Purification Of Metals Research Articles

Application of Iron Powder Reduction Method to Remove Heavy Metals in Waste Pickling Acid

The removal of heavy metals in waste pickling acid by iron powder reduction was studied. The effects of reaction time, reaction temperature and dosage of iron powder on the removal efficiency of Zn, Cr, Ni and Pb in waste pickling acid were investigated. The results showed that, the removal rate of Cr tended to be stable after 2 h of reaction under magnetic stirring. After 4 hours, the removal rate of Zn,Ni and Pb tended to be stable. The temperature was increased from 20°C to 90 °C, the removal rates of Ni and Pb could be increased by 9.09% and 11.6%, while the removal rates of Zn and Cr were only increased by 1.15% and 2.85%; Increasing the dosage of iron powder was beneficial to the removal of heavy metals in waste pickling acid, and the combined amount of free acid in the waste acid would affect the removal efficiency of heavy metals. The research results had important guiding significance for the practical application of iron powder reduction method in the heavy metal purification project of waste pickling acid.

CO2 capture drives metal purification

Capturing the carbon dioxide emitted by fossil fuel power stations or industrial plants offers a vital way to reduce global greenhouse gas emissions. But carbon capture technologies are still considered too costly for widespread deployment. Now chemists at the University of Lyon have developed a method to capture CO2 while simultaneously purifying mixtures of metals. By coupling these two processes together, they argue, CO2 capture can generate value in the form of purified metals, potentially making carbon capture more economically viable (Nat. Chem. 2019, DOI: 10.1038/s41557-019-0388-5). Current carbon capture systems often use amines that react with CO2 in flue gas to form carbamates. These compounds can be separated and heated to release a stream of pure CO2, regenerating the amine so that it can be cooled and reused. But the huge temperature swings involved make this a costly approach. Meanwhile, the CO2 released from the amines is sometimes used to

Simultaneous CO2 capture and metal purification from waste streams using triple-level dynamic combinatorial chemistry.

A reduction in CO2 emissions is required to mitigate global warming. Post-combustion carbon capture is one of the most developed technologies that has the potential to meet this goal, but its cost prevents its widespread use. A different approach would be to use CO2 directly as it is captured, before it is stored. Here we explore spontaneous CO2 fixation by industrial polyamines as a strategy to generate dynamic libraries of ligands for metal separation and recovery. We identify the CO2 loadings and solvents promoting the optimal precipitation of each metal from the dynamic libraries of complexes. We demonstrate the separation of lanthanum and nickel using the exhaust gas of an internal combustion engine vehicle, and show that the three metal constituents of the La2Ni9Co alloys used to manufacture the batteries of electric vehicles can be separated and recovered by successive CO2-induced selective precipitations. Beyond the concept of CO2-sourced multi-level dynamic coordination chemistry, this study provides a potential framework for integrated CO2 capture and use through sustainable processes.

Magnetic purification of non-precious metal fuel cell catalysts for obtaining atomically dispersed Fe centers

This paper proposes a facile magnetic purification approach for obtaining atomically dispersed Fe centers in non-precious metal fuel cell catalysts, which has been evidenced by X-ray absorption spectroscopy and microscopy.

Vaidyasaramu (Siddhavaidyasaramu/Navanatha Siddha Saramu) of Rayasam Peraya

Background: Rayasam Peraya's Vaidyasaramu is a valuable Ayurvedic text written in Telugu verses. It is a popular Ayurvedic text with simple and unique formulations. In the old Andhra region, the Siddha tradition was very popular. Nagarjuna and other Siddha physicians, belonging to this place, influenced Ayurvedic scholars of this region, and they became well versed in using mercury, poisons, and other metals, minerals, gems, etc., in purified and incinerated form along with herbal drugs. The present text represents such Ayurvedic tradition mingled with the Siddha tradition. Aim: To highlight the content of Rayasam Peraya's Vaidyasaramu and draw the attention of scientific fraternity for further research and utilization of its unique formulations. Review results: Unique formulations with clinical significance are highlighted in this paper. Tiktakoshataila, Hanumantataila, Angarakataila, Kadalikandaghrita, Ramasitadi Churna, Ashvattadi Churna, Hayavati Churna, Vamanadi Churna, etc. are some examples. Certain variations in disease descriptions in comparison to popular Ayurvedic texts are also highlighted. Conclusion: This text comprises the author's formulations and compilation of certain popular Ayurvedic texts. This medical text described in Telugu Chhandas verses is our pride to show that we had our beautiful past which is forwarded to the future with intensified fragrance. Research on unique formulations may give leads to clinical studies. Clinical significance: The text describes purification and incineration of many metals, mercury, gems, poisonous substances, and their usage in various diseases. Medically, it is an important text because of unique, simple, and useful formulations with clinical significance. Certain disease descriptions like the types of diseases mentioned in this text are different in comparison to popular classical Ayurvedic texts like Brihatrayi and Laghutrayi. Further study may reveal new diseases in comparison to disease descriptions of contemporary medical sciences.

Study on Iron-nickel Separation Using Ion Exchange Resins with Different Functional Groups for Potential Iron Sub-production

ABSTRACT This research study reviews a direct comparison of the loading capabilities and selectivity of 13 different ion exchange resins represented in 24 different commercial resins for the removal of Fe(III) from synthetic Ni(II) leach liquor. The use of ion-exchange resins for selectively removing high concentrations of Fe(III) from leach liquor is presented as an alternative to current Fe precipitation processes in base metal industry. Our results show that resins with aminophosphonic, iminodiacetic, a combination of phosphonic-sulfonic groups, and methyl-glucamine groups favored the Fe(III) loading over Ni(II) and obtained high percentage of metal loadings. Resins with carboxylic, amidoxime, phosphoric, and phosphinic acid groups also favored the Fe(III) loading but achieved low percentage of metal loadings. Resins with active sulfur groups containing thiourea, isothiouronium, and thiol showed compromised adsorption preferences to Fe(III), and achieved low percentage of metal loadings. Sulfonic groups showed no adsorption preferences for Fe(III) but achieved relatively high metal loadings. Contrarily, bis-picolylamine groups showed preferences for Ni(II) loading. Our results suggest that resins with methyl-glucamine and amidoxime groups have the best potential to achieve successful Fe(III) removals. Thus, the recovery of high concentrations of Fe(III) at similar Ni(II) concentrations by ion exchange resins is confirmed at laboratory scale supporting its potential to replace precipitation in the base metal purification process. Further technical and economic studies for the development and scale-up process are still required to confirm its industrial application.

Removal of Different Kinds of Heavy Metals by Novel PPG-nZVI Beads and Their Application in Simulated Stormwater Infiltration Facility

Polyvinyl alcohol and pumice synthetized guar gum-nanoscale zerovalent iron beads (PPG-nZVI beads) were synthesized, and their adsorption towards Pb2+, Cu2+, and Zn2+ ions was evaluated. The adsorption kinetics of metal ions was well fitted by the pseudo-second-order model. The adsorption rate decreased followed in the order of Cu2+ > Pb2+ > Zn2+, consistent with the reduction potential of the ions. The sorption isotherm was well fitted by Langmuir model. The maximum adsorption capacity decreased followed in the order of Pb2+ > Cu2+ > Zn2+, which suggested that the strength of covalent bonds between the metal ions and surface functional groups substituted to the beads is one of the major factors in the adsorption process. Adsorption increased with the increase of pH and the largest sorption occurred at pH 5.5, while ionic strength did not significantly influence the adsorption process. The application of PPG-nZVI beads as filling materials in the simulated stormwater infiltration facility shows good removal efficiency in treating the contaminated water containing Pb2+, Cu2+, Zn2+, Cr6+, and Cd2+ and the removal rate was more than 65% at least. The results indicated that the PPG-nZVI beads could be applied as promising sorbents for purification of heavy metal contaminated water.

Molybdenum Electrorefining in Ionic Liquids

Molybdenum is a valuable refractory metal used to harden and protect metal alloys. Additionally, certain nuclear reactors can be used to produce Mo99, a valuable radioactive isotope with important medical applications. To qualify for medical use, the isotope must be isolated in high purity molybdenum. One method of metal purification is electrorefining. Electrorefining consists of anodically dissolving a target metal of inadequate purity, and then depositing it onto a substrate at a higher purity. Conventional aqueous-based electrolytes are not suitable for Mo electrorefining owing to their instability in the potential range needed for Mo deposition and the tendency of molybdenum to form insoluble oxides. Ionic liquids offer the wider electrochemical window needed to process Mo. Such liquids are often referred to as ‘designer solvents’ due to the plethora of possible constituents that can render different properties. The purpose of this study was to explore Mo electrorefining in ionic liquids, and to identify solvents with properties suitable for this type of molybdenum purification. In this study, the effectiveness of molybdenum electrorefining was examined in a few different ionic systems, including choline-chloride-based deep eutectic systems. Cyclic voltammetry was utilized to determine oxidation and reduction potentials given against an Ag/Ag+ reference electrode. Deposits were characterized with EDX and morphologies examined with SEM. Furthermore, faradaic efficiencies and methods for optimizing deposition were determined. Our findings show that the effectiveness of a solvent for Mo electrorefining is determined by the coordinating nature of the solvent. Weakly coordinating ligands, such as BF- 4, are not ideal for electrorefining because Mo ion replenishment via anodic dissolution is inhibited by low solubility. Ethylene glycol-choline chloride, which is more strongly coordinating, has shown effective dissolution at room temperature. In addition, deposition has been observed in this DES at temperatures above 80° C with aggressive stirring, indicating that it is transport controlled. Despite low faradaic efficiencies for deposition, deposit morphology and adherence can be improved through pulse deposition. This is believed to be the first report of molybdenum deposition or electrorefining in a deep eutectic solvent.

Identity of certain species of plants of unknown source from Rasendramangala

Combination of plant and mineral products were derived in the process of exploring safe and effective remedies which can cure severe and deadly diseases. Some plants are used for processing, purification and calcination of minerals, metals and gems. Mainly the purpose of plants in Rasa shastra is to obtain absorbable metallic molecules in the maximum possible minute form. But some plants mentioned in textbook of Rasa-shastra are not identified properly, because Rasa siddhas like Nagarjuna and Rasa Vagbhata have used some rare synonyms of plants, to conceal them from the knowledge of unknown and mischievous personalities, to avoid misuse. But at present, it is necessary to identify them properly, to use the plants for exact calcination and purification for the benefit of mankind. In the present study, nearly ten plants out of 47 unidentified plants are selected from Rasendra Mangala written by Acharya Nagarjuna in the period of 7th and 8th Century A.D. and a trial has been made to work out on such unidentified plants depending upon their synonyms, utility and combination with other drugs. To quote some, Kanchuki, Chandali, Choraka, Chandravalli and Sarpakshi.

An environmentally friendly closed loop process to recycle raw materials from spent alkaline batteries

Abstract This study proposes a nearly-zero waste and simple hydrometallurgical process for efficiently recycling the main metal components (manganese-Mn and zinc-Zn) from spent alkaline batteries waste with a high grade of purity. The process is based on the novel combination of a single microwave-assisted reductive acid leaching step followed by a single solvent extraction (SE) step for simultaneous extraction and purification of both metals, respectively. An optional ion exchange (IE) step to improve the purity of the Mn solution may be included, if desired. When compared with conventional leaching methods, microwave-assisted leaching decreased substantially the reaction time whilst maintaining high leaching performance for both metals. Subsequently, a single SE step, using Cyanex 302, resulted in a high pure aqueous Mn solution and a high concentrated and pure Zn solution after its complete stripping from the organic phase. Additional purification of the Mn solution by IE, using a bispicolylamine resin, resulted in a highly pure Mn solution. In conclusion, this work demonstrates a novel and optimized process for recycling almost all metal content from spent alkaline batteries into proper secondary raw materials for production of new batteries.

Adsorptive purification of heavy metal contaminated wastewater with sewage sludge derived carbon-supported Mg(II) composite.

A rod-like SDBC-Mg(II) composite was synthesized and optimized in the conditions of 25% Mg(II) loading and 500 °C calcination temperature. As-prepared SDBC-25%Mg(II)-500 adsorbent attained equilibrium in 30 min, with an extraordinary capacity of 2931.76 mg g-1 (Pb(II)) and 861.11 mg g-1 (Cd(II)), revealing a promising adsorbent for the removal of such metals so far. The adsorption kinetics was well described by the pseudo-second-order model while the adsorption isotherm could be fitted by Redlich-Peterson model. Furthermore, SDBC-25%Mg(II)-500 has a high anti-interference and selectivity in the presence of competing ions/other environmental factors and, also effectively eliminates >99% of Pb2+, Cd2+, Ag+ and Cu2+ ions from pond water, lake water and tap water. The adsorption process demonstrated a synergetic adsorption mechanism comprised of ion exchange with Mg(II), coordination with surface and inner carboxylic or carbonyl functional groups and co-precipitations as metal silicates, which is responsible for its superb adsorption performance. Besides, surface carvings of Mg(II) and tunnels on the rods resulting from the sludge carbonization provided a high surface area (91.57 m2 g-1), extra sorption sites and room for easy pollutant diffusion which contributed to surface physical adsorption. Furthermore, this technique demonstrate an alternative pathway that will relieve the burdens of sewage sludge treatment process and turn this solid waste into highly efficient adsorbent for eliminating heavy metal ions from wastewater. This can be considered as a feasible waste resource utilization to meet with the requirement from both ecology and economy for auspicious applications in industries.

Efficient gas-phase purification using chloroform for metal-free multi-walled carbon nanotubes

Gas-phase treatments using chloroform (CHCl3) and water vapor were used to remove metal impurities (MIs) from as-prepared multi-walled carbon nanotubes (AP-MWCNTs), which is a non-destructive way to produce highly pure CNTs with extremely low MI content and with retention of CNT properties. After purification using CHCl3, the MIs in the AP-MWCNTs had significantly decreased to 12 ppm, representing a purification efficiency of 99.8%. This purification method, applicable to various AP-MWCNTs with high contents and different compositions of MIs, is more effective than liquid-phase purification using acids and does not damage the CNT structure and morphology. This moderate purification is due to a combination of factors. Chlorine radicals and hydrochloric acid from the thermal decomposition of CHCl3 react with MIs encased by graphitic carbon layers to form metal chlorides that sublime at high temperature. Hydrogen, oxygen, and water vapor generated during the formation of the metal chlorides etch graphitic carbon layers and lead to the formation of new pores and cracks, which provide fast reaction and diffusion paths. During metal purification, the MWCNT surface becomes lightly coated with chlorine or chlorinated carbon, which are eliminated from the surface post-treatment using water vapor.

Biosorption of Nickel (II) from Aqueous Solutions onto Pistachio Hull Waste as a Low-Cost Biosorbent

There are many different industrial wastewater containing heavy metals that contribute to environmental pollution and raw agricultural waste is an effective adsorbent for the removal of heavy metals. The adsorption behavior of pistachio hull powder (PHP) as a low-cost adsorbent, with respect to nickel (II) ions, has been studied in order to consider its application to the purification of metal finishing wastewater. In this work, adsorption of nickel on pistachio hull has been studied by batch techniques. The adsorption depends on the process time, the pH of the solution, initial concentration of metals and the adsorbent concentration in the suspension. The kinetics of adsorption were relatively fast, reaching equilibrium for less than 60 minutes. Kinetic and isotherm modeling studies demonstrated that the experimental data best fit a pseudo-second order and Freundlich model, respectively. The maximum Langmuir adsorption capacity was 14 mg/g. The optimum pH required for maximum adsorption was found to be 4-6. The initial concentration of the adsorbate and the concentration of pistachio hull strongly affect the process. No influence of particle size was evidenced. A degree of adsorption higher than 75% can be achieved for nickel (II) ions.

Magnesiothermic Reduction from Titanium Dioxide to Produce Titanium Powder

Titanium metallic powder (2.98 wt% O) of irregular and semi-spherical particles sizes ranging between 0.5 and 3.5 µm was obtained by magnesiothermic reduction of TiO2 and a leaching purification process. Magnesiothermic reduction experiments were carried out to evaluate the influence of temperature and molar ratio of Mg/TiO2. A rotary tube reactor in three different configurations was used to promote solid–liquid and solid–gas model reaction. The best configuration resulted when solid–gas model reaction was promoted. Different mixtures of acid as 6M HCl, 3M HCl, 0.55M HCl plus a mixture of 8 HCl% + 3 HNO3% were used to evaluate the purification of solid titanium metal by dissolution of Mg, MgO, Ni, Fe, magnesium titanates, and titanium oxides.

Phase Formation in the TiO2–H2SO4–HF–Nd(NO3)3–H2O System at 20°C

The phases NdF3 (I), x (II), NdTi2O4.75F0.5(SO4)0.5 · 3H2O (III), NdTiF3(SO4)2 · 6H2O (NdTiOF(SO4)2 · 6H2O) (IV), Nd2(SO4)3 · 8H2O (V), and Nd2(SO4)3 · 4H2O (VI) formed in sulfuric acid and fluorine-containing solutions during the synthesis of materials from feedstocks and the purification and separation of metals were separated. The regions of their existence were schematically presented. Particles with a “core-shell” structure were detected. The compounds were studied by elemental, crystallooptic, X-ray diffraction, and thermal analyses. The composition was determined for phase III (from thermogravimetric (TG) data) and spherolith-like particles of H6NdF7.8(SO4)0.5 · 3.75H2O (VII) (by X-ray diffraction microanalysis). Freshly separated particles evolved HF. Phase IV corresponding to NdTiF3(SO4)2 · 6H2O (according to TG data) acquired the composition and form of the known NdTiOF(SO4)2 · 6H2O phase after storage.

Magnesium Removal from Concentrated Nickel Solution by Solvent Extraction Using Cyanex 272

The refinery of mixed hydroxide precipitate (MHP) from nickel laterite processing by acidic re-leaching will generate a concentrated nickel solution containing some magnesium difficult to remove. Fluorite precipitation method is often used for nickel purification from magnesium contamination, causing serious risk of environmental pollution. Solvent extraction technology has obvious advantages in metal separation and purification which has been widely used in nickel cobalt industries. Magnesium separation from nickel in a synthetic re-leach solution by solvent extraction using Cyanex 272 (bis (2, 4, 4-trimethylpentyl) phosphinic acid)) and its analogue of P 507 (2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester) was studied. It was found that the separation factor of magnesium over nickel reached higher than 200 at pH 5.5, which is much better than that of P507 with the maximum separation factor of 88 at pH 5.0. The conditions including equilibrium pH, organic concentration and A/O ratio for metal extraction and separation of Mg and Ca from nickel with Cyanex 272 in a concentrated synthetic nickel solution were optimized. A five-stage counter-current batch continuous test was carried out with Cyanex 272 under optimized conditions. More than 99% of the magnesium was removed from the synthetic solution containing 3.4 g/L Mg and 106 g/L Ni using 0.5 M Cyanex 272, leaving only 38 mg/L Mg in the purified nickel solution, which is suitable for the electrowinning.

Integration of metal hydride devices with polymer electrolyte fuel cells and electrolyzers for stationary applications

This paper presents the experimental results of the system integration of a fuel cell (FC), an electrolyzer and a metal hydride hydrogen storage and purification system. A pilot scale experimental power installation H2Smart with an electric power of 1 kW is developed, and the results of its operation in different regimes are presented. The problems of hydrogen desorption for the supply of FC and hydrogen sorption from the electrolyzer at the start are shown. Possible solutions of this problem are proposed.

Impurity removal with highly selective and efficient methods and the recycling of transition metals from spent lithium-ion batteries.

The use of lithium-ion batteries (LIBs) is skyrocketing since they are widely applied in portable consumer devices and electric vehicles. However, at the end of their lifetime, large amount of spent LIBs will result in a negative environmental impact and aggravate the problem of resource shortage without proper disposal. Therefore, recycling is an effective solution, which will be enforced in the near future. Herein, the purification, recovery and reuse of transition metals from spent LIBs were thoroughly studied. First, the target impurities in a solution were effectively removed individually. Iron(iii) and aluminum(iii) impurities were removed by adjusting the pH value, whereas copper(ii) was purified using highly selective electrodeposition technology and solvent extraction. Second, Ni0.41Co0.21Mn0.38(OH)2 was co-precipitated by adjusting the pH value of the purified metal solution, containing nickel(ii), cobalt(ii) and manganese(ii) ions to 11 with NaOH and a proper amount of NH3·H2O. The comprehensive loss in nickel(ii), cobalt(ii) and manganese(ii) was only 0.37% in the purification and co-precipitation procedures. Finally, LiNi0.41Co0.21Mn0.38O2 (marked as LNCM-R) synthesized with the recycled materials was tested and compared with LiNi0.41Co0.21Mn0.38O2 (marked as LNCM-N) synthesized with new materials as the control group. The XRD, SEM and TEM results indicate that both samples have the same structure and morphology. Furthermore, the charge–discharge tests, initial dQ/dV curves, EIS and GITT results indicate a similar electrochemical performance of the LNCM-R and LNCM-N samples. The purification and recycling strategies in our research have high efficiency and comparatively low cost, which provide great guidance for the industrial recycling of spent Li-ion batteries.

Melting heat transfer with radiative effects and homogeneous–heterogeneous reaction in thermally stratified stagnation flow embedded in porous medium

The present article deals with thermally stratified stagnation-point flow saturated in porous medium on surface of variable thickness along with more convincing and reliable surface condition termed as melting heat transfer. Homogeneous–heterogeneous reaction and radiative effects have been further taken into account to reconnoiterproperties of heat transfer. Melting heat transfer and phenomenon of homogeneous–heterogeneous reaction have engrossed widespread utilization in purification of metals, welding process, electroslag melting, biochemical systems, catalysis and several industrial developments. Suitable transformations are utilized to attain a scheme of ordinary differential equations possessing exceedingly nonlinear nature. Homotopic process is employed to develop convergent solutions of the resulting problem. Discussion regarding velocity, thermal field and concentration distribution for several involved parameters is pivotal part. Graphical behaviors of skin friction coefficient and Nusselt number are also portrayed. Concentration of the reactants is found to depreciate as a result of strength of both heterogeneous and homogeneous reaction parameters. With existence of melting phenomenon, declining attitude of fluid temperature is observed for higher radiation parameter.

Novel 2D Nanosheets with Potential Applications in Heavy Metal Purification: A Review

AbstractOver the past decades, extensive studies have been carried out for the design of advanced materials for water purification. Heavy metal pollution in water is a serious global environmental problem due to their toxicity and carcinogenicity. With the discovery of graphene, novel 2D nanosheets, derived from the wide variety of traditional materials, have emerged as some of the most promising candidates for heavy metal purification. This review summarizes the recent progress on the novel 2D nanosheets with their applications in heavy metal purification. First, the authors introduce the unique advances on 2D nanomaterials, followed by the description of their composition and crystal structures. Some novel 2D nanosheets with great success in heavy metal purification field are then summarized, including insights on their advantages over traditional materials and limitations in practical applications, along with some advances in interfacial structure modifications for future work. The functional design of more and more novel 2D interfacial materials with unique properties is still demanding for future industrial applications.