Adsorption Of Toxic Heavy Metals Research Articles

Nanocellulose: A sustainable functional construct for the remediation of heavy metal ions from water

Heavy metals are considered to be a significant pollutant in water bodies, adversely affecting human health by causing various severe diseases after passing down the food chain. The rise in environmental problems due to the usage of non – biodegradable materials leads to the necessity of eco–friendly materials. The abundant and eco-friendly nature of the nanocellulose makes them promising substitutes for non-sustainable materials, nowadays. It is also possible to find the chemical components (cellulose, hemicellulose, and lignin) present in a source and the cellulose yield. In this context, nanocellulose has gained considerable attention among nanomaterials as a promising candidate for the adsorption of toxic heavy metal ions because of its large surface area, light weight, low cost, biocompatible nature, etc. Moreover, the numerous surface hydroxyl groups present in its surface make them suitable for the wide range of surface functionalization with different groups. They can thus be used individually or in combination with other materials for excellent adsorption towards various toxic heavy metal ions. The state of research on modified nanocellulose as an adsorbent for heavy metals is principally discussed in this review. Mainly two types of plant-based nanocelluloses; cellulose nanofibers (CNFs) and cellulose nanocrystals (CNCs), are discussed in detail in this review. The extraction of nanocellulose via a green approach was also covered. This review comprises comprehensive details on the modifications and other relevant properties of nanocellulose which would facilitate the adsorption of toxic heavy metals.

Investigation of Efficient Adsorption of Toxic Heavy Metals (Chromium, Lead, Cadmium) from Aquatic Environment Using Orange Peel Cellulose as Adsorbent

Heavy metals in the environment cause adverse effects on living organisms. Agro-wastes have the potential to remove heavy metals from aqueous solutions. In this study, the orange peel cellulose (OPC) beads were utilized as adsorbents to remove metals from wastewater. The surface of the adsorbent was studied by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy coupled with energy dispersive x-ray spectroscopy (SEM-EDS). The concentrations of the metals before and after adsorption were measured using inductively coupled plasma mass spectrometry. The removal of the metal ions (i.e., Cr6+, Cd2+, and Pb2+) using the OPC was investigated by varying the pH, contact time, and adsorbent dosages parameters. The maximum removal efficiency obtained for the metal ions occurred at pHs 4–8. The use of the Langmuir isotherm and Freundlich isotherm models demonstrated the statistical significance of the heavy metal adsorption processes (R2 > 0.96). At a neutral pH, the OPC adsorption order was Pb2+ > Cd2+ > Cr6+ with % removal values of 98.33, 93.91, and 33.50, respectively. The adsorption equilibrium for Cr6+ was reached after 36 h. For Cd2+ and Pb2+, equilibrium was reached after 8 and 12 h, respectively. The FT-IR and SEM-EDS confirmed the presence of many functional groups and elements on the adsorbent. The adsorption of heavy metals using the OPC is a low-cost, eco-friendly, and innovative method for the removal of metals in aquatic environments. The findings of this study will be highly significant for the public in the affected areas worldwide that have credible health concerns due to water contamination with heavy metals.

Development of a New Eco-Friendly Copolymer Based on Chitosan for Enhanced Removal of Pb and Cd from Water.

Worldwide, concerns about heavy metal contamination from manmade and natural sources have increased in recent decades. Metals released into the environment threaten human health, mostly due to their integration into the food chain and persistence. Nature offers a large range of materials with different functionalities, providing also a source of inspiration for scientists working in the field of material synthesis. In the current study, a new type of copolymer is introduced, which was synthesized for the first time by combining chitosan and poly(benzofurane-co-arylacetic acid), for use in the adsorption of toxic heavy metals. Such naturally derived materials can be easily and inexpensively synthesized and separated by simple filtration, thus becoming an attractive alternative solution for wastewater treatment. The new copolymer was investigated by solid-state nuclear magnetic resonance, thermogravimetric analysis, scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray photon electron microscopy. Flame atomic absorption spectrometry was utilized to measure heavy metal concentrations in the investigated samples. Equilibrium isotherms, kinetic 3D models, and artificial neural networks were applied to the experimental data to characterize the adsorption process. Additional adsorption experiments were performed using metal-contaminated water samples collected in two seasons (summer and winter) from two former mining areas in Romania (Roșia Montană and Novăț-Borșa). The results demonstrated high (51–97%) adsorption efficiency for Pb and excellent (95–100%) for Cd, after testing on stock solutions and contaminated water samples. The recyclability study of the copolymer indicated that the removal efficiency decreased to 89% for Pb and 58% for Cd after seven adsorption–desorption cycles.

Performance of eggshells powder as an adsorbent for adsorption of hexavalent chromium and cadmium from wastewater

This study explores the kinetic and equilibrium performance of eggshell as an adsorbent for hexavalent chromium and cadmium ion removal from wastewater. The experimental removal of the two metal ions was performed batch-wise and the influence of variables like initial metal loading, pH, contact time, and adsorbent dose. Fourier-transform infrared spectroscopy spectra reveals that chromium and cadmium ion interact with carbonyl, carboxylic, hydroxyl functional groups in eggshell. The best pH is 6, and the adsorption capacity improves with increasing initial concentration of adsorbate, pH, contact time and adsorbent dosage for chromium and cadmium ion. Pseudo-second-order kinetics is the most suitable model for the removal of chromium and cadmium ion, while the equilibrium agrees with Freundlich isotherms. These outcomes reveal that eggshell is a promising cheap adsorbent for adsorption of toxic heavy metals like chromium and cadmium ion from aqueous solution.

Green Graphene-Chitosan Sorbent Materials for Mercury Water Remediation.

The development of new graphene-based nanocomposites able to provide synergistic effects for the adsorption of toxic heavy metals in realistic conditions (environment) is of higher demand for future applications. This work explores the preparation of a green nanocomposite based on the self-assembly of graphene oxide (GO) with chitosan (CH) for the remediation of Hg(II) in different water matrices, including ultrapure and natural waters (tap water, river water, and seawater). Starting at a concentration of 50 μg L–1, the results showed that GO–CH nanocomposite has an excellent adsorption capacity of Hg (II) using very small doses (10 mg L–1) in ultrapure water with a removal percentage (% R) of 97 % R after only two hours of contact time. In the case of tap water, the % R was 81.4% after four hours of contact time. In the case of river and seawater, the GO–CH nanocomposite showed a limited performance due the high complexity of the water matrices, leading to a residual removal of Hg(II). The obtained removal of Hg(II) at equilibrium in river and seawater for GO–CH was 13% R and 7% R, respectively. Our studies conducted with different mimicked sea waters revealed that the removal of mercury is not affected by the presence of NO3– and Na+ (>90% R of Hg(II)); however, in the presence of Cl–, the mercury removal was virtually nonexistent (1% R of Hg(II)), most likely because of the formation of very stable chloro-complexes of Hg(II) with less affinity towards GO–CH.

The effect of sulfur and nitrogen/sulfur co-doping in graphene surface on the adsorption of toxic heavy metals (Cd, Hg, Pb)

The adsorption of toxic heavy metals (THMs), including cadmium (Cd), mercury (Hg), and lead (Pb), on the graphene (G) and six sulfur- and nitrogen/sulfur-co-doped graphene surfaces (G@1N@1S, G@1N@2S, G@2N@1S, G@1S, G@2S, G@3S) has been studied using electronic structure methods. The doping of graphene surface with the nitrogen and sulfur atoms increases the adsorption energies of THMs. The strongest interaction is seen with adsorption of Pb atom on the surfaces, following the order Pb > Cd > Hg and is confirmed by the atoms in molecules analysis, noncovalent interaction plots, and frontier molecular orbitals. The free energy of adsorption calculation shows that the adsorption process of Pb atoms on the surfaces is exothermic and proceeds spontaneously, while the nature of adsorption of Cd and Hg atoms is endothermic. Significant changes in the electronic structure of the surfaces are seen with adsorption of THMs. A significant change in the HOMO–LUMO energy gap (Eg) and electrical conductivity (σ) of the surfaces is observed with adsorption of Pb atoms, in contrast to Cd and Hg atoms counterparts. Moreover, the calculated optical properties of the surfaces and their complexes with THMs using time-dependent density functional theory reveal that the absorption spectra of the surfaces undergo appreciable changes after adsorption of THMs. These studies indicate the potential use of defect engineering and decoration of vacant sites by chalcogens/pnictogens for sensing of toxic heavy metals.

Adsorption of toxic heavy metals on organofunctionalized acid activated exfoliated bentonite clay for wastewater treatment goals

Adsorption of toxic heavy metals on organofunctionalized acid activated exfoliated bentonite clay for wastewater treatment goals

Comparative evaluation for the adsorption of toxic heavy metals on to millet, corn and rice husks as adsorbents

This study was carried out to evaluate the efficiency of metals Ni Cr and Mn removal using raw and carbonized rice millet and corn husks as low cost adsorbents The sorption of these metal ions from aqueous solution was determined using Atomic Absorption Spectroscopy Analysis AAS Characterisation of the adsorbents using Fourier Transform Infra Red FTIR and Scan Electron Microscopy SEM images revealed some changes before and after the adsorption process This indicated that most likely adsorption has been taken place between the metal ions and the adsorbents in the aqueous solution Batch experiments were carried out to determine the effect of different parameters such as adsorbent dose pH of the medium contact time and agitation rate The result obtained showed that the sorption process was largely dependent on metal ion concentration adsorbent dose and contact time The experimental data was analyzed using paired sample ndash T test The study also showed that all the husks were effective for the quantitative removal of various toxic heavy metals and can be used as low cost and highly efficient adsorbents for the removal of heavy metal ions from industrial effluents

Smectite for Medical Use and Their Toxin Binding Capacity

A detoxification product (Symbio®detox), containing diosmectite, boswellia and Commiphora resin was tested in terms of its adsorption behavior. We showed that it was able to adsorb large amounts of various toxins, including heavy metals,ammonium and histamine. At pH=2.0 is 9.5% of lead 98% of mercury and 8.8% zinc were adsorbed, while ammonium (2.5%) remained largely unaffected. At pH 6.5, we observed significantly increased adsorption for lead (60.4%), ammonium (7.2%) and histamine (91%); the adsorption of zinc (11.2%) was only slightly higher than at pH=2.0. By contrast, the adsorption of mercury (84.6%) was slightly lower under these conditions. The adsorption of toxic heavy metals including mercury and lead was greater than that of zinc. Thus, Symbio®detox may be used as a medical product because of its excellent binding capacity for toxins including heavy metals, ammonia and histamine. In addition, the product is not likely to result in deficiency of the essential mineral zinc. Finally, we did not detect adsorption of the pharmaceutically relevant ingredients Boswellia serrata resin and Commiphora molmol resin.

Facile fabrication of silk protein sericin-mediated hierarchical hydroxyapatite-based bio-hybrid architectures: excellent adsorption of toxic heavy metals and hazardous dye from wastewater

Facilely fabricated silk protein sericin-mediated hierarchical hydroxyapatite hybrid architectures show excellent adsorption of toxic heavy metal ions of Pb(ii), Cd(ii) and Hg(ii) and a hazardous dye, Congo red (CR), from wastewater.

Practical Homemade Copper Filter by Banana Peels, Sand and Charcoal for Wastewater Treatment

Copper ions are commonly contaminated in the effluents from many electronic factory. In copper filtration, most filter types are usually expensive and causes toxic residues and creates another health and environmental problem. Therefore, this research has been developed a copper filtration approach based on homemade non-hazardous residues of banana peels, unmeshed sand, and charcoal. The results showed that baked, minced banana peels media could absorb synthetic water having copper ion at 50 ppm with filtration efficiency of 70% within 2 hr. Baked minced banana peels in combination with sand and charcoal could adsorb Copper (II) at 50 mg/ mL more than 80%. However, the swollen structure of banana peels during copper (II) filtration caused limit filtration efficiency to 4-5 hour extraction period. The tentative wastewater treatment application is, therefore, the use of bio-adsorbent for effective adsorption of toxic heavy metals from effluents open discarded from agricultural wastes in the environment.

Separation of Zn(II) and Cd(II) ions from Synthetic Waste Water by Adsorption on Activated Carbon Derived from Tridax procumbens

The use of activated carbon derived from Tridax procumbens for the treatment of waste water containing heavy metals is an innovative method. It constitutes a simple, effective and economical means for waste water treatment. Adsorption of toxic heavy metals viz. Zn(II) and Cd(II) were studied from synthetic waste water on activated biocarbon derived from Tridax procumbens. Batch adsorption experiments were performed with activated biocarbon as a function of pH, contact time and amount of activated biocarbon. The most favourable pH required for maximum adsorption was found to be 3.6 and 3.8 for Zn(II) and Cd(II) respectively. The maximum contact time for the equilibrium condition was found to be 180 min. The maximum efficiencies of Zn(II) and Cd(II) removal by biocarbon were 97.74 % and 90.62 % respectively. When the amount of activated biocarbon was increased, percentage removal of metal ions also increased for the system containing upto 3.0 g of biocarbon. Beyond this no appreciable change was observed. The linear Langmuir and Freundlich models were applied to describe equilibrium isotherms and both models fitted well.

Heavy metal complexation on hybrid mesoporous silicas: an approach to analytical applications

Recent advances in the development of new materials are having a major impact on Analytical Chemistry. For example, the unique properties of ordered mesoporous silicas have been shown to enhance the analytical performance of many existing techniques or allow new, exciting ones to be developed. Likewise, the introduction of organo-functional groups makes mesoporous silicas highly versatile and enables them to perform specialized tasks, such as the adsorption of toxic heavy metals from aqueous solutions. In this tutorial review, we present readers with a brief introduction to the most relevant achievements in the preparation of hybrid mesoporous silicas functionalized with chelating ligands for the complexation of heavy metals. We also provide some recent examples from the last ten years regarding the analytical applications of such hybrid silicas. Two topics of great current interest in environmental water analysis for heavy metal detection, namely the use of hybrid mesoporous silicas as sorbents for solid-phase extraction and the use of these materials to develop new strategies for electrochemical detection of heavy metals by stripping voltammetry, are addressed.

Applicability of the Pinus bark (Pinus elliottii) for the adsorption of toxic heavy metals from aqueous solutions

Current research evaluates the efficaciousness of pine (Pinus elliottii) bark as adsorbent of the toxic heavy metals cadmium (Cd), lead (Pb) and chromium (Cr) from aqueous solutions, at two pH conditions: 5.0 and 7.0. Approximately 500 mg of adsorbent material and 50 mL of solution contaminated by Cd, Pb and Cr at different concentrations prepared from standard solutions of each metal were added in 125 mL Erlenmeyer flasks. Flasks were stirred during 3h at 200 rpm at 25oC. Further, 10 mL aliquots were then retrieved and concentration of metal Cd, Pb and Cr determined by AAS. Adsorption isotherms for each metal were consequently obtained and linearized according to Langmuir and Freundlich's mathematical models. Results show that the Pinus bark was efficacious in the removal of toxic heavy metals Cd, Pb and Cr from contaminated solutions and that the bark's adsorption capacity depended on pH solution.

Modification of poly acrylic acid using calix[4]arene derivative for the adsorption of toxic heavy metals

AbstractPoly acrylic acid (PAA) was grafted with p‐t‐butyl calix[4]arene diamine (distal cone) (2) to adsorb toxic heavy metal and alkali metal cations. The grafting method includes the amidation reaction of PAA with calixarene diamine derivative 2 which was carried out in N,N‐dimethylformamide (DMF) and N–methyl‐2‐pyrrolidone (NMP) as solvents. The modified PAAs (PAA‐C1 and PAA‐C2) were characterized by FTIR, 1H‐NMR, thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). PAA‐C1 and PAA‐C2 were used to evaluate the sorption properties of some toxic heavy metal cations (Co2+, Cu2+, Cd2+, Hg2+), alkali metal cations (Na+, K+, Cs+), and Ag+. Results showed that the modified PAAs were good sorbents for heavy metal and alkali metal cations. The main goal of this project is to design hydrophobically modified PAA that is suitable for ion selective membranes and chemical sensor devices for adsorption of toxic heavy metals. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Pelletized ponderosa pine bark for adsorption of toxic heavy metals from water

ark flour from ponderosa pine (Pinus ponderosa) was consolidated into pellets using citric acid as cross-linking agent. The pellets were evaluated for removal of toxic heavy metals from synthetic aqueous solutions. When soaked in water, pellets did not leach tannins, and they showed high adsorption capacity for Cu(II), Zn(II), Cd(II), and Ni(II) under both equilibrium and dynamic adsorption conditions. The experimental data for Cd(II) and Zn(II) showed a better fit to the Langmuir than to the Freundlich isotherm. The Cu(II) data best fit the Freundlich isotherm, and the Ni(II) data fitted both Freundlich and Langmuir isotherms equally. According to the Freundlich constant KF, adsorption capacity of pelletized bark for the metal ions in aqueous solution, pH 5.1 ± 0.2, followed the order Cd(II) > Cu(II) > Zn(II) >> Ni(II); according to the Langmuir constant b, adsorption affinity followed the order Cd(II) >> Cu(II) ≈ Zn(II) >> Ni(II). Although data from dynamic column adsorption experiments did not show a good fit to the Thomas kinetic adsorption model, estimates of sorption affinity series of the metal ions on pelletized bark derived from this model were not consistent with the series derived from the Langmuir or Freundlich isotherms and followed the order Cu(II) > Zn(II) ≈ Cd(II) > Ni(II). According to the Thomas kinetic model, the theoretical maximum amounts of metal that can be sorbed on the pelletized bark in a column at influent concentration of ≈10 mg/L and flow rate = 5 mL/min were estimated to be 57, 53, 50, and 27 mg/g for copper, zinc, cadmium, and nickel, respectively. This study demonstrated the potential for converting low-cost bark residues to value-added sorbents using starting materials and chemicals derived from renewable resources. These sorbents can be applied in the removal of toxic heavy metals from waste streams with heavy metal ion concentrations of up to 100 mg/L in the case of Cu(II).

Removal of heavy metals from industrial wastewaters by adsorption onto activated carbon prepared from an agricultural solid waste

Activated carbon was prepared from coirpith by a chemical activation method and characterized. The adsorption of toxic heavy metals, Hg(II), Pb(II), Cd(II), Ni(II), and Cu(II) was studied using synthetic solutions and was reported elsewhere. In the present work the adsorption of toxic heavy metals from industrial wastewaters onto coirpith carbon was studied. The percent adsorption increased with increase in pH from 2 to 6 and remained constant up to 10. As coirpith is discarded as waste from coir processing industries, the resulting carbon is expected to be an economical product for the removal of toxic heavy metals from industrial wastewaters.