Solid–liquid extraction of terbium from phosphoric acid solutions using solvent‐impregnated resin containing TOPS 99

BACKGROUND: In this work, the solid‐liquid extraction of terbium from phosphoric acid solutions using solvent‐impregnated resin containing TOPS 99, an equivalent of di‐2‐ethylhexyl phosphoric acid, has been investigated. The parameters studied include equilibration time, acid concentration, amount of resin, metal concentration, kinetics, temperature, loading, elution, regeneration and recycling. RESULTS: FT‐IR results confirm the physical interaction of the extractant with the resin. The extraction of terbium with TOPS 99 impregnated Amberlite XAD 4 resin was acid dependent and transfer of metal follows a cation exchange mechanism. The loading capacity of TOPS 99‐impregnated resin for terbium was calculated to be 23.8 mg g^?1 resin. Controlling mechanism of the adsorption was found to be a chemical reaction following pseudo‐second‐order kinetics. The endothermic nature of extraction was confirmed by temperature studies. Among the various eluants studied, H₂SO₄ was the best. Regeneration and recycling of the resin indicated the resin can be used for continuous cycles. CONCLUSIONS: Terbium was successfully extracted from phosphoric acid using TOPS 99 extractant impregnated into Amberlite XAD4 with a maximum loading of 23.8 mg g^?1 resin and fully recovered with 1 mol L^?1sulfuric acid. The resin was subjected to seven cycles of extraction and elution without any loss of performance. Further studies showed that terbium could be separated from lutetium. Copyright © 2010 Society of Chemical Industry     

Ethanol production from wood via concentrated acid hydrolysis,chromatographic separation,and fermentation

BACKGROUND: Production of bioethanol from wood using concentrated acid hydrolysis has received less attention than the dilute acid hydrolysis route. The feasibility of producing lignocellulosic bioethanol from spruce and birch via concentrated acid hydrolysis was studied experimentally. Hydrolysis with sulfuric acid, chromatographic purification of the hydrolysate, and fermentation of the monosaccharides were investigated. RESULTS: Monosaccharide yields of 70% were obtained in the hydrolysis of spruce and birch. Only low amounts of by‐products were formed. With chromatographic purification of the hydrolysate, over 90% of the hydrolysis acid was recovered for recycling, and furfural and HMF were removed completely. Most of the acetic acid was recovered in a separate fraction. The monosaccharide yield in a single pass separation was approximately 70%. In the fermentation, S. cerevisiae produced higher amounts of ethanol and more efficiently than P. stipitis. Chromatographically purified hydrolysates gave higher ethanol productivities and yields than Ca(OH)₂ neutralized hydrolysates. CONCLUSIONS: Chromatographic purification of concentrated acid lignocellulosic hydrolysates has advantages when compared with neutralization with Ca(OH)₂. With chromatography, most of the inhibitory compounds can be removed from the hydrolysates. In addition, due to the recycling of the hydrolysis acid, the economy of the bioethanol manufacturing process is increased considerably. Copyright © 2011 Society of Chemical Industry     

Utilization of spent petrochemical sulfuric acid in the production of wet‐process phosphoric acid

The possibility of the application of spent sulfuric acid from the petrochemical industry in wet‐process phosphoric acid technology was investigated. The effect of organic impurities in sulfuric acid from benzol acidic refining on the solubility of calcium sulfate hydrates is discussed. Solubility isotherms and regression equations for CaSO₄–H₃PO₄–H₂SO₄–H₂O (pure and containing impurities) systems are presented. Phase transition temperatures between dihydrate and hemihydrate calcium sulfate were determined. The difference between pure and polluted sulfuric acid systems observed is negligible over the range of typical wet‐process phosphoric acid technology parameters. It is concluded that the application of spent sulfuric acid from benzol acidic refining does not have a negative influence on the crystallization process of dihydrate calcium sulfate and therefore can be applied in wet‐process phosphoric acid technology. Copyright © 2005 Society of Chemical Industry     

Sorption Studies of Uranium on Novel Imino Diacetamide Grafted Styrene Divinyl Benzene Polymeric Resin

Imino diacetamide styrene divinyl benzene (IDAA SDVB) resin was evaluated for the sorption of uranium from sulphuric acid medium. Uranium sorption on to the resin was fast, the kinetic data fitted well in pseudo second order kinetics model. Sorption of uranium was found to increase with the increase in initial concentration of uranium in aqueous feed solution, the sorption isotherm data fitted closely in to Langmuir isotherm model. The sorption of uranium is observed to decrease with the increase in initial feed acidity thereby, allowing sorption and desorption at lower (0.1 M H₂SO₄) and higher (1.0 M H₂SO₄) acidities, respectively.     

弱碱性树脂处理β-萘磺酸废水的吸附分离热力学性能

研究了β-萘磺酸废水中β-萘磺酸、H₂SO₄、H₂SO₃ 单组分吸附平衡,并以Langmuir、Freundlich模型对其进行模拟.吸附过程的热力学计算及分析结果表明,吸附过程为放热的化学吸附过程,吸附量顺序为H₂SO₄>NSA>H₂SO₃,推动力大小顺序为H₂SO₄>NSA>H₂SO₃,吸附过程熵增加.以D301R弱碱性树脂为吸附剂,可有效地实现三者的分离.     

Effect of temperature on sorption of metals by silica-supported 2-(aminomethyl)pyridine. Part II: Sorption dynamics

The effect of temperature has been studied on metal-binding rates and dynamic column separation behavior of an adsorbent containing 2-(aminomethyl)pyridine groups supported on silica–polyamine composite. Binding kinetics of H₂SO₄ as well as copper and nickel sulfates has been measured by batch experiments at temperatures between 25 and 90 °C using synthetic sulfate solutions. The data were correlated with the non-ideal adsorption (NICA) model and a diffusion model of porous particles. The estimated model parameters were utilized in a dynamic column model to calculate the break-through curves obtained with the synthetic metal sulfate solutions and a concentrated ZnSO₄ process solution.The adsorption rate of sulfuric acid and metal sulfates is controlled by pore diffusion and increasing temperature markedly increases the sorption rate. The experimental batch uptake curves can be well correlated with the proposed diffusion model and with constant diffusion coefficients. The estimated activation energies of pore diffusion are about 9 and 20 kJ/mol for the acid and the metals, respectively. In column separation, increasing temperature substantially improves copper removal from the ZnSO₄ process solution. The improvement is predominantly due to enhanced intra-particle mass transport. The effect is further amplified by marked decrease in viscosity of the feed solution.     

Designing Wet Scrubbers for SO2 Absorption into Fairly Concentrated Sulfuric Acid Solutions Containing Hydrogen Peroxide

Absorption of SO₂, diluted with nitrogen up to concentrations of 500 Pa, was performed at 20 °C and 1 atm, with water and sulfuric acid solutions containing hydrogen peroxide in two different contactors: a packed column and a cable scrubber. The absorption rate was determined for various SO₂ partial pressures, as well as different concentrations of sulfuric acid (up to 40 wt %) and of hydrogen peroxide in the scrubbing liquid. It was found that the SO₂ absorption rate increases with the hydrogen peroxide concentration, and decreases as the acidity of the scrubbing liquid increases. Taking into account hydrodynamic and mass transfer characteristics of the packing for both scrubbers, a practical enhancement factor depending on the liquid phase H₂SO₄ and H₂O₂ contents, was deduced from semi‐continuous tests. As a good concordance was observed between results determined for both contactors, a single correlation is proposed, allowing the computation of this kinetic factor for quite simple simulation or design of SO₂ scrubbers, provided the gas and liquid phase mass transfer coefficients k_Ga and k_La are known.     

Dynamic rheological properties and microstructures of liquid-crystalline poly(<Emphasis Type="Italic">p</Emphasis>-phenyleneterephthalamide) solutions in the presence of single-walled carbon nanotubes

The rheological properties and microstructures of both poly(p-phenylene terephthalamide)/sulfuric acid(PPTA/H₂SO₄) and poly(p-phenylene terephthalamide)/ single-walled carbon nanotubes/sulfuric acid (PPTA/SWNT/H₂SO₄) dopes were investigated with flat plate rotational rheometer, polarized optical microscope and differential scan calorimeter. The results showed that, the two types of dopes presented typical shear thinning behaviour even at low frequencies, at various temperatures as well as at all polymer concentrations, and that the relationships between complex viscosity and freqency and between zero shear viscosity and weight average molecular weight implied the tight PPTA chain contacts, somewhat the feature of flexible polymer entanglements. The protonation due to concentrated sulfuric acid allowed SWNT to be well dispersed in PPTA/SWNT/H₂SO₄ dopes. At the concentrations of SWNT, approximately over 0.2 wt%, a novel type of single phase nematic liquid crystal was formed. The dopes can be used to fabricate high performance fibers by dry-jet wet spinning process.     

Study on Industrial Scale Chromatographic Separation Methods of Galactose from Biomass Hydrolysates

Galactose is an aldohexose, which has commercial uses in the pharmaceutical and food industries. Since monomeric galactose is not a freely occurring compound, it must be produced from galactose‐containing hydrolysates. This paper reports the results of experimental studies of the chromatographic separation of galactose in aqueous solutions by ion exchange resins on an industrial scale. Until now, galactose has only been determined from various solutions by liquid chromatography (HPLC) on an analytical scale. Chromatographic separation of galactose from carbohydrate mixtures was studied with strong acid cation exchange resins in Na⁺, Ca²⁺ forms and strong base anion exchange resin in SO₄^2– form. The feed solutions were hydrolysates from three possible galactose sources: lactose, gum arabic and hemicellulose in spent sulfite liquor. The main monosaccharide impurities in these raw materials were glucose, arabinose, and xylose. It was demonstrated that large scale liquid chromatography can be used effectively for galactose separation from complex carbohydrate mixtures such as plant hydrolysates as well as lactose hydrolysate.     

Solid‐Liquid Extraction of Terbium from Phosphoric Acid Medium using Bifunctional Phosphinic Acid Resin,Tulsion CH‐96

Solid‐liquid extraction of terbium from phosphoric acid medium has been studied using the commercially available macroporous bifunctional phosphinic acid resin, Tulsion CH‐96. The parameters studied include equilibration time, acid concentration, amount of resin, metal concentration, temperature, loading, elution, regeneration, and recycling. In the wide range of phosphoric acid concentration 0.01–7.8 M the percent extraction of terbium decreases from 98.9% at 0.01 M to 16.0% at 1 M due to an ion‐exchange mechanism and increases to 36% at 7.8 M due to a coordination mechanism. The percent extraction increases with an increase in weight of the resin from 2.7% at 0.05 g to 80.7% at 1.2 g. Under the studied experimental conditions, the loading of Tulsion CH‐96 for terbium was determined to be 3.52 mg per gram of resin. The percent extraction of terbium increases with the increase in temperature, indicating the endothermic nature of the extraction process. Screening of various eluants suggested 1 M (NH₄)₂CO₃ as the best with an efficiency of 99.8%. The extraction behavior of commonly associated metals with terbium such as yttrium, holmium, erbium, dysprosium, ytterbium, and lutetium has been studied as a function of phosphoric acid concentration to determine the separation factors and possible separation.     

Comparison of rigid divinylbenzene with flexible 1,7‐octadiene crosslinks in acrylic acid resins—effects on kinetics of swelling and loading of heavy metal ions from water

Acrylic acid–1,7‐octadiene resin was synthesized in beaded form by a two‐step process: suspension polymerization of ethylacrylate and 1,7‐octadiene monomers, followed by hydrolysis using either 98% H₂SO₄ or 10 M NaOH. Acrylic acid–divinylbenzene resins were also synthesized by the same process for the purpose of comparing a rigid divinylbenzene with a flexible 1,7‐octadiene crosslinkage in the acrylic acid resins. Swelling of the resins in distilled water shows that replacing divinylbenzenes with 1,7‐octadiene makes the resin achieve greater swelling in a significantly shorter time. 1,7‐Octadiene also allowed for an increase in crosslinkage to 20% compared to 4% in the case of divinylbenzene, without compromising the loading rates of toxic heavy metal ions like Pb²⁺, Cu²⁺, and Cr³⁺ from water samples. The acrylic acid–1,7‐octadine resin was found useful for removal of the toxic heavy metal ions from wastewater samples. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41038.     

Removal of linuron from water by natural and activated bentonite

The sorption of linuron on bentonite desiccated at 110°C untreated, and acid‐treated with H₂SO₄ solutions over a concentration range between 0.25 M and 1.00 M from aqueous solution at 25°C has been studied by using batch experiments. In addition, column experiments were carried out with the bentonite sample treated with the 1.00 M H ₂SO₄ solution [B‐A(1.00)] by using two aqueous solutions of linuron of different concentrations (C=4.97 mg dm⁻³ and C=7.63 mg dm⁻³ ). The experimental data points have been fitted to the Langmuir equation in order to calculate the sorption capacities (X_m) of the samples; X_m values range from 0.02 g kg⁻¹ for the untreated bentonite [B‐N] up to 0.20 g kg⁻¹ for the sample acid‐treated with the 1.00 M H₂ SO₄ solution. The removal efficiency (R ) has also been calculated; R values ranging from 15.86% for the [B‐N] sample up to 41.54% for [B‐A(1.00)]. The batch experiments show that the acid‐treated bentonite is more effective than the natural bentonite in relation to sorption of linuron. The column experiments show that the B‐A(1.00) sample might be reasonably used in removing linuron, the column efficiency increasing from 61.8% for the C=7.63 mg dm⁻³ aqueous solution of linuron up to 77.6% for the C=4.97 mg dm⁻³ one. © 1999 Society of Chemical Industry     

Adsorption of SO2 on Activated Carbon for Low Gas Concentrations

Adsorption experiments of SO₂ on activated carbon has been carried out for low concentrations (about 100 ppm) at room temperature (15 to 33 °C) with varying humidity in the air. The breakthrough curves show that at high relative humidity or relative higher SO₂ concentration, the load capacity increases with respect to temperature. The humidity of the air is also of benefit to the load capacity of SO₂. When an adsorption process is interrupted and the activated carbon is kept closed for a while, the SO₂ concentration at the exit of a fixed‐bed adsorber is similar to that of the fresh activated carbon and begins at a very low value. It appears that the sorption potential has been refreshed after the storage period. Analysis of desorption experiments by simultaneous thermal analysis combined with mass spectrometry (MS) after loading, shows that the physisorbed SO₂ and H₂O are desorbed at low temperatures. At higher temperatures, the MS peak of SO₂ and H₂O occur at the same time. Compared with desorption immediately after loading, after one day, the desorption peak due to the physisorbed SO₂ disappears. From this, it can be concluded that the refreshment of the loading capacity of the activated carbon after storage is mainly due to a change in the nature of the SO₂ from a physisorbed state to a chemisorbed form. The same mechanism leads to a continuous refreshment of the sorption potential by means of a chemical reaction during the adsorption process.     

Ion‐Exchange Separation of Pu from Macro Concentration of Th in HNO3 Medium

Abstract

Sorption behavior of Th and Pu from anion‐ as well as cation‐exchange resin was investigated from nitric acid medium by both batch and column methods. The anion‐exchange studies involved anionic nitrate complexes of Pu⁴⁺ and Th⁴⁺ sorbed onto DOWEX 1x4 resin (50–100 mesh), and the cation‐exchange studies involved the sorption of Pu³⁺ and Th⁴⁺ onto BIORAD AG 50Wx8 (50–100 mesh) or DOWEX 50Wx4 (50–100 mesh) resin. The batch data gave a separation factor (K _d,Pu/K _d,Th) of 22 for the anion‐exchange method and 0.017 for the cation‐exchange method at 3 and 2 M HNO₃, respectively. A two‐stage ion‐exchange separation method was developed for the quantitative separation of Pu (8 g/L) from a macro amount of Th (200 g/L) in nitric acid medium. The first step involved the quantitative sorption of plutonium from the mixture while about 90% of Th could be washed in 6 column volumes. The plutonium, eluted (as Pu³⁺) using 0.5 M HNO₃ + 0.2 M hydrazinium nitrate (HN) + 0.2 M hydroxyl ammonium nitrate (HAN), and the residual (～10%) Th were subsequently loaded onto a cation‐exchange column in the second step. Greater than 99% Pu was recovered with 2 M HNO₃ (in ～8 column volumes) containing 0.2 M HN + 0.2 M HAN. The final elution of thorium from the cation‐exchange column was achieved in about 6 column volumes of 1 M α‐hydroxy isobutyric acid. A (Pu, Th)O₂ fuel scrap sample was dissolved in 16 M HNO₃ containing 0.005 M HF and was used subsequently as the feed for the anion‐exchange column. The eluted Pu was subsequently loaded onto a cation‐exchange column for final purification. The recovery of plutonium and thorium was found to be >99% and >98%, respectively, while the respective decontamination factors were estimated to be 215 and 292.     

Effect of different acids during the synthesis of urea-formaldehyde adhesives and the mechanical properties of medium-density fiberboards bonded with them

The characteristics of urea-formaldehyde (UF) adhesives condensed by catalysis with four different acids, namely formic (HCOOH), hydrochloric (HCl), phosphoric (H₃PO₄), and sulfuric (H₂SO₄) acids, under alkaline–acidic–alkaline conditions at a molar ratio F/U = 1.12 were studied. The thermal curing properties of UF adhesives catalyzed with acid were characterized by differential scanning calorimetry at 10 °C/min heating rate. The resin structure examined by ¹³C-NMR spectroscopy showed that the resin catalyzed with HCl had a lower proportion of methylol groups, resulting in a lower level of formaldehyde emission. It was interesting to note that HCOOH resulted in the best overall mechanical properties of the medium-density fiberboard (MDF) panels. The HCl catalyst resulted in the poorest performance, providing the lowest internal bond strength, modulus of elasticity, and thickness swelling, with the exception of the free formaldehyde content. The resin catalyzed with H₂SO₄ had the highest free formaldehyde and the highest formaldehyde emission. H₂SO₄ and H₃PO₄ resulted in MDF mechanical properties relatively lower than for HCOOH. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47256.     

Trickle‐bed scrubbing of flue gas SO2 using non‐aqueous solvents

Experiments were carried out on the performance of several ketone solvents for the scrubbing of dilute SO₂ from a gas stream and its conversion to sulfuric acid in a trickle‐bed reactor packed with activated carbon. Using a bench‐scale trickle bed packed with a structured packing based on Sulzer static mixers coated with Centaur^TM activated carbon and a Teflon binder, measurements of SO₂ removal, conversion to acid and catalyst productivity showed that all were considerably greater than levels achieved with water flushing. The combination of Teflon‐coated Centaur activated carbon with a non‐aqueous solvent as the flushing agent provided from 10 to 100 times higher catalyst productivity than those obtained with water alone and other activated carbons. Also, the productivities obtained by this combination were up to 40 times higher than the productivity of typical vanadium pentoxide catalyst operating at 350°C to 400°C.     

SULFURIC ACID RECOVERY THROUGH SOLVENT AIDED DECOMPOSITION OF AMMONIUM SULFATE.

A process for the recovery of sulfuric acid through anmonium sulfate (I) is described. This process is based on extraction-aided disproportionation of anmonium hydrogen sulfate to ammonium sulfate and sulfuric acid. Acid-base couple solvents were found to be more suitable for this process than oxygenated solvents as they can operate at higher temperatures and concentrations. A solvent composed of 0.50M methyl tricaprylyl ammonium salt of dinonyl naphthalene sulfonic acid in aromatics-free white spirits, was chosen. Sulfuric acid, at a concentration of about 35%, can be obtained from the H₂SO₄-(NH₄)₂SO₄-H₂O system. This disproportionation may be applied to recover sulfuric acid from gypsum. CaSO₄ is converted in reaction with carbon dioxide, anmonia and water to CaCO₃ and ammonium sulfate, which is thermally decomposed to ammonia and ammonium hydrogen sulfate. The overall process is equivalent to the displacement of H₂SO₄ from CaSO₄. by means of CO₂ and thermal energy.     

Adsorption and desorption behaviors of S-adenosyl-L-methionine in a fixed-bed ion-exchange column

S-adenosyl-L-methionine (SAM) is one of most versatile molecules in nature and has wide medical applications. The ion-exchange separation process of SAM of the extract of yeast cells has many advantages over selective precipitation by picrolonic acid. Experiments of the dynamic column process of SAM on JK110 resin were carried out in a fixed-bed ion-exchange column. The effects of different operation parameters on the adsorption and desorption behaviors of SAM were investigated. The results show that the ion-exchange adsorption of SAM is successfully implemented at 2BV/h, 10 g/L, pH 5.0; the adsorbed SAM in the ion-exchanged bed is efficiently desorbed by 0.2 N H₂SO₄ solution at the flow rate of 2BV/h. According to material balance, the recovery yield of SAM for this ion-exchange process is 90.1%. Finally, this ion-exchange process was successfully scaled up to separate SAM at high yield and purity.     

Dual-Temperature Ion-Exchange Separation of Copper and Zinc by Different Techniques

Abstract

Separation of copper from zinc-containing acidic solutions has been advanced by different techniques of dual-temperature ionexchange fractionation on iminodiacetic resin Amberlite IRC 718. Cycling-zone adsorption and parametric pumping (using single-column as well as double-column set-ups) experiments have been carried out in fixed-bed ion-exchange column. Measurement of equilibrium characteristics of the resin-solution system has shown that separation results from the variation of the ions sorbability with temperature. It has been found that temperature variation leads to reverse of selectivity between copper and hydrogen ions. Cycling-zone adsorption technique has allowed the copper content to be decreased up to 4 times in the resin phase and increased up to 1.7 times in the effluent when carrying out the process at 80 and 20 °C, respectively. The copper concentration has been decreased 4.4 fold after 9 treatment cycles of solution aliquot (15 BV) by single-column mode of the parametric pumping method. Two steps of the fractionation process (loading and elution) have been performed by continuous mode of operation in two counter-current columns. Continuous separation is preferred over fixed-bed column techniques. The steady-state sorption fronts have been formed on both stages of the process due to the reverse of selectivity mentioned above.     

Kinetic studies of hemicellulose hydrolysis of corn stover at atmospheric pressure

The object of this work was to study the xylose production by hydrolysis of corn stover with diluted sulfuric acid at 100 °C. Several concentrations of H₂SO₄ (2%, 4% and 6% w/w) and reaction time (0–300 min) were evaluated. Kinetic parameters of mathematical models for predicting the concentrations of xylose, glucose and furfural in the hydrolysates were found. Optimal conditions for hydrolysis were 5.5% H₂SO₄ at 100 °C for 60 min; under these conditions, 86.7% of xylose yield and 2.82 g/g selectivity were attained, leading to liquors containing up to 18.73 g/l xylose, 6.64 g/l glucose and 0.63 g/l furfural. The models could be successfully used to predict the concentrations of xylose, glucose and furfural within 0–300 min under experimental acid concentrations. Furthermore, the hydrolysis process of corn stover using dilute acid could be conceived as the first stage of an integrated strategy for corn stover utilization.