Extraction Of Thiocyanate Research Articles

Natural deep eutectic solvent as a green extraction medium for the ultrasonic-assisted extraction of sinapine thiocyanate from black mustard seeds

Herein, several choline chloride-based (ChCl) natural deep eutectic solvents (NADESs) were investigated for the ultrasonic-assisted extraction (UAE) of sinapine thiocyanate (ST) from black mustard seed (BMS). The NADES consisting of choline chloride and ethylene glycol (EG) was screened as the extraction solvent and single-factor experiments were carried out. In addition, compared with the conventional extraction solvents and extraction methods. The optimized extraction conditions were described below: NADES synthesized by ChCl and EG was used as an extractant with a water content of 20 %, and the solid–liquid ratio was 1:30 g∙mL−1. The mixture was extracted under the ultrasonic parameters of 60 ℃ and 200 W for 75 min. The extraction rate obtained using this method was higher than traditional solvents such as methanol, ethanol and water, and the time consumed was also greatly reduced compared to heated reflux extraction. A variety of instruments were used to characterize the experimental materials and further elucidate the extraction mechanism. Meanwhile, the antioxidant capacity of the ChCl/EG extract of BMS was determined by ultraviolet–visible spectrophotometry. The green evaluation of the method was carried out by the complex green analytical procedure index (ComplexGAPI). This work provides a green technique for valid extraction of ST from BMS, which is expected to be expanded to pharmaceutical, food and other related industries.

Preparation and characterization of very thin polymer inclusion membranes (PIMs) and their application to the transport of thiocyanate

The possibility of reproducible fabrication of functioning polymer inclusion membranes (PIMs) thinner than 10 μm, referred to as very thin PIMs (VT-PIMs), was demonstrated with four membrane compositions used successfully in previous studies for the extraction of thiocyanate. These compositions included Aliquat 336 as extractant (carrier) and 70 wt% of one of the following base polymers: poly(vinyl chloride) (PVC), cellulose triacetate (CTA) or poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP). One PVC- and one CTA-based PIMs contained 10 wt% 1-tetradecanol as modifier and 20 wt% Aliquat 336, while another CTA-based PIM and the PVDF-HFP-based PIM contained only 30 wt% Aliquat 336.The PVDF-HFP-based membrane (effective thickness 7.4 μm) exhibited the highest rate of transport of thiocyanate between a feed and a receiving solution among the newly developed VT-PIMs. Its initial flux was found to be more than twice that of a conventional thickness PIM (50 μm) of the same composition while the long-term stability of these two PIMs, studied in consecutive transport experiments, was virtually identical. The results obtained indicated that VT-PIMs offered a promising way of significantly improving the transport performance of PIMs, thus making them attractive to separation applications in industry.The paper also reports on the development of a reliable method for determining the effective thickness of PIMs using their density, which is particularly useful for VT-PIMs where thickness measurements using optical microscopy are difficult to perform.

Purification of highly concentrated cyanide-containing wastewater via stepwise recovering of valuable components

This study develops an efficient technique to purify the highly concentrated cyanide-containing industrial wastewater by recovering the valuable components. Firstly, sodium sulfide, sodium polysulfide and ferrous sulfate were respectively used as the precipitating agents to retrieve zinc, copper and iron from wastewater stepwise. In the meantime, cyanide presented as free cyanide and copper–cyanide complexes were transformed into thiocyanate by polysulfide. Afterwards, the solvent extraction of thiocyanate was systematically conducted with trioctylamine (TOA) as the extraction agent and sodium hydroxide solution as the stripping agent. The results showed that the contents of zinc, copper and iron in the solution after precipitation were less than 1 mg·L−1. Focusing on the reaction between copper–cyanide complex and polysulfide, three stages were established for the first time. In the first stage, Cu(CN)32− was gradually converted to CuCN0 and thiocyanate was rapidly generated. In the second stage, in addition to the formation of thiocyanate, Cu(I) was oxidized by polysulfide and precipitated as CuS ultimately. With an apparent activation energy of 70.9 kJ∙mol−1, kinetic analysis of the second stage suggested a significant effect of temperature on the copper–cyanide complex conversion rate. The apparent reaction orders of zero-valent sulfur and cyanide was 1.34 and 2.33, respectively. After the extraction and stripping process, the extraction efficiency of thiocyanate was nearly 100 % and the concentration of it can be enriched to 125 g·L−1 in the stripping solution. TOA and thiocyanic acid formed an extraction complex in a 1:1 ratio. This approach achieves the simultaneous recovery of valuable metallic ions (zinc, copper and iron) and cyanide conversion under the alkaline condition, which provides a new idea for the treatment of highly concentrated cyanide-containing wastewater with a complicated composition.

Uses of some monomers and polyamides of aminodibenzo - 18 - crown - 6 in solid - liquid extraction of potassium permanganate, dichromate, chromate, thiocyanate and nitrate

Crown ethers are very important compounds in the extraction of alkali, alkaline earth, and transition metal ions that by formation of complexes with these ions .Crown ether polymers may have more ability of extraction compared with their monomers .In addition these polymers may be less poison, expensive, and can be used as catalysts.This study had been aimed for using of some monomers and polymers contains dibenzo-18-crown-6 in solid – liquid extraction of potassium permanganate, dichromate, chromate and thiocyanate.The value of E% (D) was found to be increased with time in the case of extraction of KNO3, K2Cr2O7 and KMnO4 for all compounds expect in the case ofDB18C6, cis-DNDB18C6 and trans-DNDB18C6 when were used for KNO3 and KMnO4 extraction. In case of K2CrO4, a decrease was observed in the values of E% (D) after 15-30 minutes.

EXTRACTION OF ANIONIC CADMIUM COMPLEXES WITH ORGANIC SOLUTIONS OF QUATERNARY AMMONIUM SALTS

The anion-exchange extraction of thiocyanate, chloride and iodide cadmium complexes by solutions of quaternary ammonium salts chlorides in organic solvents (toluene, carbon tetrachloride, ethyl acetate, isobutyl alcohol, nitrobenzene) was studied. Extraction involves solutions of alkyl dimethylbenzylammonium chlorides (R-N+(CH3)2-CH2C6H5-Cl-) and alkyl dimethylethyl-benzylammonium (R-N+(CH3)2-CH2-CH2C6H5-Cl-), where R is a straight alkyl chain, mainly C12 - C14. The composition of the cadmium anionic complexes was established by the analysis of the calibration curves E = f (pCCd (II)) constructed from cadmium sulfate solutions against the background of various contents of thiocyanate, chloride and iodide ions (ndicator electrode - ion-selective electrode with a membrane, which based on a nitrobenzene solution of tetradecylammonium bromide). The extraction process is estimated quantitatively using a distribution coefficient (D). The value of D is calculated taking into account the cadmium concentration in the aqueous phase before and after extraction. The dependence of the distribution coefficient on the organic solvent dielectric constant, the concentration and stability of the anionic complexes of cadmium is shown. So, for the indicated cadmium acidocomplexes, the minimum D values were obtained using low-polar toluene and carbon tetrachloride, and the maximum values were obtained using highly polar isobutyl alcohol and nitrobenzene. If the concentration of cadmium (II) is reduced by a factor of 100 for the cadmium rhodanide and iodide complexes, the value of D decreases by 1.6-1.9 times, for the chloride complex, by 1.2 times in the case of polar isobutyl alcohol and nitrobenzene, and 2.9-3.5 times in the case of low-polar solvents. It was experimentally established that in the series [Cd(SCN)4]2- - [CdI4]2-- [CdCl4]2- the value of D decreases for all the studied systems. The observed regularity is related both to the stability of the corresponding cadmium (II) complexes in aqueous solutions and to their hydrophobicity.

Transparent polymer sensor for visual and photometrical detection of thiocyanate in oilfield water

A novel colorimetric sensor has been proposed for sensitive and accurate visual and spectrophotometric detection of thiocyanate using polymethacrylate matrix, which also has the potential for use with samples without pretreatment. The determination method is based on shaping of a Fe3+-thiocyanate colored complex into a transparent polymer matrix, followed by measurement of absorbance at 490 nm. The principle of this colorimetric sensor is not ordinary colorimetry, but a new colorimetric strategy that combines solid phase extraction and spectrophotometric determination of thiocyanate following completion of the color change processes. The method ensures determination of 0.8–30.0 mg L−1 of thiocyanate with the detection limit of 0.3 mg L−1. The proposed simple method makes it possible to determine visually in the concentration above 6.0 mg L−1 using a color scale. The test results show that the polymethacrylate matrix can be used for determination of thiocyanate in oilfield water.

Headspace sorptive solid phase microextraction (HS-SPME) combined with a spectrophotometry system: A simple glass devise for extraction and simultaneous determination of cyanide and thiocyanate in environmental and biological samples

A simple, low cost and efficient headspace sorptive solid phase microextraction (HS-SPME) method for determination of cyanide has been developed. The system comprises of a glass tube with two valves and a moveable glass slide fixed at its centre. It includes an acceptor phase polyurethane foam treated mercury (II) dithizonate [Hg(HDz)2–PUF] complex fixed inside by a septum cap in a cylindrical configuration (5.0cm length and 1.0cm diameter). The extraction is based upon the contact of the acceptor phase to the headspace and subsequently measuring the absorbance of the recovered mercury (II) dithizonate from PUFs sorbent. Unlike other HSSE, extraction and back – extractions was carried out in a closed system, thereby improving the analytical performance by preventing the analyte loss. Under the optimized conditions, a linear calibration plot in the range of 1.0–50.0µmolL−1 was achieved with limits of detection (LOD) and quantification (LOQ) of 0.34, 1.2µmolL−1 CN−, respectively. Simultaneous analysis of cyanide and thiocyanate in saliva was also performed with satisfactory recoveries.

The use of poly(vinylidenefluoride-co-hexafluoropropylene) for the preparation of polymer inclusion membranes. Application to the extraction of thiocyanate

Abstract The successful use of the solvent evaporation casting technique for the preparation of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) based polymer inclusion membranes (PIMs) is described for the first time. PIMs consisting of 70 wt% PVDF-HFP as the base polymer and 30 wt% Aliquat 336 as the carrier were prepared by the solvent evaporation casting and phase inversion techniques from solutions of the membrane components in tetrahydrofuran (THF) and N,N-dimethylformamide. These PIMs were compared in terms of their ability to extract the thiocyanate anion as a model target chemical species whose removal from gold mining process and tailings waters is of considerable technological and environmental interest. Best results were achieved with the PIMs produced by solvent evaporation from THF solutions. These membranes were translucent, flexible and homogeneous. Scanning electron microscopy images did not reveal the presence of a pore structure. The 30 wt% Aliquat 336 PVDF-HFP-based PIMs also exhibited significantly higher extraction and back-extraction rates for SCN− and long-term stability compared to PVC-based PIMs containing the same Aliquat 336 concentration. The results obtained in this study indicate that the use of PVDF-HFP as the base polymer in PIMs, prepared by conventional solvent evaporation casting, improves their performance in comparison to PIMs with traditionally used polymers such as poly(vinyl chloride) (PVC) and cellulose triacetate (CTA).

A polymer inclusion membrane for extracting thiocyanate from weakly alkaline solutions

A new polymer inclusion membrane (PIM) has been developed for the extraction of thiocyanate from weakly alkaline aqueous solutions. The composition of this membrane in mass percent (m/m) is 20% (m/m) Aliquat 336 as carrier, 10% (m/m) 1-tetradecanol as modifier and 70% (m/m) PVC as the base-polymer. This composition has been arrived at after extensive screening of a large number of CTA and PVC-based membranes using various plasticizers and modifiers. This membrane is homogeneous, flexible and transparent and extracts thiocyanate from weakly alkaline solutions with considerable speed for a PIM with an initial flux value of 7.86 × 10 −6 mol m −2 s −1. Quantitative back extraction is achieved using 1 M NaNO 3. The membrane has been cycled 10 times through extraction and back extraction without loss of performance. Its use in the extraction of thiocyanate from wastewater from the cyanide leaching of low grade gold ores has been successfully tested.

Solid Phase Extraction and Spectrophotometric Determination of Trace Amounts of Thiocyanate in Real Samples

A simple, selective and rapid method for solid phase extraction and spectrophotometric determination of thiocyanate using a manganese (III) tetrakis (p-sulfonatophenyl) porphyrin, [Mn (TPPS) OAC] bound to Amberlite IR-400 has been developed. The influence of pH, amount of solid phase, sample matrix, type and amount of eluting agent and flow rates i.e. variables affecting the efficiency of the extraction system were evaluated and conditions of the sample, eluting solution and active phase were optimized. The maximal capacity was found to be as 1.16 microg mL(-1) for 1200 mL. Thiocyanate ions can be eluted quantitatively with 8 mL 0.3 M ferric chloride. The enrichment factor was 150. The linear range of the determination is between 0.4-2.0 microg mL(-1) for preconcentration method with a limit of detection of 2.8 ng mL(-1). The method has been successfully applied for determination of trace amounts of thiocyanate in tap water, saliva sample and a synthetic mixture.

Solvent Extraction of Chromium(III) Perchlorate, Thiocyanate, Nitrate, Bromide, and Iodide with Trioctylphosphine Oxide in Hexane

Abstract Chromium(III) ion was extracted from aqueous 1 mol dm-3 NaX (X- = ClO4-, SCN-, NO3-, Br-, and I-) solutions with trioctylphosphine oxide (TOPO) in hexane at 298 K. The extraction was rapidly equilibrated, except from a NaNO3 solution. The number of TOPO molecules solvating to the extracted chromium(III) perchlorate and thiocyanate was 6. That to the bromide and iodide was 5. That to the nitrate was 5 at the beginning of extraction, and changed to 3 within a few hours of two-phase agitation. The hydration number of extracted Cr(ClO4)3·6TOPO was 17.2±0.5. The different solvation number of TOPO among these salts is supposed to be an unstable second hydration sphere of the extracted chromium(III) ion, which may be easily removed by the counter anions.

Separation of Cobalt from Synthetic Intermediate and Decontamination Radioactive Wastes Using Polyurethane Foam

Studies have been carried out on the removal of radioactive cobalt (60Co) from synthetic intermediate level waste (ILW) and decontamination waste using neat polyurethane (PU) foam as well as n-tributyl phosphate–polyurethane (TBP–PU) foam. The radioactive cobalt has been extracted on the PU foam as cobalt thiocyanate from the ILW. Maximum removal of cobalt has been observed when the concentration of thiocyanate in the solution is about 0.4 M. Cobalt can be separated from decontamination waste containing ethylenediaminetetraacetic acid (EDTA) and iron(II). The extent of extraction of cobalt is slow and the separation of iron and cobalt is better with the neat PU foam compared to the TBP–PU foam. The presence of iron in the decontamination waste facilitates the extraction of cobalt thiocyanate on the PU foam. Column studies have been carried out in order to extend these studies to the plant scale. The capacities of the PU foams for cobalt have been determined. The effect of density and the surface area of PU foam have been investigated. Fourier Transform Infrared (FT-IR) spectral studies have been conducted to find out the interaction between PU foam and cobalt thiocyanate species.

Solvent Extraction and Indirect Spectrophotometric Determination of Cyanate, Thiocyanate and Selenocyanate Anions with the Copper(II) Complex of Di-2-pyridylmethanone 2-Quinolylhydrazone

The extraction of cyanate, thiocyanate or selenocyanate ions with the copper(II) complex of di-2-pyridylmethanone 2-Quinolylhydrazone (DPQH) into benzene has been investigated spectrophotometrically at 25°C and μ=0.1. Copper(II) reacts with DPQH in a weakly acidic solution to form a dipositively charged mono complex (Cu(HL)2+) with the formation constant of logβCu(HL)=9.47. This complex undergoes deprotonation to a highly colored CuL+ species in the higher pH range, the proton dissociation constant having been determined to be pKac=4.53. In the presence of the abovementioned anions both complex species can be extracted into benzene as a highly colored ternary complex, Cu(L)A (A=NCO-, NCS- or NCSe-). The extraction constant, defined as Kex=[Cu(L)A]o/[Cu(L)+][A-] (the subscript (o) denotes the organic phase), is found to be 4.96 for NCO-, 6.15 for NCS- and 5.56 for NCSe- in logarithmic units. On the basis of the above observations, a sensitive spectrophotometric method for the determination of up to 3×10-5M of the anions has been developed by measuring the absorbance of the organic phase at 540nm.

Spectrophotometric determination of zinc with hydrazidazol in the presence of Triton X-100 and its application in metal analysis

A new spectrophotometric method for the determination of zinc is proposed. The chromogenic agent Hydrazidazol forms a 1:1 chelate with zinc in the presence of Triton X-100 in a medium containing 20–40% ethanol. The molar absorptivity and conditional formation constant have been found to be 2.7 × 1O 4 l.mole −1.cm −1 (at 640 nm) and 10 5.32 respectively. Beer's law is obeyed for zinc over the range of 0.2–0.8 μg/ml with a standard deviation of 0.024 μg/ml. The method can be applied to the determination of zinc in cadmium metal and its oxide after preconcentration by selective extraction of zinc thiocyanate into ethyl acetate in the presence of EDTA and thiosulphate as masking agents.

Extraction of zirconium and hafnium thiocyanate with polyurethane foam

Conditions for the extraction of zirconium and hafnium thiocyanate by polyether-type polyurethane foam were studied in detail. The composition of the extractable species was found to be dependent on both the thiocyanate and metal-ion concentrations. The extraction efficiency for zirconium and hafnium depended on the size of the counter-cation as well as on the type of anion.

Ion-pair extraction of thiocyanate from plasma and its gas chromatographic determination using on-column alkylation.

Ion-pair extraction of thiocyanate from plasma and its gas chromatographic determination using on-column alkylation.

Extraction of ruthenium thiocyanate and its separation from rhodium by polyurethane foam

Conditions for the formation and extraction of the thiocyanate complex of ruthenium are reported. Distribution coefficients of more than 10 4 and a capacity of about 0.24 mole per kg of foam were obtained. The effect of the chloride salts of various univalent cations on the extraction of Ru(SCN) 6 3− indicated that the efficiency of ruthenium extraction depends on how well the cation fits into the polyether segment of the polyurethane foam, which agrees with the “cation-chelation” mechanism. The separation of ruthenium and rhodium indicated that more than 95% of the rhodium remained in the aqueous phase and about 95% of the ruthenium was retained by the polyurethane foam and could be easily recovered.

Extraction of osmium thiocyanate and its separation from ruthenium by polyurethane foam

A detailed investigation of the conditions for formation and extraction of the thiocyanate complex of osmium by polyether-type polyurethane foam is reported. The complex which formed in solution was extracted through the “cation-chelation” mechanism and distribution coefficients of more than 10 4 were obtained. By using conditions which inhibit the formation of the osmium-thiocyanate complex, it was possible to leave 95% of osmium in the aqueous phase while extracting more than 95% of ruthenium into polyurethane foam.

Extraction of palladium thiocyanate with polyurethane foam

Conditions for the extraction of the thiocyanate complex of palladium by polyether-type polyurethane foam are reported. Distribution ratios of more than 10 6 with a capacity of about 0.8 mole per kg of foam were obtained. The palladium could be rapidly recovered from the foam with high efficiency by use of ammonia solution. The efficiency of palladium extraction depends on how well the cation associated with the complex fits into the polyether segment of the polyurethane foam.

Liquid-liquid extraction of cobalt(II) thiocyanate with hexamethyl phosphoramide: Direct spectrophotometric determination in the organic phase

Liquid-liquid extraction of cobalt(II) thiocyanate with hexamethyl phosphoramide: Direct spectrophotometric determination in the organic phase