Metal Removal Research Articles

Unlocking the potential of biochar: an iron-phosphorus-based composite modified adsorbent for adsorption of Pb(II) and Cd(II) in aqueous environments and response surface optimization of adsorption conditions.

In this work, iron-phosphorus based composite biochar (FPBC) was prepared by modification with potassium phosphate and iron oxides for the removal of heavy metal ions from single and mixed heavy metal (Pb and Cd) solutions. FTIR and XPS characterization experiments showed that the novel modified biochar had a greater number of surface functional groups compared to the pristine biochar. The maximum adsorption capacities of FPBC for Pb(II) and Cd(II) were 211.66mg·g-1 and 94.08mg·g-1 at 293K. The adsorption of Pb(II) and Cd(II) by FPBC followed the proposed two-step adsorption kinetic model and the Freundlich isothermal adsorption model, suggesting that the mechanism of adsorption of Pb(II) and Cd(II) by FPBC involved chemical adsorption of multiple layers. Mechanistic studies showed that the introduction of -PO4 and -PO3 chemisorbed with Pb(II) and Cd(II), and the introduction of -Fe-O increased the ion exchange with Pb(II) and Cd(II) during the adsorption process and produced precipitates such as Pb3Fe(PO4)3 and Cd5Fe2(P2O7)4. Additionally, the abundant -OH and -COOH groups also participated in the removal of Pb(II) and Cd(II). In addition, FPBC demonstrated strong selective adsorption of Pb(II) in mixed heavy metal solutions. The Response Surface Methodology(RSM) analysis determined the optimal adsorption conditions for FPBC as pH 5.31, temperature 26.01°C, and Pb(II) concentration 306.30mg·L-1 for Pb(II). Similarly, the optimal adsorption conditions for Cd(II) were found to be pH 5.66, temperature 39.34°C, and Cd(II) concentration 267.68mg·L-1. Therefore, FPBC has the potential for application as a composite-modified adsorbent for the adsorption of multiple heavy metal ions.

Optimizing 2D MoS2 for removal of anionic heavy metals from water: insights from density functional theory study

Optimizing 2D MoS2 for removal of anionic heavy metals from water: insights from density functional theory study

Punica granatum and Citrus limetta biowaste-derived sorbents for the removal of heavy metals and organic compounds: sustainability perspectives

Punica granatum and Citrus limetta biowaste-derived sorbents for the removal of heavy metals and organic compounds: sustainability perspectives

Heavy metals removal in a graphene engineered concrete-based filter column

In this study, crushed aggregate surfaces were coated with reduced graphene oxide (RGO) using a chitosan-derived solution and included in porous concrete-based filter column samples to improve heavy metal removal. The RGO coating strengthened the aggregate and cement interfaces, thus improving the compressive strength of these samples by up to 18 %. The removal of lead and copper in samples containing RGO coated aggregate (GCA) operated with a minimum hydraulic load was found to be 97 % and 92 %. Increasing the hydraulic load reduced this heavy metal removal, but the presence of GCA increased the active sites for heavy metal ions to immobilize, leading to improved copper removal under such operating conditions. Calcium ions from the cement hydrates were found to leach from the concrete matrices during such a wastewater passage. This leaching of calcium ions was determined to be relatively lesser in RGO decorated concrete samples, pointing out the positive effects of GCA on the resistance of the concrete matrices to aggressive chemicals. Clay particles containing highly turbid water were also passed through these concrete samples to examine the effects on the infiltration rate. Clay particles were found to clog pores, marginally reducing the infiltration rate. Concrete-based water filters are easy to operate and have low maintenance requirements, and industries responsible for heavy metal pollution in aquatic environments can widely adopt them instead of complex treatment methods.

Novel chitosan-modified biochar prepared from a Chinese herb residue for multiple heavy metals removal: Characterization, performance and mechanism

In this study, the sorption properties of Cr(VI), As(III), and Pb(II) on chitosan-modified magnetic biochar (CMBC) derived from residues of Ligusticum chuanxiong Hort. were investigated. CMBC was found to be a valuable material for removing three heavy metals from water simultaneously. Kinetic analysis suggested Cr(VI), As(III), and Pb(II) were chemisorbed onto CMBC, while isotherm data conformed well to Langmuir model, the maximum adsorption capacity of CMBC was found to be 65.74 mg/g for Cr(VI), 49.32 mg/g for As(III), and 69.45 mg/g for Pb(II). Experiments, characterization, and density functional theory (DFT) calculations were employed to explore the mechanisms. Furthermore, CMBC demonstrated excellent removal rates of over 95% for Cr(VI), 99% for As(III) and Pb(II) from contaminated water bodies. This work shows that CMBC holds significant potential for wastewater treatment of heavy metals and provides an effective solution for the utilization of Chinese herb residues in environmental remediation.

Bioremediation potential of microalgae for copper ion from wastewater and its impact on growth and biochemical contents: Equilibrium isotherm studies

Abstract In this study, the green microalgae Chloroidium ellipsoideum and Desmodesmus subspicatus were used to study copper uptake from nutrient media and its effect on algal growth and metabolism. The growth of C. ellipsoideum and D. subspicatus generally decreased with increasing copper concentrations. There was a decrease in the carbohydrate content of C. ellipsoideum , but an increase was observed in D. subspicatus by treatment with various copper concentrations. Low concentrations of copper helped to increase the protein content of C. ellipsoideum , but a decline in protein content was reported for D. subspicatus. By increasing the copper concentrations, an increase in the free amino acids and a decrease in the total lipid content of C. ellipsoideum and D. subspicatus were recorded. At 0.1 mgl–1,the maximum reduction of Cu2+ was 68.66% and 59.52% for C. ellipsoideum and D. subspicatus. The Langmuir, Freundlich, Temkin and Dubinin–Radushkevich models were applied to describe the isothermal biosorption of Cu2+ ions in studied algae. The Dubinin–Radushkevich model indicated that the copper biosorption mechanism was physical in nature. Cu2+ has a greater affinity for D. subspicatus than C. ellipsoideum , suggesting that C. ellipsoideum was relatively more resistant to Cu2+ toxicity than D. subspicatus. FT-IR analysis revealed that carboxyl, amide, amino, carbonyl, hydroxyl, methyl and alkyl groups were the key groups responsible for the biosorption process. Therefore, D. subspicatus and C. ellipsoideum are efficient biosorbents for Cu2+ and can be used as biosorbents for heavy metals removal from wastewater.

Demineralization effects on physicochemical and combustion characteristics of biomass: Insights into distributed kinetics, flue gas evolution, and slag formation

Biomass as the only carbon-bearing renewable energy has enormous potential to challenge the established energy structure dominated by fossil resources, and incineration technology is one of the most direct and efficient pathways for utilizing biomass resources, unfortunately enduring the inevitable sintering and slagging problems owing to the excessive alkali metals. Herein, we comparatively investigated the effects of five leaching solvents (water, acetic acid, wood vinegar, hydrochloric acid, and oxalic acid) on the physicochemical properties and ash-removal capabilities of wheat straw (WS) and rice husk (RH), with a view to achieving better performance in the subsequent combustion characteristics, kinetic examination, flue gas, and slag evolution. Results indicated with ionization ability increased (water < acetic acid < hydrochloric acid), the WS exhibited a strong demineralization performance (maximum 61.1%), further leading to a steep weight loss in its combustion characteristic curve at approximately 350 °C and a delayed peak temperature after the removal of alkali metal. Multiple distributed activation energy model and sensitivity analysis revealed that leaching pretreatment enhanced the activation energy (189–191.8 kJ mol−1) and optimized energy distribution at the preliminary stage of the combustion reaction. In addition, the absence of alkali metals suppressed the catalytic oxidation reaction in the flue gas, remarkably limiting the formation of CO2 but facilitating the release of CO and CH4. Meanwhile, a considerable optimal in biomass ash slagging, in which the initial temperature of the liquid phase slag for WS ash increased to 991 °C. Notably, HCl showed the strongest demineralization performance among the five leaching solvents during pretreatment, but the high-temperature slag content was still higher than that of acetic acid. Therefore, slagging performance is not only associated with the demineralization ability of leaching solvents, but also with ash composition.

Investigation on applying sapropel for removal of heavy metals (cadmium, chromium, copper, and zinc) from aqueous solutions

Sapropel is a layer of sediment composed of organic and inorganic substances that accumulates at the bottom of lakes. The water of such lakes often have elevated levels of heavy metals such as Cd, Cr, Cu, and Zn, which can pose risks to human health. Sapropel may be used as a biosorbent in removing these heavy metals from aqueous solutions. Various doses of sapropel ranging from 1 to 50 g/L and different mixing times from15 to150 minutes have been tested. The maximum removal efficiencies for Cd (93%), Cr (31%), Cu (84%), and Zn (84%) from aqueous solutions were achieved using the minimum doses of sapropel (50 g/L). The study has shown that mixing sapropel for 15 minutes is sufficient for the removal of Cr, 30 minutes for Cd and Cu, and 60 minutes for Zn.

Coupling of bioleaching and electrokinetic soil flushing for the in-situ removal of impurity from Pb-Zn mine tailings

This study combines bioleaching and electrokinetics (EK) for the in-situ removal of metals from polluted mine tailings collected from an abandoned Pb-Zn mine. The proposed treatment strategy consisted in the external production of an acid bioleaching (BL) medium in a bioreactor by means of autochthonous acidophilic microorganisms incubated from real mine tailings; next, the BL medium was subsequently used as anolyte and placed in contact in situ with the polluted soil, taking advantage of EK mechanisms r for dissolution and transport of metals to the cathode compartment. After obtaining a microbial culture capable of producing the bioleaching medium, lab-scale EK experiments were performed, and the influence of the voltage dosage (0.5, 1.0 and 1.5 V cm−1) was assessed. The results obtained showed that the BL medium improved the metal removal efficiency, and that the applied voltage gradient had a clear influence. Specifically, the combination of an electric current under 1.5 V cm−1 and the BL medium increased the metal removal rates by 17 % (Fe), 4 % (Cu), 2 % (Zn), 12 % (Mn), 12 % (Ni), 1 % (Cr) and 7 % (Co), as compared to those without using BL. With this novel treatment, it was also possible to comply with the local regulatory requirements for most of the metals studied. This technology offers several advantages over other EK-bioleaching configurations previously reported. It was found that the limiting factor in the process was the voltage gradient applied, as higher voltages increased metal removal yields but also producing higher soil heating with the consequent energy losses.

Effect of pH on degradation and mineralization of catechol in calcium-aid ozonation: Performance, mechanism and products analysis

Catechol, common in industrial wastewater, is very toxic and non-biodegradable, and its desirable removal is still a challenge. Catalytic ozonation as an effective advanced oxidation process, however was limited by the application of intricately fabricated catalysts. Herein, catalytic ozonation by OH– (generated by common sodium hydroxide) with the aid of calcium was developed for catechol degradation and mineralization in this study. The removal performance, mechanism and products were investigated. The results showed that ozonation at pH 12.5 could achieve complete catechol removal and excellent mineralization (maximum of 75 % COD removal efficiency) within 15 min. The adorable effect of calcium for enhanced organics removal was observed at pH 12.5, with the formation of precipitates as well. Catechol and COD removal were fitted to the pseudo-first-order kinetic model, while the reaction constant was increased by higher pH and calcium concentration. The results of quenching experiment and EPR affirmed •OH and •O2– radicals were pivotal for the enhanced organics removal. In addition, DFT calculation revealed the O atoms were reactive sites for electrophilic and radical attack via molecular electrostatic potential, highest occupied molecular orbital, lowest unoccupied molecular orbital and Fukui index. UPLC-Q-TOF-MS analysis revealed the intermediate products and verified the brilliant performance of catalytic ozonation. According to reactive sites and intermediates identification, the degradation pathway of catechol was proposed. As tawny precipitate appeared after reaction, the characteristics of insoluble product was analyzed using FTIR, XRD and XPS. The component of the precipitate was recognized as calcium oxalate and calcium carbonate, accompanied by the decreased Ca2+ concentration at high pH, which declared the enhanced removal was linked to the precipitation of Ca2+. Finally, toxicity assessment stated the lower acute toxicity, bioconcentration factor, developmental toxicity and mutagenicity of intermediates, indicating that calcium-aid ozonation catalyzed by high pH was useful for both catechol degradation and toxicity reduction. This study provides a reference for understanding the performance and mechanism of catechol degradation. More importantly, as an environmentally friendly process, catalytic ozonation possesses a great application potential for treatment of wastewater containing metal ions in terms of simultaneous removal of organics and metal ions.

Exfoliated MXene nanosheet by double layer forces for preparing magnetic adsorbents of toxic metal ions and recycling with hyperthermic effect

The conventional etching method for exfoliating MXene using hydrofluoric acid solution is time-consuming and inefficient in productivity. A double layer force is generated through polarization among the heterogeneous layers of MXene due to their different dielectric properties. The exfoliated MXene by the polarization method in an acidic solution was employed to synthesize magnetic MXene (MXFe) with Fe3O4 nanoparticles. MXFe was coated on polyacrylonitrile microspheres (PANs) as precursors (PAN@MXFe) by Pickering emulsion polymerization. The core@shell polyvinyltetrazole@MXFe (PVT@MXFe) was obtained as the adsorbent after subsequent cyano-tetrazole conversion of PAN@MFs for the removal of toxic metal ions. The maximum adsorption capacities of Hg(II) on the MXFe and PVT@MXFe coating 2 wt% of MXFe were 579 and 324 mg/g, respectively, indicating the high use efficiency of MXFe. At 8.5 kHz of high frequency, hyperthermia occurs on the PVT@MXFe, facilitating the desorption of the toxic metal ions from the adsorbents. Compared with reuse using an acidic solution, the PVT@MXFe can be reused repeatedly 10 times without obvious damage under the AMF. Our proposed polarization exfoliation method not only provides a novel methodology to exfoliate MXene but also develops an ideal adsorbent for universal adsorption, simple separation, stable regeneration, and low secondary pollution.

Heavy Metal Ion Adsorbent in Aqueous Solution: A Review on Chitosan and Chitosan Composites

One prominent contributor to environmental degradation is the presence of heavy metal ions, which are commonly introduced into ecosystems through diverse channels, including mining operations, paint manufacturing, battery production, and agricultural practises. The unprocessed waste from these industries typically undergoes direct discharge into rivers and seas, thereby adversely influencing the potable water supply and marine ecosystem. This results in the accumulation of heavy metals within living organisms and subsequent environmental degradation that poses a significant risk to human health, as their prolonged consumption can harm various organs and the nervous system. Therefore, the United States Environmental Protection Agency (US-EPA) and the World Health Organisation (WHO) have established stringent regulations regarding the allowable levels of heavy metal intake, particularly concerning potable water consumption. The imperative lies in surmounting this challenge by discovering the optimal technique for extracting heavy metals. This paper examines the primary methods of eliminating heavy metal ions using chitosan-based materials. Specifically, the methods under scrutiny include electrocoagulation (E.C.), bioremediation, ion-exchange, membrane filtration (purification), and adsorption. Adsorption, as a highly efficient method, presents itself as a viable strategy for the remediation of dyes in textile wastewater due to its advantageous characteristics. Notably, this approach obviates the need for extensive spatial requirements and exhibits a commendably swift treatment duration. Chitosan exhibits promising adsorptive characteristics owing to its advantageous physical attributes, including crystalline structure, porous nature, and particle dimensions, all of which synergistically enhance the adsorption capacity of chitosan. Research findings indicate that the adsorption characteristics of chitosan are subject to variation contingent upon the distinct heavy metal ions under consideration and the specific experimental parameters employed. Hence, optimising these parameters becomes imperative to attain enhanced chitosan adsorption capabilities for heavy metal ion removal.

Heavy metal application of response surface optimized-lipopeptide biosurfactant produced by Pseudomonas aeruginosa strain CGA-02 in low-cost substrate

Cost-effective methods of biosurfactant production with minimal environmental impact are needed as global demand continues to increase. This study evaluated lipopeptide biosurfactant production in a Pseudomonas aeruginosa strain CGA-02 using a low-cost carbon substrate. The structural properties of the biosurfactant and applicability of the biosurfactant in heavy metal removal were evaluated. Response surface methodology (RSM) involving central composite design (CCD) was used to optimize process parameters to maximize biosurfactant production. The study identified sugar cane molasses and sodium nitrate as carbon and nitrogen sources of choice for bacterial growth and biosurfactant production, with a relatively 2.64-fold increase in biosurfactant yield under optimized conditions. Analysis of the biosurfactant measured a surface tension reduction of water from 72.2 ± 0.26 to 30.5 ± 0.2 mN/m at 40 mg/L critical micelle concentration. GC–MS and FTIR analysis revealed structural properties of the lipopeptide biosurfactant, with fatty acid components predominantly 9-octadecenoic acid (oleic acid), n-hexadecanoic acid, cyclotetrasiloxane and trimyristin, and infrared peaks belonging to amine, carboxyl, nitrile, alkanol, ether and carbonyl groups. Capture of heavy metals using the biosurfactant was evaluated in soil microcosms. Removal rates of 80.47, 100, 77.57, 100, and 97.57% were recorded for As, Pb, Hg, Cd and Cr respectively after 12 weeks of incubation. There was no significant difference (p < 0.05) in the removal efficiency of the biosurfactant and an analogous chemical surfactant, sodium dodecyl sulphate. First and second-order kinetic models described heavy metal removal rates by the biosurfactant. We demonstrate the production of a useful biosurfactant using low-cost waste carbon.

Removal of metal ions by adsorption on Al based metal organic frameworks

The electroplating wastewater contains heavy metals at levels that considered to be hazardous to the surrounding environment and is risky to public health. Herein, removal of Cu(II) and Ag(I) ions from the wastewater was studied by using Al-based metal organic frameworks (Al-MOFs). Using different organic linkers, three different Al-MOFs were synthesized and namely Al-BDC-H, Al-BDC-COOH Al-BDC-SO3H. The synthesized Al-MOFs showed with different geometrical shapes represented in plate-like, flacks-like and agglomerated particles structures for Al-BDC-H, Al-BDC-COOH and Al-BDC-SO3H, respectively. The three synthesized Al-MOFs were applied in removal of Ag(I) and Cu (II) ions from wastewater and the adsorption followed the order of Al-BDC-H < Al-BDC-COOH < Al-BDC-SO3H. The obtained Al-MOF showed higher affinity for Ag(I) ions compared with Cu (II) ions. At using of Al-BDC-SO3H, the maximum adsorption capacities were 214.9 mg/g for Ag(I) ions and 134.5 mg/g for Cu (II) ions. In comparison with Al-BDC-H and Al-BDC-COOH, the adsorption capacity was enlarged by factor of 3.4 – 3.7 and 1.7 – 1.9 by applying of Al-BDC-SO3H, respectively. After 5 recycles, the adsorption capacity of Al-BDC-SO3H was lowered by 15.3–––17.8 %. The applied Al-BDC-SO3H exhibited higher adsorption capacities with good stability compared with Al-BDC-H and Al-BDC-COOH.

Recycling lithium-ion battery graphite: Synthesis of adsorbent materials for highly efficient removal of dye and metal ions from wastewater

The fate of residual graphite derived from hydrometallurgical treatment of spent Lithium-ion batteries remains uncertain. This study dwells on the aim of identifying the potentialities of recycling residual graphite for wastewater treatment. Graphite was recovered hydrometallurgically, and new adsorption materials: graphite oxide (GO) and graphene oxide (GrO) were synthesized from the residual graphite using the chemical oxidization method. Synthesized materials showed higher interlayer spacings (GO = 0.81 nm, GrO = 0.78 nm) than the commercially available similar materials. Adsorption studies revealed higher adsorption capacities for both dye (>550 mg/g in all cases) and metal ions (highest ∼93 mg/g for Ni2+ and lowest ∼68 mg/g for Zn2+). GrO showed superior results than GO due to its high surface area and porosity despite GO having more functional groups. Moreover, produced materials showed about 97 % removal of dye and about 94 % removal of contaminated metals which are higher performance than existing commercial or similar materials. These findings highlight the promising recycling capabilities of waste graphite and suggest its potential as a substitute for natural graphite.

Nanocellulose-Based Adsorption for the Removal of Heavy Metal from Wastewater—A Review

Nanocellulose-Based Adsorption for the Removal of Heavy Metal from Wastewater—A Review

High-performance thin film composite forward osmosis membrane for efficient rejection of antimony and phenol from wastewater: Characterization, performance, and MD-DFT simulation

The effective removal of heavy metals and phenolic pollutants from aqueous solutions has received widespread attention in the field of wastewater treatment. In this work, a novel PAN/CNTs/UiO-66-NH2 modified forward osmosis (FO) membrane was prepared for efficient removal of antimony (Sb) and phenol from wastewater. The membrane was synthesized using a facile and cost-effective method. The PAN/CNTs substrate membrane was prepared using electrospinning technology, and UiO-66-NH2 MOF particles were loaded onto the surface of the active layer during the interfacial polymerization (IP) process. The presence of CNTs in the spinning solution regulated the pore structure and properties of nanofibers. Characterization of the membrane confirmed its unique structure and enhanced properties. When the CNTs addition was 0.01 g, and UiO-66-NH2 addition was 0.05 wt%, the FO membrane exhibited the optimal operational performance. In the AL-FS mode, the water flux, reverse salt flux (RSF), and Js/Jw ratio were 14.68 LMH, 0.17 gMH, and 0.01 g/L, respectively. As a comparison, the water flux, RSF, and Js/Jw ratio were 21.19 LMH, 0.65 gMH, and 0.032 g/L in the AL-DS mode, respectively. Simultaneously, efficient removal of antimony and phenol was achieved in both modes, with antimony removal efficiencies of 99.26 % and 97.98 %, and phenol removal efficiencies of 96.61 % and 93.18 %, respectively. The modified membrane exhibited excellent performance in rejecting Sb and phenol. Molecular dynamics simulations and density functional theory calculations provide theoretical support for the excellent performance of membranes. The membrane demonstrated a high water flux, making it promising for practical applications. Additionally, it exhibited remarkably low reverse salt flux, highlighting its suitability for desalination processes. The exceptional removal efficiency of Sb and phenol, coupled with the membrane's impressive hydraulic performance, makes it a promising candidate for the treatment of industrial effluents containing these challenging contaminants. The results presented in this study underscore the potential of PAN/CNTs/UiO-66-NH2 FO membranes as an advanced solution for addressing water pollution challenges.

Nano-revolution in heavy metal removal: engineered nanomaterials for cleaner water

Engineered nanomaterials have emerged as a promising technology for water treatment, particularly for removing heavy metals. Their unique physicochemical properties enable them to adsorb large quantities of metals even at low concentrations. This review explores the efficacy of various nanomaterials, including zeolites, polymers, chitosan, metal oxides, and metals, in removing heavy metals from water under different conditions. Functionalization of nanomaterials is a strategy to enhance their separation, stability, and adsorption capacity. Experimental parameters such as pH, adsorbent dosage, temperature, contact time, and ionic strength significantly influence the adsorption process. In comparison, engineered nanomaterials show promise for heavy metal remediation, but several challenges exist, including aggregation, stability, mechanical strength, long-term performance, and scalability. Furthermore, the potential environmental and health impacts of nanomaterials require careful consideration. Future research should focus on addressing these challenges and developing sustainable nanomaterial-based remediation strategies. This will involve interdisciplinary collaboration, adherence to green chemistry principles, and comprehensive risk assessments to ensure the safe and effective deployment of nanomaterials in heavy metal remediation at both lab and large-scale levels.

Cellulose-Based Hydrogels for Wastewater Treatment: A Focus on Metal Ions Removal.

The rapid worldwide industrial growth in recent years has made water contamination by heavy metals a problem that requires an immediate solution. Several strategies have been proposed for the decontamination of wastewater in terms of heavy metal ions. Among these, methods utilizing adsorbent materials are preferred due to their cost-effectiveness, simplicity, effectiveness, and scalability for treating large volumes of contaminated water. In this context, heavy metal removal by hydrogels based on naturally occurring polymers is an attractive approach for industrial wastewater remediation as they offer significant advantages, such as an optimal safety profile, good biodegradability, and simple and low-cost procedures for their preparation. Hydrogels have the ability to absorb significant volumes of water, allowing for the effective removal of the dissolved pollutants. Furthermore, they can undergo surface chemical modifications which can further improve their ability to retain different environmental pollutants. This review aims to summarize recent advances in the application of hydrogels in the treatment of heavy metal-contaminated wastewater, particularly focusing on hydrogels based on cellulose and cellulose derivatives. The reported studies highlight how the adsorption properties of these materials can be widely modified, with a wide range of adsorption capacity for different heavy metal ions varying between 2.3 and 2240 mg/g. The possibility of developing new hydrogels with improved sorption performances is also discussed in the review, with the aim of improving their effective application in real scenarios, indicating future directions in the field.

Semi-continuous cultivation of EPS-producing marine cyanobacteria: A green biotechnology to remove dissolved metals obtaining metal-organic materials

Given the necessity for bioprocesses scaling-up, the present study aims to explore the potential of three marine cyanobacteria and a consortium, cultivated in semi-continuous mode, as a green approach for i) continuous exopolysaccharide-rich biomass production and ii) removal of positively charged metals (Cu, Ni, Zn) from mono and multi-metallic solutions. To ensure the effectiveness of both cellular and released exopolysaccharides, weekly harvested whole cultures were confined in dialysis tubings. The results revealed that all the tested cyanobacteria have a stronger affinity towards Cu in mono and three-metal systems. Despite the amount of metals removed per gram of biomass decreased with higher biosorbent dosage, the more soluble carbohydrates were produced, the greater was the metal uptake, underscoring the pivotal role of released exopolysaccharides in metal biosorption. According to this, Dactylococcopsis salina 16Som2 showed the highest carbohydrate productivity (142 mg L−1 d−1) and metal uptake (84 mg Cu g−1 biomass) representing a promising candidate for further studies. The semi-continuous cultivation of marine cyanobacteria here reported assures a schedulable production of exopolysaccharide-rich biosorbents with high metal removal and recovery potential, even from multi-metallic solutions, as a step forward in the industrial application of cyanobacteria.