Sorption Of Molybdenum Research Articles

Adsorption behavior of Mo(VI) from aqueous solutions using tungstate-modified magnetic nanoparticle

A new magnetic nanoparticle modified with sodium tungstate (Mnp-Si-W) was synthesized and employed for the sorption of molybdenum from aqueous solutions. The prepared nanoparticles (Mnp-Si-W) were characterized by different advanced techniques. Different parameters that influenced the adsorption percent of Mo(VI) were investigated using a batch process. Based on a systematic investigation of the adsorption isotherms and kinetics models, Mo(VI) adsorption follows the Langmuir model and pseudo-second-order kinetics. According to the Langmuir isotherm model, the Mnp-Si-W nanoparticles exhibited a maximum adsorption capacity of 182.03 mg g−1 for Mo(VI) at pH 2.0. The effect of competing ions showed that the prepared nanoparticles have a high selectivity for the sorption of molybdenum. Moreover, the effect of some interfering anions on Mo(VI) ion sorption is found in the following order: phosphate < sulfate < chromate. Finally, the nanoparticle (Mnp-Si-W) can be successfully reused five times.

Sorption Of Rare Metal Ions by Ionite Based on Diglycidyl Thiourea and Various Amines

The article studies the process of sorption of molybdenum and vanadium ions on anion exchangers obtained on the basis of thiourea, epichlorohydrin and various amines. Various amines (urea, guanidine, melamine, polyethylene polyamine, ethylenediamine, etc.) are used as substances containing ionic groups. The regularities of ion exchange and the main properties of the tested anionites are given, the influence of the pH of the medium and interfering ions in the process of sorption of molybdenum and vanadium ions are studied. For vanadium, the use of empirical partition relations and of an extended Freundlich equation were tested, with promising results. The objective of this paper is to investigate the use of the pH dependent Freundlich model of Gustafsson et al., for describing vanadate(V) sorption to 26 mineral soils (all having less than 12% organic C), and to discuss the possible use of the model for risk assessments. The kinetic curves of the sorption process, the values of the diffusion coefficients for the initial periods of molybdenum sorption are given. In particular, the distribution coefficient of the radiotracers of 99Mo and 131I as homologs of Sg and Ts using the surface modification of chabazite was investigated as liquid-solid system in the present study. The kinetics of molybdenum sorption was carried out under static conditions from an ammonium molybdate solution with a concentration of 1 g/L for molybdenum ions and at pH 4.5–5. Under the same conditions, molybdenum ions are sorbed much faster by the DGT + M anion exchanger in comparison with AN-2F anion exchangers, in which the diffusion coefficient is much lower. The static exchange capacity (SEC) was determined in industrial solutions in the presence of mineral acids (hydrochloric, sulfuric and nitric), usually contained in them. The obtained kinetic equilibrium parameters of the tested anion exchangers were compared with those of industrial polycondensation anion exchangers, such as AN-2F and AN-1.

Investigation of the sorption method of processing molybdenum-containing raw materials to extract rare metals

The article investigates the sorption method of concentrating rare metals on various sorbents (brands “Purolight”: A-100, A-170, A-172 and BO-020) and determines the optimal conditions for their extraction. It is shown that the extraction of molybdenum on the sorbent “Purolight A-100” was 98%. The proposed sorption mechanism consists in the formation of molybdenum complexes with functional phosphor basics and sulfate groups of sorbents. Sorption of rhenium on the Purolite A-170 sorbent was 93%. Sorption of rhenium on the sorbent BO-020 is described by the Langmuir equation with a maximum static exchange capacity of 94%. Based on the sorption and desorption kinetics of molybdenum and rhenium on various ion-exchange sorbents, it was shown that the sorption of molybdenum and rhenium proceeds most efficiently on low-basic anion exchangers A-100 Mo and A-170, respectively, and after double recleaning of the “rough” rhenium concentrate, ammonium rhenium of qualification was obtained AR-0.

Property and mechanism on sorption of molybdenum from tungstate solution with a porous amine resin

The sustainable development of tungsten and molybdenum resources requires a new clean and recyclable separation technology. This work proposes a recyclable clean separation technology of tungsten and molybdenum with a porous amine resin. The resin was well prepared by assembling amine groups on trioctylamine (TOA) and the porous resin matrix D301 by the dipping method. Here, pH 7.8, temperature 25 °C, and reaction time 240 min was used as optimum condition, resulting in the highest sorption capacity 236 mg g−1, and it has a good cycle performance, exhibiting a retention rate of 90% after five cycles. Experimental spectroscopy combined theoretical calculation confirmed that this sustainable sorption behavior is substantially related to the amine functional groups on the resin. Experimental spectroscopy illustrated that the Cl− ions in the amine resin and the MoS42− ions were subjected to ion exchange. Theoretical investigations further confirm that the sorption site is at the N atoms, the sorption behavior is chemical binding with the binding energy −0.055 Ha, and the bonding method is the s orbit of the N atoms in the amine resin hybridized with the s orbit of the S atoms in the amine resin. Owing to such an excellent performance in the selective sorption of molybdenum from the tungstate solution, the amine resin is greatly promising in the tungsten and molybdenum waste recovery field.

Sorption of Mo (VI) From Nitric Acid Solution Using SM-4 Copolymer Resin Impregnated with CYANEX 923

Sorption of molybdenum (VI) from nitric acid solution by solvent impregnated resin (SIR) technique using bio-beads styrene divinyl benzene copolymer (SM-4) impregnated with tri-alkyl phosphine oxide (CYANEX 923 or CY 923) extractant through batch and column techniques was investigated. The effects of the different parameters affecting the adsorption of Mo (VI) such as shaking time, V/m ratio, nitric acid, extractant, nitrate ion, hydrogen ion and metal ion concentrations as well as temperature were separately investigated. The batch results show that the extracted organic species is HMOO3(NO3).2CY and the average Kex value for Mo(VI) extraction using 30% CYANEX 923/SM-4 system was found to be 4.95 ± 0.2 M−3. The experimental results show that sorption of Mo (VI) obeys Freundlich isotherm. Desorption studies were carried out using different concentrations of stripping agents and maximum desorption was found to be 78% and 83% with 2 M sodium acetate and 0.25 MNaOH, respectively. Breakthrough curves indicate that column performs better with low feed, low flow rate and concentration and high bed height. An application was carried out on Gattar granite to recover Mo (VI) from other metals by applying the optimum experimental conditions of 30% CYANEX 923/SM-4 system and the obtained results indicate the selectivity of the investigated technique for molybdenum recovery from nitric acid solution.

Highly efficient sorption of molybdenum from tungstate solution with modified D301 resin.

The separation of molybdenum (Mo) from tungstate solution is a bottleneck problem in tungsten (W) metallurgy, and it hinders the development of high-purity tungsten materials. In this research, a modified D301 resin was used to adsorb and separate molybdenum from tungstate solution. The maximum sorption capacity (Qe) of modified D301 for MoS42− was found to be 428 mg g−1 and the separation coefficient (β) was 108.9 when the contact time was 4 h and the reaction temperature was 25 °C and the pH value of the tungstate solution was 7.2. The sorption process conforms to Langmuir isotherm models and the quasi-second-order kinetic model. The sorption mechanism was also discussed, which was a single layered spontaneous sorption process. Theoretical calculations infer bonding behavior between the N atom on the resin and the S atom on the MoS42− molecule. The sorption energy is −7.67 eV, which indicated that the sorption process is stable chemical sorption. The desorption experiment showed that more than 90% molybdenum could be desorbed from the loaded resin when the concentration of sodium hydroxide solution was 5 w%. Finally, after three-stage sorption–desorption, almost all molybdenum in the solution was adsorbed, achieving better separation of tungsten and molybdenum.

The effect of anionic impurities on the sorption extraction of molybdenum from leaching solutions

Molybdenum is one of the most important uranium-related metals. In the ores of many deposits, the molybdenum content is comparable to the uranium content. The processing of complex uranium-molybdenum ores is based on the methods of acid and soda autoclave leaching, in which uranium and molybdenum pass into solution. At the present time, the associated extraction of molybdenum by the sorption method has been developed and introduced. In this case, the capacity of ion exchangers with respect to uranium and molybdenum substantially depends on the salt composition of the medium. The aim of this work is to study the sorption of molybdenum from a carbonate leach solution on BD-301G-I anion exchange resin in the presence of the most common anionic impurities in industrial solutions. Studies of the sorption capacity of anion exchange resin with respect to molybdenum were carried out under static conditions with stirring of the solution with the sorbent during eight hours. Sorption of molybdenum was carried out from carbonate solutions with the corresponding given concentrations of impurity components. According to the results of studies, it was found that, according to the strength of the depressing effect, the considered anions arranged in the following row: S2O32- &gt; NO3- &gt; Cl- &gt; SO42- &gt; HCO3- &gt; CO32- &gt; PO43-. The results of this study can be used to further study the sorption of molybdenum from real industrial solutions of carbonate leaching.

Sorption of Molybdenum onto Titanium Hydroxide

Three types of ionic groups with different pKi values were revealed for T-5 sorbent by potentiometric titration: for acid groups, pK1 = 7.5 ± 0.5, pK2 = 10.2 ± 0.5, and pK3 = 11.0 ± 0.2; for base groups, pK4 = 6.5 ± 0.2, pK5 = 4.5 ± 0.2, and pK6 = 2.7 ± 0.2. Thus, titanium hydroxide is an amphoteric ion exchanger. Each exchange group of T-5 sorbent, characterized by its definite pKi value, was assigned to a definite hydroxy group. T-5 and T-52 sorbents exhibit high specificity to Mo in acid and neutral solutions. All the isotherms logCS–logCL are described by the Langmuir equation for the polyfunctional sorbent for at least two exchange sites in both nitric and sulfuric acid solutions, irrespective of the Mo speciation. Two groups of values were obtained and confirmed for T-5 and T-52 sorbents depending on the Mo concentration: kd ≈ 104 mL g–1 at concentrations lower than 10–5 M and kd = 1000–2000 mL g–1 at a concentration of 10–5 M. The exchangeable hydroxy groups in T-5 sorbent exhibit high heat resistance, and even the sorbent calcined at 900°C preserves certain reliably measurable capacity for Mo. For T-5, the capacity for Mo only slightly depends on the solution acidity and composition and is about ~1 mmol g–1.

Application of the liquid-phase polymer-based retention technique to the sorption of molybdenum(VI) and vanadium(V)

This research is focused on molybdate and vanadate removal from aqueous solutions by the liquid-phase polymer-based retention (LPR) technique. In this technique, a cationic water-soluble polymer based on the ammonium quaternary group poly(diallyldimethylammonium chloride), PDDA, was used as a polymeric sorbent, and a regenerated cellulose ultrafiltration membrane was used as a filter. The removal of molybdenum and vanadium using the LPR technique was analyzed by both the washing and enrichment methods. The removal experiments using the washing method were conducted by varying the pH, polymer/metal molar ratio, concentration of metal ions, pressure and presence of interfering ions. In addition, the enrichment method was used to determine the maximum retention capacity of PDDA. The obtained results showed the highest retention capacity of molybdate (100%, using 30 mg/L in the feed) for PDDA at pH 3 and 9. The optimum molar ratio was 20:1 polymer/Mo(VI). The efficient vanadate retention (approximately 90%) was obtained at pH 6 with 10:1 polymer/V(V) molar ratio. The effect of metal concentration on the retention showed a higher retention of Mo(VI) independent of its concentrations. In the case of V(V), the maximum retention was reached when 60 mg/L of vanadium was used in the feed. The enrichment method showed the maximum retention capacities of 370 mg Mo(VI)/g PDDA and 520 mg V(V)/g PDDA. The presence of interfering ions did not affect the retention capacity of PDDA. These results showed that the combination of PDDA with ultrafiltration membranes could represent an alternative method for the removal of molybdate and vanadate from water.

Сорбция ионов молибдена (VI) новыми синтетическими сорбентами

Изучена сорбция ионов молибдена (VI) новыми анионитами на основе 4,4-оксиэтилендиамина и некоторых полиаминов. Установлено, что они обладают высокими сорбционными свойствами по отношению к ионам молибдена. Как показали исследования, синтезированные иониты обладают высокой обменной емкостью – до 11,0 мг-экв·г-1 и, соответственно, повышенной сорбционной способностью. Хорошая устойчивость в агрессивных химических средах (5 н Н2SO4, NaOH) и при температурных воздействиях допускает возможность их использования в различных технологических схемах. Состав и структуру комплексообразующего анионита исследовали методами ИК-спектроскопии и элементного анализа.

Sorption of molybdenum(VI) ions on natural mineral sorbents

The sorption of Mo(VI) ions on natural sorbents (zeolite tuffs and clinker) is investigated. It is estimated that zeolite tuffs sorb polymer forms of Mo(VI) ions in acidic media, while the monomer form of molybdate ion is sorbed in basic media. It is concluded that the rate of sorption of molybdenum(VI) ions on zeolite tuffs is regulated by an intradiffusional mechanism. Values of the activation energy indicate that the adsorption of molybdenum(VI) ions on zeolite tuffs is governed by a physical mechanism. The excretion of crystalline phase (probably calcium molybdate) on surfaces of zeolite tuff is estimated via scanning electron microscopy.

Molybdenum-phosphate retention and transport in soils

Transport and retention experiments were carried out to quantify the mobility and sorption of molybdenum (Mo) and phosphate (P) in two different soils. Batch experiment was used to determine sorption isotherms over a wide range of concentrations for Mo and P. For both soils, sorption isotherms were nonlinear with higher affinity of P than Mo. Sorption of Mo was significantly reduced as the amount added P in solution increased. This was observed for both soils and is indicative of competitive sorption for available site. Miscible-displacement experiments were carried out using soil column where a pulse of Mo solution was introduced in each soil. Breakthrough curves (BTCs) indicated extensive sorption of Mo where as much as 50% of that applied was retained by a predominant kaolinatic soil. Subsequently, a pulse of mixed solution (of Mo and P) was introduced in each column. Results of BTCs for Mo indicated enhanced mobility of Mo in the presence of P for both soils. A five step sequential extraction procedure provided evidence that majority of applied Mo was strongly and/or irreversibly retained. A competitive transport model (CMRTM) based on the Sheindorf-Rebhun-Sheintuch (SRS) equation was capable of describing BTCs of Mo and to a lesser extent for P. Future research should focus on improvement of models that accounts for chemical mechanisms of competitive sorption.

Synthetic strong base anion exchange resins: synthesis and sorption of Mo(VI) and V(V)

The result of synthesizing anion exchangers bearing trimethylammonium functionalities is presented. Ion exchange resins of poly(4-vinylbenzyltrimethylammonium chloride) (PVBTAC) (Resin 1) and poly(3-acrylamidopropyltrimethylammonium chloride) (PAPTAC) (Resin 2) were obtained via the radical polymerization technique and studies on the sorption of molybdenum and vanadium ions were conducted at 20, 30, and 40 °C using the batch method from single-component aqueous solutions. The greatest total sorption capacities were 198 mg Mo(VI) g−1 at 20 °C and 193 mg V(V) g−1 at 40 °C for Resin 1. The calculated thermodynamic parameters demonstrated that the sorption of Mo(VI) was an exothermic process, while the uptake of V(V) was endothermic. The kinetic studies revealed the compliance of the process with a quasi-second-order kinetic model. Simultaneously, equilibrium was achieved within 15 min in two rate-controlled stages. The fitting of the Langmuir and Freundlich mathematical models demonstrated the chemical character of the sorption processes. Elution and reuse studies showed that Mo(VI) may be completely recovered from both resins using a sodium carbonate solution. Moreover, the investigated materials are suitable for repeated sorption/desorption cycles.

Performance of anion exchangers based on aniline, epichlorohydrin, and polyamines in sorption of molybdenum(VI) ions

Polyfunctional anion exchangers based on aniline, epichlorohydrin, and some polyamines were synthesized. The composition and structure of the anion exchangers were studied by IR spectroscopy and elemental analysis. Molybdenum sorption was studied by classical polarography, and dependences of the sorption of molybdenum(VI) ions on the solution acidity, concentration of metal ions, and time of contact of the resins with the Na2MoO4 solution were determined in batch experiments. These ion exchangers exhibit high performance in sorption of molybdenum ions. The developed sorbents with increased sorption ability can successfully solve problems of removing molybdenum(VI) ions from process effluents in nonferrous metallurgy.

Enhanced adsorption capacity and selectivity towards molybdenum in wastewater by a persimmon tannin waste based new adsorbent

AbstractBACKGROUNDTaking advantage of their voluminous availability as agricultural or industrial waste and ease of chemical modification, it is always a promising strategy to fabricate waste biomass materials as adsorbents for selective uptake of concerned metal ions. In the present paper, an environmentally “green” adsorbent was developed by introduced triethylamine (TEA) group on persimmon waste and its potentiality for adsorption, desorption behavior, and mechanism of molybdenum were evaluated.RESULTSAs compared to the persimmon tannin waste based other adsorbents, TEA‐CPT gel exhibited reasonable uptake capacity (287.21 mg g−1) and selectivity for the adsorption of molybdenum. Chelation action between the O‐atom of molybdenum poly‐anions and the N‐atom of tertiary amine is considered to be responsible for selective binding and sorption of molybdenum over co‐existing metal ions. In addition, the adsorbed molybdenum was very effectively eluted with low concentration NH3H2O solution (1%) in column experiment and the regenerated adsorbent exhibited undiminished sorption efficiency for at least six cycles.CONCLUSIONResults show that the TEA‐CPT gel modified by triethylamine has the good stability and the selectivity, etc make it a promising candidate for selective recovery of molybdenum from aqueous system. © 2014 Society of Chemical Industry

Pre-concentration of molybdenum in water samples using coconut husk

Molybdenum accompanies uranium in various types of deposits and plays an important role as a pathfinder element in the hydrogeochemical survey for uranium. In the present study, coconut husk was used for the pre-concentration of molybdenum in hydrogeochemical samples, prior to its analysis by ICP-OES. Quantitative sorption of molybdenum was observed at pH 2 and desorption was achieved by 8M HNO3. Enrichment factor obtained by this procedure was 50. Molybdenum concentrations up to 1.0 ng/ml can be determined easily after pre-concentration using this method. This pre-concentration technique was applied for the determination of molybdenum in hydrogeochemical samples.

Consecutive sorption of molybdenum(VI) and chromium(VI) from a single sample onto fiber materials filled with an anion exchanger and their solid-phase determination with phenylfluorone and diphenylcarbazide

We have considered the possibility of the sorption-spectrometric determination of molybdenum(VI) with phenylfluorone and chromium(VI) with diphenylcarbazide from a single sample by consecutive sorption from different media onto fiber materials filled with an AV-17 anion exchanger. The dependences of analytical signals of molybdenum and chromium on the sorption conditions (pH of the initial solution, NaCl concentration, sizes of the support disc, agitation time) have been studied in the batch mode. The conditions of analytical signal registration have been determined and the analytical ranges have been established (0.01–0.06 μg/mL for Cr and 0.02–0.2 μg/mL for Mo). It has been demonstrated that molybdenum and chromium can be determined at their ratios from 1: 1 to 5: 1 from a single sample after chromium sorption from 0.1 M HCl and molybdenum sorption at pH 4 by diffuse-reflection spectroscopy or visual test. The selectivity of molybdenum and chromium determination in the presence of interfering ions has been studied.

The sorption of molybdenum from solutions of nitric acid

The sorption of molybdenum(VI) on KU-2 × 8 and AV-17 × 8 ionites from 6 n solutions of nitric acid was studied. The sorption of molybdenum(VI) on the cationite and anionite changed depending on solution composition and nitric acid concentration. The sorption and electromigration data were used to determine the isoelectric point of molybdenum in solutions of nitric acid.

Sorption of molybdenum(VI) from mineral salt solutions

Changes in the ionic forms of molybdenum and conditions of sorption on the anionite AV-17 × 8 from mineral salt solutions at concentrations of 0.05–2 N and pH of medium 1–6 were revealed.

The sorption of molybdenum(VI) by ionites from solutions in hydrochloric acid

The sorption of molybdenum(VI) by KU-2 × 8 and AV-17 × 8 ionites from solutions in hydrochloric acid (1 × 10−5−6 N) was studied. Changes in the sorption of molybdenum(VI) by cationite and anionite were observed. The isoelectric point of molybdenum in solutions in hydrochloric acid was determined from sorption and electrical migration measurements.