Removal Efficiency Of Heavy Metals Research Articles

Enhanced and efficient removal of heavy metals by amino-decorated membranes in coordination with multi-function

A multi-functional MA/GMA@PVDF membrane with abundant amino groups was first prepared by grafting the intermediate with an epoxy group from glycidyl methacrylate (GMA) into a defluorinated polyvinylidene fluoride (PVDF) and subsequently conducting an ammonifying process with melamine. The highest pure water flux of the selected 0.2 %-MA/GMA@PVDF was up to 562 L/(m2·h), with a high flux recovery ratio of 97.7 %, indicating excellent antifouling performance. Cu(II) concentration in the treatment volume of 47.44 L/m2 met the discharge limitation of 0.5 mg/L, which was more than 5.3 times that of the PVDF membrane. The obvious enhancement was mainly attributed to the grafted amino groups, which could coordinate with Cu(II) with the lone-pair electrons. Moreover, inorganic salts and organic matter could improve 0.2 %-MA/GMA@PVDF rejection performance in mixed systems. Among them, NaNO3 could increase the effective treatment volume to 55.12 L/m2 by charge shielding and compression double layer interaction owing to the unique property of amino groups. The maximum removal of Cu(II) by citric acid was increased by 48.63 % by the complexation of NH2/NH groups. Thus, the multi-functional membrane decorated with amino groups shows great potential as a promising material to efficiently remove heavy metals from complex wastewater.

Programmable and low-cost biohybrid membrane for efficient heavy metal removal from water

Heavy metal pollution in rivers and lakes from industrial development poses great challenges to environmental remediation, especially of low-concentration metal ions. Current technologies for removing low-concentration heavy metal ions are typically expensive, and there is therefore an urgent need to develop new strategies. Low-cost microbial amyloid nanofibers (MAN) have demonstrated excellent abilities in removing heavy metal ions. In this study, we used synthetic biology strategies to design programmable MAN in silico and create artificial MAN for biohybrid membrane preparation. It was found that MAN could be largely produced and self-assembled, and it exhibited a removal rate of more than 98 % for 50 mg/L lead ions. Furthermore, genetic edits of MAN with functional peptides endowed the specific binding ability to heavy metals even at 1 mg/L. Impressively, biohybrid membranes using activated carbon as the supporting material based on programmable MAN showed long lifecycles and low costs in scale-up water purification systems. This study provides a programmable and low-cost strategy for the efficient treatment of heavy metal wastewater.

Applicability and Extraction Characteristics of Aluminum Sulfate as Extractant of Harmful Heavy Metals for On-Site Treatment of Deep-Sea Mining Tailings

This research was focused on the eco-friendly treatment of deep-sea mining tailings in the sea areas and mainly dealt with evaluating the optimal conditions by comparing aluminum sulfate (AS), which had been proven recently to have an effect as a heavy metal extractant, with ethylenediaminetetraacetic acid (EDTA) in terms of environmental and economic feasibility. Harmful heavy metals in the manganese nodules (2%, w/v) were chemically washed by mixing with each EDTA and AS concentration for 16 elapsed times. Copper, zinc, nickel, and cadmium, which could have a fatal effect due to their high total content or high bioavailable content, were selected as the primary treatment target materials. The content of harmful heavy metals was 293.2 times more for nickel when compared with environmental standards of various countries. When 1% AS was used as the extractant, the removal efficiency of harmful heavy metals compared to the bioavailable content was 32.77% on average. It has been verified that multi-stage treatment could be necessary, and the short treatment time could be an important factor. Within a short elapsed time (3 h), the remediation efficiency of zinc and nickel under the 1% AS condition was higher than with 0.1 M EDTA. In terms of environmental and economic feasibility, it was verified that the use of 1% AS would be reasonable. The results of this research could be valuably applied to process design and optimization as basic data presented before the development of remediation technologies in the future.Graphical

Polymer Membranes as Innovative Means of Quality Restoring for Wastewater Bearing Heavy Metals.

The problem that has aroused the interest of this review refers to the harmful effect of heavy metals on water sources due to industrial development. In this respect, the review is aimed at achieving a literature survey on the outstanding results and advancements in membranes and membrane technologies for the advanced treatment of heavy metal-loaded wastewaters. Particular attention is given to synthetic polymer membranes, for which the proper choice of precursor material can provide cost benefits while ensuring good decontamination activity. Furthermore, it was also found that better removal efficiencies of heavy metals are achieved by combining the membrane properties with the adsorption properties of inorganic powders. The membrane processes of interest from the perspective of industrial applications are also discussed. A noteworthy conclusion is the fact that the main differences between membranes, which refer mainly to the definition and density of the pore structure, are the prime factors that affect the separation process of heavy metals. Literature studies reveal that applying UF/MF approaches prior to RO leads to a better purification performance.

Factorial Design and Optimization of Date Stone as A Natural Coagulant for Organic and Heavy Metals Removal from Industrial Wastewater

<p>Several chemical coagulants previously utilize for wastewater treatment with significant performance in removing heavy metals and other parameters. However, their cost effective and the residual of toxic chemical precipitates that pose problems to human health and the environment. Therefore, using plant-based natural coagulants is considered as an alternative technique which is non-toxic, biodegradable and environmentally friendly. This research aims to explore the performance of date stones as a natural coagulant in iron and steel plant wastewater treatment and to optimize the operating parameters to assess the feasibility of using date stones in the wastewater treatment sector. Response Surface Methodology (RSM), a statistical experimental design, was used to improve the COD, TSS, NH3-N, and heavy metals removal efficiency using 1.4 g/200 mL date stones as control parameters, as well as pH and settling time. At pH 8, the most significant removal efficiency for COD, NH3-N, Fe, Mn, Al, Cu, and Ni was 61, 63, 93, 93, 96.5, 51, and 86 %, respectively. The quadratic models for the parameters chosen were found to be significant with low probability (<0.001), except for NH3-N (0.004), Fe (0.0042), and Ni (0.0025). The study's results revealed the potential of utilizing date stones as a natural coagulant for the treatment of iron and steel industrial wastewater</p>

A Dual Media Filter using Zeolite and Mortar for the Efficient Removal of Heavy Metals in Stormwater Runoff

Stormwater runoff from expressways contains high concentrations of various heavy metals. However, heavy metal removal in most current runoff treatment facilities, using infiltration and filtration, is limited and poses substantial risks. Therefore, this study proposes and evaluates a dual media system of mortar and Na-zeolite, which are inexpensive and readily available, using long-term continuous column experiments for the removal of heavy metals. The results showed significant Cu2+ removal with Na-zeolites that was improved by the addition of a thin mortar layer, while a sand layer provided negligible improvements. The removal of Cu was further enhanced by increasing mortar layer thickness. The removal of Cu2+, Zn2+, Fe3+, and Ni2+ in a mixture was enhanced as the mortar layer’s thickness increased, while the contribution of Na-zeolite was significant in 232 h experiments with a fixed empty bed contact time (EBCT) of 1.8 min. Moreover, the media were not saturated with Fe throughout the operation period. These results suggest that the dual media system is cost-effective and efficient in the removal of heavy metals from stormwater runoff via precipitation, filtration, and adsorption with a short EBCT.

Novel oily sludge treatment process: Based on biological leaching

The performance of bioleaching technology was studied for the demulsification, oil content reduction and efficient removal of heavy metals from oily sludge. A method was established for treating oily sludge from an oil refinery. Firstly, bioleaching bacteria were enriched and acclimated. The effects of substrate type (FeSO4·7H2O and Na2S2O3·5H2O), concentration and aeration conditions on treatment performance were investigated, with response surface methodology used to optimize the treatment process. Finally, the effects of operating parameters on heavy metal removal under continuous flow conditions were investigated. Results show that an optimal treatment effect was achieved when 5.00 g/L FeSO4·7H2O and 5.64 g/L Na2S2O3·5H2O were used as substrates and the aeration ratio (air-water ratio) was 14.53 L/L. Under these conditions, the oily sludge reduction rate was 51.76 %, and the oil removal rate was 57.67 %. The removal rates for Pb, Hg and Cu ranged between 40 % and 70 %, with a stable total heavy metal reduction rate of 50 %. These results show that bioleaching technology is feasible for the treatment of oily sludge and heavy metal removal, with good potential for practical application.

Fabrication of robust ceramic supported polymeric composite nanofiltration membrane for heavy metal contaminated wastewater treatment

Nanofiltration (NF) membranes with positive charge are essential for efficient removal of heavy metals and salts from waste water. In this work surface modified positively charged novel ‘ceramic-supported-polymeric’ (CSP) composite NF membranes were fabricated with the copper ions embedded crosslinked polyethyleneimine polymer matrix over tubular ceramic substrate using facile dipcoating method. EDX, ATR-FTIR, XPS, FESEM, AFM and contact angle analyses were performed to characterize the chemical structures and morphologies of the prepared membranes. The composite NF membrane exhibited satisfactory pure water permeability (PWP) of 8.1 L.m−2.h−1.bar−1 and promising salt (87.19 % and 74.41 % for Mg2+ and Ca2+, respectively) and heavy metal ion rejections (91.73 %, 83.15 % and 75.50 % for Zn2+, Ni2+ and Cd2+, respectively). Activation energy and overall size-exclusion-dehydration phenomena along with steric hindrance and Donnan electrostatic exclusion plays an important role for heavy metals and salts rejection. In addition, the membrane showed excellent antifouling properties (>99 % humic acid removal) with high flux recovery ratio (77.6 %) and low flux decline ratio (33 %) for 5 h operations (3rd cycle) together with outstanding antibiofouling ability towards Brevibacillusagri and Leclerciaadecarboxylata. Furthermore, excellent chemical stability of the membrane suggests its potential application for waste water treatment under critical conditions.

Insight into biosorption of heavy metals by extracellular polymer substances and the improvement of the efficacy: a review.

Heavy metals are continuously released into aquatic environments in which they accumulate. This phenomenon endangers public health because heavy metals accumulate along the food chain. However, conventional remediation methods are inefficient, expensive and yield toxic intermediate products, which adversely affect the environment. The discovery of green bio-adsorbents such as microbial extracellular polymer substance (EPS) has quickly attracted considerable worldwide attention because of their low cost, high removal efficiency of heavy metals and industrial availability. Hence, this review considers the sources, hazards and treatment methods of heavy metals pollution, particularly the biosorption mechanism of EPS to heavy metals and the influencing factors of the bio-adsorption process, which are significant in the efficient removal of heavy metals-containing wastewater treatment. This review also focuses on strengthening the process of EPS adsorption of heavy metals, which can further contribute to heavy metals removal. Finally, it has been proposed that improving the yield, stability, selectivity and recoverability of EPS is the key direction of further research.

Heavy Metal Removal Efficiency of Tulsi (Ocimum Sanctum) from Water – A Review

Presence of heavy metal concentration in water is generally resulting from industrial pollution. Certain amount of some metals in water is good for human health but their elevated concentration in water is toxic for us as it causes irreversible damage to the organs. Therefore it is essential to monitor concentration of metals in water and to adopt proper mitigation measures to remove their excess concentration. Adsorption is one of the economic and environmental friendly methods to remove metal contamination from water and many bioadsorbents are used for the purpose. This review will focus on ability of a medicinal plant Tulsi (Ocimum Sanctum) to remove heavy metals (Pb, Cd, Cr, Fe, Cu, Zn) from water.

Application of Algal Nanotechnology for Leather Wastewater Treatment and Heavy Metal Removal Efficiency

Wastewater from tanneries may ruin agricultural fields by polluting them with trace metals. The synthesis of nanoparticles (NPs) from algal sources and their application could help in decreasing hazardous materials, for environmental safety. The potential of zinc oxide nanoparticles made from Oedogonium sp. was evaluated for removal of heavy metals from leather industrial wastewater. Synthesized algal nanoparticles (0 (control), 0.1, 0.5, and 1 mg) were applied to treat wastewater by using different concentrations of leather industrial effluents (0%, 5%, 10%, 15%, and 100%) for 15, 30, and 45 d. The wastewater collected was dark brown to black in color with very high pH (8.21), EC (23.08 μs/cm), and TDS, (11.54 mg/L), while the chloride content was 6750 mg/L. The values of biological oxygen demand (BOD) and chemical oxygen demand (COD) ranged between 420 mg/L and 1123 mg/L in the current study. Prior to the application of nanoparticles, Cr (310.1), Cd (210.5), and Pb (75.5 mg/L) contents were higher in the leather effluents. The removal efficiency of TDS, chlorides, Cr, Cd, and Pb was improved by 46.5%, 43.5%, 54%, 57.6%, and 59.3%, respectively, following treatment with 1 mg of nanoparticles after 45 d. Our results suggested that the green synthesis of ZnO nanoparticles is a useful and ecofriendly biotechnological tool for treating tannery effluents, before they are discharged into water bodies, thus making the soil environment clean.

Surfactant combined with PASP enhance electrokinetic remediation removal heavy metal and hydrocarbon from contaminated soil

ABSTRACT In this work, a new electrokinetic remediation technology was used to remove heavy metal and hydrocarbon from contaminated soil. The surfactant combined with PASP (Polyaspartic acid) was used to enhance heavy metal and hydrocarbon removing from contaminated soil. Electric current, soil pH, electroosmotic flow, water content variation, heavy metal removal efficiency and residual content distribution, heavy metal speciation, removal of TPH (total petroleum hydrocarbons), group composition of oil, mechanism of enhance electrokinetic remediation were investigated during the electrokinetic remediation process. Results indicated that Rhamnolipid, PASP, Tween 80 and SDS (sodium dodecyl sulphate) can reduce the heavy metal precipitation during the electrokinetic remediation process. Also, it can promote EOF (electroosmotic flow) and electrolyte evaporation during the EK remediation. The rhamnolipid (3.0 g.L−1) combined with PASP (3.0 g.L−1) can significantly improve Cu, Cr, Ni, Pb and hydrocarbon mobility and solubility during the EK remediations. Cu, Cr, Ni and Pb obtained the dominant removal efficiencies, which were 66.0 ± 3.45%, 61.2 ± 4.35%, 67.1 ± 3.21%, 61.8 ± 4.22%, respectively. Also, the TPH has attained a dominant removal efficiency of 80.2 ± 4.36% after the enhanced electrokinetic remediation. This research provides a novel in-situ remediation approach for reducing heavy metals and hydrocarbon from contaminated soil in an environmentally friendly way.

MoS42- intercalated magnetic layered double hydroxides for effective removal and expedient recovery of heavy metals from soil

Mg-Al layered double hydroxides with MoS42- intercalated and magnetic modification by Fe3O4 (M−MoS4−LDH) was synthesized by one-pot method for capturing and separating heavy metals (Cu2+/Pb2+/Zn2+/Ni2+) from soil. The intercalation of MoS42- considerably improved the removal efficiency of heavy metals, and magnetic materials facilitated the separation of heavy metals from the soil to overcome the potential risk of the absorbed heavy metals. Removal kinetics of heavy metals were found to better follow the intraparticle diffusion model and pseudo-second-order kinetic model. The adsorption results of Cu2+ and Pb2+ were better described by the Freundlich isotherm, and Langmuir isotherm model well fitted the Zn2+ and Ni2+ adsorption data. Additionally, adsorption mechanism of M−MoS4−LDH for Cu2+/Pb2+/Zn2+/Ni2+ with different concentrations was also be explored. As the concentration of Cu2+/Pb2+/Zn2+/Ni2+ in soil was small, MoS42- preferentially combined with heavy metals, and heavy metals were immobilized in the interlayer of LDHs layer. With the increase of heavy metals, the precipitation for Cu2+/Pb2+ and the isomorphic substitution for Zn2+/Ni2+ were investigated and proposed. The co-existing ions experiments demonstrated that M−MoS4−LDH has high selective adsorption efficiency for heavy metals, column leaching experiments indicated that the heavy metals eventually immobilized by M−MoS4−LDH and prevented further migration in soil. Regeneration and recovery experiments suggested that M−MoS4−LDH could be reused for several time with high-efficiency and avoiding secondary contamination. This work provided an excellent removal and convenient recovery strategy for the treatment of heavy metal contaminated soil.

A novel integrated system for heavy metals removal and biodiesel production via green microalgae: A techno-economic feasibility assessment

The removal of heavy metals combined with biodiesel production by microalgae in a cost-effective way is a promising approach. Herein, we grew two green microalgal species, Chlorella sorokiniana and Scenedesmus acuminatus, in media contaminated with Cu2+ (3.2 ppm) or Zn2+ (65.4 ppm) to investigate their growth and full metabolic profile. Furthermore, to integrate the potential economic impact of biodiesel production with heavy metals removal efficiencies. Although acute exposure to heavy metals, on the other hand, reduced growth and increased removal efficiencies of Cu2+ (59.4, 98.1%) and Zn2+ (72.4, 98.2%) in C. sorokiniana and S. acuminatus, respectively. Besides, Cu2+ and Zn2+ increased primary metabolites, particularly lipids (49, 47% in S. acuminatus, 27, 26% in C. sorokiniana), with a significant induction in the unsaturation levels. Indicating that C. sorokiniana and S. acuminatus are excellent phycoremediators for industrial drainage and future sustainable algal-biofuels platform. Economic assessment of daily 1000-tonne biodiesel production from S. acuminatus grown on highly polluted wastewater via Na4SiO4 transesterification catalysis has all been assessed with an accuracy of ± 10% for the price of the diesel of US$ 1000/tonne and for the cost of the evaluated algal biomass of US$ 430/tonne. The daily 1000 T algal diesel business was viable, with a return on high investment (16.4%) and a payback period of 5 years. According to break-even and sensitivity analyses, the algal diesel cost that makes this business viable should be greater than US$ 147/barrel, while the biomass cost should not exceed US$ 462/tonne. Brent Crude Oil Spot exceeds US$ 95/barrel indicating promising prospects for algal fuel industrialization. Furthermore, the protein and amino acids-based waste biomass may serve as a sustainable biorefienry platform for various biofuel industries through biomass conversion technologies.

Valorization of Oil Palm Trunk Biomass for Lignocellulose/Carbon Nanoparticles and Its Nanomaterials Characterization Potential for Water Purification

ABSTRACT This study has two broad objectives, which include: 1) valorization of oil palm trunk (OPT) biomass for non-activated carbon nanoparticles (NAc-CNPs) and lignocellulose nanofibers (LCNFs) and 2) characterization of these nanomaterials for heavy metal removal efficiency. These nanomaterials were also tested for their heavy metal adsorption efficiency. From this study, it was established that these nanomaterials have diameters size lesser than 100 nm. NAc-CNPs have a stacked particle structure, whereas LCNFs form web-like features with entangled individual LCNF; thus, they form more stable aggregates in dilute water than NAc-CNPs. In the aqueous state, NAc-CNPs comparatively had more aggregates with the appearance of bimodality and multimodality in particle size distribution. LCNFs have a higher crystallinity index due to the presence of deposited crystalline cellulose and silica crystallites. There was no pronounced chemical change in functional groups in both NAc-CNPs and LCNFs. These nanomaterials demonstrate excellent heavy metals removal efficiency and are favorable to adsorb Cu, Pb, Fe, and Zn ions, especially in contaminated water, wastewater, and peatland.

Adsorption performance of layered double hydroxides for heavy metals removal in soil with the presence of microplastics

Microplastics (MPs) are widely presence in soil, and the uncertain influence of MPs is ineluctable. In this study, the influence of removal efficiency for heavy metals by LDHs with the presence of polyethylene (PE) and polypropylene (PP) is investigated. And the removal efficiency of heavy metals Cu2+, Pb2+, Zn2+, Ni2+ by LDHs from soil is investigated by contact time, initial concentration, PP/PE contents, pH and coexisting ions. The adsorption capacities of heavy metals with the presence of PP/PE are larger and the effects with high content of PP/PE is more obvious on removal of heavy metals. The isothermal experiment data are well described by the Generalized Langmuir isothermal model, denoting that the adsorption sites on the absorbents are certain, and the sites are inhomogeneous with different adsorption energy. In order to further explore the influence of PP/PE on the removal of heavy metals by LDHs, the interaction between LDHs and PP/PE is analyzed by XRD, FT-IR, Zeta potential and SEM. The sites energy distribution theory is employed to analyze the distribution of accessible adsorption sites and the heterogeneity of sites. The results show that with the presence of PP/PE in soil, LDHs interacts with PP/PE preferentially on account of electrostatic attraction, and the combination of LDHs and PP/PE increases the accessible adsorption sites for the removal of heavy metals and is beneficial to the adsorption process. These findings contribute to understanding environmental behavior of heavy metals with the presence of MPs and guide the application of LDHs in soil.

A novel electrocoagulation process with centrifugal electrodes for wastewater treatment: Electrochemical behavior of anode and kinetics of heavy metal removal

Anodic passivation is a key problem to impair the efficiency of in the electrocoagulation (EC) process. Process intensification of EC has attracted increasingly greater attention. In this work, a novel centrifugal electrode reactor was designed and applied in EC process to enhance the treatment of simulated heavy metal wastewater using aluminum anode. Results showed that the removal efficiency of heavy metals was significantly improved by the centrifugal electrodes, compared with the stationary electrodes. Electrochemical behavior of centrifugal electrodes was analyzed by an improved rotating disk electrode system. Anodic polarization behavior of aluminium showed a typical characteristic of dissolution in centrifugal electrodes, rather than passivation in static condition. Anode dissolution was controlled by the diffusion of Cl− ion that was enhanced by centrifugal electrodes. Thus, anode passivation was reduced. In addition, the kinetics analysis indicated that the removal of heavy metals in EC by centrifugal electrodes conformed to Variable-Order-Kinetic (VOK) model based on the Langmuir adsorption.

Co-pyrolysis of biomass and phosphate tailing to produce potential phosphorus-rich biochar: efficient removal of heavy metals and the underlying mechanisms.

Application of biochar to treat heavy metal polluted wastewater has received increasing attention; however, the immobilization ability of pristine biochar for metal ions is still limited. In this study, phosphate tailing was co-pyrolyzed with sawdust and peanut shell to acquire phosphorus-rich biochars with high removal rates for Cd, Zn, Pb, and Cu. Meanwhile, the improvement mechanisms by phosphate tailing were clarified by XRD, FTIR, SEM-EDS, BET-N2, and model fitting. Results showed that after phosphate tailing impregnation, surface area of sawdust, and peanut shell biochars increased from to 11.6 m2 g-1, and from 43.5 to 53.4 m2 g-1, respectively. Functional groups of -COOH and CO32- on biochar increased and the P2O74- newly generated. Besides, large amounts of Ca(PO3)2 and Ca2P2O7 crystals were detected in biochar ash. As for sawdust biochar, loading of phosphate tailing raised the sorption rates of Cd, Zn, Pb, and Cu by 0.35, 0.61, 1.10, and 2.64 times, respectively, as for peanut shell biochar, it was raised by 0.12, 0.47, 0.11, and 1.98 times, respectively. The sorption isotherms by phosphate tailing-loaded biochars were better fitted to Langmuir (R2 = 0.85-1.00) than Freundlich model (R2 = 0.58-0.91). Heavy metals could bind with -OH and -COOH on phosphate tailing-loaded biochars, meanwhile generated phosphorus-rich precipitation with PO3- and P2O74+, including Cd2P2O7, Cd(PO3)2, Zn (PO3)2, Pb (PO3)2, Pb2P2O7, Cu(PO3)2, and Cu2P2O7. This study proposed an innovative method to produce phosphorus-rich biochars by loading phosphate tailing for highly efficient removal of heavy metals from water bodies, and also realized the resource utilization of phosphate tailing, which was of great significance to reduce environmental pollution.

Bioremediation of heavy metals from wastewater: a current perspective on microalgae-based future

Heavy metals-containing drinking water and wastewater are posing a severe threat to the environment, and living beings on land, air and water. Different conventional, advanced nanomaterials-based and biological method has been employed for the treatment of heavy metals. Among the biological methods, microalgae are an important group of micro-organisms that have numerous environmental applications and can remediate heavy metals from wastewater. Also, it has numerous advantages over conventional remediation processes. Microalgae cells can uptake the heavy metal via different physiological and biological methods and are utilized as a nutrient source to regulate its metabolic process for the production of biomass. Furthermore, the enhancement in heavy metal removal efficiency can be improved using different strategies such as immobilization of algal cells, development of algal consortia and designing of microalgae-based nanocomposite materials. Also, it can significantly contribute towards environmental sustainability and future. Thus, the review provides a critical overview of heavy metals and their existence along with their negative effects on humans. This review provides insight on recent advanced nanomaterial approaches for the removal of heavy metals, overviews of microalgae-based heavy metal uptake mechanisms and their potential for the amputation of different heavy metals. Furthermore, the special focus is on recent strategies that enhance heavy metal removal efficiency and contribute towards sustainability for the development of a microalgae-based future.

Thiol/nitrogen functionalized Fe3O4@ZIF-8-DMTD by one-pot post coordination modulation for efficient and rapid removal of trace heavy metals from drinking water

The deep purification of trace heavy metals in drinking water is of great significance and has received considerable attention worldwide. 2,5-dimercapto-1,3,4-thiadiazole (DMTD) functionalized magnetic ZIF-8 adsorbent (Fe3O4@ZIF-8-DMTD) using a novel one-pot post coordination modulation method at room temperature could effectively adsorb trace heavy metals from drinking water through cooperating with the abundant functional groups and surface charges. The negative surface charges promoted the rapid accumulation of trace heavy metals on the surface of the adsorbent, meanwhile, the abundant thiol/nitrogen sites contributed to their adsorption, thus the adsorption rate and adsorption capacity of trace heavy metals were greatly improved. For trace Pb(II) (150 ppb), the effluent concentration could meet the World Health Organization (WHO) standard (≤10 ppb) within 10 s after adsorption by Fe3O4@ZIF-8-DMTD, and the cumulative adsorption capacity that met WHO standard was 12.11 mg/g. Fe3O4@ZIF-8-DMTD also showed high stability in a broad pH range and excellent adsorption performance in a wide low concentration range. The effluent concentration still could meet the WHO standard when the initial Pb(II) concentration was 11.70 ppm, and the corresponding adsorption capacity reached 35.00 mg/g. Moreover, the capture experiments for multiple heavy metals that coexisted in tap water showed that the effluent concentrations of Hg(II), Pb(II), Cu(II), Cd(II), and Cr(III) could be lower than the allowable limits in a few minutes. The adsorbent could also be easily recovered using magnets and regenerated by thiourea solution, which showed great application potential for the purification of trace heavy metals in drinking water.