Technology For Recovery Of Metals Research Articles

Electrochemical treatment of wastewaters containing metal-organic complexes: A one-step approach for efficient metal complex decomposition and selective metal recovery

Metal-organic complexes, especially those of ethylenediaminetetraacetic acid (EDTA) with metals such as copper (Cu) and nickel (Ni) (denoted here as Cu-EDTA and Ni-EDTA), are common contaminants in wastewaters from chemical and plating industries. In this study, a multi-electrode (ME) system using a two-chamber reactor and two pairs of electrodes is proposed for simultaneous electrochemical oxidation of a wastewater containing both Cu-EDTA and Ni-EDTA complexes as well as separation and selective recovery of Cu and Ni onto two different cathodes via electrodeposition. Our results demonstrate that the ME system successfully achieved 90% EDTA removal, 99% solid Cu recovery at the Cu recovery cathode and 56% Ni recovery (33.3% on the Ni recovery cathode and 22.6% in the solution) after a four-hour operation. The system further achieved 85.5% Ni recovery after consecutive five cycles of operation for 20 h. While Cu removal was mainly driven by the direct reduction of EDTA-complexed Cu(II) at the cathode, oxidation of EDTA within the Ni-EDTA complex at the anode was a prerequisite for Ni removal. The oxidation of metal-bound EDTA and free EDTA was driven by •OH and direct electron transfer on the PbO2 anode surface and graphite anode, respectively. We further show that ME system performs well for all pH conditions, treatment of real wastewaters as well as wastewaters containing other metals ions (Cr and Zn) along with Cu/Ni. The separation efficiency of Cu and Ni is dependent on applied electrode potential as well as nature and concentration of binding ligand present with comparatively lower separation efficiency achieved in the presence of weaker binding capacity and/or at lower ligand concentration and lower applied electrode potential. As such, some optimization of electrode potential is required depending on the nature/concentration of ligands in the wastewaters. Overall, this study provides new insights into the design and operation of EAOP technology for effective organic abatement and metal recovery from wastewaters containing mixtures of various metal-organic complexes.

Phytoremediation technology for recovery of Ni by Acacia plants in association with Bacillus amyloliquefaciens isolated from E-waste contaminated site

Electronic waste (e-waste) illegally disposal in Thailand is becoming more widespread. A sustainable metal recovery technology is needed. A phytotechnology called “phytomining” of metals such as nickel (Ni) is a promising technology providing a sustainable solution to the growing e-waste problems. This study investigated the ability of Acacia species in association with e-waste site isolated, plant growth-promoting rhizobacteria (PGPR), Bacillus amyloliquefaciens. Acacia mangium accumulated higher Ni in their tissues when Ni concentrations in soil were lower than 200 mg kg−1. The inoculation of PGPR B. amyloliquefaciens enhanced Ni uptake and accumulation in the leaves, stem, and root. The results showed that the highest Ni concentration was found in the root ash (825.50 mg kg−1) when inoculated plants were grown in soil containing 600 mg kg−1 Ni. Hence, the Ni recovery process and mass balance were performed on root ashes. The highest Ni recovery was 91.3% from the acid (H2SO4) leachate of the ash of inoculated plant treated with 600 mg kg−1 Ni. This demonstrates the feasibility of PGPR-assisted phytomining from Ni-contaminated soil. Phytomining of Ni from any e-waste contaminated sites using Acacia mangium in combination with B. amyloliquefaciens can promote plant growth and improve the uptake of Ni.

Optimal design of a new Halbach array magnetic roller with axial eddy current force

Non-ferrous metal recovery is of great significance to the sustainable development of resources. Small-sized nonferrous metal particles account for a large proportion of nonferrous metals in solid waste, but the recovery efficiency is low. Eddy current separation is an important technology for physical recovery of non-ferrous metals. Optimizing its magnetic roller is extremely important for improving the recovery efficiency and economy of small-sized non-ferrous metals. In this study, COMSOL Multiphysics is used to establish a three-dimensional transient simulation model of the vertical rotary-drum ECS. On the basis of the two-dimensional Halbach array magnetic roll, the magnetic system of the magnetic roll is designed in the axial direction, so that the particles are subjected to the axial eddy current force opposite to the direction of gravity for the first time. This force can slow down the falling velocity of particles, increase the difference in falling trajectory and repulsion distance, improve recovery efficiency. In addition, due to the generation of axial eddy current force, the interlayer dislocation type magnetic roller can achieve the same recovery effect by only using 1/3 of the length of the basic type magnetic roller. Based on the electromagnetic theory and particle dynamics, by comparing the axial magnetic density distribution of different magnetic rollers, the axial eddy current force and the trajectory of non-ferrous metal particles, the generation mechanism of the axial eddy current force and the magnetic system structure that can generate the axial eddy current force are clarified.

A novel approach for recovering multiple valuable metals from gallium-rich residues of phosphorus flue dust by two-stage vacuum reduction

In this study, the gallium-rich residue (GRR) obtained from phosphorus flue dust (PFD) after phosphorus removal was taken as the research object, and a novel technology for efficient recovery of valuable metals from GRR was proposed. This technology mainly adopted a two-stage vacuum carbothermal reduction process to selectively recover Zn and Pb and concentrate Ga. The feasibility of separating these three metals from GRR was investigated by thermodynamic analysis, and the effects of temperature, reducing agent dosage and holding time on metals recovery were explored. A promising recovery rate of up to 96.84%, 97.98% and 86.32% was achieved for Zn, Pb and Ga, respectively, under the optimal conditions. The purity of Zn and Pb in the condensate reached 98.57% and 80.56%, respectively, which can be used as raw materials for downstream enterprises and have high economic value. Additionally, the resulting Ga-rich condensate contained 1.49 % Ga, which is much higher than other traditional Ga-containing secondary resources, and can be further purified by hydrometallurgical process or other technologies. The whole process has almost no secondary pollution, with remarkable efficiency, providing a new approach for the comprehensive utilization of PFD.

A review on technologies for recovery of metals from waste lithium-ion batteries

Lithium-ion batteries (LiBs) market has emerged drastically, and the amount of obsolete or waste LiBs also increased. The present review discusses a variety of current technologies for the secondary utilization of used LiBs (echelon utilization) and recycling waste LiBs (direct recycling, hydrometallurgy, pyrometallurgy, bioleaching, and other alternative biological processes), with the goal of advancing waste LiBs recycling, especially in support of industrialization and recycling processes. A bibliometric analysis on the recycling of waste LiBs and their associated technologies carried out using VOSviewer software indicated that the biological techniques have not yet been developed as compared to direct, hydrometallurgical, and pyrometallurgical technologies. Furthermore, it provides a brief overview of advances in biological approaches, such as bioleaching, biosorption, and bio-electrochemical systems, towards the recovery of metals from waste LiBs. In this study, new directions for effective waste LiBs processing towards resource/waste management sustainability are also identified.

How far does the Copper/Nickle recovery from the practical application in the electroplating wastewater?

Metal recovery from electroplating wastewater presents a promising alternative approach for Cu/Ni resource procurement, alleviating traditional mineral mining shortages. This article reviews diverse metal recovery technologies, including adsorption, electrocoagulation, chemical precipitation, resin adsorption, extraction, membrane separation, and electrodeposition. Most studies successfully transfer Cu2+ or Ni2+ from electroplating wastewater to intended metal carriers in lab-scale technologies, thus purifying the wastewater and concurrently enriching desired metals. However, these studies primarily focus on lab-scale heavy metal enrichment and purification, often yielding a mixture of metals with impurities or concentrated salt solution. The importance of reutilization of the recovered metal mixture or metal salt solution, largely unexplored in existing research, is pivotal for sustainability. We propose that future works prioritize pilot-scale experiments, emphasizing reutilization strategies for recovered materials. Consequently, a comprehensive environmental impact evaluation of metal recovery from electroplating wastewater could be made via life cycle assessment, underscoring the importance of reuse in this process.

Extraction of valuable metals from spent cathode materials by reductive roasting in methane atmosphere

Against the backdrop of the increasing amounts of lithium-ion batteries, it is reducing environmental pollution and relieving the stress on resource requirements through the sustainable recycling of spent lithium batteries. Here we targeted the reduction of the material phase by methane roasting and then achieved a step separation of Li, Ni, Co, and Mn by differentiation in water solubility and magnetic strength. The principal reduction factors were also optimized. The results show that the spent cathode powder converts mainly to water-soluble Li2CO3, that the leaching selectivity of lithium is 100%, and that other metals can be separated by wet magnetic separation under optimal conditions. A reasonable explanation of the phase conversion during the reduction process is provided, and a preliminary process evaluation is presented at the end. Notably, this work has the strengths of step recovery of elements, rapid processing, and zero chemical use, which has great potential for the industrial recycling field and provides a new idea for the development of green and efficient valuable metal recovery technologies for spent LIBs.

Continuous single-stage elemental sulfur reduction and copper sulfide precipitation under thermoacidophilic conditions

Metal sulfide precipitation is a viable technology for high-yield metal recovery from hydrometallurgical streams, with the potential to streamline the process design. A single-stage elemental sulfur (S0)-reducing and metal sulfide precipitating process can optimize the operational and capital costs associated with this technology, boosting the competitiveness of this technology for wider industrial application. However, limited research is available on biological sulfur reduction at high temperature and low pH, frequent conditions of hydrometallurgical process waters. Here we assessed the sulfidogenic activity of an industrial granular sludge previously shown to reduce S0 under hot (60–80 °C) and acidic conditions (pH 3.6). A 4 L gas-lift reactor was operated for 206 days and fed continuously with culture medium and copper. During the reactor operation, we explored the effect of the hydraulic retention time, copper loading rates, temperature, and H2 and CO2 flow rates on the volumetric sulfide production rates (VSPR). A maximum VSPR of 274 ± 6 mg·L−1·d−1 was reached, a 3.9-fold increase of the VSPR previously reported with this inoculum in batch operation. Interestingly, the maximum VSPR was achieved at the highest copper loading rates. At the maximum copper loading rate (509 mg·L−1·d−1), a 99.96% copper removal efficiency was observed. 16 s rRNA gene amplicon sequencing revealed an increased abundance of reads assigned to Desulfurella and Thermoanaerobacterium in periods of higher sulfidogenic activity.

Enabling Metal Sustainability with Polymer Inclusion Membranes: A Critical Review

Polymer inclusion membranes (PIMs) have shown excellent performance in separating metal ions—a critical step in metal recycling processes. However, progress in PIM research has been limited to empirical approaches that typically require redundant membrane fabrication optimizations. Recent reports may provide essential insight into basic knowledge on the nature of the membrane and what challenges and disputes need to be addressed. In this review, we first introduce a basic understanding of how a PIM works in metal separation and the brief history behind its invention. Fundamental principles of the membrane design are established based on consistent data trends in the literature. We then highlight recent findings that have implications for both practical applications and theoretical consequences. In addition, challenges to understanding plausible mechanisms and transport models across PIMs are identified systematically. Finally, we include some perspective on each finding and an outlook regarding the future direction of PIM research, focusing on the application as a metal recovery technology.

Fluidized–bed homogeneous granulation for potassium and phosphorus recovery: K-struvite release kinetics and economic analysis

BackgroundThe last few decades have seen the critical role of global cattle industry in agricultural development. However, while giving prosperity and significant benefits to the countryside, the industry also produces wastewater streams, that cause eutrophication in water bodies. The streams, if treated effectively, could act as a valuable nonconventional water source to help address the global freshwater crisis. Moreover, resources recovered from these wastewater streams, e.g., potassium (K) and phosphorus (P), could be converted to valuable commodities such as fertilizers. We, therefore, propose to use a continuous K–struvite granulation process as an effective method for the treatment of swine wastewater (SW) and recovery of K–struvite. Results show that the P and K were efficiently removed and that wastewater-derived K–struvite is a promising green chemistry agent for a slow–release, reinforcing a promising pathway to global P and K conservation. MethodsThe fluidized-bed homogeneous granulation (FBHG) has recently emerged as an advanced metal recovery technology with high efficiencies for several metals and low moisture products. Based on the principle of chemical precipitation, FBHG technology requires less chemicals while producing insignificant amounts of sludge, thereby alleviating burden on sludge management often encountered in conventional chemical precipitation and others. Significant findingsHerein, we investigate the potential use of FBHG technology for simultaneous recovering K and P while treating swine wastewater. The recovered products are in the form of K–struvite pellets having a studded quasi-spherical form with a rough surface and sharp spikes that resemble sea urchins. The pellets are almost free of heavy metals, which make them promising candidates for use as fertilizer without significant harm. We observed that the release of K was faster than that of P. The formation, size, morphology, purity, and crushing strength of the pellets greatly affected the up-flow velocity value condition. The FBHG could potentially be scaled up for more extensive nutrient recovery.

Precious Metal Recovery and Recycling Technology Using Silica with a Special Structure

Precious Metal Recovery and Recycling Technology Using Silica with a Special Structure

Repeated Recovery of Rare Earth Elements Using a Highly Selective and Thermo‐Responsive Genetically Encoded Polypeptide

AbstractRare earth elements (REEs) have become increasingly important materials owing to their use in the high‐tech and clean‐energy industries. However, the unpredictable supply, possible health risks, and environmentally unsustainable extraction practices associated with REEs have encouraged the development of green technologies for the selective extraction and recovery of metals. This study presents a simple and innovative approach for the selective extraction and recovery of total REEs. Elastin‐like polypeptide (ELP) and the REE‐binding domain (lanmodulin) are fused to form REEs‐sensitive and thermo‐responsive genetically encoded ELP called RELP, where ELP offered a reversible, inverse phase transition for repeated uses. The RELP are purified and used for the selective extraction of total REEs from competing non‐REEs metals by controlling the solution temperature (4 and 37 °C) and pH. RELP exhibit high REE specificity, even in the presence of non‐REE metal ions. The bound REEs are readily recovered during at least six repeated cycles, and the efficiency is maintained. Moreover, REEs are selectively recovered by RELP from steel slag leachate, a potential industrial source of REEs. RELP offers a rapid, selective, and scalable method for REE extraction and recovery. This technology can be adapted to recover other precious metals and commodities.

Atomic H* enhanced electrochemical recovery towards high-value-added metallic Sb from complex mine flotation wastewater

Simultaneous recovery and value-added conversion of hazardous heavy metal ions from complex wastewater sources is of great significance yet challenging. Herein, we demonstrate that highly toxic antimonite Sb(III) could be effectively recovered from antimony (Sb) mine flotation wastewater and converted into high-value-added metallic Sb using a novel facile atomic H* enhanced electrochemical reduction avenue coupled with thermal reduction by H2 gas. The high production of atomic H* generated from the electrochemical cathode with an optimum reduction potential of –1.2 V vs. Ag/AgCl, which is lower than the Sb(III) reduction potential of –1.0 V, might be attributable to the superior Sb recovery capabilities. Furthermore, the metallic Sb concentration at –1.2 V was 14.43 times greater than at –1.0 V due to the strong reductivity of atomic H*. In addition, Sb(III) removal efficiency was found to be as high as 98.52%, with a metallic Sb recovery rate of up to 1.67 mg min–1. The efficiency of Sb(III) recovery was demonstrated throughout a wide pH range, with metallic Sb being the main product, independent of the presence of multiple coexisting ions. Economic analysis also indicated that treating Sb mine flotation wastewater per ton may yield a net profit of $40.09. This research contributes to the advancement of an atomic H* enhanced electrochemical technology for high-valued heavy metal recovery from complex heavy metal-polluted wastewater.

Flotation response of cerussite after hydrothermal treatment with sulfur and the sulfidation mechanism

Hydrothermal sulfidation followed by flotation is well known as a promising technology for recovery of valuable metals from refractory non-ferrous ores. Cerussite (PbCO3), as one of the most representative lead oxide minerals, was selected as the research object in this paper. Hydrothermal sulfidation performances were directly characterized by flotation tests and the sulfidation mechanism was further revealed by XRD, XPS and EPMA–EDS. Flotation tests results showed that flotation recovery of cerussite reached approximately 80% at a suitable S/PbCO3 mole ratio and pH. XRD analyses results confirmed that the cerussite was transformed into mainly PbS and PbSO4 after hydrothermal sulfidation. XPS analyses results indicated that more lead-bearing species including PbSn and PbO·PbSO4, besides mainly PbS and PbSO4, were generated at the surface. EPMA–EDS results showed that the core part of particle remained lead carbonate, but the out layer of particle was completely converted into sulfur-bearing compounds. A reaction model of hydrothermal sulfidation of cerussite with sulfur was designed and the sulfidation process can be divided into five steps: disproportionation of sulfur, adsorption of disproportionation products, dissolution of carbonate ion, formation of lead sulfide precipitate and diffusion of carbonate ion. These findings can lay a good theoretical foundation for optimizing the hydrothermal sulfidation process to recover cerussite and even other non-ferrous metals oxide materials by using the hydrothermal sulfidation–flotation processes.

Thermodynamic modeling of iron and zinc reduction from B<sub>2</sub>O<sub>3</sub> ‒ CaO ‒ Fe<sub>2</sub>O<sub>3</sub> ‒ ZnО melt by СО ‒ CO<sub>2</sub> and H<sub>2</sub> ‒ Н<sub>2</sub>О mixtures

The paper presents the thermodynamic modeling results of zinc and iron reduction from B2O3 ‒ CaO ‒ Fe2O3 ‒ ZnО melts by CO ‒ CO2 and H2 ‒ H2O mixtures containing 0 – 60 % CO2 (H2O) at 1273 – 1673 K using a technique describing the reduction of metals from an oxide melt by gas in bubbling processes, under conditions that provide an approximation to real systems. Its originality is equilibrium determination for each individual portion of gas supplied into the working fluid. The reducible metals oxides content in each calculation cycle is taken from the previous data. During the calculations, changes in the content of zinc (СZnO ) and iron (СFe2O3 , СFe3O4 and СFeO ) oxides in the melt and the degree of their reduction were estimated. When using CO or H2 as a reducing agent, this process proceeds in three stages. In the first stage, Fe2O3 is reduced to Fe3O4 and FeO. CFe2O3 values decrease to almost zero, while CFe3O4 and CFeO increase simultaneously. By the end of the stage, СFe3O4 reaches its maximum value. At the second stage, the Fe3O4 → FeO transition occurs, when СFeO values reach its maximum. At these stages, there is a slight increase in the CZnO . At the third stage, the values CFeO and CZnO decrease, and iron and zinc are reduced. An increase in temperature dramatically reduces the gas consumption for zinc reduction by 2 – 3 times, and the replacement of CO with H2 reduces it by less than 20 %. In the presence of oxidizing agents (CO or H2O), only zinc is reduced. The process ends when the final content of zinc oxide in the melt corresponds to the equilibrium with the initial gas composition. The higher the temperature, the less CZnO is. The obtained data are useful for the development of technologies for the selective recovery of metals.

Rejection Capacity of Nanofiltration Membranes for Nickel, Copper, Silver and Palladium at Various Oxidation States.

Electroplating and metalworking industries produce enormous amounts of waste containing heavy metals in their effluents, leading to potential threats to biotic and abiotic life. According to regulation, heavy metal contamination must be kept within the regulated standard of a few parts per million, which has led to a recent pique in interest in the utilization of nanofiltration technology for metal recovery. The effect of feed pH, pressure, metal concentration, and oxidation of metal on the rejection of heavy metal ions using three commercial nanofiltration membranes (NF, NF90, and NF270) were explored. To begin, studies of electrolyte salts, contact angle, and water permeability were employed to characterize the nanofiltration membranes. A dead-end module was used to test the permeation and retention capacities of the nanofiltration membranes. The results showed an increase in salt rejection for all metals examined irrespective of the membrane, at a pH below the isoelectric point. For divalent cations, the NF90 membrane achieved recovery capacities of 97% and 85% at 200 ppm and 20 ppm respectively, as compared to the recovery observed for Ni2+, Cu2+, and Pd2+ ions by NF and NF270. At a pH 2, 20 ppm and 5 bar, the NF90 membrane had the highest percent recovery, but at a pH 3, the recovery was at 95%. Mono and divalent stable Ag+ and Ni2+ ions showed a comparatively high percent recovery as compared to Pd2+ and Cu2+, which have high molecular weight and charge effect. In the presence of chelating agents, the membrane surface area is increased, resulting in high divalent ion recovery capacities due to favourable interaction with the polyamide functional group of the membranes. This study establishes the significance of oxidation in high removal efficiency cation in varying experimental conditions.

Carbon black-polydopamine-ruthenium composite as a recyclable boomerang catalyst for the oxidative cleavage of oleic acid

A new composite heterogeneous catalytic system is proposed for the transformation of cheap unsaturated fatty acids into value-added molecules through their oxidative cleavage. The valorization of oleic acid to azelaic and pelargonic ones (which are demanded in pharmacology) is specifically studied. The reaction is efficiently performed with a novel composite catalyst inspired from metal recovery technology, namely Ru species supported on a carbon black that was previously oxidized and then functionalized with polydopamine. Being a polymer with hydroxyl and amine groups polydopamine provides moieties acting as tweezers able to complex Ru species. A representation of this novel composite catalyst is built from its characterization by FTIR, TGA, N2 physisorption TEM and XPS. Using NaIO4 as oxidizing agent in a biphasic system at room temperature the conversion of oleic acid, and selectivity towards pelargonic and azelaic acids, reached around 95% after 3 h. The reaction mechanism is explored by UV–Vis spectrophotometry, ICP elementary analysis and NMR spectroscopy, together with recyclability and hot centrifugation tests. The occurrence of a boomerang mechanism is demonstrated. The solid catalyst is indeed recyclable at least 5 times without activity loss, but at the same time Ru species are shown performing the reaction in homogeneous phase namely in a dissolved state. Actually, polydopamine is confirmed to recover Ru species once the reaction ends, guarantying the recyclability of the catalyst. The composite catalyst therefore combines the advantages of homogeneous and heterogeneous catalysis in the investigated reaction.

Current technologies for recovery of metals from industrial wastes: An overview

Fast industrialization has increased the demand for heavy metals, on the other hand, high-grade ore natural reserves are belittling. Therefore, alternative sources of heavy metals need to be investigated. Massive amounts of industrial wastes are being generated annually. The majority is sent to landfills or to incinerators, which eventually poses environmental challenges such as ecological contamination and health hazards to living beings. Such industrial wastes contain hazardous elements of various metals (Au, Ag, Ni, Mo, Co, Cu, Zn, and Cr), whose improper disposal leads to adverse effects to human being and the environment. As a result, methods for industrial waste management such as reuse, remanufacturing, and recycling have received much attention due to the fact that they improve cost effectiveness over time and enable the metal recovery businesses to thrive profitably. The present study provides a state of art review on the current technologies existing for the recovery of precious metals from industrial wastes streams to analyse the sustainability. Among the wastes, spent petroleum catalysts, medical waste, electronic scraps, battery wastes, metal finishing industry waste, and fly ash are some of the largest industrially-generated wastes. Various metal recovery processes involve physical, chemical, and thermal characteristics of waste streams and target metals for separation and extraction. The current challenges of pyrometallurgy, modification on the hydrometallurgy, physical and chemical methods and other advanced technologies are presented in this review. The hydrometallurgical method, which involves dissolving and leaching, is a proven and successful process for recovering metals from various raw materials. Several other recovery methods have been proposed and are currently being implemented; the problem is that most of them are only successful in retrieving certain metals based on specific properties of industrial waste. The recovered metal solutions are further concentrated and purified using adsorption, cementation, chemical precipitation, ion exchange, membrane filtration and ion flotation techniques, which can also be applied to other liquid waste streams. The recovery method only makes sense if the recovery cost is much less than the value of the precious metal. The limitations placed on waste disposal and stringent environmental legislation require environmental-friendly metal recovery technologies. This review paper provides critical information that enables researchers to identify a proper method for metal recovery from different industrial wastes, and also it benefits researchers and stakeholders in determining research directions and making waste management-related decisions. • Methods for metal recovery from solid/liquid waste streams are critically reviewed. • Pyrometallurgical methods effectively recover less reactive oxides in solid waste. • Hydrometallurgical methods rely on chemical reactions in various leaching mediums. • Metal recovery from wastewaters is based on either chemical or physical techniques. • Physical metal recovery method is superior by low chemical use and sludge produced.

Toward Alginate-Based Membrane Technology for High Performance Recovery of Heavy Metals in Cells.

One of the major environmental problems is a global metal contamination. Heavy metals are nonbiodegradable and tend to accumulate in living organisms. Therefore, searching for biocompatible materials with enhanced sorption capabilities for selective removal of toxic elements from complex environments, low cost, ease of operation, and large available quantities that meet all requirements of the Green Chemistry concept is a current engineering and analytical task. We present a comprehensive study toward construction of an advanced biomembrane-based technology for recovery of several heavy metals and ruthenium by microdimensional alginate scaffolds. The chosen design of alginate scaffolds and their operational conditions were monitored during removal of Cd(II), Co(II), Pb(II), As(III), and Ru(III) in modeled aqueous solutions, cell culture medium, and in the presence of A549 lung cells by a tandem of biological (live/dead cell test), physical nanoanalytical (TEM/EDX, SEM/EDX), and chemical (FT-IR, HR-ICP-MS) assays. More precisely, the impact of certain experimental conditions, viz., medium acidity and matrix effects on sorption capacity of the above-mentioned elements, was investigated in detail. Remarkably, a different attachment behavior during adsorption of chosen elements by alginate scaffolds was observed. In addition, we revealed an essential concentration dependent effect of loaded heavy metals and ruthenium on cultivated cells. The obtained data allow us to gain a deeper insight into the interactions occurring in the studied biomaterial-inorganic system. Moreover, the obtained dependencies can be widely used for the development of alginate-based membrane technology employed for the protection of environmental and biological samples from the toxic pollutants.

Selective metal extraction by biologically produced siderophores during bioleaching from low-grade primary and secondary mineral resources

Siderophores are a class of biogenic macromolecules that have high affinities for metals in the environment, thus could be exploited for alternate sustainable metal recovery technologies. Here, we assess the role of siderophores in the extraction and complexation of metals from an iron oxide-rich metallurgical processing residue and a low-grade primary Ni ore. Evaluation of the biological siderophore production by three pseudomonads, P. fluorescens, P. azotoformans and P. putida identified that P. putida could generate the highest siderophore yield, which was characterized as a hydroxamate and catecholate mixed-type pyoverdine PyoPpC-3B. Key physicochemical parameters involved in raw siderophore mediated metal extraction were identified using a fractional factorial design of experiments (DOE) and subsequently employed in purified PyoPpC-3B leaching experiments. Further targeted experiments with hydroxamate and catecholate functional analogues of PyoPpC-3B confirmed their marked ability to competitively or selectively leach and chelate hard metal ions, including Al(OH)4-, Mn2+ and Zn2+. Interestingly, complexation of Mn and Zn ions exceeded the natural affinity of pyoverdine for Fe3+, thus despite the low metal recoveries from the materials tested in this study, this work provides important new insights in siderophore-metal interactions.