyoctakis[[[(N,N-diethylamino)carbonyl)]methyl]oxy]calix[8]arene (BOC8A) in a nitro alkane based diluent nitro octane (NO). A mixture of 0.03 M CC6 and 0.01 M BOC8A in NO showed high selectivity (separation factor greater than 100) towards Cs (Dcs = 4.0) & Sr (DSr = 4.6) with respect to almost all other element except Na (DNa = 0.9), Ba (DBa = 1.48) and Pu (IV) (DPu = 0.4) present in the simulated high level liquid waste (SHLLW). Role of different parameters effecting distribution of Cs & Sr such as equilibration time, feed acidity, extractant concentration, and temperature were evaluated to optimize the condition of extraction and stripping of Cs & Sr. Extraction of Cs & Sr was found to be exothermic in nature. The outcome of this work gives an insight into amenability of co-decontamination of heat generating fission products from high level waste (HLLW) using mixture of BOC8A & CC6 in NO diluent.

Solid-phase excitation-emission matrix spectroscopy for chemical analysis of combustion aerosols.

Exposure to ultrafine combustion aerosols such as particulate matter (PM) from residential woodburning, forest fires, cigarette smoke, and traffic emission have been linked to adverse health outcomes. Excitation-emission matrix (EEM) spectroscopy presents a sensitive and cost-effective alternative for analysis of PM organic fraction. However, as with other analytical chemistry methods, the miniaturization is hindered by a solvent extraction step and a need for benchtop instrumentation. We present a methodology for collecting and in-situ analysis of airborne nanoparticles that eliminates labor-intensive sample preparation and miniaturizes the detection platform. Nanoparticles are electrostatically collected onto a transparent substrate coated with solid-phase (SP) solvent—polydimethylsiloxane (PDMS). The PM organic fraction is extracted into PDMS and analyzed in-situ, thus avoiding liquid-phase extraction. In the SP-EEM analysis, we evaluated external and internal excitation schemes. Internal excitation shows the lowest scattering interference but leads to signal masking from PDMS fluorescence for λ<250nm. The external excitation EEM spectra are dependent on the excitation light incident angle; ranges of 30–40° and 55–65° show the best results. SP-EEM spectra of woodsmoke and cigarette smoke samples are in good agreement with the EEM spectra of liquid-phase extracts. The SP-EEM technique can be used to develop wearable sensors for exposure assessments and environmental monitoring.

Construction of bifunctional 3-D ordered mesoporous catalyst for oxidative desulfurization

The development of catalysts with the functions of catalyzing the oxidation of organosulfur and separating the products from reaction mixturesis facilitates to achieve high-efficiency oxidative desulfurization (ODS) of fuel. Herein, the MoO3 nanoparticles (mean diameter = 1.33 nm) confined in Ti-doped KIT-6 could be synthesized by triblock copolymer (EO20PO70EO20)-assisted in-situ synthesis method combined with stepwise pyrolysis. The prepared catalyst (Mo/KIT-6-Ti) exhibited excellent ODS performance. When cumene hydroperoxide (CHP) was used as the oxidant, Mo/KIT-6-Ti not only could completely remove dibenzothiophene (DBT) in the model gasoline at room temperature in 40 min but also had the excellent ability to adsorb and separate the sulfone product from the model gasoline. After five reaction-regeneration cycles, the DBT conversion over Mo/KIT-6-Ti still reached above 99% in 60 min. Furthermore, kinetic studies revealed that the oxidation reaction of DBT on Mo/KIT-6-Ti had extremely low activation energy (34.9 kJ/mol). Data from radical scavenger experiments suggested that hydroxyl radicals play a dominant role in the ODS. This catalyst has the potential to negate the need for a solvent extraction step in fuel desulfurization and produce ultralow sulfur fuel.

Application of Argent Metric in the Estimation of Mesna in Tablets and Injections. Application to Content Uniformity Testing

A new, accurate, sensitive and simple indirect spectrophotometric method for the estimation of sodium 2-mercaptoethanesulfonate (mesna) has been developed. This procedure base on the reaction of mesna with excess of silver nitrate and a known amount of methyl orange and the increase in absorbance at 520 nm, caused by a decrease in pH due to release of nitric acid, is measured and related to drug concentration .The absorbance results increased with increasing concentration of mesna . Beer’ s law is obeyed and linear at the concentration range of 2-28µg/ml. Apparent molar absorbance, Sand ell’s sensitivity values were 7.16×103 Lmol-1cm-1. And 22.93 ng.cm-2 respectively, The present method is considered to be simple because it does not need either heating or hydrolysis or solvent extraction steps. The ingredients often formulated with Metoclopramide hydrochloride have been shown not to interfere, and the proposed method is suitable for the routine determination of mesna. The (RSD) of this method was less than 2 and average recovery (accuracy) is 100 ± 0.75. The method applied successfully for estimation of mesna in (tablets and injections pharmaceutical formulations).and Application to Content Uniformity Testing

Lithium‐Chelating Resins Functionalized with Oligoethylene Glycols toward Lithium‐Ion Battery Recycling

AbstractRecycling spent lithium‐ion batteries (LIBs) is an important consideration both to preserve metal resources and to reduce hazardous waste. One recycling method is to extract lithium and cobalt ions using organic solvents that contain battery components. However, it is hard to achieve the complete separation of metal ions and this also requires multiple steps. Herein, functionalized polymeric resins are reported, that can capture both lithium and cobalt ions from organic solutions and separate them chromatographically. Specifically, Merrifield resin is functionalized with oligoethylene glycol derivatives, which are structurally similar to crown‐ethers. To test the lithium‐ion depletion, these resins are incubated with bulk solutions of lithium cations at ≈50 ppm in acetonitrile. The results showed 30–45% depletion after filtration in optimal cases. To test this polymer support for chromatographic separation and check the potential for LIB recycling, a column is packed with the functionalized resin beads, and a mixture of lithium (≈200 ppm) and cobalt (≈200 ppm) ions is loaded. The column can achieve baseline separation of these ions and can be used multiple times without degradation. These results suggest that the current solvent extraction steps during recycling processes can be greatly simplified.

Valorization of mangaba residue (Hancornia speciosa Gomes) for polygalacturonase production from Aspergillus niger IOC 4003 and fabrication of active chitosan films

The present study proposes to obtain polygalacturonases, antioxidant compounds, and active chitosan films from a valorization scheme of mangaba residue. After extraction with ethanolic solution, the mangaba residue was used as a substrate for solid state fermentation (SSF) of Aspergillus niger IOC 4003, which obtained 76.32 U g−1 for polygalacturonase after 96 h cultivation. The previous step of solvent extraction increased the enzyme productivity and allowed the production of pH-tolerant polygalacturonase in SSF experiments. The addition of polygalacturosanase under 1.0 U mL−1 enabled the reduction of turbidity (34%) and viscosity (11%) of mangaba juice compared to enzyme-free condition. Solid residue from the SSF step was used in the extraction of alkaline lignin with sodium hydroxide, which allowed the recovery of 21.82% of the initial Klason lignin content. Supplementation of chitosan films with ethanolic extract and 0.1% (w v−1) alkaline lignin changed the values of antioxidant activity (increase of 86.5% and 45.4%) and permeability (reduction of 43.2% and 2.3%).

Acid recovery from copper metallurgical process streams polluted with arsenic by diffusion dialysis

A copper smelter generates solutions containing H2SO4 (220 ± 10 g/L), non-metals (3.4 ± 0.2 g/L As) and metals (0.5 ± 0.1 g/L Zn, 0.13 ± 0.01 g/L Fe and 0.11 ± 0.01 g/L Cd) that are treated with lime as disposal option. In order to promote circularity, the recovery of H2SO4 by diffusion dialysis (DD) was evaluated with a lab-stack unit containing Anion Exchange Membranes (Neosepta-AFX) that allow the transport of HSO4− and H+, while rejecting metallic species in cationic form. Initially, dialysis coefficients were determined with cycling type experiments, which showed the possibility to purify H2SO4, but As was also transported. Then, dynamic experiments were carried out to study the effect of different variables, such as operational ones (acid and water flow rates) and As speciation (As(V) or As(III)). At the optimum operating conditions (water and acid flow rates of 0.86 L/m2h), Neosepta-AFX proved to allow the transport of H2SO4 (67 ± 2 % of acid was recovered, 146 ± 12 g/L) and rejected the metallic impurities (>85 %) effectively. Nevertheless, As permeated across the membrane (1.26 g/L in the recovered acid) due to its presence as neutral species (H3AsO4/ H3AsO3). In order to overcome it, the use of a solvent extraction step devoted to remove As before the treatment with DD was proposed.

Recent progress in impurity removal during rare earth element processing: A review

Supply of rare earth elements (REEs) critical to the development and maintenance of industrialized economies has become uncertain in recent years owing to the limited number of REE producers. In order to develop alternative REE sources, new mines are being explored and end-of-life secondary sources have been targeted for REE recovery. However, the composition of ores and secondary sources often differ significantly from one source to another and hydrometallurgical practices are not rigorously established or matured for many alternative REE sources. This presents a challenge in processing these materials while minimizing the entrainment of impurities. This work presents a comprehensive and systematic review on recent progress in impurity removal during REE processing. A large number of original research articles covering techniques including solvent extraction, ion exchange, precipitation, and other emerging technologies have been reviewed in detail and critically assessed to understand the role and behaviour of specific impurities in REE processing (including Al, Ca, Mg, Fe, Si, Th, U, Ti, Zr, Hf, Cr, Mo, Mn, Co, Ni, Cu, Zn, Sn, Pb, and Bi). Control of the most troublesome impurities for industry (Al, Fe, Th, U) depends on their concentration, redox ratio, and the degree of purity required. Most aluminum, ferric iron, thorium, and uranium(IV) selectively precipitate as hydroxides prior to REEs. Ferrous iron does not usually co-extract with REEs in their ion exchange or solvent extraction circuits. Precipitation of REE oxalates is effective to partition REEs and uranyl (UO22+) species. To remove thorium and uranium to the highest degree requires separate solvent extraction or ion exchange steps designed to specifically extract these impurities by anion exchange.

Experimental determination of pesticide processing factors during extraction of seed oils

ABSTRACT Processing Factors (PFs) reflect the concentration or dilution of pesticide residues resulting from food processing. PFs are key elements to demonstrate the compliance of processed foods with Maximum residue levels (MRLs) as set by Regulation 396/2005. While efforts have been made by the European Food Safety Authority (EFSA) and by national authorities to compile PFs from processing studies, such PFs are not available for all pesticides/processed product combinations. The EU vegetable oil and proteinmeal industry association (FEDIOL) has therefore developed a theoretical approach to approximate MRLs in crude vegetable oils and fats, based on the partition coefficient (log Pow) of the pesticides and on the oil content of the raw materials. To substantiate this approach, a pilot-scale processing study was initiated with rapeseeds spiked with selected pesticides and the experimental PFs for these pesticides determined. The aims of this study were (i) to study the reliability of pilot-scale conditions for PF determination and (ii) to assess the experimental PFs obtained in comparison to the theoretical PFs proposed by FEDIOL. This study demonstrated that production yields obtained for crude oil and meal in this processing study are similar to those in industrial processes even if differences were observed in the individual production steps (mechanical or solvent extraction steps). The experimental PFs obtained confirmed that the chosen fat-soluble pesticides did concentrate in the oil fraction. For metalaxyl-M having a log Pow lower than 3, a partitioning between the oil and the meal was observed, as expected. By comparing the experimental PFs and theoretical PFs, it can be concluded that the FEDIOL approach can be recommended as a suitable tool when PFs derived from specific processing studies are missing. Similar studies on pesticides with wider ranges of log Pow are required in order to complete our conclusions on default PFs for vegetable oils.

Supramolecular solvent-based high-throughput sample treatment for monitoring phytohormones in plant tissues

Quantification of endogenous hormones in plants is essential to understand their growth, development and response to biotic and abiotic stresses. However, it is challenging to develop high-throughput sample treatments from complex plant tissues containing low amounts of structurally unrelated and labile phytohormones while delivering clean and analyte-enriched extracts. In this paper we propose the use of supramolecular solvents (SUPRASs) made up or inverted hexagonal nanostructures of alkanols to address this challenge. The strategy was applied, as a proof of concept, to the quantification of stress-related phytohormones belonging to different categories (abscisic acid, salicylic acid, jasmonic acid, methyl jasmonate and 3-indoleacetic acid) in melon and pepper leaves. Sample treatment consisted in a single extraction-cleanup step involving the use of a low volume of SUPRAS (244 μL), the stirring (5 min) and centrifugation (15 min) of the sample at room temperature, and the direct analysis of the extract by liquid chromatography tandem mass spectrometry (LC-MS/MS). This high-throughput sample treatment method delivered excellent results for the target phytohormones regarding absolute recoveries (80–92%), method quantification limits (0.05–2 ng g−1), reproducibility (1–7%) and matrix effects (+13 to −31%), in both melon and pepper leaves, compared to reported methods based on repetitive solvent extraction, purification and solvent evaporation steps. The method was successfully applied to determine target hormones in melon and pepper plants for the evaluation of the effect of thermal stress. It was found that their concentration increased in the ranges 1.2–1.9 and 1.3–3.8 times in melon and pepper leaves, respectively, compared with control samples.

Recovery of Metal Values from Ni-Cd Cake Waste Residue of an Iranian Zinc Plant by Hydrometallurgical Route

This paper concerns the development of an environment-friendly hydrometallurgical flowsheet dedicated to the recovery of zinc and nickel from a waste residue collected from an Iranian zinc plant. In particular, valuable metals from Ni-Cd cake waste generated at this plant were recovered by a simple hydrometallurgical process using minimum acid for leaching, and solvent extraction step was designed such that addition of sodium hydroxide was not required and the effluent generated is safe to dispose off. The waste was leached with a mixture of hydrochloric acid and sulfuric acid in the presence of hydrogen peroxide in order to achieve a good selectivity towards iron and calcium. Afterwards, cementation was performed at pH 5 in order to remove cadmium. Liquid–liquid extraction was then implemented to produce high-purity solutions of zinc and nickel. Zinc-nickel separation was obtained at pH 2 by using a mixture of bis-(2-ehtyl-hexyl)-phosphoric acid (HDEHP) and tris-2-ethylhexyl amine (TEHA) diluted in an aliphatic kerosene. TEHA did not directly participate but helped in the extraction of zinc by scavenging the protons released by HDEHP. Therefore, no alkaline solution was necessary for maintaining the equilibrium pH during liquid–liquid extraction. Finally, this flowsheet allowed to recover more than 95% of zinc and nickel from the residue with more than 99% purity.

The Ins and Outs of 14C Dating Lead White Paint for Artworks Application.

Lead white is known as one of the oldest pigments in art and can be used as a dating material. Upon production following the Stack process, the 14C isotope of atmospheric carbon dioxide is fixed in the carbonate, and its radiocarbon dating can be used as a proxy for the age of a painting. The previously reported carbonate hydrolysis protocol reaches its limitation when confronted with samples presenting a mixture of carbonates, such as lead carbonate (cerussite or hydrocerussite), calcium carbonate (calcite), and/or calcium magnesium carbonate (dolomite). Thermogravimetric analyses indicate that decomposition of lead carbonate can be achieved at 350 °C in TGA diagrams, as other mineral carbonates only decompose to carbon dioxide at temperatures above 700 °C. Thus, a thermal approach is proposed to separate the various carbonates and isolate the specific 14C signature to the lead carbonate. In practice, however, discrepancies between the measured radiocarbon ages and expected ages were observed. FTIR analyses pointed to the formation of metal carboxylates, an indicator that the organic binder is not inert and plays a role in the dating strategy. Upon drying, oxidation and hydrolysis take place leading to the formation of free fatty acids, which in turn interact with the different carbonates upon heating. Their removal was achieved by introduction of a solvent extraction step prior to the thermal treatment, which was confirmed by GC-MS analyses, and thus, the collected carbon dioxide at 350 °C results can be assigned correctly to the decomposition of the lead white pigment. The proposed procedure was furthermore verified on mixed carbonate-bearing paint samples collected from a Baroque oil painting.

Recovery of Rubidium and Cesium Resources from Brine of Desalination through t-BAMBP Extraction

50 billion cubic meters of brine every year creates ecological hazards to the environment. In order to reuse brine efficiently, rubidium and cesium were recovered in this experiment. On the other hand, the main impurities which were needed to be eliminated in brine were lithium, sodium, potassium, calcium, and magnesium. In the procedure, seawater was distilled and evaporated first to turn into simulated brine. Perchloric acid was then added into simulated brine to precipitate potassium perchlorate which could reduce the influence of potassium in the extraction procedure. After that, t-BAMBP and ammonia were separately used as extractant and stripping agent in the extraction and stripping procedures to get rubidium hydroxide solutions and cesium hydroxide solutions. Subsequently, they reacted with ammonium carbonate to get rubidium carbonate and cesium carbonate. In a nutshell, this study shows the optimal parameters of pH value to precipitate potassium perchlorate. Besides, pH value in the system, the concentration of t-BAMBP and ammonia, organic phase/aqueous phase ratio (O/A ratio), reaction time, and reaction temperature in solvent extraction step were investigated to get high purities of rubidium carbonate and cesium carbonate.

Toward an efficient multi-step separation protocol to recover metallic components from waste leachates

This work presents a study of the separation and recovery of metal elements, through a multi-step protocol based on solvent extraction, stripping and chemical precipitation processes. The waste leachate was produced during the treatment of the mixed solid waste from the decommissioning of a coal-fired power plant. The organophosphorus acid, di-(2-ethylhexyl) phosphoric acid (DEHPA) was investigated as organic extracting agent during the solvent extraction (Step 1). A factorial design with three levels for the organic phase/aqueous phase ratio (O/W), DEHPA concentration and contact time were carried out and a prediction model obtained using a neural-fuzzy approach. Optimized extraction values for Ti (93.4 %), (V) 94.6 % and (Zn) 89.8 % were obtained using 60min of contact time, a DEHPA concentration of 0.5M and O/W ratio of 4. Stripping tests were performed using HCl, H2SO4, NaOH and KOH as stripping agents. The stripping step (step 2) showed optimum results (82 % of Zn and 31 % of V) using 1M H2SO4 solution as stripping agent. A selective precipitation step (step 3) allowed the final separation of metals in aqueous solutions produced in Step 1 and 2. The results showed that an effective separation of Mn and Ni could be carried out at pH 9, while the best separation results for the solution obtained during the stripping step, which contains V and Ti, was obtained at pH 12.

Recycling of mixed cathode lithium‐ion batteries for electric vehicles: Current status and future outlook

AbstractWorldwide trends in mobile electrification, largely driven by the popularity of electric vehicles (EVs) will skyrocket demands for lithium‐ion battery (LIB) production. As such, up to four million metric tons of LIB waste from EV battery packs could be generated from 2015 to 2040. LIB recycling directly addresses concerns over long‐term economic strains due to the uneven geographic distribution of resources (especially for Co and Li) and environmental issues associated with both landfilling and raw material extraction. However, LIB recycling infrastructure has not been widely adopted, and current facilities are mostly focused on Co recovery for economic gains. This incentive will decline due to shifting market trends from LiCoO2 toward cobalt‐deficient and mixed‐metal cathodes (eg, LiNi1/3Mn1/3Co1/3O2). Thus, this review covers recycling strategies to recover metals in mixed‐metal LIB cathodes and comingled scrap comprising different chemistries. As such, hydrometallurgical processes can meet this criterion, while also requiring a low environmental footprint and energy consumption compared to pyrometallurgy. Following pretreatment to separate the cathode from other battery components, the active material is dissolved entirely by reductive acid leaching. A complex leachate is generated, comprising cathode metals (Li+, Ni2+, Mn2+, and Co2+) and impurities (Fe3+, Al3+, and Cu2+) from the current collectors and battery casing, which can be separated and purified using a series of selective precipitation and/or solvent extraction steps. Alternatively, the cathode can be resynthesized directly from the leachate.

High Purity Nickel Recovery from an Industrial Sidestream Using Concentration and Liquid\u2013Liquid Extraction Techniques

This article outlines an alternative flowsheet for the purification of a multi-metal industrial sidestream (16.3 g/l Ni, 0.7 g/l Co, 0.6 g/l Ca and 1.6 g/l Mg) to allow high-purity nickel recovery. The methodology comprises an initial evaporation step to achieve Ca removal followed by impurity (Ca, Mg) and valuable (Co, Ni) element separation via two-step solvent extraction with organophosphorus extractants. Results indicate that > 80% of Ca is selectively removed as CaSO4·2H2O by evaporation with a concentration degree > 6. In the following treatment, ~ 90% of residual Ca (0.6 g/l) can be selectively extracted with Na-D2EHPA. The subsequent solvent extraction step with Na-Cyanex 272 separates Co (> 99%) and Mg (> 95%). The resultant nickel sulfate solution (61.7 g/l Ni, 0.3 g/l Mg and Co 0.007 g/l) of > 99.5% purity can be directly integrated into state-of-the-art nickel recovery processes.

Colorimetric Assay of Thiamine Hydrochloride in Pharmaceutical Preparations

A simple, rapid, accurate and sensitive spectrophotometric method for the determination of thiaminehydrochloride has been developed. The method is based on the formation of the Schiff’s base between the primary amino group present in thiamine hydrochloride and aldehyde group present in the vanillin reagent to produce a yellow colored complex having maximum absorption at 390 nm. Beer’s law has obeaid over the concentration range of 2-28µg/mL, with molar absorptivity of 0.96x104L/mol.cm. The average recovery which is a measure of accuracy is 100±1.3% and the relative standard deviation (RSD) is less than1.5 .The present method is considered to be simple because it does not need heating, hydrolysis and solvent extraction steps. The ingredients often formulated with thiamine and have been shown not to interfere, and is suitable for the routine determination of thiamine hydrochloride. The proposed method has been successfully applied for the determination of thiamine hydrochloride in pure form and in pharmaceutical preparations.