Acid Cation Exchange Research Articles

SYNTHESES OF CATION EXCHANGER WITH MACROPOROSITY AND INVESTIGATING SPECIFIC PROPERTIES

Obtained new strongly acid cation exchanger of macroporous structure based on furfural and dipheniloxide. The optimal amount of the poreformed agent and the molar ratio of the reacting substances were determined. Initially results showed that the polymer matrix using camphor as pore forming agent present a uniform surface with inter-connected pores and adding camphor into the polymer matrix could attain more abundant pores than adding n-heptane. We studied the components, surface and pore structures of the сation exchanger by Fourier transform infrared spectroscopy and scanning electron microscopy (SEM). SEM observations showed that the resin abounded in macropores as large as 7.4 to 22.6 µm both in the surface and the interior. The parameters of the porous structure of the samples are calculated using by equation BET (Brauner., at al.) and the total pore volume of ion exchangers and the radius of submicroscopic capillaries were determined. Finally dates testing prototypes under application conditions, allow us to recommend this cation exchanger for sorption of small radius ions at high speed, as fundamentals upon receipt of ion exchangers, etc.

Surface complexation modelling of chromium(III) ion exchange by a strong cation exchange resin

ABSTRACT In the present study, the removal of chromium(III) from tannery wastewaters by means of ion exchange was investigated to develop a possible recovery. Experimental investigations were carried out using a strongly acidic cation exchange resin, Amberlite 200. The first part of experiments comprised the measurement of the equilibrium of exchange of Cr(III) for H+. For this purpose different amounts of resins were contacted with a fixed volume of chromium-bearing solution. For evaluation of equilibrium parameters, the surface complexation theory was applied. In the second part, chromium(III) species elimination was studied in column experiments with repeated exhaustion and regeneration series. As a result, it was obtained successful results for removal and recovery of chromium with strong cation exchange resin, Amberlite 200.

LC-MS/MS Analysis of Choline Compounds in Japanese-Cultivated Vegetables and Fruits.

Choline is an essential nutrient and choline esters are potential functional food ingredients. We aimed to analyze the choline compound content in 19 cultivated fruits and vegetables and identify those with high acetylcholine content. We utilized liquid chromatography with tandem mass spectrometry to quantify choline compounds according to the standard addition method. Choline compounds were extracted from lyophilized fruit/vegetable powders and passed through a weakly acidic cation exchange column, resulting in a concentrated solution of choline compounds. The compounds were separated on a pentafluorophenyl column and then analyzed using positive mode electrospray ionization. Results showed that acetylcholine and choline were the primary choline compounds in all agricultural products; propionylcholine and butyrylcholine were minor compounds in 17 and 12 agricultural products, respectively. The acetylcholine concentration was 2900-fold higher in eggplants (6.12 mg/100 g fresh weight [FW]) than in other agricultural products (average: 2.11 × 10−3 mg/100 g FW). The concentration of acetylcholine differed only 2-fold between eggplant cultivars with the highest (′Higomurasaki′: 5.53 mg/100 g FW) and lowest (′Onaga nasu′: 2.79 mg/100 g FW) concentrations. The half-life of acetylcholine in eggplants was approximately 16 days, which is longer the shelf life of eggplants. Thus, eggplants can be a good source of acetylcholine.

Heterogeneous PVC cation-exchange membrane synthesis by electrospinning for reverse electrodialysis

AbstractBlue energy (or salinity gradient energy) is a renewable, carbon-neutral, and continuous electrical energy source that can be obtained via the reverse electrodialysis (RED) technique. The viability of this technology strictly depends on the performance and cost of the ion-exchange membranes (IEMs) that compose the RED units; designing the optimal membrane represents a critical challenge due to the complex relation between the performance, properties, and structure of the membrane. In this work, we present our findings on an electrospun cation-exchange membrane based on polyvinyl chloride (PVC), a strongly acidic cation exchange resin, with sodium dodecyl sulfate (SDS) as an additive. We contrast it with a similar membrane produced with the more conventional casting solution technique. The electrospinning technique provides thinner and more homogeneous membranes than those synthesized via casting. The membranes were characterized using morphological, spectroscopic, and analytical methods. Scanning electron microscopy images depicted an intertwined nanofiber mesh within the membrane. We also synthesized the same electrospun cation exchange membrane without SDS; this membrane presented 63% less swelling, and a significant increase in the fixed charge density (CDfix) (119.6 meq/g) when compared to its casting solution counterpart (34 meq/g). This suggests an enhanced permselectivity, and thus better performance for blue energy generation in RED units.

Kinetics and thermodynamics of rebaudioside A adsorption on a strongly acidic cation exchange resin.

To explain the mechanism underlying the adsorption of stevia's polar component rebaudioside A in hydrophilic interaction liquid chromatography mode, the characteristics of rebaudioside A adsorption on various resins in an organic-solvent-rich system were studied. Among the tested resins, the strongly acidic cation resin FPC11 showed the best adsorption behavior for rebaudioside A. The factors affecting the adsorption kinetics of the resin for rebaudioside A are discussed. The results showed that the pseudo-second-order reaction model and intra-particle diffusion model best described the adsorption kinetics of rebaudioside A on the resin. The adsorption rate was controlled by physical sorption, mainly via electron sharing or electron transfer between the adsorbent and the adsorbate. The adsorption process with multiple stages involved weak initial adsorption behavior. Thermodynamic studies showed that the adsorption of rebaudioside A on the resin was not an ideal monolayer adsorption, but mutual adsorption effects between the adsorbates. The adsorption was a spontaneous, entropy-increasing endothermic process. The synergistic effect of hydrogen bonding and ion-dipole was a possible driving force.

Electro-assisted regeneration of pH-sensitive ion exchangers for sustainable phosphate removal and recovery

Removal and recovery of phosphate from wastewater can minimize deleterious environmental impacts and supplement fertilizer supply. Hybrid anion exchangers (HAIX, with doped ferric oxide nanoparticles (FeOnp)) can remove phosphate from complex wastewaters and recover concentrated phosphate solutions. In this study, we integrate HAIX with a weak acid cation exchanger (WAC) to enrich phosphate and calcium in mild regenerants and precipitate both elements for recovery. We demonstrated an electro-assisted regeneration approach to avoid strong acid and base input. Based on demonstrated pH sensitivities of both materials, electrochemically produced mild electrolytes (pH 3 and pH 11), which are 100–1000 times less concentrated than typical regenerants, preserved 80% WAC and 50% HAIX capacities over five batch adsorption-regeneration cycles. FeOnp in HAIX facilitated regeneration due to pH sensitivity and their likely distribution on the resin particle surface, which reduced intraparticle diffusion path length. In column tests, repeatable phosphate removal (> 95%) from synthetic wastewater (3 mg P/L) was achieved with 20 kWh/kg P specific energy consumption. After removal, a similar 50% HAIX regeneration efficiency as batch experiments was achieved. In spent regenerant, more than 95% phosphorus was recovered as hydroxyapatite. This novel approach enhances ion exchange by minimizing chemical inputs.

Technology of the comprehensive desalination of wastewater from mines

The issue of desalination is relevant for many countries of the world; the most promising technology for demineralization appears to be membrane technology. The stabilizing treatment of water before feeding it to the membrane filters involved the ion exchange softening of the solution based on the weakly acidic cation exchanger DOWEX MAC-3 in the H + and Na + forms. This makes it possible to improve the efficiency of baromembrane desalination and the service time of membranes. The nanofiltration membrane OPMN-P ensures the purification of low mineralized waters from sulfates (by 74–93 %) and hardness ions (67–90 %); at the same time, the membrane has low selectivity in terms of bicarbonate anions and does not retain chlorides. This avoids the accumulation of these in the concentrates at the nanofiltration purification of low mineralized waters. The inverse osmotic membrane Filmtec TW30-1812-50 shows selectivity for sulfates and hardness ions of over 99 %. The selectivity for chlorides is 83–94 % for low mineralized water, and 90–95 % for highly mineralized water. The concentrates contain hardness ions, sulfates, chlorides, and bicarbonate anions in significant concentrations. We have defined conditions for the effective softening of the formed concentrates at the comprehensive treatment by lime and aluminum coagulants. When desalinizing the concentrate of low- and highly mineralized waters, the sulfate concentration decreased to 2.55–6.53 mg-equiv./dm 3 and 3.31–9.02 mg-equiv./dm 3 , respectively. At the same time, the concentration of hardness ions was 3.31–9.02 mg-equiv./dm 3 and 4.20–10.65 mg-equiv./dm 3 . Creating comprehensive technologies for the purification of mineralized waters makes it possible to ensure the proper efficiency of water desalination and to utilize the waste formed with obtaining useful products. That could reduce anthropogenic pressure on the environment and solve the problem of freshwater shortage for people and industry

Three-dimensional graphene-wrapped porous carbon/sulfur composite for cathode of lithium–sulfur battery

Lithium–sulfur battery with high theoretical capacity becomes the subject of recent attention. Its commercial progress is impeded by its poor electrical conductivity and high dissolubility of intermediate products in organic electrolyte. In the present work, we report a novel three-dimensional graphene-wrapped porous carbon (3D-G) to accommodate sulfur, which consists of outside highly stable interconnected graphene-like sheets and inner activated porous carbon. The 3D-G was synthesized from cheap polyacrylic acid cation-exchange resin, which introduces nickel ions as catalysts in the carbonization process, as a cost effective, facile and simple method. This 3D-G showed hierarchical pores: 0.7 nm micropores and macropores, providing a large specific surface area of 1375.08 m2 g−1. Benefiting from this unique structure, the 3D-G performed well as host materials to achieve a high sulfur content (75.4 wt%). Such a 3D-G@S composite exhibits capacity-fading rate as low as 0.28% per cycle over 100 cycles at 0.1 C, and good cyclability at various cycling rates (0.1–1 C).

PRODUCTION OF SULFOCATIONITE BY MODIFICATION OF NATURAL COAL WITH CONCENTRATED SULFURIC ACID

Monitoring the content of rare metals in environmental objects at the level of their maximumpermissible concentrations is an important environmental task. The widely used physicochemical methods do notalways provide a direct solution to this problem because of the influence of the matrix composition of the sample onthe results of the determinations, as well as low concentrations of the determined elements. This article proposes anew modified sulfonated charcoal based on coal from the Shubarkul deposit for sorption of rare metal ions fromwater bodies. Concentrated sulfuric acid (H2SO4) is used as a modifier. The synthesis of new highly permeable crosslinked, sulfonated cation exchangers and their composition, structure by chemical and physical methods wasinvestigated. The static exchange capacity (SЕС) of sulfonated coal was calculated. The article shows an increase inSEC from the concentration used in the modification of H2SO4. During the synthesis, the static exchange capacity ofsulfonated coal increases at 240 min. heating up. The temperature stability of sulfonated coal is higher to (100-120 °)C. Sulfonated coal refers to medium acid cation exchangers, which work effectively at pH 2-14. The resultingsorption materials are recommended for use in treatment plants for the removal of rare metal ions.

Field validation of multifunctional ion exchange process for reverse osmosis pretreatment and phosphate recovery during impaired water reuse

Conventional reverse osmosis (RO) pretreatment hardly achieves multifunctionality for simultaneous membrane scaling prevention and nutrient recovery during impaired water reuse. To address the challenge, we probed a multifunctional ion exchange pretreatment process achieving pH adjustment, calcium and organic compound removal, and phosphate recovery using real impaired surface water. Three types of ion exchangers were integrated in train including a polystyrene strong base anion exchanger (psSBA), a shallow-shell weak acid cation exchanger (SSWAC), and a hybrid anion exchanger (HAIX). The novelty is that SSWAC, which decreased aqueous pH from neutral to ∼ 5 and removed > 70 % calcium, was regenerated by recovered waste CO2 (> 80 % regeneration efficiency) to avoid strong acid regenerants and achieve CO2 utilization and sequestration. The front-positioned psSBA selectively pre-removed hydrophobic ionizable organic compound (HIOC) such as diclofenac at > 80 % removal to reduce HIOC interference on the latter-positioned HAIX. HAIX doped with ferric oxide nanoparticles (FeOnp) enabled selective phosphate removal from complex real impaired water. Over 70 % removal of phosphate and calcium by HAIX and SSWAC reduced calcium phosphate scaling risk and facilitated phosphate recovery as hydroxyapatite from spent regenerants that enriched with calcium and phosphate. We envision this study to facilitate resource recovery in water-nutrient-carbon nexus via engineered multifunctional ion exchange processes.

Influence of the Composition of the Sulfuric Acid Cation Exchanger on the Efficiency of Chromatographic Purification of Petroleum Vanadyl Porphyrins

The development of efficient methods for preconcentration and purification of petroleum metal porphyrins is the necessary condition for further progress of basic and especially applied research concerning the properties of these compounds and their role in oil genesis and maturation. This study deals with chromatographic preparation of high-purity vanadyl porphyrins using a sulfuric acid cation exchanger that can be readily prepared from silica gel and sulfuric acid and is simple in use. At the silica gel : sulfuric acid : water weight ratio of 60 : 15 : 25, the suggested sulfuric acid cation exchanger retains most efficiently nonporphyrin impurities of the asphaltene polar extract, whereas a significant fraction of vanadyl porphyrins (up to ~50%) passes through the chromatographic column virtually without retention with the stationary phase. In contrast to traditional adsorbents, the suggested sulfuric acid cation exchanger allows preparation of spectrally pure vanadyl porphyrins in one chromatographic purification step, thus ensuring the minimal consumption of the eluent and adsorbent. High purity of the vanadyl porphyrins obtained was confirmed by mass-spectrometric and spectroscopic methods of analysis.

Sorption of nickel (II) and manganese (II) ions from aqueous solutions

Mine water from non-ferrous metal deposits is often contaminated with nickel and manganese ions. The entry of these ions, especially nickel, into surface waters and underground aquifers is undesirable since it has a negative effect on living organisms and worsens the condition of drinking water sources. One of the promising methods for selectively extracting nickel ions and obtaining an eluate suitable for further use is sorption by weakly acid cation exchangers with chelate groups of iminodiacetic acid.
 As part of the study, sorption isotherms of nickel and manganese ions by Lewatit MonoPlus TP 207 cation exchanger in mono- and bicomponent systems were obtained. In monocomponent systems, the maximum static exchange capacity (SEC) of the cation exchanger for nickel ions is 952 mmol/dm3, and in bicomponent systems – 741 mmol/dm3; for manganese ions– 71 mmol/dm3 and 49 mmol/dm3, respectively. It is obvious that the studied cation exchanger has a greater capacity for nickel ions than for manganese ions.
 The influence of a temperature increase from 300 to 330 K on the sorption of nickel and manganese ions was established: in monocomponent systems, the maximum degree of extraction of the former increases from 65 to 77 % (SEC from 337 to 399 mmol/dm3), and the latter from 21 to 35 % (SEC – from 140 to 229 mmol/dm3); in bicomponent systems, the extraction of nickel ions increases from 59 to 78 % (SEC – from 307 to 429 mmol/dm3), and manganese ions decreases from 20 to 17 % (SEC – from 164 to 131 mmol/dm3). The predominant increase in the indicators is due to the filling of the sorption centers of the ion-exchange resins, which are energetically unfavorable for the exchange of counterions at a lower temperature.
 The influence of the pH of the solution on sorption was determined: the intensification of the process for nickel ions is observed in the pH range of 8.0-8.5 in a monocomponent solution and 8.0-9.0 in a bicomponent solution, for manganese ions in the range of 8.0-9.5 in both cases. The increase in the degree of extraction of ions and the exchange capacity of the ion exchanger with increasing pH is associated with the appearance of singly charged hydroxocations, dissociation of the functional groups of the sorbent and, to some extent, with the subsequent formation of insoluble forms of nickel and manganese. However, with increasing pH, a decrease in the selectivity of nickel extraction is observed: the ion separation coefficient decreases from 14.0 to 6.0 in the pH range of 6.0-11.0.

Interaction of a Weak Acid Cation Exchange Resin (Dowex Mac 3H) with the Belousov‐Zhabotinsky Reaction and Estimation of Metal Ions

AbstractThe work pertains to the study on direct and indirect interaction of a macroporous weak acid cation exchange resin‐Dowex Mac 3H form with Belousov‐Zhabotinsky (BZ) reaction based on malonic acid‐cerium‐bromate‐sulfuric acid system. In the direct mode, the above reaction was perturbed by adding 10% (w/w) of Dowex Mac 3H at three different time intervals, i. e., before the start of induction period, during the induction period and after the commencement of oscillations. This mode of interaction was studied to investigate the effect of heterogeneity on the dynamics of BZ reaction. The indirect interaction of the resin was studied by interacting the resin individually with the optimized metal catalyst for a particular period of time after which the supernatant was used as initial reagent in the otherwise optimized BZ system. The interaction was monitored with respect to the change in oscillatory parameters before and after loading the resin with metal catalyst. The selectivity of the resin towards cerium and iron (ferroin) was studied through the said BZ reaction using potentiometry as the main technique. It was found that resin is more selective towards ferroin. The selectivity of the resin towards the various metal ions was followed by their estimation using UV‐Visible spectrophotometry. The effect of solvents on the ion exchange capacity (IEC) of the resin was also studied through the BZ reaction. Some solvents increased its IEC while others decreased it. The potentiometric results obtained were validated by spectroscopic findings and electrochemical studies.

Multifunctional ion exchange pretreatment driven by carbon dioxide for enhancing reverse osmosis recovery during impaired water reuse

Reverse osmosis (RO) has been increasingly applied for impaired water reuse in arid areas. However, enhancing RO recovery from scarce water resources is limited by energy demand for overcoming elevated brine osmotic pressure, and membrane scaling caused by concentrated poorly soluble salts. In this study, we present a hybrid ion exchange desalination process (HIX-Desal) as multifunctional RO pretreatment to enhance RO recovery by simultaneously desalinating feed water and removing multiple scale-forming ions (calcium, sulfate, and phosphate). The novelty of HIX-Desal is that carbon dioxide was the sole regenerant for a two-column train containing a hybrid anion exchanger (HAIX, with doped ferric oxide nanoparticles) and a shallow shell weak acid cation exchanger (SSWAC). We probed the desalination abilities of HIX-Desal at both lab and pilot scales using impaired water sources with varying total dissolved solids (TDS), where consistent desalination was achieved at 50–60% TDS reduction. Field tests demonstrated >80% removal of calcium, sulfate, and phosphate simultaneously. System configuration and SSWAC structure, i.e., intraparticle diffusion path length, were demonstrated to govern the HIX-Desal process during desalination and CO2 regeneration cycle. We envision this study to facilitate RO recovery enhancement and upcycling industrial carbon emission.

Fluoride removal from groundwater using Zirconium Impregnated Anion Exchange Resin

Drinking water containing excess fluoride is a major health concern across the globe. The present study reports the feasibility of zirconium impregnated hybrid anion exchange resin (HAIX-Zr) for treating fluoride contaminated groundwater. The HAIX-Zr resin was prepared by impregnating ZrO2 nanoparticles on polymeric anion exchanger resin. Fluoride uptake by HAIX-Zr was quite rapid, 60% removal was obtained within 30 min. Kinetics of fluoride uptake by HAIX-Zr resin followed the pseudo-second-order kinetic model and adsorption data fitted best to Freundlich adsorption isotherm model. Maximum fluoride uptake capacity was observed as 12.0 mg/g. The defluoridation capacity of the resin decreases with increase in solution pH. The co-existing anions like chloride, phosphate, bicarbonate, nitrate, and sulphate at 100 mg/L concentration significantly affected fluoride removal and bicarbonate showed the highest interference. Continuous flow packed bed experiments were performed with real groundwater. To maintain a lower pH, weak acid cation exchange resin (INDION-236) was used before HAIX-Zr. It was observed that reducing the pH of the sample water to 4–4.5, increased the number of treated bed volumes fifteen times. Regeneration of fluoride-containing resin was done by passing 3% NaOH and 3% NaCl solution through an exhausted resin bed. The results revealed that HAIX-Zr can effectively remove fluoride from groundwater.

Исследование возможности использования промышленных стоков для регенерации натрий катионитовых фильтров в процессе водоподготовки

One of the main tasks of environmental protection enterprises is to reduce industrial effluents. Industrial effluents with a content of sodium chloride 24-25% and sodium sulfate 1.5-3.0% are formed at one of the plants. The high content of sodium chloride in the effluent allowed us to make an assumption about the possibility of their use in the regeneration of Na-cation exchanger in the process of water treatment for vapor-vapor cooling of operating metallurgical units. The aim of the work was to determine the feasibility of using industrial salt effluents in the water treatment process while ensuring optimal conditions for the operation of Na-cation exchanger. In the process of water treatment used the method of removing impurities from water - cationization. This method is applied to soften water and is of independent importance in the preparation of additional water for low pressure boilers and make-up water for heating networks, if the source water has low alkalinity. The object of the study is a strongly acidic cation exchanger in the Na-form (Purolite PPC-100Na) designed to soften process water. In the course of the regeneration of cation exchange resin with a sodium sulfate-containing salt solution, the concentration of the latter should be controlled - this is due to the high exchange capacity and the real danger of the formation of the gypsum layer. The volume of spent regeneration solution (OPP) will contain sparingly soluble calcium sulfate and soluble magnesium sulfate. Under certain conditions, most of the calcium sulfate can be separated from the ORP in the form of a suspension of a two-water compound and detached from the solution. Laboratory studies were conducted on the effect of a solution of NaCl salt (24-25%) with an admixture of sodium sulfate (1.5-3.0%) on the total and working exchange capacity of cation exchange resin. In order to reduce the salt background of the regenerated solution, studies were carried out on the use of a 10% NaCl salt solution with an admixture of sodium sulfate (1.5-3.0%) on the static, dynamic and full dynamic working exchange capacity of cation exchange resin (SOE, DOE and PDOE). We used the methods of alkalimetric and complexometric titration to control the capacity value of the cation. It was determined that the numerical values of the DOE and PDOE of the studied cation exchanger during its regeneration with a saline solution of sodium chloride with a content of 1.5-3.0% sodium sulfate vary in the range of 1.96-1.22 and 2.58-1.89 mEq/g dry resin, respectively.

Nickel nanoparticles-loaded three-dimensional porous magnetic graphene-like material for non-enzymatic glucose sensing

Here, we prepared a nickel nanoparticles-loaded three-dimensional porous magnetic graphene-like nanocomposite (NiNPs/3D-PMG) using D113 type macroporous weakly acidic cation exchange resin as the precursor by a simple one-step strategy, which was utilized as a novel electrode modifier for the non-enzymatic electrochemical sensing of glucose. The prepared NiNPs/3D-PMG material was characterized by a series of techniques. In alkaline medium, NiNPs in the nanocomposite modified on electrode surface can be electrochemically transformed to NiOOH, which exhibits high catalytic activity toward glucose oxidation. Benefiting from the large specific surface area of the highly conductive 3D porous graphene-like structure and the catalytic performance of NiOOH, the prepared NiNPs/3D-PMG nanocomposite exhibits prominent electrocatalytic activity toward glucose oxidation. By using a magnetic electrode as the substrate for the immobilization of our NiNPs/3D-PMG with magnetic property, the stability and reusability of the fabricated electrochemical sensor are greatly improved. Under the optimized conditions, a linear amperometric response range from 2 μM to 0.22 mM was obtained, and the detection limit (S/N = 3) was 1 μM. This electrochemical sensor based on the NiNPs/3D-PMG exhibits a rapid response to glucose with high sensitivity, excellent reproducibility and strong anti-interference performance. Furthermore, our sensor has been successfully utilized to detect glucose in human serum with satisfactory results. It provides an effective new method for direct detection of glucose.

Adsorption potential of macroporous Amberlyst-15 for Cd(II) removal from aqueous solutions

The macroporous ion exchange resins are unique and most suitable for the adsorption of heavy metal ions due to their porous three-dimensional structures and large specific surface areas. In the current investigation, a macroporous sulphonic acid cation exchange resin Amberlyst-15 was implemented for the adsorption of Cd (II) using batch adsorption technique to evaluate its removal efficiency. The characterization of resin surface was performed by several techniques: Scanning Electron Microscopy/Energy dispersive x-ray Spectroscopy (SEM/EDS), Thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FT-IR), Brunauer–Emmett–Teller (BET) surface area and Point of zero charge (PZC). The effects of various experimental parameters such as time, temperature, concentration, pH and dosage amount were examined in detail. The optimum pH for maximum uptake of Cd(II) onto the Amberlyst.15 was observed at pH 3 showing the efficient working of resin under highly acidic conditions. The results also proved that Amberlyst-15 showed tremendous adsorption potential toward Cd(II) removal; 99.95% removal within 30 min reaction time and 2.01 mmol g−1 maximum adsorption capacity at 323 K. The adsorption data was well described by Langmuir adsorption isotherm and pseudo second order models. The thermodynamic parameters revealed that the adsorption was endothermic, spontaneous and feasible process with increased randomness at resin surface. The free energy of adsorption (E) (13–15 kJ mol−1) determined from Dubinin-Radushkevitch (D-R) model proved the ion exchange reaction mechanism for Cd(II) adsorption. The experimental results reported herein validate that Amberlyst.15 resin is a promising adsorbent for the enhanced removal of Cd(II) and other toxic metals from contaminated water and waste effluents.

Recycle of vanadium from aluminum slag of ferrovanadium

Vanadium is a rare chemical element and it primarily comes from the by-product of other minerals. In this study, the material source mainly comes from vanadium-rich aluminum slag. This experiment aims to separate vanadium and other impurities, such as aluminum and zirconium. First, the slag was dissolved in the sodium hydroxide solution at pH value 13, and part of the alumina was precipitated. After removing the precipitation, the strong acid cation exchange resin, Dowex® G26, was added to eliminate the remaining impurities. In this procedure, the parameter of reaction time, the mass of ion exchange resin and pH value were supplied. Moreover, the adsorption isotherms described by means of the Langmuir and Freundlich isotherms were used to investigate the ion-exchange behaviors of vanadium. To sum up, this study will provide the best conditions of ion exchange to get high purity about 95% of vanadate.

Adsorption studies of fluoride on weak base anion exchangers and surface modified strong acid cation exchangers in aqueous medium

Adsorption studies of fluoride on weak base anion exchangers and surface modified strong acid cation exchangers in aqueous medium