Recovery Of Heavy Metals Research Articles

Removal of hexavalent Chromium-Industry treated water and Wastewater: A review

Heavy metals present in industrial effluents enter the biological cycle through aquatic organisms. Heavy metals undergo bioconcentration and prove to be toxic even in trace quantities. Chromium is necessary for carbohydrate metabolism, but in higher concentrations, it tends to be harmful. Hexavalent chromium Cr (VI) ions are prevalent, and its toxicity causes environmental and public health concerns. Chromium (IV) based industrial effluents have become a worldwide menace. This collection of toxic metals ions from effluent streams affects both humans and the environment. The non-depleting heavy metal ions cause severe damage to the environment. Environmental pollution affects both human life and eco-system. Water pollution from municipal sources and industries are matter of concern. The solution to the fast-depleting natural water bodies and acquifiers is to reuse treated effluent. Several remediation technologies are available, for reclaiming effluent after treatment for heavy metals like Cd, Cr, Cu, Hg, Ni, Pb, and Zn. This paper attempts to assimilate concise information on removing hexavalent chromium through laboratory experiments to implement cost-effective, plausible industrial treatments practically. The importance of efficient industrial effluent treatment lies in the recovery of heavy metals and usage of the treated effluent. A list of techniques is thought of for the treatment of heavy metals removal that has minimal impact on the environment in liquid / solid phases, cost of treatment, and scaling up to industrial levels. Adsorption is one of the prominent techniques used for heavy metals treatment. The adsorption kinetics and isotherms help understand the reduction of Cr (VI) from effluent streams. The wastewater treatment techniques currently employed treat hexavalent chromium-containing effluent streams with low-cost industrial byproducts. Emphasis is on novel techniques of wastewater treatment electrochemical techniques for Cr (VI), contributing to various environmental problems based on their toxicity.

Photoelectrochemical concurrent hydrogen generation and heavy metal recovery from polluted acidic mine water

The feasibility of a solar-driven photoelectrochemical process to generate hydrogen fuel from metal mine polluted water while simultaneously recovering heavy metals has been explored.

Progress, Challenges, and Perspectives of Bioleaching for Recovering Heavy Metals from Mine Tailings

The accumulation of mine tailings on Earth is a serious environmental challenge. The importance for the recovery of heavy metals, together with the economic benefits of precious and base metals, is a strong incentive to develop sustainable methods to recover metals from tailings. Currently, researchers are attempting to improve the efficiency of metal recovery from tailings using bioleaching, a more sustainable method compared to traditional methods. In this work, the research status of using biological leaching technologies to recover heavy metals from tailings was reviewed. Furthermore, CiteSpace 5.7.R2 was used to visually analyze the keywords of relevant studies on biological leaching of tailings to intuitively establish the current research hotspots. We found that current research has made recent progress on influencing factors and microbial genetic data, and innovations have also been made regarding the improvement of the rate of metal leaching by biological leaching combined with other technologies. This is of great significance for the development of bioleaching technologies and industrial production of heavy metals in tailings. Finally, challenges and opportunities for bioleaching provide directions for further research by the scientific community.

Investigation of competitive adsorption and desorption of heavy metals from aqueous solution using raw rock: Characterization kinetic, isotherm, and thermodynamic

Heavy metals are the most dangerous inorganic pollutants Due to their bioaccumulation and their nonbiodegradability, for this, several studies have focused on the recovery of these metals from water using different techniques. In this context, our study consists of evaluating an efficient and eco-friendly pathway of competitive recovery of heavy metals (Cd, Cr and As) from aqueous solutions by adsorption using raw rock. This adsorbent was characterized before and after the adsorption process by several techniques. The multi-metals adsorption process in the batch mode was undertaken to evaluate the effect of adsorbent mass, contact time, pH, Temperature, and initial heavy metals concentration. The kinetic data were analyzed using the pseudo-first-order, pseudo-second-order and intra-particle diffusion kinetic models. According to the modeling of the experimental results, the adsorption kinetics of heavy metals were adapted to the pseudo-second-order model. The adsorption isotherms were evaluated by the Langmuir and Freundlich isotherm models. The experimental isotherm data of heavy metals were better fitted with the Langmuir model rather than Freundlich isotherm models. The maximum experimental adsorption capacities (Qmax) predicted by the Langmuir model are 15.23 mg/g for Cd (II), 17.54 mg/g for Cr (VI) and 16.36 mg/g for As (III). The values of thermodynamic parameters revealed that the heavy metals adsorption was exothermic, favorable, and spontaneous in nature. The desorption process of heavy metals showed that this raw rock had excellent recycling capacity. Based on the results, these untreated clays can be used as inexpensive and environmentally friendly adsorbents to treat water contaminated by heavy metals.

Hydrometallurgical processes for heavy metals recovery from industrial sludges

Hydrometallurgical approaches have been successfully employed for metal separation and recovery from various types of waste materials. Therefore, hydrometallurgy is a promising technology for metal recovery and the removal of potentially toxic heavy metals found in industrial sludge. However, a comprehensive review that focuses on the heavy metal recovery from industrial sludge using hydrometallurgical approaches has not been conducted in the recent past. The present review discusses the capacity of hydrometallurgical techniques in recovering heavy metals sourced from different types of industrial sludges, highlighting recent scientific findings. Hydrometallurgical approaches primarily consist of three process stages: metal dissolution, concentration and purification, and metal recovery. The chemical characteristics of industrial sludge, including the type, concentration and speciation of heavy metals, directly impact selection of the best recovery method. Solvent extraction, ion-exchange, and adsorption are the major techniques employed in concentration and purification, whereas electrodeposition and precipitation are the main methods used in metals recovery. Future research should focus on the development of more efficient and environmentally-friendly methods for metal dissolution from industrial sludges contaminated with multiple metals, while increasing selectivity and energy use efficiency in the concentration and purification, and recovery steps.

Inventory of MSWI Fly Ash in Switzerland: Heavy Metal Recovery Potential and Their Properties for Acid Leaching

From the year 2021 on, heavy metals from Swiss municipal solid waste incineration (MSWI) fly ash (FA) must be recovered before landfilling. This is predominantly performed by acid leaching. As a basis for the development of defined recovery rates and for the implementation of the recovery process, the authorities and plant operators need information on the geochemical properties of FA. This study provides extended chemical and mineralogical characterization of all FA produced in 29 MSWI plants in Switzerland. Acid neutralizing capacity (ANC) and metallic aluminum (Al0) were additionally analyzed to estimate the effort for acid leaching. Results show that all FA samples are composed of similar constituents, but their content varies due to differences in waste input and incineration conditions. Based on their geochemical properties, the ashes could be divided into four types describing the leachability: very good (6 FA), good (10 FA), moderate (5 FA), and poor leaching potential (8 FA). Due to the large differences it is suggested that the required recovery rates are adjusted to the leaching potential. The quantity of heavy metals recoverable by acid leaching was estimated to be 2420 t/y Zn, 530 t/y Pb, 66 t/y Cu and 22 t/y Cd.

Novel PSt/PGMA/PIN ternary composite for SPE and analysis of some heavy metals in various cosmetics and food products by flame AAS

ABSTRACT In this investigation, a solid-phase extraction (SPE) process was improved for selective separation of Cr, Cu, Fe, Mn, Pb and Zn ions on novel ternary composite. These heavy metals were analyzed by flame atomic absorption spectrometry (Flame-AAS). To prepare the novel ternary composite, FeCl3was used as an oxidant agent in the chemical polymerization technique by formating polystyrene/polyglycidylmethacrylate/polyindole(PSt/PGMA/PIN) [25:25:50]. The structure of novel ternary composite was characterized by FTIR, TGA, X-RD and BET analysis technique. Themorphological surface analysis has been carried out by using SEM and AFM technique. Morphological studies have been show that composite has a smooth surface. To maximum recoveries of heavy metals, the optimum experimental conditions and analytical parameters were searched. These quantitative recoveries of analytes ions were determined at pH7. The detection limits (DL) were found as minimum of 0.9 μg/L and maximum 1.4 μg/L for Cr, Cu, Fe, Mn, Pb and Zn ions. Relative standard deviation (RSD) of the developed SPE process is below 3.3%. This improved SPE process is simple and selective. By the improved extraction method in which PSt/PGMA/PIN ternary composite used as solid phase, analyte ions were determined in certified reference material (CRM), various cosmetic and food products by flame AAS.

Treatment, reuse, leaching characteristics and genotoxicity evaluation of electroplating sludge

Electroplating sludge (ES) is a waste that is generated by the galvanization industry and is highly toxic because it contains heavy metals. This study examined the physiochemical properties of ES residue, the recovery of the present metals, and the reuse of these metals to add value to this residue and avoid environmental contamination through its inadequate disposal. The potential for leaching of ES was investigated using various tests, and a decrease in the germination speed of Lactuca sativa seeds and the appearance of chromosomal aberrations in the cytotoxicity tests were observed. The reduction of the pH and dynamic leaching conditions favor the leaching of ES heavy metals. An increase in the ES concentration in soil decreases the speed of germination and increases the number of chromosomal aberrations that are related to aneugenic phenomena that promote tumor development. Metals were recovered through solubilization, followed by selective precipitation. The recovery of heavy metals from ES decreased its toxicity by eliminating toxic components. The reuse of the metals in the electroplating process may reduce the cost of disposal of ES, thereby rendering it an economically and environmentally friendly alternative. The products that were galvanized using the recovered solution showed the best results in the corrosion test, thereby demonstrating the viability of the use of this solution in industrial galvanization.

Transformation behaviors and environmental risk assessment of heavy metals during resource recovery from Sedum plumbizincicola via hydrothermal liquefaction

Environmentally sound disposal of hyperaccumulator harvests is of critical importance to industrialization of phytoremediation. Herein, transformation behaviors and environmental risk of heavy metals were comprehensively examined during subcritical hydrothermal liquefaction of Sedum plumbizincicola. It is concluded that low temperature liquefaction favored resource recovery of heavy oil and hydrochars in terms of higher energy density, improved carbon sequestration and less energy consumption. Heavy metals were mainly distributed into hydrochars and water soluble phase with less than 10% in heavy oil. All metal elements except As could be accumulated in hydrochars by extending reaction time, whereas more than 96% of As was redistributed into water soluble phase. Prolonged liquefaction time facilitated immobilization of Cd, Cr and As in hydrochars, but fast liquefaction favored Pb stabilization. Liquefaction significantly reduced environmental risk level of Cd, Zn and As, but may mobilize Pb and Mn, especially for Mn to very high risk level at 240 ºC. High temperature with long reaction time tended to inhibit leaching rate of Mn, whereas low liquefaction temperature with short reaction time prevented the leaching of Zn and As from hydrochars. Overall, these findings are essential for downstream upgrading of heavy oil and metals recovery from hydrochars.

A Review of Micellar Enhanced Ultrafiltration Technique in the Removal of Heavy Metals from Aqueous Solutions

The pollution of the aquatic ecosystems with heavy metal ions has become a global problem in recent years. Heavy metals normally occur in nature and are essential to life at trace levels. However, they can be toxic when their concentrations exceed the upper permissible limits. Heavy metal contaminated habitats have the ability to bioaccumulate in aquatic ecosystems, which, in turn, may enter into the food chain and lead to health problems. Therefore, it is necessary to remove these heavy metals from aquatic ecosystems. Several technologies are already in operation, but these conventional technologies involve high operational costs and may produce harmful impacts on aquatic ecosystems. Micellar enhanced ultrafiltration (MEUF) is an alternative technique to remove the trace concentrations of heavy metals from aquatic ecosystems. The uniqueness of MEUF is that it requires less energy due to low membrane cost and working pressure. Although various researchers have been carried out the MEUF study on the removal of heavy metal ions, few review papers indicate the factors on MEUF technique. That is the reason why this article focuses on reviewing of different parameters such as membranes, surfactants, operating conditions in the MEUF technique. In this technique, heavy metal ions’ removal even at lower concentrations has reached over 99%, which is evidently demonstrated in the presented review. The use of water-soluble ligands in combination with MEUF is a hybrid process to remove selectively and enhance the recovery of heavy metals. As understood in this study, an investigation is needed to treat highly concentrated solutions and real wastewater.

Biosorption and removal of toxic heavy metals by metal tolerating bacteria for bioremediation of metal contamination: A comprehensive review

Heavy metal pollution caused due to the industrialization has been considered as a significant public health hazard, and these heavy metals exhibit various types of toxicological manifestations. Conventional remediation methods are expensive and also yield toxic by-products, which negatively affect the environment. Hence, a green technology employing various biological agents, predominantly bacteria, algae, yeasts, and fungi, has received more attention for heavy metal removal and recovery because of their high removal efficiency, low cost, and availability. However, bacterial biosorption is the safest treatment method for the toxic pollutants that are not readily biodegradable such as heavy metals. Metal biosorption by bacteria has received significant attention due to a safe, productive, and feasible technology for the heavy metal-containing wastewater treatment. These metal tolerating bacteria can bind the cationic toxic heavy metals with the negatively charged bacterial structures and live or dead biomass components. Due to the large surface area to volume ratio, these bacterial biomasses efficiently act as the biosorbent for metal bioremediation under multimetal conditions. This review summarizes the biosorption potentials of bacterial biomass towards different metal ions, cell wall constituent, biofilm, extracellular polymeric substances (EPS) in metal binding, and the effect of various environmental parameters influencing the metal removal. Suitable mathematical models of biosorption and their application have been discussed to understand and interpret the adsorption process. Furthermore, different desorbing agents and their utilization in heavy metals recovery and regeneration of biosorbent have been summarized.

Metal Accumulation Using a Bacterium (K-142) Identified from Environmental Microorganisms by the Screening of Au Nanoparticles Synthesis.

The use of technology that uses organisms to synthesize metal nanoparticles is necessary to maintain a sustainable society. In this study, we investigated and screened the microorganisms isolated from environmental water by quantifying the reproducibility of synthetic Au nanoparticles and the ability of large amount synthesis. The microorganism (K-142) of the Bacillus genus showed the best activity in the investigation. K-142 can also synthesize Ag, CdS and PbS nanoparticles, and the deposition efficiency of Ag, Al, Cd, Cu, and Pb was about 64.8–99.2%. According to the observation results under the microscope after fluorescent staining, K-142 could survive after being treated with 0.5 mM metal solution for 24 h. Therefore, it is expected that K-142, which is easy to cultivate, would also have a high ability to reduce and deposit metal substances. K-142 can be applied to the concentration and recovery of heavy metals in environmental water, thereby opening up channels for biological water purification.

Continuous removal and recovery of metals from wastewater using inverse fluidized bed sulfidogenic bioreactor

Acid mine drainage (AMD) is a serious environmental hazard in many countries with historic or ongoing mining industries. Biological sulfide precipitation is an emerging technique for both removal and recovery of heavy metals from such wastewater. This study demonstrated heavy metal removal and recovery from synthetic wastewater containing Cd2+, Cu2+, Fe3+, Ni2+, Pb2+ and Zn2+ using two continuously operated sulfidogenic anaerobic inverse fluidized bed reactors (referred as R1 and R2) supplied with an influent of pH 7.0 and 3.0, respectively. In case of R1, more than 95% metal removal efficiency was achieved for all the metals except for Fe3+ (90%) and Ni2+ (85%), and in case of R2 the removal was more than 90% for all the metals except with Fe3+ (88%) and Ni2+ (82%). The metals were subsequently recovered in the form of metal nanopowder from the reactor bottom and equalizer, and the metal recovery was in the order: Cu > Pb > Cd > Zn > Ni > Fe. However R1 yielded a good recovery percentage (50–65%) of the metals in comparison with the reactor supplied with influent of pH 3.0 (46–55%). The presence of immobilized sulfate reducing bacteria onto the support material in the bioreactors were identified using field emission scanning electron microscopy. The size and shape of the biometal nanoparticles were confirmed using field emission transmission electron microscopy, which revealed their excellent potential for industrial application. This study demonstrates successful recovery of metal sulfides in the form of nanoparticles using IFBR.

Extracellular Polymeric Substance Produced by Lysinibacillus sp. SS1 in Response to Petroleum Crude Oil Stress Facilitates Removal of Heavy Metals from Aqueous Solutions

The use of microbial extracellular polymeric substances (EPS) as bioflocculants opposed to synthetic and organic flocculants in the treatment of heavy metal polluted wastewater is currently gaining importance. The present study focuses on the characterization and application of EPS produced by Lysinibacillus sp. SS1 in heavy metal removal. Lysinibacillus sp. SS1 (10%v/v), isolated from used engine oil contaminated soil, produced EPS and circular white spongy masses on the utilization of 3% petroleum crude oil (PCO) in the Bushnell Haas medium in 10 d. Analysis of extracted EPS and masses revealed that it contained carbohydrates, lipids, and proteins in proportions of 1.3: 94.6: 3.6 and 2.3: 91.5: 6.2, respectively. Characterization by LCMS and FT-IR analysis confirmed that they were predominantly lipids with proteins and polysaccharide groups. Masses could remove 48% of lead and 40% of mercury from aqueous solutions by adsorption on their surface as confirmed by SEM-EDAX. Extracted EPS (100 mg/L) could remove 94.9% of lead from aqueous solution (150 mg/L) in 72 h by precipitation of lead as nanoparticles of sizes ranging from 30–40 nm. This study shows the potential of Lysinibacillus sp. SS1 and its EPS in response to PCO in heavy metal removal and recovery.

Ethylenediamine-functionalized Zr-based MOF for efficient removal of heavy metal ions from water

Ethylenediamine-functionalized Zr-based metal-organic framework (MOF, UiO-66-EDA) was prepared via Michael addition reaction to investigate its potential for adsorption of heavy metal ions from water. Specifically, the influence of agitation time, solution pH, the dosage of the adsorbent, initial metal ion concentration, temperature, and coexistence of other metal ions was investigated on the removal efficiency of UiO-66-EDA towards Pb(II), Cd(II), and Cu(II) metal ions. The pseudo-second-order kinetic model governed the adsorption of these ions onto the UiO-66-EDA. Langmuir isotherm model matched the experimental isotherm of adsorption with a maximum adsorption capacity of 243.90, 217.39, and 208.33 mg/g for Pb, Cd, and Cu ions, respectively. The adsorption of Pb, Cd, and Cu ions onto UiO-66-EDA was dependent on electron exchange, electron sharing, electrostatic and covalent interactions between the metal ions as well as the abundant functional groups on UiO-66-EDA surface. Thermodynamic parameters such as free energy changes (ΔG), standard enthalpy changes (ΔH), and standard entropy changes (ΔS) were calculated, which revealed spontaneous and endothermic nature of the adsorption process. The UiO-66-EDA was stable and recyclable during adsorption studies of Pb, Cd, and Cu ions, suggesting its potentiality as an adsorbent for heavy metals recovery.

Recovery of Heavy Metals from Liquid Effluent by Galvanic Cementation

Copper was recovered from copper sulfate solution in a batch-recycled galvanic reactor operated under forced convection with the generation of electrical energy during the cementation process. The divided galvanic cell consisted of parallel copper and zinc plates. The mass transfer rate and the amount of electrical energy generated were found to be directly proportional to the solution flow rate and the initial concentration of metallic ions and inversely proportional to the distance between electrodes. The experimental results were expressed in terms of a dimensionless correlation including all parameters. The wastewater treatment presented herein cell can be utilized to recover many soluble heavy metal ions from solution with high efficiency.

Facile conversion of nickel-containing electroplating sludge into nickel-based multilevel nano-material for high-performance pseudocapacitors

The recovery of heavy metals from electroplating sludge is an important technology, which can not only reduce environmental pollution, but also serve as a secondary source of metals. However, the current techniques are either non-selective or difficult to operate, which limits its applications in recovery technologies. Herein, based on the existence of multiple metal ions in electroplating sludge, Fe and Al co-doped ultrathin α-Ni(OH)2 nanosheets embedded in Ni(HCO3)2 nanowire assembly spheres were prepared by adjusting the ratio of urea under hydrothermal condition. Under the optimum conditions, the recovery of Ni, Fe, and Al are 92.58%, 81.52%, and 61.19% respectively. In addition, at the current density of 1 A g−1, the specific capacitance of the spherical composite electrode is as high as 495.6 C g−1, and the retention rate of the initial capacity is 55.58% after 3500 cycles in 6 M KOH electrolyte, showing good cycling stability. Furthermore, the ASC device (NN-4//AC) achieved a high energy density of 30.27 Wh kg−1 at a power density of 0.37 kW kg−1. A new method for converting electroplating sludge into nickel-based energy storage materials was developed, which provided a new strategy and idea for the harmless and resourceful treatment of electroplating sludge.

Usage of microbial combination degradation technology for the remediation of uranium contaminated ryegrass

Post phytoremediation accumulation of heavy metals in plants is causing an environmental issue worldwide. In this study, we investigated the ability of eight different kinds of microorganisms to degrade and release heavy metals from heavy metal enriched ryegrass, including 5 species of bacteria (Bacillus subtilis, Bacillus licheniformis, Bacillus pumilus-I, Bacillus pumilus-II and Bacillus cereus) and 3 of fungi (Phanerochaete chrysosporium, Trichoderma ressei and Pterula sp. strain QD-1), by growing them under uranium stress and assessing their ability to degrade biomass. After 30 days, the degradation ability of fungi was found better than that of bacteria, while the metal leaching ability of bacteria was found better. The highest degradation rate (upto 60%) was obtained by using P. chrysosporium, Pterula sp. strain QD-1 exhibited the best leaching rate for uranium (upto 77%). The overall degradation rate of lignin and cellulose and hemicellulose was found lower (40% and 60%, respectively). According to the antagonistic characteristics of microbes, we combined different dominant species, in which under optimal conditions the T2 combination (P. chrysosporium, T. reesei, and Pterula sp. strain QD-1 and B. subtilis) was able to degrade 80% of the ryegrass, 51% of lignin, 74% of cellulose and hemicellulose, releasing 78% of U, 90% of Pb and the releasing rate of other heavy metals was more than 95%. FTIR analysis showed the least degradation of lignin, while SEM-EDX analysis of the degradation residues displayed the microstructure of ryegrass being greatly damaged. Only a small amount of U was found in the residues of the researched combinations. This study provides efficient Microbial Combined Degradation Technology for heavy metal enriched biomass, which can effectively deal with heavy metal enriched plants, and provide a basis for the recovery and utilization of heavy metals, avoiding secondary pollution in the environment caused by this type of biomass.

Preparation of green biosorbent using rice hull to preconcentrate, remove and recover heavy metal and other metal elements from water

Sodium hydroxide treated rice hulls were investigated to preconcentrate, remove, and recover metal ions including Be2+, Al3+, Cr3+, Co2+, Ni2+, Cu2+, Zn2+, Sr2+, Ag+, Cd2+, Ba2+, and Pb2+ in both batch mode and column mode. Sodium hydroxide treatment significantly improved the removal efficiency for all metal ions of interest compared to the untreated rice hull. The removal kinetics were extremely fast for Co, Ni, Cu, Zn, Sr, Cd, and Ba, which made the treated rice hull a promising economic green adsorbent to preconcentrate, remove, and recover low-level metal ions in column mode at relatively high throughput. The principal removal mechanism is believed to be the electrostatic attraction between the negatively charged rice hulls and the positively charged metal ions. pH had a drastic impact on the removal for different metal ions and a pH of 5 worked best for most of the metal ions of interest. Processed rice hulls provide an economic alternative to costly resins that are currently commercially available products designed for metal ion preconcentration for trace metal analysis, and more importantly, for toxic heavy metal removal and recovery from the environment.

Recovery of chromium, copper and vanadium combined with electricity generation in two-chambered microbial fuel cells.

Microbial fuel cells (MFCs) offer a promising solution towards recovery and treatment of heavy metal pollutants. In this study, two-chambered MFCs were employed for recovery of chromium, copper and vanadium (Cr (VI), Cu (II) and V (V)). One g/L concentrations of K2Cr2O7, CuCl2 and NaVO3 served as catholytes, while a mixed culture was used as anolyte. Cr (VI), Cu (II) and V (V) were reduced biologically into less toxic forms of Cr (III), Cu and V (IV) respectively. Power density and cathodic efficiency were calculated for each of the catholytes. Cr (VI) gave the maximum power density and cathodic efficiency due to its high redox potential. Current produced depended on the concentration of the catholyte. Over a period of time, biological reduction of catholytes lead to decrease in the metal concentrations, which demonstrated the application of MFC technology towards heavy metal treatment and recovery in a reasonably cost-effective manner.