Removal Of Toxic Metals Research Articles

Novel Thin-film, Chitosan-polyaniline Nanofiltration Membrane Effectively Removes Toxic Heavy Metals From Wastewaters

Background: Membrane technology for water purification has gained much attention in many industries and for healthier human life. Also, improving the elimination of toxic heavy metals is a much needed strategy for the filtration of public water supplies. This study investigated the removal of toxic heavy metals from wastewater, using a novel thin-film membrane. Methods: We investigated the structural, physico-chemical, and antifouling properties of the membrane, and its ability to remove toxic elements from water. Seven parameters were examined: Contact angle, water ionic contents, Fourier’s transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), 3D-surface imaging, water flux, and antifouling effects. Results: The results indicated that a thin-film layer formed on the membrane. The 3D-images demonstrated that the surface roughness decreased when the polyaniline ratio to nanoparticles increased. The surface hydrophilicity increased by incorporating polyaniline into the surface. The water flux increased from 8.04 (L/m2.h) to 14.74 (L/m2.h) in the virgin membrane. The sodium sulfate rejection was 61% for the virgin membrane whereas it was >67% in the thin-film coated membrane. The data demonstrated excellent anti-fouling properties for the novel membrane, with a flux recovery ratio of >94.65% while it was about 79% for the virgin one. The rejection rates of chromium and copper ions for the novel membrane were >86% and >84%, respectively. These values were significantly higher than those of the virgin membrane (>53% and >51%). Conclusion: The thin-film composite membrane significantly improved the removal rate of toxic heavy metals from the wastewater samples compared to the virgin membrane.

Biosynthesis of aluminium oxide nanobiocomposite and its application for the removal of toxic metals from drinking water

This work aimed to synthesize the aluminium oxide nanoparticles using Ixoro coccinea leaf extract. Furthermore, the synthesized Ixoro coccinea aluminium oxide nanoparticles (I–Al2O3-NPs) and nanocomposites (I–Al2O3-NC), including them as the fillers in a chitosan matrix were characterized, and I–Al2O3-NC was applied to remove the toxic metals (TMs) including Cd, Ni, and Pb from water. Optimization of different batch experimental adsorption parameters (pH, concentration of TMs, dose of I–Al2O3-NC, temperature, and time of contact) was done to check the feasibility of I–Al2O3-NC for maximum removal of TMs from water. The extreme adsorption capacities using nanocomposites for Cd, Ni, and Pb were 66.0, 60.0, and 66.4 mg g−1, respectively. The I–Al2O3-NC followed the Freundlich isotherm model for removing Cd and Ni while showing the monolayer surface coverage for the removal of Pb. For this process, the best-fitted kinetic model was the pseudo-second-order equation. The enthalpy, entropy, and free energy of metal ion adsorption, among other parameters of thermodynamics, were estimated. The process was found to be exothermic, advantageous, and spontaneous. Kinetic studies show that intra-particle diffusion is essential for eliminating TMs. In addition, I–Al2O3-NC was applied for the adsorption of TMs from surface water and determined to be effective in removing these contaminants up to an acceptable drinking water standard. Regeneration of adsorbent suggested that green synthesized I–Al2O3-NC may be an active tool for removing Cd, Ni, and Pb ions from contaminated water.

Green polyampholytic ionic scavengers as an alternative to crude oil derived chelating resins for removal of toxic metals from aqueous solutions

A group of six amino-hypophosphite polyampholytes (AHPs) was obtained and investigated for potential scavenging of four toxic metal ions – copper(II), cobalt(II), nickel(II), and lead(II). The materials were synthesised with a convenient green one-pot reaction from simple building blocks, including polyalkylenepolyamine, paraformaldehyde, and hypophosphorous acid. The AHPs are produced in a process that is greener and simpler than conventional chelating scavengers, which are mostly crude oil derived materials and difficult to dispose of in a sustainable way. The materials were characterised with FTIR spectra and tested for removal of four different toxic metal ions. It was found that all of the AHPs obtained possess ion scavenging properties in a wide pH range (2.0–8.0). Some AHPs exert a certain selectivity towards specific metal ions. The highest values of the ionic capacities derived from cation removal experiments vary in the range 0.7–2.5 mmol Me2+·g−1 of acidic AHP and 1–4 mmol Me2+·g−1 of basic AHP. These features suggest their potential application for toxic metal ion removal processes in a wide spectrum of wastewater types.

Roll-to-Roll Processing of Hybrid MOF and Nylon Membranes for High Efficiency Removal of Toxic Gases, Heavy Metals, and Dyes

Roll-to-Roll Processing of Hybrid MOF and Nylon Membranes for High Efficiency Removal of Toxic Gases, Heavy Metals, and Dyes

Kinetic and equilibrium studies on bioadsorption of copper and lead by water hyacinth (Eichhornia crassipes) plant powder

AbstractCommon water hyacinth plant (Eichhornia crassipes) found in various water bodies in Assam, India, was used as bioadsorbent for removal of toxic metals (Cu and Pb) from synthetic medium. The functional groups present in the bioadsorbent, water hyacinth plant powder (WPP) were determined by using Fourier transform infra red spectroscopy (FTIR) and surface topography by scanning electron microscopy (SEM) technique. The specific surface area of WPP was also determined. The optimum adsorption properties of WPP was determined by considering pH, agitation time, metal concentration, temperature and the amount of adsorbent. The adsorbent showed good adsorption of toxic metal, Cu and Pb from synthetic medium. Water hyacinth plant was used to treat ten synthetic mediums containing 40, 50, 60 70 and 80 mgL‐1 of the two heavy metals, Cu and Pb. From the batch study, it was observed that the adsorption mechanism for the studied metals follow the 2nd order kinetics and the isotherm study showed that Langmuir model is suitable for explaining the adsorption equilibrium data for bioadsorption of Cu2+ and Pb2+ ions on WPP. For Cu(II) adsorption on WPP, the maximum adsorption was observed at pH 7 while for Pb(II), the maximum adsorption was observed at pH 5.

Synthesis of Floral-Shaped Nanosilica from Coal Fly Ash and Its Application for the Remediation of Heavy Metals from Fly Ash Aqueous Solutions

Every year a large amount of coal fly ash (CFA) is generated and dumped in fly ash ponds. Fly ash has numerous toxic heavy metals, which leads to water pollution due to the percolation of these heavy metals. Heavy metal toxicity has become a major issue for the whole globe. Moreover, CFA has several value-added minerals, such as silica, alumina, and ferrous in large amounts. Therefore, the synthesis of silica nanoparticles from CFA and their application for the removal of toxic heavy metals from fly ash aqueous solution will prove to be an economical and efficient approach. Here, in the present research work, investigators synthesized nanosilica from CFA by alkali dissolution and sol-gel methods and applied them for heavy metal removal. Firstly, CFA was treated with high molar NaOH, along with stirring and heating. Further, the sodium silicate leachate from CFA was treated with dilute HCl till the formation of a white gel at neutral pH. Purification of the nanosilica was achieved by treating with 1M HCl along with stirring followed by calcination at 400 °C for 4 h. The synthesized nanosilica was characterized by UV-Vis, Fourier transform infrared (FTIR), particle size analyzer (PSA), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), electron diffraction spectroscopy (EDS), and high-resolution transmission electron microscope (HR-TEM). The sizes of the floral-shaped nanosilica particles were 20–70 nm, and the purity was 90–95%, as confirmed by microscopy and EDS, respectively. The XRD and FTIR revealed the amorphous nature of nanosilica. Finally, the potential of the nanosilica was assessed for the removal of heavy metals from 20% CFA aqueous solutions in batch experiments. The nanosilica showed about 40–90% removal of heavy metals (Al, Pb, Cd, Cu, Cr, Ni, Co, Zn, Mn) from the fly ash aqueous solution.

Toxic Heavy Metals Elimination from Contaminated Effluents Utilizing Various Adsorbents: Critical Mini-Review

The release of massive pollutants amounts continuously because of urbanization and industrialization has caused a big ecological problem worldwide. Due to their activities, effluents of many industries: mining operations, paper/pulp, and batteries, release different heavy metals, including Copper (Cu), Lead (Pb), and Nickel (Ni), into the environment. Heavy metals are of big concern due to their high toxicity, big bioaccumulation susceptibility, and serious threat to humans and ecosystems. Compared to organic pollutants, which are highly influenced by biological and chemical degradation, heavy metals have no degradation into end products using these methods. Therefore, the removal of such metals is considered a big challenge in water purification. For metals removal, different techniques have been applied, such as precipitation, ultrafiltration, and coagulation. However, those applications have many drawbacks: low-efficiency, high consumption of reagents, and generation of toxic sludge. In contrast, adsorption considers an effective method for metal removal, owing to the method’s simplicity, economic and versatility, making it the most convenient way for toxic metals removal. Many conventional adsorbents, such as activated carbon and alumina, have been effectively employed. Nevertheless, the biggest disadvantages of using such adsorbents appear to be their price due to high activation costs and limited reusability. Biosorption has lately emerged as a method with several advantages, including minimal cost, ease of use, and great efficacy, even for trace amounts of metallic ions. This paper aims to review the relevant literature regarding the adsorption method for heavy metals removal from wastewater. Different treatments of heavy metals from wastewater and their related features are highlighted. The metals’ toxicity and hazards to health and the environment are also discussed. The application of various materials as bioadsorbents is explored, such as natural adsorbents and industrial and agricultural wastes.

Removal of Toxic Metals from Sewage Sludge by Acid Hydrolysis Coupled with EDTA Washing in a Closed-Loop Process.

Contamination with toxic metals prevents the use of sewage sludge (SS) as a soil fertilizer. Hydrodynamic cavitation, thermal microwaving, microwave-assisted alkaline, and acid hydrolysis coupled with ethylenediaminetetraacetate (EDTA) washing were tested as a method to remove toxic metals from SS. Acid hydrolysis coupled with EDTA washing was most effective and was used in a closed-loop process based on ReSoil technology. EDTA and process solutions were recycled at a pH gradient of 12.5-2, which was imposed by the addition of quicklime (CaO) and H2SO4. An average of 78%-Pb, 76%-Zn, 1%-Cu, and 17%-Cr were removed from SS in five consecutive batches. No wastewater was generated, only solid waste (40%). The EDTA lost in the process (42%) was resupplied in each batch. In a series of batches, the process solutions retained metal removal efficiency and quality. The treatment removed 70% and 23% of P and N, respectively, from SS and increased the leachability of Zn, Cu, Mn, and Fe in the washed SS by 11.7, 6.8, 1.4, and 5.2 times, respectively. Acid hydrolysis coupled with EDTA washing proved to be a technically feasible, closed-loop process but needs further development to reduce reagent, material, and nutrient loss and to reduce toxic emissions from the washed sludge.

Theoretical study of M2CO2 MXenes stability and adsorption properties for heavy metals ions removal from water

Heavy-metals ions are one of the reasons to cause the pollution of water. The toxic heavy metal ions, such as Pb2+ and Cu2+, have been aroused worldwide concern due to their high toxicity and carcinogenicity. Two-dimensional (2D) transition metal carbide materials (MXenes) exhibit the hydrophilic surface, and the excellent chemistry stabilities, and can be the potential materials for water decontamination field. Here, by using density functional theory calculations, the adsorption behaviors of heavy metals, Ag, Au, Cu, Pb, and Zn on M2CO2 (M = Sc, Ti, V, Cr, Zr, Nb, Mo, Ta, and W) are investigated. Results show that Pb can stably be adsorbed on V2CO2, Cr2CO2, and Zr2CO2 MXenes with the corresponding adsorption energy lower than 0 eV. Densities of states and charge transfers analysis show that the hybridization of O* p orbital with Pb p and d orbitals promote the binding strength of M2CO2 (M = V, Cr, Zr) with Pb. In addition, it shows that the high Pb coverage on M2CO2, the F mixed in the terminal O* of M2CO2, and the strain in M2CO2 can alter the adsorption ability of M2CO2 for Pb. Ab initio molecular dynamics (AIMD) simulations results indicate that the adsorbed Pb on the M2CO2 cannot aggregate into clusters at conducting temperature (300 K). Moreover, the results of the reaction energy, the binding energy, and the formation energy of hydrated Pb2+ ([PbH2On]2+) on M2CO2, and the change of bond lengths of Pb-O, dPb-O in ([PbH2On]2+) indicate that the Pb2+ can be efficiently removed from waste water even it was hydrated into [PbH2On]2+. This work illustrates that the 2D MXenes can be the promising materials for the removal of toxic metals (such as Pb2+) from water.

Synergistic effects of multifunctional nanostructured WO3-WS2 decorated on polypyrrole (WO3-WS2/PPy) for the removal of toxic heavy metals from wastewaters and high supercapacitor performance

Nowadays, developing a simple, economic, and scalable approach for environmental remediation and producing energy storage devices remains challenging. Herein, we report a novel WO3–WS2 decorated polypyrrole (WO3–WS2/PPy) nanocomposite for the removal of heavy metals, i.e., Cd(II) and Ni(II) and high-performance supercapacitor electrodes.The WO3–WS2/PPy showed significant improvement in the removal of Cd(II) (95.33%) and Ni(II) (89.95%), while WO3–WS2 and PPy revealed removal efficiency of 87.02 and 77.01% for Cd(II) and 82.97 and 74.66% for Ni(II), respectively. For the competitive adsorption experiment, Cu2+/Zn2+ causes a significant influence, while Na+/K+/Mg2+/Ca2+ exerted less effect on the adsorption of the aforementioned metal ions. The WO3–WS2/PPy exhibited higher selectivity toward Cd2+ than Ni2+. Along with, the WO3–WS2 decorated PPy based electrode showed a high specific surface area and support conductive networks, which synergistically improved charge storage capability. The WO3-WS2/PPy-based electrodes exhibit superior electrochemical performance with excellent rate capability, offering the high specific capacitance value of 624 F/g at 3 A/g current density and retaining capacitance stability of 81% after 5000 cycles in 1 M Na2SO4 electrolyte solution. The outcomes of this research infer that WO3-WS2/PPy is a promising candidate for wastewater treatment and high-performance energy storage applications.

Effective removal of trace-level toxic metals from flue gas desulfurization wastewater using SiO2 supported hydrogel sorbent

Flue gas desulfurization (FGD) wastewater generated from coal-fired power plants contain potentially harmful heavy metal pollutants that pose a threat to public health and clean water. In this work, we present a water stable polyethylenimine-n,n’-methylenebisacrylamide (PEI-MBAA) functionalized SiO2 solid sorbent material (PMS-1.2/1/4) and investigate its metal adsorption kinetics, selectivity, regenerability, and space velocity. The kinetic studies of six of the toxic heavy metals (As, Cd, Cr, Pb, Se, and Hg) prepared with single elements in Milli-Q water showed the effect of chemical bonding and intraparticle mass transfer resistance on the sorption process. The selectivity studies demonstrated the significant adsorption efficiency toward trace-level heavy metals (Se, Cd, U, Al, etc.) from authentic industrial FGD wastewater. Through five consecutive adsorption−desorption cycles with the FGD (uptake)-citrate (release)-based buffer pair, the sorbent showed high heavy metal removal ability and good reusability. The maximum flow rate for the removal of Se from industrial FGD wastewater was determined to be as high as 8 bed volumes/minute of the sorbent bed. The results demonstrate the PMS-1.2/1.4 sorbent is a promising candidate for the removal of heavy metals from practical aqueous solutions.

Versatile Magnetic Mesoporous Carbon Derived Nano-Adsorbent for Synchronized Toxic Metal Removal and Bacterial Disinfection from Water Matrices.

Contamination of water resources by toxic metals and opportunistic pathogens remains a serious challenge. The development of nano-adsorbents with desired features to tackle this problem is a continuously evolving field. Here, magnetic mesoporous carbon nanospheres grafted by antimicrobial polyhexamethylene biguanidine (PHMB) are reported. Detailed mechanistic investigations reveal that the electrostatic stabilizer modified magnetic nanocore interfaced mesoporous shell can be programmatically regulated to tune the size and related morphological properties. The core-shell nano-adsorbent shows tailorable shell thickness (≈20-55nm), high surface area (363.47 m2 g-1 ), pore volume (0.426 cm3 g-1 ), radially gradient pores (11.26nm), and abundant biguanidine functionality. Importantly, the nano-adsorbent has high adsorption capacity for toxic thallium (Tl(I) ions (≈559mg g-1 ), excellent disinfection against Staphylococcus aureus and Escherichia coli (>99.99% at 2 and 2.5µg mL-1 ), ultrafast disinfection kinetics rate (>99.99% within ≈4min), and remarkable regeneration capability when exposed to polluted water matrices. The Tl(I) removal is attributed to surface complexation and physical adsorption owing to open ended mesopores, while disinfection relies on contact of terminal biguanidines with phospholipid head groups of membrane. The significance of this work lies in bringing up effective synchronic water purification technology to combat pathogenic microorganisms and toxic metal.

Super-stable mineralization of Cu, Cd, Zn and Pb by CaAl-layered double hydroxide: Performance, mechanism, and large-scale application in agriculture soil remediation

The synthesized CaAl-layered double hydroxide (CaAl-LDH) shows excellent performance in potentially toxic metals (PTMs) removal, and the removal capacity of CaAl-LDH toward Cu2+, Zn2+ and Pb2+ in aqueous solution is 502.4, 315.2 and 600.0 mg/g respectively. Cu2+ and Zn2+ are removed through isomorphic substitution of laminate Ca and dissolution-reprecipitation, leading to the formation of CuAl-LDH and ZnAl-LDH mineralization products. Pb2+ is removed by the complexation and precipitation to form Pb3(CO3)2(OH)2. The application of CaAl-LDH in laboratory-scale soil remediation shows that target PTMs are gradually mineralized into relatively stable oxidizable and residual state, and the immobilization efficiency of available Cu, Zn, Cd and Pb reaches 84.62 %, 98.66 %, 96.81 % and 70.27 % respectively. In addition, practical application in farmland results in the significant reduction of available Cu, Zn, Cd and Pb with the immobilization efficiency of 30.15 %, 67.30 % and 57.80 % and 38.71 % respectively. Owing to the super-stable mineralization effect of CaAl-LDH, the content of PTMs in the roots, stems and grains of cultivated buckwheat also decreases obviously, and the growth and yield of buckwheat are not adversely affected but improved. The above prove that the super-stable mineralization based on CaAl-LDH is a promising scheme for the remediation of PTMs contaminated agriculture soil.

One-pot removal of pharmaceuticals and toxic heavy metals from water using xerogel-immobilized quartz/banana peels-activated carbon

ABSTRACT Here, we report the efficient one-pot removal of heavy metal ions and pharmaceuticals using xerogel, activated carbon and gravel. The simplest xerogel from tetramethyl orthosilicate showed ∼ twice the adsorption capacity of activated carbon derived from banana peels at 600 °C and far greater (x 35) than quartz pellets of diameter ∼300 μm. Functional groups present in both xerogel and activated carbon greatly enhanced the adsorption process. The combination of the three adsorbents resulted in the removal of > 95% of heavy metal ions and pharmaceuticals from water. The data fitted well in linear equations of Langmuir and Freundlich adsorption isotherms, and pseudo-first-order and pseudo-second-order kinetics, an indication for physisorption, chemisorption, adsorption and desorption processes during pollutant capture by the adsorbents.

Efficient removal of fluoride on aluminum modified activated carbon: an adsorption behavioral study and application to remediation of ground water

In recent times, ground water contamination by toxic elements is of great concern and it is to be addressed for consumption of human, animal, and plant growth. In this context, we have synthesized an adsorbent by modifying commercially available activated carbon with aluminum and tested for de-fluoridation studies. The activity results suggested that the optimized adsorbent is highly efficient in removing the fluoride from ground water. Adsorption maxima are obtained over a wide pH range from 4 to 9, with a contact time of 15 minutes at a dosage of 4 g/L. The results also revealed that the synthesized adsorbent is suitable for application in ground water without any pH adjustment and has exhibited 85%–95% tolerance for common anions in the range of 100–500 mg/L. Equilibrium adsorption isotherm models as well as kinetics of adsorption were applied for the system. An adsorption capacity of 20.4 mg/g and fast kinetics observed are most favorable for defluoridation. Reuse of adsorbent over repeated cycles was investigated. Residual amount of aluminum in treated water is found to be negligible. The removal of toxic elements like Pb, Cd, Cr, Cu, Ni, Zn, As, and Se under the optimized experimental conditions has also been investigated. Al-AC found to be a highly promising material for removal of fluoride and toxic metals from drinking water.

A review on nanomaterial-based heterogeneous photocatalysts for removal of contaminants from water

The rising concentration of pollutants in the environment due to partially treated or untreated wastewater entering the surface waters has seriously challenged the integrity of the ecosystem and the quality of water for human health. Therefore, it is crucial to establish a productive and economical process to degrade recalcitrant pollutants from various water matrices owing to the ineffectual removal of these contaminants by conventional treatment methods. In this regard, advanced oxidation processes (AOPs), especially photocatalysis, have gained much attention due to their unique properties, such as low-cost, easy synthesis, and ability to produce reactive radicals under light irradiation with complete mineralization of recalcitrant pollutants. In this review, heterogenous photocatalysts, their fundamental properties, and their working mechanism have been described, along with their applications in the degradation of contaminants in water. Recent progress on pristine and modified nanomaterial-based photocatalysts for the degradation of various pollutants in water has been discussed. In particular, the removal of toxic heavy metals, pesticides, dyes, pathogens, pharmaceuticals, and other miscellaneous contaminants from water using a wide variety of nanomaterial-based heterogeneous photocatalysts has been summarized. The effect of temperature, solution pH, and loading of photocatalysts was found to be the most critical factors influencing the photocatalytic degradation of pollutants. Subsequently, the photocatalyst immobilization process using various support materials including carbon-based materials, glass, zeolites, and polymers in designing the efficient photocatalysts and future perspectives have been outlined.

Critical Assessment of Polyaniline-based Biocomposites for Removal of Toxic Heavy Metals from Aqueous Media

Polyaniline (PANI) is useful for the adsorption of hazardous substances because of its multiple N-containing functional groups, high adsorption capacity, superior selectivity and chemical durability. Although it is cheap and easy to synthesize, PANI has low processability and mechanical strength, which can be overcome by preparing composites of PANI with biomass waste. Biomass waste is a rich source of useful biopolymers, judicious use of which can also solve the problem of biomass-waste management. Furthermore, biomass waste provides excellent support and possesses functional groups, which help to synergistically remove potentially toxic elements (PTEs) from wastewaters. Composites of PANI have shown tremendous potential in the removal of PTEs from wastewaters. More recently, the focus of studies have been on PANI-based inorganic composites. Considering the environmental impact of these materials, use of PANI-based biosorbents would be more economical, environmentally friendly and promising. This review discusses the mechanisms of removal of PTEs by PANI biocomposites, factors affecting adsorption, characteristics and role of different biomass materials in the removal of PTEs, their advantages and limitations. This article also discusses the potential use of waste microbial biomass-polyaniline composites, which has not been fully explored thoroughly. The vast potential for future research has also been acknowledged, though much more study is needed before this method can be used to its full potential.

Removal of toxic metals from aqueous phase using cacao pod husk biochar in the era of green chemistry

Cacao pod husk biochar was used as an adsorbent for the adsorption of toxic metals from aqueous phase. Cacao pod husk signifies a readily available source of eco-friendly and low-cost adsorbent in Sub-Saharan Africa that has scarcely been paid attention to. The experiment was conducted in a monosystem to determine how cacao pod husk biochar can efficiently adsorb lead (Pb2+), mercury (Hg2+) and cadmium (Cd2+) from aqueous phase. The experiment was conducted with 100 mL of varied toxic metal concentrations of the aqueous phase with a contact time of 60 min and a constant rotary speed of 14.8 U/min. The removal efficiency of cacao pod husk biochar for Pb2+, Hg2+ and Cd2+ ranged from 99.20 to 99.94%, 99.97 to 99.99%, and 99.85 to 99.99%, respectively. Freundlich adsorption isotherm was favourable for the adsorption of toxic metals onto the cacao pod husk biochar. The toxic metals had a stronger binding affinity to the cacao pod husk biochar. Hence, cacao pod husk was efficient for toxic metals elimination.

The removal of toxic metals from liquid effluents by ion exchange resins. Part XVIII: Vanadium(V)/H+/Amberlite 958

The ion exchange resin Amberlite 958 was used to investigate its behaviour on the removal of hazardous vanadium(V) from aqueous media. This investigation was carried out under various hydrodynamic conditions and chemical conditions, such as variation of the stirring speed, variation of the pH of the aqueous solution, resin dosage, initial vanadium(V) in the aqueous solution, and temperature. Vanadium(V) uptake onto the resin was highly dependent on the pH of the solution, and thus, to the vanadium(V) speciation in this phase; the ion exchange process had an endothermic character. The experimental data, under different experimental conditions, were fitted to various models: kinetics (stirring speed), rate law (vanadium concentration) and model isotherms (resin dosage). Multiwalled carbon nanotubes were also investigated on vanadium(V) removal from the solution. Vanadium(V) loaded onto the resin can be eluted under acidic conditions.

Removal of Heavy Metals from Industrial Wastewater using Low-Cost Waste Materials

The most serious environmental problem in the world is heavy metal pollution due to industrialization and urbanization. A special concern is to be taken for the removal of heavy metals in the environment. In developing countries, the price effectiveness might be a major factor in the removal of heavy metal toxicity which is a major threat to the environment for several decades. In this study, heavy metal contamination of water bodies has been reviewed here. The toxic effluents from the textile industry, shredding facilities, glass industry, metal industry, refinery, automobile industry, pharmaceutical industry, semiconductor industry, printing industry, catering industry landfill leakage contain a huge amount of heavy metals in their waste. The conventional methods are very expensive, energy-intensive and sometimes generate a toxic byproduct. The current review focuses on the adsorption technique of heavy metals removal using different adsorbent materials from waste naturally. Numerous low-cost adsorbents are widely used such as garlic peel, jack fruit peel, oil palm trunk fiber, rice bran and wheat bran, broad bean peel, groundnut shell, raw agricultural solid waste, papaya seeds, leaf biomass etc. explored for the removal of toxic heavy metal from wastewater. These absorbents materials naturally have their origin by themselves such as zeolites, clay, sphagnum moss and polysaccharide which are found to be efficient agents for the removal of toxic metals like lead Cd, Zn, Cu, Ni, Hg, Cr, etc. Numerous agricultural wastes like rice husk, neem bark, black gram, waste tea-coffee, walnut-shell, coconut coir, coconut husk, bagasse etc., are widely used for the heavy metal removal in a sustainable nature.