Removal Efficiency Of Heavy Metals Research Articles

Electro-catalytic ozonation of contaminants in landfill leachate: Optimization by BBD, economic evaluation, mechanism, and reaction pathway

An electro-catalytic ozonation process with ZnO nano-granules as a catalyst (CFR-EC/O3-UV@ZnO process) was developed to treat raw landfill leachate. LC-MS analysis was applied to determine organic compounds. After CFR-EC/O3-UV@ZnO process, COD, TOC, BOD5, NH4+-N, P-PO4−3, color, and turbidity were reduced to 90.9%, 89.4%, 89.1%, 89.5%, 87.7%, 99.1%, and 99.7%, respectively under the optimum conditions of 10 g.hr−1 O3 dosage, pH 11.0, and 0.006 L.min−1 flowrate. At the same conditions removal efficiencies of heavy metals (HMs): Cr6+, Pb2+, As3+, Mg2+, B3+, Mn3+, Ni2+, Ba2+, Hg2+, Co2+, Fe2+, and Li+ were obtained 90%, 84.7%, 90%, 99%, 83.7%, 95%, 20%, 75%, 91%, 90%, 78% and 60%, respectively. In spite of high COD and BOD5 removal efficiencies, the process could not remove two organic substances including diphenylamine and 2,2,4-trimethyl-1,3-pentanediol. A high R2 value of 0.99 demonstrated the accuracy of the selected model. Economic evaluation depicted that the current process cost 0.95 $.m−3. Finally, this process is suggested for the treatment of landfill leachate with relatively high efficiency.

Investigation of nanofiltration systems efficiency for removal of chromium and copper from groundwater resources

AbstractThere is a vital need and constraint for providing water of good quality all around the world. Thus, with the aim of groundwater treatment, different methods of water treatment have been reviewed. Considering modern methods of membrane filtration, in this study efficiency of nanofiltration for removing heavy metals (copper and chromium) has been examined. The investigation has been accomplished in two separate phases for removing copper and chromium. To prepare the samples of groundwater, urban waters have been utilized and for preparation of chromium‐contaminated and copper‐contaminated waters, powder of chromium‐oxide and powder of copper sulfate pentahydrate have been added into samples, respectively. In this research, system‐operating pressure has been changed, while concentration and pH were kept constant. The effect of pressure on the efficiency of heavy metals removal has been checked and optimum pressure of the process has been achieved. Then, with optimal pressure as system operating pressure, the removal of heavy metals in different pH have been checked and accordingly, the optimal pH for the process was obtained. The Optimum Pressure and pH for chromium and copper are 7.5 bars and 6.3, and 7.5 bars and 6.7, respectively. Taking into account the result of this study, Nano filtration is a suitable method with high efficiency (90% and higher in optimum pressure and pH) for the removal of heavy metals from groundwater.

Comparison of Pb2+ Adsorption Properties of Biochars Modified Through CO2 Atmosphere Pyrolysis and Nitric Acid

Acid modification has been widely used to modify the structural properties of biochars. However, acid modification led to the large consumption of acid, increased difficulty of waste effluent disposal, and a high application cost. To evaluate the advantages and application potential of biochars prepared under CO2, utilizing pyrolysis to directly modify biochars to improve heavy metal removal efficiency and reduce production cost, would be an important prerequisite for the broad application of biochars. The sorption performance of Pb2+ with CO2-modified biochars was compared with that of HNO3-modified biochar. The elemental compositions and structural properties of biochars were characterized through elemental analysis, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The results revealed that for biochars produced at 500℃, HNO3 modification produced abundant carboxylic groups and -NO2 (asy) and -NO2 (sym) groups, promoting the surface activities and complexing abilities of biochars. The CO2-modified biochars contained abundant carbonate minerals, which could remove Pb2+ by electrostatic ion exchange and coprecipitation or complex. In addition, compared to that of HNO3-modified biochars, CO2-modified biochars had the larger specific surface area and better microporous structures, which were beneficial to the diffusion of Pb2+ and further promoted surface sorption. CO2 modification increased the maximum Pb2+ sorption capacity of W500CO2 and W700CO2, which were 60.14 mg·g-1 and 71.69 mg·g-1. By contrast, HNO3-modified biochars W500N2-A and W700N2-A showed the lower Pb2+ sorption capacities, which were 42.26 mg·g-1 and 68.3 mg·g-1, respectively. The increasing of the specific surface area and functional groups simultaneously promoted the sorption capacity of CO2-modified biochars. Consequently, the CO2-modified biochar had the advantages of low cost, environmental friendliness, and high heavy metal removal efficiency, which is a modification method worthy of promotion and application.

Emission characteristics and removal of heavy metals in flue gas: a case study in waste incineration and coal-fired power plants.

Heavy metal pollutants such as Hg, As, Pb, Cr, and Cd emitted from coal and waste combustion have received widespread attention. In this study, we systematically investigated the emission characteristics of heavy metals in waste incineration and coal-fired flue gases, focused on testing the removal effect of self-made cold electrode electrostatic precipitator (CE-ESP) on heavy metals in flue gas, and made a comparative analysis with the existing air pollution control devices (APCDs). Test results from waste incineration power plant showed that each APCD showed a certain effect on the removal of heavy metals in condensable particulate matter (CPM), with an average removal efficiency of bag filter was 86%, but its effect on Hg removal was slightly worse. Under the coupled field with electrified cold electrode plate operation mode, the average removal efficiency of CE-ESP on heavy metals in CPM was as high as 93%, including 76% for Hg. The removal efficiency of heavy metals (especially Hg) in CPM increased with the increase of flue gas temperature difference between inlet and outlet of CE-ESP. Test results from this coal-fired power plant showed that heavy metals were enriched in fly ash to a higher degree than in slag, the synergistic control of heavy metals in submicron particulate matter by the dust remover was not obvious, and there was a significant correlation between each heavy metal emission factor and its content in coal. Under the temperature field with non-electric cold electrode plate operation mode, the overall effect of CE-ESP on the removal of gaseous heavy metals was better than that of particulate heavy metals. Under the conventional electric field operation mode, CE-ESP was less effective in removing particulate Cr and gaseous Hg0. Under the coupled field with electrified cold electrode plate operation mode, the average removal efficiencies of CE-ESP for particulate and gaseous heavy metals were 82.37% and 76.16%, respectively.

Hydrophobic deep eutectic solvents characterization and performance for efficient removal of heavy metals from aqueous media

In this study, we successfully extracted copper, cobalt, and nickel metals from aqueous media using hydrophobic deep eutectic solvents (DESs). The DESs designed for this research consisted of a combination of carboxylic acids, namely Octanoic acid, Nonanoic acid, Decanoic acid, and Dodecanoic acid. Before and after the extraction process, the prepared DESs underwent comprehensive characterization using various analytical techniques. Viscosity measurements demonstrated that the prepared solvents exhibited low viscosity at room temperature, making them well-suited for extraction processes. Moreover, Karl Fischer Titration was employed to accurately determine the water content, which is crucial for evaluating hydrophobicity. We investigated the influence of various parameters on the metal extraction yield, including the initial concentration, temperature, and time. Under optimized conditions, using Dodecanoic acid + Octanoic acid as the most efficient DES, extraction yields of 85.61 % for Cu, 96.19 % for Co, and 76.54 % for Ni were achieved. Furthermore, through approximately three extraction steps, complete removal of metal ions from the aqueous medium was achieved. Due to its superior performance, the DES composed of Dodecanoic acid + Octanoic acid was selected for further investigations. The DESs exhibited favorable characteristics such as low viscosity and hydrophobicity, positioning them as promising for extraction in aqueous environments.

Potential of ash from agricultural waste as substitute of commercial FeCl3 in primary treatment of landfill leachate

Due to the ever increasing global population, higher volumes of industrial waste discharges to landfill have caused major problems for the environment. This study investigated the performance of rice straw ash (RSA) as a natural coagulant under different conditions for the treatment of landfill leachates by coagulation-flocculation and microfiltration, with and without addition of FeCl3. The highest performing treatment conditions (RSA = 2.48 g/L, FeCl3 = 4.98 g/L, settling time = 54.75min) were achieved with the combined use of RSA and FeCl3 as coagulant and led to a sludge volume index of 41.65 mL/g, 51.27% COD removal and 76.48% total suspended solid removal. In contrast, FeCl3 alone achieved slightly better COD and total suspended solid removal rates, however it resulted in higher sludge volume index and sludge production. The combined use of RSA and FeCl3 reduced the consumption of these two coagulants by 78.76% and 46.69% respectively. Functional groups and thermal stability of the flocs showed that RSA + FeCl3 synergistically enhance the mechanisms of the coagulation-flocculation process, including adsorption by particle's bridging, charge neutralization and size of flocs. Combining the coagulants resulted in increased van der Waals forces and lower attractive forces of the inter-colloidal energy barrier in the leachate. Additionally, the highest and lowest heavy metals removal rates for treatment by microfiltration were found for Fe (92.15%) and Mg (7.63%), with a total heavy metals removal efficiency in the range of 6.08–90.78%. The findings of this study show that RSA can serve as a natural eco-friendly coagulant both alone and in combination with FeCl3 in the leachate treatment.

A concise review on wastewater treatment through microbial fuel cell: sustainable and holistic approach.

Research for alternative sources for producing renewable energy is rising exponentially, and consequently, microbial fuel cells (MFCs) can be seen as a promising approach for sustainable energy production and wastewater purification. In recent years, MFC is widely utilized for wastewater treatment in which the removal efficiency of heavy metal ranges from 75-95%. They are considered as green and sustainable technology that contributes to environmental safety by reducing the demand for fossil fuels, diminishes carbon emissions, and reverses the trend of global warming. Moreover, significant reduction potential can be seen for other parameters such as total carbon oxygen demand (TCOD), soluble carbon oxygen demand (SCOD), total suspended solids (TSS), and total nitrogen (TN). Furthermore, certain problems like economic aspects, model and design of MFCs, type of electrode material, electrode cost, and concept of electro-microbiology limit the commercialization of MFC technology. As a result, MFC has never been accepted as an appreciable competitor in the area of treating wastewater or renewable energy. Therefore, more efforts are still required to develop a useful model for generating safe, clean, and CO2 emission-free renewable energy along with wastewater treatment. The purpose of this review is to provide a deep understanding of the working mechanism and design of MFC technology responsible for the removal of different pollutants from wastewater and generate power density. Existing studies related to the implementation of MFC technology in the wastewater treatment process along with the factors affecting its functioning and power outcomes have also been highlighted.

Comparison of Three Materials Derived from Waste EPS for Heavy Metal Removal Efficiency

Comparison of Three Materials Derived from Waste EPS for Heavy Metal Removal Efficiency

Utilizing a settling pond-based constructed wetland for the treatment of shrimp aquaculture wastewater – From laboratory to field scale: A case study in Ben Tre Province, Vietnam

The shrimp aquaculture industry, while bringing high economic benefits, simultaneously presents many environmental challenges for many countries, including Vietnam. Our survey results regarding shrimp farming management in 30 representative rural households within Ben Tre province have revealed that 96.7% of wastewater does not meet the allowable standards. Although approximately 76.66% of which is crudely treated by settling ponds, the percentage of substandard wastewater is reduced only to 70%. Unfortunately, >93% of the wastewater is discharged directly into the environment. Faced with that situation, a proposed wastewater treatment option suitable for the rural areas is to utilize settling ponds and indigenous reeds (P.australis and P.vallatoria) to build constructed wetlands (CW). A lab-scale CW was designed to mimic a settling pond on the surveyed farm, which was scaled down to a ratio of 1:500, aiming to validate the efficacy of the CW approach. Accordingly, the P.vallatoria-planted CW with a density of 25 roots/m2 effectively treats the wastewater to meet the permissible standard within 4 weeks. The removal efficiencies of organics, nutrients, heavy metals, and total coliform could reach up to 80, 85, 91, and 41%, respectively. Upon transitioning to the field scale, these efficiencies increased up to 13.09, 18.79, 29.47, and 5%, respectively. More importantly, the treatment time could be shortened to 3 and 2 weeks, respectively, when the wastewater is diluted 1.5 and 3 times, thereby serving as a foundation to upgrade the current farming model from intensive to super-intensive.

Preparation of landscape gardening soil using undersized fraction from aged MSW by EDTA or citric acid coupled with humic acid: Effect assessment, properties, and optimization

ABSTRACT Undersized fraction from aged municipal solid waste (UFAMSW), as a kind of soil-like material, has been proved effective in providing a large amount of organic matter and nutrients for soil and plants. The characteristics and effectiveness of heavy metal pollution removal in UFAMSW attracted tremendous research interest from scientists recently. In this study, the heavy metal removal efficiencies and bioavailability of washing on contaminated UFAMSW were evaluated with three washing reagents including ethylene diamine tetra acetic acid (EDTA), citric acid (CA), and humic acid (HA). The effects of chelating agent concentration, pH, and washing time on metal removal were investigated and response surface methodology (RSM) was employed to optimize the washing conditions. The results indicated that the removal efficiencies of Cu, Zn, and Mn could be 53.68%, 52.12%, and 30.63% by EDTA/HA washing and 42.36%, 39.67% and 28.49% by CA/HA washing, respectively. The European Community Bureau of Reference (BCR) sequential extraction was applied to analyze the fraction change of heavy metals in UFAMSW before and after washing, and it was found that chelating agent combined with HA could contribute to the removal of the exchangeable fraction. Physical and chemical properties of UFAMSW were improved to some extent after washing with mixed HA and chelating agent and could achieve the quality standard of landscape gardening soil. Accordingly, the mixture of HA and other chelating agents could be a promising washing process for preparation of landscape gardening soil using UFAMSW. Implications: Our manuscript studies the removal of heavy metals from the contaminated undersized fraction from aged municipal solid waste (UFAMSW). UFAMSW, as a kind of soil-like material, has been proved effective in providing a large amount of organic matter and nutrients for soil and plants however often limited by heavy metal pollution. The UFAMSW used in this experiment was collected after the excavation and screening-sorting of aged refuse from Changshankou Domestic Waste Sanitary Landfill in Wuhan City, Hubei Province, Southern China. This study investigated the effects of EDTA, CA, HA, mixed EDTA/HA, and mixed CA/HA washing on heavy metal removal (Cu, Zn, and Mn), bioavailability of residual heavy metal and properties. The effects of chelating agent concentration, pH, and washing time on metal removal were investigated and then response surface methodology was employed to optimize the washing conditions. The results showed that washing by CA/HA and EDTA/HA, had a higher removal efficiency of heavy metals (Cu, Zn, and Mn) in UFAMSW compared to single HA. Meanwhile, HA has a higher removal for exchangeable fraction of heavy metals, the exchangeable concentration of Cu, Zn, and Mn in CA/HA and EDTA/HA washed UFAMSW were lower compared with UFAMSW washed by single CA and EDTA. Thus, mixing HA with EDTA or CA makes a less risk to environmental and the removal efficiency is acceptable. Additionally, CA/HA and EDTA/HA washing tend to improve soil physicochemical properties and soil fertility. Thus, mixing HA with different washing agent are potential methods for preparation of landscape gardening soil using UFAMSW.

FABRICATION AND CHARACTERIZATION OF SUGARCANE BAGASSE BASED CELLULOSE ACETATE/ZEOLITE (CA/Ze) MATERIAL FOR ELIMINATION OF Pb AND Cu IONS FROM AQUEOUS SOLUTIONS

This study explores the synthesis and characterization of cellulose acetate/zeolite (CA/Ze) fibers as effective adsorbents for the removal of Pb2+ and Cu2+ ions from aqueous solutions. Cellulose acetate was derived from sugarcane bagasse (SCB) and integrated with zeolite to create CA/Ze fibers. Characterization techniques, including FTIR spectroscopy and SEM analyses, confirmed the successful modification and incorporation of zeolite within the fiber structure. Hydration studies revealed the fibers’ stability in water, while adsorption experiments examined factors affecting adsorption capacity, such as pH, time, initial concentration, and reuse. The Langmuir and Freundlich isothermal models were applied to analyze adsorption isotherms. The results demonstrated the potential of CA/Ze fibers for efficient heavy metal removal, with a maximum adsorption capacity for Pb2+ ions of 13.9 mg/g. While the adsorption efficiency decreased after regeneration cycles, CA/Ze fibers displayed promise as sustainable adsorbents. This research contributes to addressing heavy metal pollution while promoting eco-friendly waste utilization.

Research on the treatment of heavy metal ions by immobilized microbial technology

With the development of human industry, the mining and utilization of heavy metals has become more and more extensive, especially in the past 200 years. However, the excessive discharge of industrial and domestic sewage, overuse of pesticides and fertilizers in the production process, as well as electronic waste and medical waste in human life have led to many heavy metal ions entering the environment, exceeding the environmental capacity and entering organisms in large quantities, threatening the ecosystem and human health. Therefore, how to economically and efficiently deal with the heavy metal ion pollution generated in the process of production and life has become a hot issue. Currently, the main methods for treating heavy metal ions are chemical precipitation, ion exchange, adsorption, membrane filtration, electrochemical treatment technology, etc. However, the traditional methods for heavy metal treatment are usually faced with the problems of high cost, high complexity and high energy consumption. In recent years, microbial immobilization technology has received wide attention for its advantages of improved microbial stability, high heavy metal ion removal rate, etc. The corresponding microorganisms are encapsulated and aggregated by immobilized carriers, which enhances the cellular bioburden capacity and environmental resistance and improves the microbial removal efficiency of heavy metals.

Statistically Analyzed Heavy Metal Removal Efficiency of Silica-Coated Cu0.50Mg0.50Fe2O4 Magnetic Adsorbent for Wastewater Treatment.

Even low concentrations of pollutants in water, particularly heavy metals, can significantly affect the ecosystem and human health. Adsorption has been determined to be one of the most effective techniques of removing pollution from wastewater among the various strategies. To remove heavy metals such as Zn2+ and Pb2+, we prepared a silica-coated CuMgFe2O4 magnetic adsorbent using sol-gel method and tested it for wastewater treatment. X-ray diffraction investigation validated the creation of cubic spinel structure, while morphological analysis showed that silica coating reduces the particle size but boosts the surface roughness of the nanoparticles and also reduces the agglomeration between particles. UV-visible spectroscopy indicates a rise in bandgap and magnetic characteristics analysis indicates low values of magnetization due to silica coating. The kinetic and isotherm parameters for heavy metal ions adsorption onto silica-coated Cu0.50Mg0.50Fe2O4 nanoparticles are calculated by applying pseudo-first-order, pseudo-second-order, Langmuir and Freundlich models. Adsorption kinetics revealed that the pseudo-second-order and Langmuir models are the best fit to explain adsorption kinetics. Synthesized adsorbent revealed 92% and 97% removal efficiencies for Zn2+ and Pb2+ ions, respectively.

Insights into the interaction between mineral formation and heavy metals immobilization, mediated by Virgibacillus exopolymeric substances

Heavy metal pollution poses significant risks to both the environment and human health due to their toxicity, long residence times, and their ability to bioaccumulate and bio magnify across the food chain. To address this issue, microbial biomineralization has emerged as a promising approach to the bio-removal of heavy metals through immobilization. This process is facilitated by extracellular polymeric substances (EPS), which also play a crucial role in mediating mineral formation. In this study, the interactions between several selected heavy metals (Cd2+, Cu2+, Ni2+, Zn2+), EPS, and mineral formation were investigated using two mineral-forming Virgibacillus strains isolated from the Qatari sabkhas, which are known to be suitable sites for the formation of biominerals. An additional non-mineral-forming Virgibacillus strain isolated from the Dukhan oil waste dumpsite was also investigated. Cd2+ and Zn2+ were to inhibit mineral formation, likely due to competition with Ca2+ and Mg2+ ions during biomineralization. However, exposure to Ni2+ or Cu2+ resulted in changes in the FTIR spectra of the EPS, suggesting the presence of specific functional group bindings within the EPS matrix. The EPS produced by each strain was also directly associated with their efficiency (%) at removing heavy metals. Notably, the EPS from Virgibacillus halodenitrificans Z4D1, the non-mineral-forming strain, exhibited the highest heavy metal removal efficiency of 31.7 % for Zn2+. These findings reveal that EPS do not only affect the biomineralization process but also that the functional groups in EPS have a direct effect on the immobilization of several heavy metals. Conditions that are not suitable for mineral formation may instead be appropriate for the removal of specific heavy metals.

Nanocellulose hydrogels formed via crystalline transformation from cellulose I to II and subsequent freeze cross-linking reaction

We describe nanocellulose (NC) hydrogels formed from chemically unmodified NC by cellulose crystalline transformation and subsequent freeze cross-linking reaction. The freeze cross-linked NC hydrogel with macropores (~100 μm) was prepared by freezing a mixture of NC and NaOH (0.2 mol L−1), adding citric acid to the frozen mixture, and thawing it. Using NaOH and freezing together induced the crystalline transformation of NC from cellulose I to II via freeze concentration. After the crystalline transformation, cross-linking between the NC and CA in the freeze concentration layer provided a strong NC network structure, forming NC hydrogels with high mechanical strength. The structural changes in NC caused by NaOH, freezing, and freeze cross-linking on the angstrom to micrometer scale were investigated with FT-IR, SAXS, PXRD, and SEM. The freeze cross-linked NC hydrogel easily retained powder adsorbents in its inner space by mixing the NC-NaOH sol and the powder, and the hydrogel showed high removal efficiency for heavy metals. The results highlight the versatility of chemically unmodified celluloses in developing functional materials and suggest possible practical applications. This study also provides new insights into the efficient use of chemical reactions of cellulose under freezing conditions.

The role of nanoscale zero-valent iron (nZVI) in remediation of heavy metal contamination in groundwater overexploitation areas

This study investigates the remediation of groundwater contaminated with heavy metals in overexploited areas using a modified approach involving the use of corn plant parts to produce biochar. The biochar was modified using a hydrothermal method, employing nanoscale zero-valent iron (nZVI) material to create a composite material for adsorbing heavy metals from water bodies. Adsorption experiments were conducted on the presence of Cr, Cu, and Zn ions in the water. The experimental investigations focused on the dosage of adsorption materials, solution pH, and stability of the adsorption material to validate the enhanced capability of the nanoscale zero-valent iron modified biochar composite (Fe-CBC-MO) for removing and adsorbing heavy metal ions (Cu, Cr, and Zn) from water. The results indicate that the adsorption capacity follows the sequence: Cr > Zn > Cu. Increasing the adsorbent dosage provides more adsorption sites, thereby improving the removal efficiency of heavy metals from water bodies. Considering cost-effectiveness, an optimal dosage of 0.15 g was selected. Under alkaline conditions, Cu and Zn ions precipitated significantly, leading to sustained high removal rates of heavy metals. Correspondingly, the rate constants were also relatively high. In acidic environments, the rate constant for Cr decreased significantly due to corrosion passivation. The composite material Fe-CBC-MO exhibited remarkable removal efficiency for all three heavy metals (Cr, Cu, Zn), demonstrating a strong capability for remediating heavy metal pollution.

Performance evaluation of a pilot wetland system for wastewater treatment

Wetland systems are inexpensive and easy-to-operate wastewater systems and are widely used globally at different scales for the safe treatment of wastewater. This study aims to evaluate a pilot-scale vertical flow wetland system treating wastewater under different loadings. The wetland system was constructed using indigenous plants (Imperata cylindrical) and operated using actual wastewater for twelve-months. Samples from influent and effluent of the wetland system were collected weekly. They were analyzed for parameters listed in the Kuwait Environment Public Authority standards for reuse in irrigation, such as organic matter, nutrients, heavy metals, and microorganisms. The results showed that the high hydraulic loading rate (1.67 m3/m2.d) phase was more efficient than the low hydraulic loading rate (1.04 m3/m2.d) phase in terms of organics and nutrient removal efficiency. The range of the removal efficiency of organic matter in low and high loading rates was around 48.5–49.0% and 59.1–59.1%, respectively. In addition, the range of the removal efficiency of nutrients in low and high loading rates was around 43.7–67.7% and 24.7–76.6%, respectively. Moreover, the range of the removal efficiency of heavy metals under the low and high loading rates was − 134.3–93.8% and − 1545.7–92.6%, respectively. It was evident that he metals were leaching from the soil. Moreover, it was found that the system performance was closely linked to the ambient temperature effects during the start-up (r = 0.59) and high hydraulic loading (r = 0.43) phases for example. While ambient temperature has wider effects on wetland biota, its effects on the plants are more pronounced. In conclusion, wetland systems can be constructed using indigenous plants to treat office wastewater efficiently under the harsh climate conditions of Kuwait with adjustments in capacity, loading rates, and operational conditions.

Rapid and efficient removal of multiple heavy metals from diverse types of water using magnetic biochars derived from antibiotic fermentation residue

Pyrolysis is a promising method to treat antibiotic fermentation residue (AFR), a hazardous waste in China, with the benefits of detoxification and resource recycling. However, the application of the AFR-derived biochar has been limited yet, restricting the use of pyrolysis to treat AFR. Herein, for the first time, we reported the use of magnetic biochars derived from vancomycin fermentation residue to rapidly and efficiently co-adsorb multiple heavy metals from diverse types of water with complex matrices. The biochar prepared at 700 °C (labeled as VBC700) exhibited high affinity and selectivity for multiple heavy metals, especially for Ag(I), Hg(II), Pb(II), and Cu(II). The kinetics for Ag(I), Hg(II), and Pb(II) were ultrafast with an equilibrium time of only 5 min, while those for Cu(II) were relatively slower. The maximum adsorption capacity calculated from the Langmuir model for Ag(I), Hg(II), Pb(II), and Cu(II) reached 177.4, 105.9, 387.1, 124.5 mg/g, respectively, which were superior to much previously reported adsorbents. Impressively, Na(I), K(I), Ca(II), Mg(II), and salinity did not affect the capture of these heavy metals, and thus >99% of Ag(I), Pb(II), and Cu(II) were concurrently removed from complex water matrices including seawater, which has rarely been reported before. Furthermore, VBC700 remained high adsorption performance at pH ≥ 3. The adsorption mechanisms included ion exchange, precipitation, and inner-sphere complexation. Overall, the results demonstrate that VBC700 would be an excellent adsorbent to co-capture multiple heavy metals from diverse types of water, highlighting the feasibility of using pyrolysis to achieve a win-win goal for AFR management and heavy metal pollution control.

Improving heavy metal removal efficiency from steel sludge: Application of the coupled ultrasonic-bioleaching treatment

<p>This study assessed the efficiency of Fe, Al, Ni and Sr removal from the steel sludge using the coupled bioleaching with Thiobacillus thiooxidans and ultrasonic waves. Growth conditions were optimized using the surface response method. The bacterium was adapted successively to three heavy metal-containing solutions with different concentrations of 100, 200, and 300 mg/ml. Samples were exposed to ultrasonic waves at frequencies of 30, 60 and 90 kHz and durations of 20, 30 and 40 min for two weeks. The highest Fe removal efficiency of 98.45% was obtained using the T. thiooxidation, wave frequency of 30 kHz for 40 min, and pulp density of 100 mg/ml. The maximum removal efficiency was found to be 99.74% for Al under a wave frequency of 90 kHz for 20 min and a pulp density of 300 mg/ml, approximately 100% for Ni under a wave frequency of 30 kHz for 20 min and a pulp density of 300 mg/ml, and 98.45% for Sr under a wave frequency of 90 kHz for 20 min and a pulp density of 300 mg/mL. Results showed that the removal efficiency of Ni and Al bioleaching improved significantly (P <0.05) under the ultrasonic irradiation while the removal efficiency of Fe and Sr remained statistically unchanged (P> 0.05) with and without the application of ultrasonic waves.</p>

Efficient extraction of heavy metals from aqueous environments using magnetic effervescent Tablet-Assisted ionic Liquid-Based dispersive Solid-Phase microextraction

In this study, we successfully developed an effervescent tablet-assisted dispersive solid-phase microextraction approach using sulfanilic acid-modified magnetic graphene oxide (MGO@SA-DSPM) for the efficient removal of heavy metals (Pb(II), Cd(II), Zn(II), and Cr(II)). The study systematically investigated the impact of different variables on the extraction efficiency of heavy metals. Results demonstrated that the MGO@SA nanocomposite exhibited superior extraction yields for all four metals, with recovery rates of 100.6 % for Cd(II), 103.6 % for Zn(II), 99.39 % for Cr(III), and 87.08 % for Pb(II), surpassing those of the MGO composite (81.08 % for Cd(II), 101.5 % for Zn(II), 54.35 % for Cr(III), and 80.48 % for Pb(II)). The enhanced extraction efficiencies due to the introduction of additional functional moieties, such as sulphonyl (-SO3-) and amid (NH-CO) moieties, onto the surface of MGO through its modification with SA. This led to a significantly improved extraction process. Under optimized conditions, the MGO@SA-DSPM method achieved low limits of detection (LOD) ranging from 0.204 to 299 μg/L, and limits of quantification (LOQ) between 0.68 and 0.99 μg/L, along with satisfactory extraction recoveries (87.08 % − 103.6 %) and relative standard deviations of 1.36–1.99 % for all four heavy metals. In summary, the proposed MGO@SA-DSPM approach demonstrates promising potential for routine water quality monitoring.