Saturated Resin Research Articles

Efficient removal of nitrophenol by magnetic ion exchange resins: Role of nitrophenol functional groups based on characterisation, DFT calculations and site energy distributions

The diverse locations of functional groups on different nitrophenol cause uncertainty concerning the removal efficiency and mechanisms of nitrophenol. Adsorption behavior and mechanisms of nitrophenol pollutants (2-nitrophenol (ONP) and 4-nitrophenol (PNP)) on magnetic ion exchange (MIEX) resin were investigated by a combination method of characterization, DFT calculations, and site energy analysis. The results showed pore filling, hydrophobicity, hydrogen bonding, van der Waals forces, π-π conjugation, ion exchange, and electrostatic attraction were included in the removal mechanisms. Solution pH influenced the adsorption mechanism by inducing electrostatic attraction, hydrogen bonding and ion exchange. DFT calculations found that hydrogen bonding was the dominant action among the removal mechanisms for the nitrophenol existing in the form of a molecular state. But distinguished from the removal of PNP by the interaction of hydrogen bonds (O⋯H-N) between the –NO2 in PNP and the –NH-CO– group in MIEX resin, the ONP was mainly removed by hydrogen bonds (H⋯O-C) between the –OH functional group in ONP and the –COOH functional group in MIEX resin. However, the ionic nitrophenol pollutants were mainly removed through electrostatic attraction and ion exchange. Increasing resin dosage facilitated the removal of nitrophenol. Humic acid demonstrated little effect. Sulfate ions showed the most severe inhibition on the removal of nitrophenol. Equilibrium was achieved after 60 min. The adsorption process was well described using the Sips isotherm. The main rate-limiting step was liquid film diffusion. Site energy analysis found that the affinity of PNP for MIEX resin was higher, and the removal of PNP was more susceptible to temperature compared to ONP. A 1.0 % sodium chloride could effectively regenerate the saturated resin, and the adsorption efficacy did not decrease significantly after four adsorption–desorption cycles. Therefore, MIEX resin has a good potential for the control of nitrophenol in polluted water sources.

The new concept of MIEX® resin dose categories. swelling effect, reactor steady-state balance, and nom removal process control

The use of powdered adsorbents for water purification has many advantages and one major drawback – lack of regeneration due to difficulty in separating powdered particles. This weakness is attempted to be broken by powdered magnetic adsorbents, in particular magnetic ion exchange resins, used to remove natural organic matter (NOM) from water. In this water treatment process, NOM removal is controlled by the adsorbent content in the reactor (adsorbent dose) and the degree of its saturation. The control over the dose and saturation is done by mutual relations between the regenerated resin stream directed to the reactor and the saturated resin stream received from the reactor. An obstacle in balancing these streams is a variable volume of the adsorbent resulting from its varied swelling, depending on the features of the solution and saturation of the adsorbent. For this reason, it was proposed to distinguish new resin dose and content categories adequate to these changes, the use of which allows full control of both streams. Thus, the reactor feed stream was associated with relative fresh resin content (RRC) and relative fresh resin dose (RRD), which indicate the volume occupied by the regenerated adsorbent in the solution of water during purification. However, the stream received from the reactor was associated with saturated resin content (SRC) and saturated resin dose (SRD), which indicate the volume occupied by saturated adsorbent in the solution of water under treatment. In turn, these two categories of contents/doses are related to the swelling degree (hSR). Another role was assigned to the third dose category, which is absolute fresh resin dose (ARD), referring to the volume occupied by the regenerated adsorbent in the solution of demineralized water. Thanks to two key features with reference properties (demineralized water, regenerated adsorbent), ARD allows one to transfer laboratory results to practice and to compare the results of various research. The resin loss factor described by the ηLS indicator was also included in this structure.

Disposal of MIEX desorbent at high salinity by ZVI/H2O2 Fenton-like system: Optimization, performance and mechanisms

Magnetic ion exchange resin (MIEX) pretreatment has been widely used to enhance the performance of waterworks, but the high-salinity organic desorbent produced during the resin regeneration is difficult to be safely disposed of. The present study aimed to investigate the removal of DOM and retention of salts from MIEX desorbent via zero-valent iron (ZVI)-assisted Fenton reaction. ZVI/H2O2 mediated Fenton reaction was further validated by various analytical approaches such as 3D-EEM, Molecular weight distribution, Zeta potential, size, dissolution of iron ions, etc. In batch experiments, 73.26% reduction of DOC and 97.66% of UV254 were achieved in 40 min at optimal H2O2 concentration (20 mM), 2 g/L dose of ZVI, and pH of 3, respectively. The removal of organics was ascribed to the direct oxidation of ZVI/H2O2 and flocculation of the iron released during the oxidation. It should be noted that the high concentration of Cl- in system favored the organic removal and its enhanced performance lied in the production and oxidation of HOCl/OCl-. The treated liquid can be reused to regenerate the saturated resin with only a small amount of salt supplementation to obtain a similar recovery performance to that of a freshly configured 10% NaCl solution. Moreover, the retrieval and utilization of ZVI particles and other properties of MIEX desorbent after ZVI/H2O2 treatment were all promising and up to the mark: after four reuses, the mineralization of organic matter differs by 8.81% from the first time, which could be compensated by supplying new ZVI. This research will facilitate the recycling of resin desorbate and expand the market for MIEX applications.

Ultra-high compressive strength of 3D woven spacer composites with bulked glass fiber and saturated resin absorption

Three-dimensional woven spacer composites (3DWSCs) have a great potential to applied in aerospace or transportation fields due to their high strength-to-weight and stiffness-to-weight ratios, with excellent skin-core debonding resistance. Among these properties, the compressive strength of the 3DWSCs which is most critical, and still needs to be improved to meet the highly requirements in practical applications. In this study, we designed and manufactured 3DWSCs with highly enhanced compressive strength and energy absorption by adopting bulked glass fibers (BGFs) as pile yarns to weave its core layer to absorb more epoxy resin. Consequently, the specific compressive strength of 3DWSCs woven by BGFs as pile yarns with saturated epoxy resin absorption was 52.54 MPa g−1 cm3, 180% higher than that of the 3DWSCs woven by regular glass fiber (RGFs). Furthermore, the work of fracture of 3DWSCs woven by BGFs as pile yarns with saturated epoxy resin absorption was 14.82 N m, which enhanced 474% compared with that of 3DWSCs woven by RGFs. The failure cross sections depicted multiple brittle fractures of the pile yarns for both composites under compression, which caused multiple peaks in their stress–strain curves.

Plastic waste as a valuable resource: strategy to remove heavy metals from wastewater in bench scale application.

Single-use plastic waste is gradually considered a potential material for circular economy. Ion exchange resin obtained from polystyrene waste by sulfonating with H2SO4 was used for heavy metal removal from electroplating wastewater. Batch mode experiments of Cu2+, Zn2+, and Cd2+ were carried out to determine effect of pH, initial concentration, equilibrium time, and the isotherm and kinetic parameters; the stability of the resin in continuous operation was then evaluated. Finally, the longevity of the resin after being exhausted was explored. The results indicated that at pH 6, a pseudo-second-order kinetic model was applicable to describe adsorption of studied heavy metals by sulfonated polystyrene with adsorption capacities of 7.48mg Cu2+/g, 7.23mg Zn2+/g, and 6.50mg Cd2+/g, respectively. Moreover, the ion exchange process between sulfonated polystyrene resin and Cu2+, Zn2+, Cd2+ ions followed the Langmuir isotherm adsorption model with R2 higher than 96%. The continuous fixed-bed column in conditions of a sulfonated polystyrene mass of 500g, and a flow rate of 2.2L/h was investigated for an influent solution with known initial concentration of 20mg/L. Thomas and Yoon-Nelson models were tested with regression analysis. When being exhausted, the sulfonated polystyrene was regenerated by NaCl in 10min with ratio 5mL of NaCl 2M per 1g saturated resins. After 4 times regeneration, the heavy metal removal efficiency of sulfonated polystyrene was reduced to 50%. These aforementioned results can figure out that by sulfonating polystyrene waste to synthesize ion exchanging materials, this method is technically efficient and environmentally friendly to achieve sustainability.

Adsorption of Acid Orange and Reactive Red by DK110 Loaded Ionic Liquid

AbstractWastewater treatment has always been a topic of concern. Adsorption is one of the commonly‐used methods to treat the dye wastewater. In this work, epichlorohydrin and N‐methylimidazole based ionic liquid were bonded to DK110 resin to synthesize a modified resin (ILDK110) loaded with an ionic liquid. Then infrared spectroscopy and thermogravimetric analysis were used to characterize the successful synthesis of ILDK110. The absorption functions of modified resins on reactive red and acid orange under different temperatures, dye concentrations and pH were investigated. The experimental results show that the adsorption amount of ILDK110 increases with the rise of temperature. At 35 °C, the adsorption amount of acidic orange and reactive red reaches 109.45 mg/g and 111.94 mg/g respectively. The pH has little effect on the amount of adsorption. In the whole adsorption process, the adsorption of reactive red and acid orange by ILDK110 was more consistent with Langmuir isothermal model. The adsorption of acid orange is suitable to be described by the first‐order kinetic equation, while the adsorption of reactive red is more suitable by the description of the second‐order kinetic equation. Under experimental conditions, the removal rates of the modified resin on both the two dyes can reach over 99 %. Furthermore, after adsorption, the saturated resin is easy to be eluted with dilute hydrochloric acid solution, and the elution rate is more than 99 %.

Study of tetracycline removal and saturated resin regenerated by dielectric barrier discharge plasma

The wastewater produced by the large-scale usage of antibiotics worldwide was more harmful to the ecological environment and human health. In the research, the coupling technology of ‘adsorption-plasma regeneration’ was taken to treat tetracycline in aqueous solution. The pollutants were adsorbed by the resins firstly and then regenerated ectopically by dielectric barrier discharge plasma. The discharge parameters, such as discharge voltage and frequency were researched to achieve the optimal regeneration efficiency and energy efficiency. Meanwhile, the analyses of the surface functional groups and microstructure were also investigated. After the five ‘adsorption-regeneration’ processes, the results showed that the optimal discharge parameters of voltage and frequency were 20 kV and 1 kHz, respectively. The regeneration efficiency and energy efficiency were above 80% and 115 g kW−1·h−1, respectively. The tetracycline adsorption by virgin resin and regenerated resin nearly followed pseudo-second order kinetics, and there was no fatal damage to the surface characteristics and physicochemical properties of the resins through the multiple plasma regeneration processes. Finally, according to the intra-particle diffusion model and the degradation products detected by GC-MS, the adsorption and degradation mechanisms of tetracycline were deduced.

Enhancing bio-hydrogen production from food waste in single-stage hybrid dark-photo fermentation by addition of two waste materials (exhausted resin and biochar)

Bio-hydrogen production from organic wastes is considered as one of the most promising alternatives for sustainable, green energy production. In this study, the effect of addition of Ca- and Mg-saturated resin and phosphate-laden biochar on single-stage hybrid dark-photo hydrogen fermentation from food waste was investigated. In the first step, fermentation was performed using different amounts of Ca- and Mg-saturated resin ranging from 2.5 to 20 g l-1 to analyze the effect of released calcium and magnesium on both the H2 production rate and the system pH. The addition of 5 g l-1 saturated resin resulted in an increase of hydrogen yield from 101.60 ± 2.4 to 164.4 ± 2.6 ml H2g−1 VS, and at the same time it prevented pH drop and improved bacterial function. In the second step, 5 g l-1 saturated resin combined with various amounts of phosphate-laden biochar were added to the reactor. The maximum accumulated hydrogen production (3130 ± 16.8 ml) and hydrogen yield (197.15 ± 2.9 mlg−1VS) was observed when 5 g l-1 resin and 0.5 g l-1 biochar was used. This corresponds to 94% increase in the yield compared with the control. The analysis of the fermentation products indicated that butyrate and acetate were the major by-products during hydrogen production. Moreover, the optimum concentrations of resin and biochar served to facilitate substrate degradation and shorten the lag phase from 8.19 ± 0.4 to 4.79 ± 0.5 h. Thus, the application of Ca- and Mg-saturated resin and phosphate-laden biochar in a single-stage hybrid dark-photo fermentation process enhanced the efficiency of the conversion of organic waste to hydrogen while maintaining the stability of the process.

Performances of novel chelating ion exchange resins for boron and arsenic removal from saline geothermal water using adsorption-membrane filtration hybrid process

The aim of this study is to investigate the performances of new N-methyl-D-glucamine functionalized resins revealing gel (1JW), expanded gel (2JW) and epidermal-like structure (2PTN) for simultaneous removal of boron and arsenic from saline geothermal water by means of adsorption-membrane filtration hybrid process. The effects of adsorbent concentration and resin replacement rate were particularly studied for boron removal from geothermal water. Boron removal with 1JW resin increased from 66% to 86% by doubling the resin concentration while the respective values found for 2PTN resin were 61% and 73%. In the case of the microporous 2PTN resin, due to its epidermal-like structure, the efficiency of the hybrid process was improved by increasing the replacement rate of fresh and saturated resins. Unlike the 2JW resin as the most efficient resin for boron removal among novel resins, the maximum arsenic removal of 35.8% was obtained by the 1JW resin using a resin concentration of 4 g/L. The Dowex XUS 43594.00 resin exhibited lower arsenic removal of 21.5% than 2PTN (4 g/L) and 2JW (2 g/L) giving arsenic removals of 22.4% and 28.8%, respectively.

Removal of legacy PFAS and other fluorotelomers: Optimized regeneration strategies in DOM-rich waters

We present the first study investigating optimized regeneration strategies for anionic ion exchange (IX) resins during the removal of persistent per- and poly-fluoroalkyl substances (PFAS, including GenX) from surface and treated wastewater effluents. IX regeneration studies are of critical importance from environmental perspectives. Specifically, the knowledge is essential for water utilities who presently operate IX (for PFAS removal) in a single use-and-dispose mode. In this study, legacy PFAS such as PFOA/PFOS were tested along with other harmful short-chained PFAS (PFBA/PFBS) and other toxic perfluorinated substitutes (GenX). Studies were performed on synthetic water (spiked with Suwannee River Natural Organic Matter (SRNOM), Fulvic Acid (SRFA) and Humic Acid (SRHA)), surface water, and wastewater effluents, and the regeneration was performed in batch stirred reactors. The resin service life with and without regeneration was investigated in the presence of background organic matter. In ultra-pure waters, all PFAS (C0 ∼10 μg/L, concentrations similar to that of natural waters) were effectively removed for >100,000 Bed Volume (BV) of operation. This was reduced to ∼23,500 BV in the presence of SRNOM (C0 = 5 mg C/L), 20,500 BV in SRFA and 8500 BV in SRHA, after which the saturated resins required regeneration. More importantly, all resin breakthrough (PFAS> 70 ng/L) corresponded to > 90% resin site saturation (in meqs), an essential information for optimizing IX loading. The competitive dissolved organic matter (DOM) fractions were estimated to be approximately 5–9% of the initial DOC, as estimated by the IAST-EBC model. Finally, it was identified that IX regeneration efficiency improved with increasing brine contact time but effectiveness plateaued for brine concentrations above 10% (W/V). Nonetheless, a regeneration with 10% NaCl solution with a contact time of 2 h was found to be optimal for IX operations in synthetic and natural waters. Therefore, this study provides key knowledge essential for the scientific community and the water industry on optimizing IX operational parameters for DOM and PFAS removal and would be highly valuable for systems which presently operate IX in a use-and-dispose mode.

Study of the possibility of molybdenum recovery from sulfate solutions on the anionite Lewatit MP62W5

This article presents the results of a study of sorption extraction of molybdenum from sulfate solutions obtained by leaching black-shale ores of Big Karatau. For the extraction of molybdenum was used the method of ion exchange weakly basic anion exchange resin Lewatit MP62W5. The study determined the optimal conditions for the sorption and desorption processes of molybdenum, which included factors such as pH, the duration of the process and the concentration of the necessary reagents. To study the optimal parameters of sorption extraction of molybdenum, the same anion-exchange resin Lewatit MP62W5 was used at a concentration of 0.073 g/l of molybdenum in initial solutions. Application of this anionite for 48 hours during the sorption process and increasing the pH to 5.5 leads to sorption of more than 88 % of the molybdenum from the solution. A solution of ammonium sulfate was used for desorption of molybdenum from saturated resins. It was found that the optimal duration of the molybdenum desorption process is 4 hours at a concentration of (NH4)2SO4 150 g/l. The degree of desorption in this case was 93-94 %

Improving the washing and desorption of tungsten-adsorbed weak base resin

The adsorption of tungsten by a macroporous weak base resin had been widely studied. However, due to the problem of the crystallization of ammonium paratungstate (APT) during the desorption process, there have been few detailed reports on subsequent steps after resin adsorption. The authors found that APT could be dissolved in ammonia in a closed container at 60 °C while achieving a high resin desorption rate, thus solving practical production problems. On this basis, the washing and desorption behavior of the high capacity ion exchange resin D314 was investigated. The lower sodium ion concentration after aeration washing indicated that the aeration washing could obtain a better washing result than the ordinary shaker shaking washing. The longer the washing time and the greater the number of washing times, the better the washing effect. Under the condition of a liquid-solid volume ratio of 1.25:1 and ammonia eluent of 150 g/L, the single desorption rate of saturated resin for 6 h could reach approximately 90% at 60 °C. A desorption rate of >99% could be achieved by multiple desorption. The industrial processes were designed to achieve the normal operation of resin desorption and the washing solution circulation. Backscattering SEM and EDS were applied to study the distributions of sodium and tungsten before and after the saturated resin treatment.

Analysis and processing of sulfate accumulation in uranium hydrometallurgy for acid in-situ leaching

ABSTRACT In order to alleviate the sulfate accumulation in uranium hydrometallurgy process, the sulfate accumulating path was studied and a new elution process was proposed. The eluate composition as a function of eluent volume during the conventional and new elution process was studied. The result showed that pre-elution of saturated resin with 0.5–0.8 BV (bed volume) mother liquor was beneficial to the discharge of accumulated sulfate and could alleviate the accumulation of sulfate. Field tests showed that the new process ensured more stable production and reduced the amount of wastewater. Finally, the mechanism of the pre-elution process was analyzed.

Fe@C carbonized resin for peroxymonosulfate activation and bisphenol S degradation

Aiming at realizing heavy metal recycling and resource utilization, a carbon-based iron catalyst (Fe@C) was synthesized through a resin carbonization method, and adopted for peroxymonosulfate (PMS) activation to remove bisphenol S (BPS), an emerging aquatic contaminant. This study demonstrated that Fe@C exhibited excellent catalytic potential for BPS degradation with a relatively low activation energy (Ea = 29.90 kJ/mol). Kinetic factors affecting the activation performance were thoroughly investigated. The obtained results indicated that Fe@C composite exhibited the superior uniformity with carbon as the framework and granular iron oxide as the coverage. pH increase could cause the inhibitive effect on BPS degradation, while the increasing catalyst loading (0.05–0.5 g/L) was conducive for the catalytic performance of Fe@C, with an optimal PMS concentration at 1.0 mM. A negative influence on BPS degradation was obtained in the presence of SO42−, HCO3− and lower concentration of Cl− (0–20 mM), compared to the promotion at higher concentration of Cl− (>50 mM). Based on the electron spin resonance (ESR) monitoring and radical scavenging results, it is demonstrated that singlet oxygen, a non-radical species, emerged together with ·SO4− and ·OH for BPS degradation. A three-channel catalytic mechanism was verified through typical characterizations. Furthermore, the degradation pathway of BPS was proposed based on the identified intermediates. This novel carbon-based activator for PMS showed notable potential for the waste resin recycling and water decontamination.A novel Fe-based activator carbonized from a saturated resin exhibits excellent performance for Bisphenol S degradation with activated peroxymonosulfate.

Fixed-bed column study for deep removal of copper (II) from simulated cobalt electrolyte using polystyrene-supported 2-aminomethylpyridine chelating resin

This study presents the deep removal of copper (II) from the simulated cobalt electrolyte using fabricated polystyrene-supported 2-aminomethylpyridine chelating resin (PS-AMP) in a fixed-bed. The effects of bed height (7.0–14.0 cm), feed flow rate (4.5–9.0 mL/min), initial copper (II) concentration of the feed (250–1000 mg/L), feed temperature (25–40 °C) and the value of pH (2.0–4.0) on the adsorption process of the PS-AMP resin were investigated. The experimental data showed that the PS-AMP resin can deeply eliminate copper (II) from the simulated cobalt electrolyte. The bed height, feed flow rate, initial copper (II) concentration of the feed, feed temperature and feed pH value which corresponded to the highest removal of copper (II) were 7.0 cm with 35 mm of the column diameter, 4.5 mL/min, 40 °C, 1000 mg/L and 4.0, respectively. The breakthrough capacity, the saturated capacity of the column and the mass ratio of Cu/Co (g/g) in the saturated resin were correspondingly 16.51 mg/g dry resin, 61.72 mg/g dry resin and 37.67 under the optimal experimental conditions. The copper (II) breakthrough curves were fitted by the empirical models of Thomas, Yoon-Nelson and Adam-Bohart, respectively. The Thomas model was found to be the most suitable one for predicting how the concentration of copper (II) in the effluent changes with the adsorption time.

Selective removal of copper from the artificial nickel electrolysis anolyte by a novel chelating resin: batch, column and mechanisms

The selective removal of copper from the artificial nickel electrolysis anolyte was presented with a novel N-octyl-2-aminomethylpyridine-funcionalized chelating resin (abbreviated as CP-AMPO) in this study. In the single system, the adsorption characters of the CP-AMPO resins for Cu2+ and Ni2+ were examined through pH of solution, concentration of metal ions, contact time and temperature. Through the experimental investigation, the isotherm adsorption behavior of Cu2+ fitted well with Langmuir isotherm, whereas the adsorption behavior of Ni2+ followed the Langmuir and the Freundlich isotherm. The kinetic adsorption parameters were proved to be in agreement with the pseudo-second kinetic model, the thermodynamics data demonstrated the adsorption behaviors of Cu2+ and Ni2+ were a spontaneous and endothermic process. Additionally, from the competitive adsorption in the binary systems, the separation factor of copper/nickel reached 2000, indicating higher selectivity for copper over nickel. Moreover, the residual concentration of copper was less than 3 mg/L at the beginning of 8 BV in the artificial nickel electrolysis anolyte after purification and the mass ratio of copper/nickel exceeded 15 in the saturated resins by the dynamic adsorption curves. The results could well satisfy the production requirement of the nickel electro-refining procedure. Therefore, the CP-AMPO resins could be used as the high-performance adsorbent to remove copper from the nickel electrolysis anolyte in the large-scale industry. Consequently, the extended study of the chelating resin on the mechanisms of selective adsorption for copper and nickel was assessed by X-ray photoelectron spectroscopy (XPS).

Geochemistry and origin of heavy oils in the south part of Zhanhua Depression, east China

Abstract The Sanhecun sag, located in the south of the Zhanhua depression, has yielded a significant amount of heavy oil in recent years and is becoming a new exploration focus in the Jiyang sub-basin. Surprisingly, oils in the deep Shahejie formation have higher densities and viscosities than those in the shallow Guantao formation. In this study, geochemical and fluid inclusion analyses of oils from different depths were carried out to clarify their source and the cause of the high densities. Oils in the Shahejie formation, with high contents of resins and asphaltenes (47%–56%), are generated from the Es4 carbonate source rocks that were deposited in a hypersaline environment with a relatively high terrigenous organic matter contribution. Maturity parameters and fluid inclusions show that the oils with low saturated hydrocarbon contents and high resin and asphaltene contents were charged to the Shahejie formation from 29 Ma to 27 Ma, when the source rocks were in the early oil generation window. Although subsequent biodegradation further increased oil density, the main control on the high densities of oils in the Shahejie formation is the nature of the source kerogen. Oils in the shallow Guantao formation can be divided into two groups: a group from Es3 source rocks in the Gunan sag and a second from Es3 and Es4 source rocks in the Bonan sag. They were expelled within the oil generation window and charged the reservoirs between 3 Ma and the present-day. Oils in the Guantao formation have undergone light to heavy biodegradation, ranging from PM levels 2 to 5. With the increase of biodegradation level, saturated hydrocarbon contents gradually decrease from 50% to 22%, while the contents of resins and asphaltenes increase from 28% to 43%. Biodegradation is the primary cause of oil densification in the Guantao formation. Although oils in the Guantao Formation suffered more severe biodegradation, they still have higher contents of saturated hydrocarbons than those in the Shahejie Formation. Source type, maturity and biodegradation thus combine, in different ways, to control the density of heavy oils in the Sanhecun sag. This study also indicates that low mature oils from Es4 carbonate source rocks can charge reservoirs in the southern part of Zhanhua depression before late Oligocene uplift, and low mature oil may be a potential future target in this area.

Processing of Chloride-Containing Productive Solutions after Uranium <i>in situ</i> Leaching by Ion Exchange Method

The uranium sorption from productive solutions containing chloride ions using anion-exchange resins was investigated. The VPAE ion exchanger had the highest values of the sorption capacity, which for the experiment in the static mode was 13 kg U m-3, and for the experiment in the dynamic mode, it was equal to 36 kg U m-3. The use of VPAE anion exchanger will make it possible for uranium recovery from productive solutions with an increased content of chloride without sacrificing the productivity of the sorption plant. The process of saturated resins regeneration by various reagents was investigated. The use of ammonium nitrate solution with sulfuric acid ensured maximum value of uranium recovery from the saturated resin phase (76–97%).

Synthesis of novel silica-supported chelating resin containing tert-butyl 2-picolyamino-N-acetate and its properties for selective adsorption of copper from simulated nickel electrolyte

Abstract A novel silica-supported tert-butyl 2-picolyamino-N-acetate chelating resin (Si-AMPY-1) was successfully synthesized and characterized by elemental analysis, FT-IR, SEM and 13C CP/MAS NMR. The adsorption behaviors of the Si-AMPY-1 resin for Cu(II) and Ni(II) were studied with batch and column methods. The batch experiments indicated that the Si-AMPY-1 resin adsorbed Ni(II) mainly via physisorption, while adsorbed Cu(II) via chemisorption. The column dynamic breakthrough curves revealed that the Si-AMPY-1 resin can efficiently separate Cu(II) from the simulated nickel electrolyte before the breakthrough point. Moreover, the concentration of Cu(II) in the column effluent was decreased to be less than 3 mg/L within the first 43 BV (bed volumes), and the mass ratio of Cu/Ni was 21:1 in the saturated resin, which completely satisfied the industrial requirements of the nickel electrorefining process. Therefore, it was concluded that the Si-AMPY-1 resin can be a promising candidate for the deep removal of Cu(II) from the nickel electrolyte.

Combined technology for gold desorption and ionite regeneration in the conical device

The principal technological scheme of desorption of gold and concomitant metal-impurities from the AM-2B resin phase used for the sorption processing of gold-bearing ores is considered. The proposed combined scheme, involving the use of two traditional, independent from each other methods (thiocyanate and acid-thiourea) for eluting gold, includes desorption of metal impurities from the resin with alkaline solutions of sodium thiocyanate, and gold with sulfuric acid solutions of thiourea. To shorten the duration of the process research of proposed technology was carried out the in a conical apparatus. The results of study of the elution of gold and impurity metals from anionite saturated with the following components, mg/g: Au – 2.6; Cu – 3.5; Zn – 1.3; Ni – 2.9; Co – 3.3, are given. It is shown that the main amount of impurity metals is desorbed from the resin upon its thiocyanate treatment, while the transition of gold into the eluate is negligible. The composition of the eluate in the thiocyanate treatment of saturated resin is, mg/l: Au – 1.7; Cu – 156.0; Zn – 53.0; Ni – 89.0; Co – 102.0. The subsequent treatment of the resin with sulfuric acid solutions of thiourea allows the conversion of 89.32 % of gold from the ion exchanger into the eluate. The resulting eluates containing ~113.0 mg/l gold and a small amount of impurities are target solutions for obtaining a valuable metal. The ion exchanger was regenerated by washing with water and treating with an alkaline solution of sodium to convert it to OH form, since gold sorption is carried out from alkaline cyanide solutions of heap leaching. Residual contents of components in the resin after regeneration were, mg/g: Au – 0.24; Cu – 0.23; Zn – 0.15; Ni – 0.07; Co – 1.29, which allows the successful use of the regenerated resin in the next stage of sorption.