Removal Efficiency Of Heavy Metals Research Articles

Suggested Sustainable Medical and Environmental Uses of Melanin Pigment From Halotolerant Black Yeast Hortaea werneckii AS1

The marine ecosystem is a complex niche with unique environmental circumstances. Microbial communities from the sea are one of the main origins of compounds with tremendous capabilities. Marine yeasts have the ability to produce secondary metabolites that are architecturally distinct from those found in terrestrial species. Melanin pigment synthesized by marine halotolerant black yeast Hortaea werneckii AS1 isolated from Mediterranean salt lakes in Alexandria, Egypt was found to exert a radical scavenging effect on 2,2-diphenyl-1-picrylhydrazyl (DPPH) with an IC50 of 61.38 μg/ml. Furthermore, it showed no cytotoxicity toward human skin fibroblast cell line (HSF) with an IC50 value above 0.1 mg/ml. The antimicrobial capability of the pigment was revealed against the tested number of bacterial and fungal strains with the highest inhibition zone of 25 mm against Aeromonas sp. and a growth inhibition percentage up to 63.6% against Aspergillus niger. From an environmental impact point of view, the pigment disclosed a heavy metal removal efficiency of 85.7, 84.8, and 81.5% for Pb2+, Cd2+, and Ni2+, respectively, at 100 mg/L metal concentration. The previously mentioned results suggested melanin from H. werneckii AS1 as a promising biocompatible candidate in various medical, cosmetics, pharmaceutical, and environmental applications.

Biosorption of chromium (VI), iron (II), copper (II), and nickel (II) ions onto alkaline modified Chlorella vulgaris and Spirulina platensis in binary systems.

The simultaneous biosorption of chromium (VI), copper (II), iron (II), and nickel (II) was investigated by alkaline-modified Chlorella vulgaris and Spirulina platensis in binary systems. The alkaline modified biosorbents were CV-KCl, SP-KCl, CV-Na2CO3, and SP-Na2CO3. The maximum removal efficiency recorded in this study was 99.7% with a biosorbent dosage of 0.3 g within a pH range of 2 to 6. The highest biosorption capacities obtained were 14.1, 13.5, 21.6, and 15.8 mg/g for Cr (VI), Cu (II), Fe (II), and Ni (II), respectively. The pseudo-second-order best described the biosorption rate, while the Langmuir isotherm model best described the biosorption equilibrium interaction. The values for Gibbs free energy (ΔG°) were in the range of 0.5 to 6.5 kJ/mol (Cr-Fe), 1.3 to 8.4 kJ/mol (Cr-Ni), and 3.9 to 11.3 kJ/mol (Cr-Cu) binary systems. This showed that the biosorption processes were characterized by physisorption reactions. The Temkin constant B values were in the range of 0.339 to 1.485 kcal/mol and the biosorption processes were largely exothermic reactions. The values for the Freundlich constant KF were between 1.4 and 10.4 (L/g), which indicated favourable biosorption. The Temkin isotherm model confirmed a strong binding affinity for Fe (II) and Ni (II). The results suggest that potassium chloride and sodium carbonate modification are very suitable for green algae and cyanobacteria for the efficient removal of heavy metals.

Potential of Canna indica in Vertical Flow Constructed Wetlands for Heavy Metals and Nitrogen Removal from Algiers Refinery Wastewater

Constructed wetlands (CWs) are important plant filters used for wastewater treatment. The behavior of the Canna indica-planted CWs in the face of a highly variable composition of industrial wastewater has yet to be understood. Here, we show the effectiveness of Canna indica-planted and unplanted vertical subsurface flow CWs for the treatment of Algiers petroleum refinery’s effluent. The selected species was placed in the CWs containing light expanded clay aggregate (LECA) and sand as a substrate. The findings indicate that the planted constructed wetlands efficiently removed 85% of total suspended solids (TSS), 96.38% of total nitrogen (TN), 96.15% of nitrate nitrogen (NO3−-N), 99.15% of ammonium nitrogen (NH4+-N), and 99.87% of nitrite nitrogen (NO2−-N). The overall mean removal efficiencies for heavy metals in the vegetated CWs were considerably greater than those of the control. Concentrations of Cr, Cu, Fe, Pb, Zn, Al, Ni, and Cd were calculated in the roots, rhizomes, leaves, and stems of the plant; then, the bioaccumulation factor (BAF) and translocation factor (TF) were determined. An initial examination using scanning electron microscopy (SEM–EDX) was also included in the study. The analysis indicated that toxic elements were adsorbed on plant tissues, concentrated in the roots, and partially transported to the aerial parts. These results are useful for the design of CWs to treat industrial wastewater, enabling water of acceptable quality to be discharged into the environment, especially as a low maintenance and cost-effective technology in developing countries.

Using ozone for activation of manufactured porous media to improve the removal efficiency of heavy metals from industrial wastewater

Using ozone for activation of manufactured porous media to improve the removal efficiency of heavy metals from industrial wastewater

Health benefits of using air purifier to reduce exposure to PM2.5-bound polycyclic aromatic hydrocarbons (PAHs), heavy metals and ions

In this study, the efficiency of air cleaners in removal of chemical components of PM2.5 (PAHs, heavy metals, and ions) in the indoor air of dormitories of Tehran University of Medical Sciences, Iran were assessed. 12 rooms were selected and randomly divided into two groups: sham air purifier system deployed room (SR) vs. true air purifier system deployed room (TR). 24-h PM2.5 samples were simultaneously collected in both TR and SR on PTFE filter papers at a flow rate of 5 L/min. The results showed overall removal efficiency of 76.5 ± 15.5%, 63.1 ± 22.5%, and 66.2 ± 24.8% for PAHs, heavy metals and ions, respectively. Moreover, the fraction of positive ions decreased when air purifiers were used in the rooms. The results showed that the smoking is an important influencing factor on the indoor air quality; smoking can leads to reduction in removal efficiency of PAHs, heavy metals and ions by 26%, 40%, and 51%, respectively. An air purifier could decreased the PM2.5 even lower than the WHO annual guideline level in non-smoker rooms. The present study revealed that use of indoor air purifiers can significantly reduce the risk of carcinogenicity and non-carcinogenicity attributed to heavy metals and PAHs, especially in places without a smoker.

Sequestration of heavy metals from contaminated water using magnetic carbon nanocomposites

Heavy metals are toxic to flora, fauna and human beings. This study focused on removing toxic metals from an aqueous medium using magnetic carbon (Fe3O4@Carbon) nanocomposites. The biogenic green synthesis approach was used to fabricate the magnetic nanocomposite using low-cost poplar sawdust powder. The characterization of the nanocomposites was done using FESEM, TEM BET and FTIR. The sequestration of Pb (II), Cu (II) and Cr (VI) from water by Fe3O4@Carbon nanocomposites were studied under batch mode. The adsorption capacities for Pb (II), Cu (II) and Cr (VI) were 151.5, 48.08, and leaves49.29 mg/g respectively. The removal of metals by magnetic composites was studied in a mono, binary and tertiary network of metal ions. Adsorption isotherms studies indicated the chemosorption of Cu (II) and Cr (VI) onto the surface of nanocomposites. The thermodynamic analysis revealed that removal of studied metals ions is spontaneous and feasible. In this study, the effectiveness of magnetic nanocomposites is also explored for the removal of other heavy metals from tap water and simulated water sample. The heavy metal removal efficiency of the nanocomposites was not affected up to thrice reuse of adsorbent.

Enhancement of heavy metal removal efficiency of plants using L. sphaericus

In this study, a pot experiment using Solanum nigrum L. grown in Cr -contaminated soil was conducted in a greenhouse. L. sphaericus was applied at three different concentrations to examine the effects on phytoremediation efficiency. According to this study, L. sphaericus can enhance the phytoremediation efficiency of S. nigrum by changing the plant growth parameters, thereby increasing the Cr uptake. At an application rate corresponding to the T3 treatment in this experiment, L. sphaericus can stimulate the dry biomass of S. nigrum by 50.2% and can increase the Cr concentrations in the aerial part by 12.83%.

Strained Zero‐Valent Iron for Highly Efficient Heavy Metal Removal

AbstractMicroscale zero‐valent iron is one of the most important multifunctional environmental remediation materials, yet its passivated iron oxide shell hampers the transportation of inherent electrons. Herein, the authors exert tensile strain onto mZVI by interstitial boron doping that destabilizes lattice FeFe interactions, thereby liberating the electrons trapped in the iron reservoir. Tensile strain also upshifts the equilibrated Fermi level at the iron/iron oxide Ohmic heterojunction, thus populating the oxide shell with abundant electrons for robust heavy metal sequestration. Strained‐mZVI exhibits a 62 times faster Cr(VI) removal rate than its unstrained counterpart and can successfully treat industrial wastewater such as landfill leachate, electroplating, and chromium effluents. The excellent property and exceedingly low cost ($2000 ton−1) of strained‐mZVI results in its great potential to remediate heavy metal‐contaminated water and soil.

Removal of microplastics and attached heavy metals from secondary effluent of wastewater treatment plant using interpenetrating bipolar plate electrocoagulation

In this study, the mixed pollutants of microplastics and heavy metals from secondary effluent of wastewater treatment plant (WWTP) were removed by interpenetrating bipolar plate electrocoagulation (IBPE) reactor. Heavy metals and microplastics in the wastewater were simultaneously removed during the experimental process with high removal efficiency. The influences of current density, initial pH and reaction time on the removal rate were analyzed. When the current density was 12 mA / cm2, the initial pH was 6 and the reaction time was 20 min, the optimal removal efficiency of heavy metals and microplastics were obtained with removal rates of 95.16% and 97.5%, respectively. Under the condition of different current densities, the change of removal rate with time was fitted through mathematical model. The complexation forms of heavy metals and surface groups of microplastics were analyzed through pseudo-voltammetry curve. The operation cost of removing microplastics and heavy metals through IBPE reactor was 0.91 $·L−1 under the optimal experimental conditions. The experimental results suggested that this process reduced the potential harm of microplastics and heavy metals to aquatic organisms and human beings. The IBPE could be applied as a clean technology for simultaneous removal of microplastics and heavy metals from secondary effluent of WWTP.

High Performance Copper Based Metal Organic Framework for Removal of Heavy Metals From Wastewater

The biggest challenge of this century is the generation of wastewater which is released to the environment due to industrial expansion. Industrial development has caused the release of various pollutants including heavy metals such as Cd, Pb, and Cr into the environment. In this study, copper diphenylamine metal-organic framework (Cu-DPA MOF) has been synthesized via hydrothermal method and its adsorption capacity toward the removal of heavy metals from wastewater was examined. The removal efficiency of heavy metals by Cu-DPA MOF was tested at optimized adsorption parameters such as optimal adsorbent dosage, pH, initial metals concentration, and adsorption time. The heavy metals concentration in the wastewater before treated with the as-synthesized MOF was determined to be 0.3027, 0.0098, and 0.1021 mg/L for Cr, Cd, and Pb, respectively. The corresponding concentrations of heavy metals in wastewater were reduced to 0.0015, 0.00024, and 0.00016 mg/L when treated with the as-synthesized MOF. As a result, a maximum removal efficiency of 97.6%, 99.5%, and 99.5% was achieved for Cd, Cr, and Pb metals, respectively. This is possibly due to the high porous nature and huge surface area of the as-synthesized MOF. The adsorption data were best fitted with Freundlich isotherm throughout this study. The study sheds light on the design of adsorbents with high removal efficiency of pollutants found in the environment.

Assessment of the effectiveness of water hyacinth (E. crassipes) in the biosorption of heavy metals from Aluminium extruding company effluents

Biosorption technique was used to assess the effectiveness of water hyacinth in the removal of heavy metal from effluents obtained from an Aluminium extruding company. Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) techniques were used to characterize the water hyacinth materials before and after adsorption. A batch experiment was set up using water hyacinth (E. crassipes) ash as absorbent. The effects of contact time, absorbent dose, pH and temperature on the heavy metal removal efficiency were determined. The experimental data were analysed by the Langmuir, Freundlich and Temkin models of adsorption. The FTIR results showed a reduction in the intensity of the adsorption bands for all the metal ions. The optimal percentage removal of the metal occurred at 30 minutes except Cd which had highest percentage removal at 20 minutes while optimal pH was at 6.0 except Pb which had its optimal removal at pH 4.0. Increase in biosorbent dosage increased the percentage removal of the metal ions with Zn (96% at 1.0 g) having the highest percentage removal of the five metal ions studied. The results revealed that Langmuir and Temkin Isotherms were the best model for the metal ions adsorption onto water hyacinth. Langmuir model had a better fit for Fe (R2 = 0.78), Ni (R2 = 0.82) and Pb (R2 = 0.78), while Temkin model fitted best for Cd (R2 = 0.92) and Zn (R2 = 0.96). The E. crassipes, therefore, could serve as effective, low-cost and environmentally friendly adsorbents.

Multi-component removal of Pb(II), Cd(II), and As(V) over core-shell structured nanoscale zero-valent iron@mesoporous hydrated silica

The application of nanomaterials for the removal of heavy metals has received a great deal of attention because of their high efficiencies in the environment. But it is difficult to remove multiple heavy metals simultaneously with high efficiency and stability. Herein, the core-shell structured nanoscale zero-valent iron (nZVI) encapsulated with mesoporous hydrated silica (nZVI@mSiO2) were prepared for efficient removal of heavy metals including Pb(II), Cd(II), and metalloid As(V). The material prepared uniformly with a high surface area (147.7 m2 g−1) has a nZVI core with the particle size of 20–60 nm and a modified dendritic mesoporous shell of 19 nm. 0.15 g L−1 of the optimal material exhibited an extraordinary performance on removing Cd(II) and the maximum adsorption capacity for Pb(II), Cd(II), and As(V) reached 372.2 mg g−1, 105.2 mg g−1, and 115.2 mg g−1 with a pH value at 5.0, respectively. The dissolved iron during the reaction showed that the mesoporous silica (mSiO2) played an important role in enhancing the stability of nZVI. In addition, the competitive relationship between the coexistence of two heavy metals was discussed and it was found that the removal efficiency of the material for both was improved when Cd(II) and As(V) were removed synergistically.

Removal and magnetic recovery of heavy metals and pesticides from soil by layered double hydroxides modified biotite

• Novel three-dimensional magnetic adsorbent by biotite supported LDHs. • High removal efficiency of heavy metals and pesticides by LDH@Bt from soil. • Removal mechanism of precipitation for Cu/Pb and surface adsorption for pesticide. • Favorable interception function of LDH@Bt in soil by column leaching experiments. • Admirable magnetic recovery ability to avoid potential contamination. Novel biotite (Bt) supported different amounts of Mg-Al layered double hydroxide (LDH@Bt) with a three-dimensional hierarchical structure was fabricated via in-situ growth method. The structural and morphology characterization indicate that LDHs stably and uniformly dispersed on Bt surface, but excessive LDHs still lead to obvious aggregation of LDHs. The removal performance of LDH@Bt for heavy metal of Cu 2+ /Pb 2+ and pesticides of glyphosate (GLY)/2-methyl-4-chlorophenoxyacetic acid (MCP) in soil was investigated, and the removal rates of LDH@Bt composite for four contaminants were higher than those of LDHs and Bt. Intraparticle diffusion and pseudo-second-order model well described the kinetics of heavy metals and pesticides removal. Adsorption isotherm data of Cu 2+ and Pb 2+ yielded better accordance of Freundlich model, while data of GLY and MCP were fitted Langmuir model well. In addition, different adsorption mechanisms for removal of Cu 2+ /Pb 2+ by precipitation and removal of GLY/MCP by surface adsorption were proposed. The application performance and recovery ability of LDH@Bt composite in soil were evaluated by column leaching experiments and magnetic collectability tests. The excellent removal performance and magnetic collectability provided a promising strategy for remediation and elimination of heavy metals and pesticides contaminations from soil.

Preparation of nano-ferrous sulfide modified with phytate for efficient Cr(VI) removal in aqueous solutions

ABSTRACT Phytate-modified nano-ferrous sulfide (IP6-nano-FeS) was successfully prepared to overcome the low efficiency of heavy metal removal by nano-ferrous sulfide (nano-FeS) due to the agglomeration and easy oxidization of this reducing agent. The results showed that IP6-nano-FeS improved the dispersion of nano-FeS particles, and the maximum Cr(VI) removal reached 436.94 ± 25.40 mg/g. A more novel contribution of this study is that Cr(VI) removal by IP6-nano-FeS was enhanced in the presence of Mg2+, Ca2+, and O2. The removal efficiency increased by ∼10% and ∼8.5% in the presence of conventional cations (Mg2+ and Ca2+: 2–10 g/L) and O2, respectively. The application potential of IP6-nano-FeS for the rapid removal of Cr(VI)-contamination in the presence of aerobic and coexisting cations was confirmed in this study.

Machine learning for the prediction of heavy metal removal by chitosan-based flocculants

The use of chitosan-based flocculants (CBFs) to remove dissolved heavy metals from wastewater is widely advocated. This study applied machine learning (ML) methods to develop a prediction model for the efficiency of heavy metals removal using CBFs. The random forest (RF) models could accurately predict the removal efficiency of heavy metals (R2 = 0.9354, RMSE = 5.67) according to flocculant properties, flocculation conditions, and heavy metal properties. The solution pH (pHsol) in flocculation conditions and the molecular weight (Mv) in flocculant properties were identified as the most dominant parameters in flocculation performance with feature importance weights of 0.294 and 0.134, respectively. The partial dependence analysis showed the impact way of each influential factor and their combined effects on the heavy metal removal efficiency using CBFs. Overall, a prediction model was successfully developed for the efficiency of heavy metals removal, which will guide rational applications of CBFs for the treatment of wastewater containing heavy metals.

Efficient removal of lead ions from aqueous solution by graphene oxide modified polyethersulfone adsorptive mixed matrix membrane

In this study, we report the combined effect of graphene oxide (GO) and polyvinylpyrrolidone (PVP) for the heavy metal removal efficiency of polyethersulfone (PES) membranes. PVP with four different amounts of GO was infused in the membrane matrix by the physical blending method. Characterizations such as porosity, contact angle, water flux and Fourier transform infrared spectroscopy were conducted for all prepared membranes. Viscid behavior of polymer dope solution was examined to understand the phase separation phenomena better. PVP enhanced the GO distribution within the membrane surface to some extent via hydrogen bond. The addition of nanoparticles enhanced the membrane physicochemical properties with water permeation, Pb2+ rejection and adsorption capacity. Permeate flux of modified membrane (m4) was found to be 150.21 L/m2h and it is 8.03 times higher than unmodified membrane (m0). Besides, all fabricated membranes were evaluated for Pb2+ rejection from synthetic wastewater and rejection % of m4 (80.6%) had increased twofold than m0 (38.9%). Membrane cleaning was performed using different methods and the best results were achieved with a concentration of 0.05 wt% sodium hypochlorite under pH 7 and further reused for the filtration test. Moreover, adsorption isotherm was tested using Freundlich and Langmuir models and the Langmuir model offered the best fitting.

Evaluating Permeable Clay Brick Pavement for Pollutant Removal from Varying Strength Stormwaters in Arid Regions

Permeable pavement is a low impact development technology for stormwater (SW) runoff control and pollutant removal. The strength of SW depends on land use of the catchment, e.g., semi-urban vs. industrial. The performance (in terms of pollutants removal) of permeable clay bricks (PCB) has not been adequately assessed for SW of varying strengths. For using the permeable clay bricks as a pavement surface layer, the present research investigates its pollutant removal capacity through SW infiltration using a laboratory setup. SW samples of two different strengths, i.e., high polluted stormwater (HPSW) and less polluted stormwater (LPSW), were tested for a pavement system consisting of the clay brick layer on top of a coarse gravel support layer. The tests were performed at a rainfall intensity of 12.5 mm/h (for a 10-year return period in Buraidah, Qassim) to evaluate the suitability of PCB for the arid and semi-arid regions. The experiments revealed that PCB became fully saturated and achieved a steady-state outflow condition after 10 min of rainfall. Irrespective of contamination level, the pollutant removal efficiency was found to be similar for both HPSW and LPSW. High TSS (>98%) and turbidity (>99%) removals were achieved for both strengths, while BOD5 (78.4%) and COD (76.1%) removals were moderate. Poor to moderate nutrient removal, 30.5% and 39.1% for total nitrogen (TN) and 34.7% and 31.3% for total phosphorus (TP), respectively for HPSW and LPSW, indicates an adsorptive removal of nutrients in the system. Heavy metal removal efficiency ranged from 6.7% to 94%, with higher removals archived for Fe, Mn, Se, and Pb. The study provides insights into the role of PCB as a surface layer in the permeable pavement for pollutant removal. The study also establishes the guidelines for the optimal permeable pavement design to deal with SW of varying contamination levels. Permeable clay bricks showed the potential to be used as a sustainable LID technology for arid regions.

Plastic waste as a valuable resource: strategy to remove heavy metals from wastewater in bench scale application.

Single-use plastic waste is gradually considered a potential material for circular economy. Ion exchange resin obtained from polystyrene waste by sulfonating with H2SO4 was used for heavy metal removal from electroplating wastewater. Batch mode experiments of Cu2+, Zn2+, and Cd2+ were carried out to determine effect of pH, initial concentration, equilibrium time, and the isotherm and kinetic parameters; the stability of the resin in continuous operation was then evaluated. Finally, the longevity of the resin after being exhausted was explored. The results indicated that at pH 6, a pseudo-second-order kinetic model was applicable to describe adsorption of studied heavy metals by sulfonated polystyrene with adsorption capacities of 7.48mg Cu2+/g, 7.23mg Zn2+/g, and 6.50mg Cd2+/g, respectively. Moreover, the ion exchange process between sulfonated polystyrene resin and Cu2+, Zn2+, Cd2+ ions followed the Langmuir isotherm adsorption model with R2 higher than 96%. The continuous fixed-bed column in conditions of a sulfonated polystyrene mass of 500g, and a flow rate of 2.2L/h was investigated for an influent solution with known initial concentration of 20mg/L. Thomas and Yoon-Nelson models were tested with regression analysis. When being exhausted, the sulfonated polystyrene was regenerated by NaCl in 10min with ratio 5mL of NaCl 2M per 1g saturated resins. After 4 times regeneration, the heavy metal removal efficiency of sulfonated polystyrene was reduced to 50%. These aforementioned results can figure out that by sulfonating polystyrene waste to synthesize ion exchanging materials, this method is technically efficient and environmentally friendly to achieve sustainability.

A review on experimental chemically modified activated carbon to enhance dye and heavy metals adsorption

Effective and low-cost removal of dye and heavy metals from wastewater still is a great challenge for researchers. Adsorption using activated carbon is widely used in removing these toxic pollutants. Physical, chemical, and biological modifications have been studied for improving activated carbon adsorption performance. Literature suggests that chemical modified activated carbon showed maximum adsorption capacity towards dye and heavy from aqueous solution. Chemical modifications, including acid, base, and impregnation, are studied extensively due to reagent availability, easy modification, and tuning facilities of surface functional groups. However, systematic documentation of chemical modifications on activated carbon is required for dye and heavy metals removal efficiency improvement from wastewater. This review focused on the up to date experimental chemically modified activated carbon that showed improved adsorption capacity towards dye and heavy metals from aqueous solution. The available experimental data recommends that an appropriate treatment strategy of a chemical modification process enhanced dye and heavy metals adsorption capacity of the modified activated carbon. Optimum modification process developed textural or surface functional groups properties of modified activated carbon that improved adsorption or binding capacity toward adsorbate or a particular species. In addition, the adsorption capacity of modified and corresponding activated carbon is compared. • Experimental works of dye and heavy metals adsorption are summarized. • Changed of physiochemical properties of AC after chemical modification are mentioned. • Optimized treatment parameters of chemical modification are focused. • Compared adsorption performance between modified and corresponding AC adsorbents. • Systematic documentation help in tailoring surface functional groups of modified AC.

A review on heavy metal ions adsorption from water by layered double hydroxide and its composites

• We selected to review topics related to the specific application of LDH removal of heavy metals. • Classify and summarize its modification methods, absorption properties, composition, structure, and other aspects. • It is determined that future research needs to reduce environmental impact and economic costs to promote the synthesis and use of LDH. • This system summary will provide helpful guidance for preparing high-efficiency LDHs-based adsorbents and offer critical clues to elucidating the adsorption behavior of heavy metals on LDHs-based materials. Heavy metal pollution is highly toxic and persistent, posing a severe threat to human health, agriculture, and the safe environment. Therefore, there is an urgent need for fast and efficient heavy metal removal technology to deal with emergency response to heavy metal leakage. In recent years, the development of a unique layered double hydroxide material has attracted widespread attention in sewage treatment. Due to these fundamental scientific issues, the general concern about environmental pollution management of LDH-based materials, and the recent significant developments in this field, it is necessary to conduct a thematic review. This article summarizes 474 related articles published since 2005 and outlines functionalized layered double hydroxide (LDH) research status as heavy metal adsorption materials. In addition, there is still a lack of reviews on the adsorption characteristics, interaction mechanism, and application of LDHs-based nanomaterials in heavy metal removal. Here, the primary purpose of this article is to systematically summarize LDHs-based materials and their applications in removing heavy metals from aqueous solutions ( Fig. 1 ). First, we will focus on its preparation and modification methods to understand LDH intuitively. Subsequently, the effects of different environmental conditions on factors such as pH, temperature, and contact time were summarized. Finally, the interaction mechanism between LDHs composites and heavy metals is briefly described, and a quick conclusion is given.