Method For Removal Of Heavy Metals Research Articles

Low-Cost magnetic adsorbent for efficient Cu(II) removal from water

Selective adsorption using magnetic adsorbent is supposed as one of the most effective methods for heavy metal removal from water for the advantage of efficient solid-liquid separation. However, the application of this technique is hindered by the high cost, unfavorable environmental effects of the chemical synthesis of magnetic adsorbents. In this study, the industrial waste coal-fly-ash magnetic sphere (CMS) were carefully processed to prepare cheap and green magnetic core material. Then, a composite bioadsorbent using CMS as core and chitosan (CS) as the shell (CMS@CS for short) was fabricated via an extrusion-dripping method. Structural investigations indicate that the obtained CMS@CS samples are hollow microsphere with a solid wall or porous solid microsphere depending on the preparation conditions. CMS particles are evenly distributed in both microspheres. The porous sample has an 81.49 m2 g−1 special surface area, 96 times larger than the hollow. The highest Cu(II) adsorption of the porous sample is measured as 22.41 mg g−1, 3.6 times larger than that of the hollow. The Cu(II) adsorption of the CMS@CS samples is closely related to the internal structure, surface chemical modification, and solution pH. The adsorption mechanism could be explained by a two-step procedure model. The CMS@CS adsorbents have an average magnetism of 10.07 emu g−1, thus could be magnetically separated efficiently. The density of CMS@CS is tested as 1.45–1.65 g cm−3. A similar density with water would improve its suspend ability in the water. The used CMS@CS adsorbent could be recycled several times after appropriate treatment.

Kinetic and equilibrium study of (poly amido amine) PAMAM dendrimers for the removal of chromium from tannery wastewater

Abstract Water gets polluted by industrial effluents, mainly composed of heavy metals and organic materials. Water soluble heavy metals can be taken up by living organisms. Chromium mainly occurs in the form of chromate and cationic hydroxo complexes in water. Apart from conventional methods of heavy metal removal, there are some novel approaches such as using dendrimers for removal of heavy metal. Dendrimers are extremely branched nano sized polymers with a three-dimensional symmetry around a core that imparts poly functionality. PAMAM (poly amido amine) dendrimers having ethylene diamine as core and methyl acrylate as repeating unit was divergently synthesized. Characterization of PAMAM dendrimers was evaluated by UV–Vis spectroscopy, zeta sizer, scanning electron microscopy (SEM) and Fourier-transform infrared (FT-IR) spectroscopy. Zero generation dendrimers have amine terminal groups, showed intense amide group peak at 1596.76 cm−1. The λ max value was 278 nm. SEM exhibited spherical shape for full generation while needle like structure for −0.5 generation. Evaluation of chromium removal from wastewater has been done by atomic absorption spectroscopy (AAS). The data revealed that optimal removal of Cr occurs at dendrimer concentration of 5 mL, Cr concentration of 300 ppm, contact time of 2 min and pH 7. The synthesized dendrimers have effectively removed Cr from tannery wastewater.

Remediation of heavy metal contaminated soils by organic acid extraction and electrochemical adsorption

Remediation of heavy metal contaminated soils remains a global challenge. Here, low-molecular-weight organic acids were used to extract Cu and Zn from polluted soils, and the extracted heavy metals were subsequently adsorbed by activated carbon electrodes. The electrochemical adsorption mechanism as well as the influence of pH, organic acid type and voltage were investigated, and the soil remediation effect was further evaluated by the cultivation of rape. After extraction by citrate at initial pH 8.3 and electrochemical adsorption at 0.9 V for 7 d, the concentrations of total and bioavailable Cu in soils decreased from 1090 to 281 to 391 and 52 mg kg−1, and those of Zn decreased from 262 to 39 to 208 and 30 mg kg−1, respectively. Cu and Zn ions were mainly electrochemically adsorbed on the carbon cathode and anode, respectively, resulting in decreases of their concentrations to below 1 mg L−1 in the leachate. The presence of organic acids improved the remediation performance in the order of citrate > oxalate > acetate. The decrease in the initial pH of citrate solution enhanced the removal rate of Zn, while seemed to have no effect on that of Cu. The removal capacity for heavy metals decreased with decreasing cell voltage from 0.9 to 0.3 V. In the rape cultivation experiment, the Cu and Zn contents in shoot and root were decreased by more than 50%, validating the soil remediation effect. The present work proposes a facile method for heavy metal removal from contaminated soils.

A review on the applicability of activated carbon derived from plant biomass in adsorption of chromium, copper, and zinc from industrial wastewater.

Metal ion contamination in wastewater is an issue of global concern. The conventional methods of heavy metal removal from wastewater have some drawbacks, ranging from generation of sludge to high cost of removal. Adsorption technique for copper(II), zinc(II), and chromium(VI) using activated carbon has been found efficient. However, it is not economical on a large scale. This, therefore, necessitates the search for economical and readily available plant biomass-based activated carbons for the sequestration of the metal ions. This review presents the state of the art on the adsorption of copper(II), zinc(II), and chromium(VI) from industrial wastewater. Based on the literature review presented, the groundnut husk and corncob based activated carbons were found to possess the maximum adsorption capacities for copper(II), zinc(II), and chromium(VI) removal, when compared with the other plant biomass-based activated carbons. The high values of the adsorption capacities obtained were as a result of the isotherms and pH of the adsorbent as well as the initial concentration of the metal solutions. From the review, the equilibrium data fitted better with Langmuir and Freundlich isotherms than with other isotherms. Research gaps were identified which include a need to investigate the kinetic and the thermodynamic behaviors of the metal ions onto the studied adsorbents. Furthermore, a comparative analysis of the three types of activation of the adsorbents should be investigated using single and multi-metals. The optimization of particle size, contact time, temperature, initial concentration, and adsorbent dosage for adsorption of copper(II), zinc(II), and chromium(VI) onto the studied adsorbents using response surface methodology is equally required.

Bioremediation of Fracking: Novel Hybrid Biofilm System Using Synthetically Engineered Curli Fibres

Hydraulic fracturing, a popular mining technique, generates heavy metal contamination in nearby freshwater aquifers. This poses a threat to both the surrounding ecosystems and human health if exposed. Existing methods of heavy metal removal can produce additional hazardous byproducts. This proposal presents the use of a hybrid biofilm filter con-taining graphene and curli fibres with metal binding sites. Curli fibres are amyloid fibrils found on the extracellular biofilm of Escherichia coli (E. coli). Through the use of plasmid vectors, E. coli will be engineered to produce secreted curli fibres with metal-binding residues. The stability and cohesive properties of the curli fibres augments the adher-ence to the graphene scaffolding, thus allowing for generation of a hybrid biofilm. With the filtration design and vari-ous experimental controls proposed, this model is ready for empirical proof of concept and subsequent quantitative optimization.

Novel hybrid biofilm system using synthetically engineered curli fibres

Hydraulic fracturing, a popular mining technique, generates heavy metal contamination in nearby freshwater aquifers. This poses a threat to both the surrounding ecosystems an human health if exposed. Existing methods of heavy metal removal can produce additional hazardous byproducts. This proposal presents the use of a hybrid biofilm filter containing graphene and curli fibres with metal binding sites. Curli fibres are amyloid fibrils found on the extracellular biofilm of Escherichia coli (E coli.). Through the use of plasmid vectors, E. coliwill be engineered to produce secreted curli fibres with metal-binding residues. The stability and cohesive properties of the curli fibres augments the adherence to the graphene scaffolding, thus allowing for generation of a hybrid biofilm. With the filtration design and various experimental controls proposed, this model is ready for empirical proof of concept and subsequent quantitative optimization.

HEAVY METAL REMOVAL IN A COMBINED UASB-DFAF AND HUASB-DFAF SYSTEM REACTORS TREATING MUNICIPAL WASTEWATER

Heavy metal pollution has nowadays becomes a serious environmental problem. Various methods for heavy metal removal from wastewater have been extensively studied in recent years. This study is carried out to investigate the removal of heavy metals (HMs) in a combined UASB-DFAF and HUASB-DFAF systems in treating municipal wastewater. The experiment was carried out as a lab scale model involving combinations of up-flow anaerobic sludge blanket as a primary treatment system, followed by down flow aerobic filter as a secondary treatment. Performance of UASB-DFAF is compared with HUASB-DFAF system to treat the heavy metals of Cd, Pb, Al, As, Zn, Mn and Fe. The removals of heavy metals were investigated in the UASB-DFAF and HUASB-DFAF against hydraulic retention time (HRT) of 23 hours, 15 hours and 11 hours. Influent COD concentration was fed into the reactors at a constant rate of 1000 mg/l. The influent is a mixture of modified domestic wastewater with glucose, peptone and meat extract. Effluent samples were collected from the reactors and were analyzed for concentration of heavy metals. Concentration of metals decreases from 0.17 to 0.04 µg/L with time for cadmium (Cd), from 10.4 to 0.88 µg L-1 for (Pb), from 36.64 to 7.12 µg L-1 for Zinc (Zn), from 2.93 to 1.56 µg L-1 for Arsenic (As), from 3077 to 650.57 µg L-1 for Ferum (Fe), from 61.53 to 13.01 µg L-1 for (Al) and increase from 349.28 to 453.03 µg L-1 for (Mn). All heavy metals analyses were conducted using ICP-MS and AAS.

Heavy Metal Removal by Fixed‐Bed Column – A Review

AbstractIndustrial wastewater often contains heavy metals that, if not removed, pose a risk to the environment. Therefore, an extended overview of different methods for heavy metal removal by columns was conducted. Column studies are dependent on the flow rate, bed height and diameter, breakthrough curve, type of wastewater, and adsorbent. The fixed‐bed column is most commonly used for metal sequestration in aqueous media. Column studies have advantages due to industrial scale applicability and can treat large quantities of wastewater. Many kinetics models are applied in column studies like Adam‐Bohart, Yoon Nelson, Bed Depth/Service Time, Thomas, and Clark. This paper deals with the use of modified or non‐modified adsorbents for the treatment of metal‐laden water and wastewater by column technique.

EXTRACELLULAR POLYMERIC SUBSTANCE (EPS) FROM KOCURIA SP. BRI 36: A KEY COMPONENT IN HEAVY METAL RESISTANCE

Objective: Evaluation of Extracellular Polymeric Substance (EPS) induced heavy metal tolerance in Kocuria sp. BRI 36.Methods: Initially, the effect of different concentrations of glucose (1-10 %) on EPS production by BRI 36 was examined. At optimum glucose concentrations, EPS levels were measured by varying heavy metal concentrations (10-50 ppm) of Pb2+, Cd 2+and Cr3+. Maximum tolerable concentration (MTC) and survival percentage of BRI 36 were determined under conditions that support EPS synthesis. Comparative analysis of extracted crude EPS was performed by Fourier Transform Infrared Spectroscopy (FTIR) to establish functional groups involved in the metal interaction. Results: Kocuriasp. BRI 36 produced maximum EPS (1g/l) at 5% glucose. Increase in EPS production up to 89% (considering 1g/l as 100%) with an increase in concentrations of heavy metals up to 40 ppm. MTC levels of BRI 36 for heavy metals increased up to 700 ppm when it was cultivated in presence of 5% glucose indicating a major role of surface polymer in metal adsorption. The function of EPS as a protective cover was also evident from an increase in survival percentage of BRI 36 up to 39.4 at MTC. Comparative analysis of extracted crude EPS by FTIR revealed the involvement of O-H, C=O, and C-O-C groups in metal adsorptionConclusion: Antarctic oceanic isolate Kocuria sp. BRI 36 has an ability to produced EPS under stress conditions of heavy metals. Simultaneously, its MTC values increased due to increase in EPS levels. These observations suggest the possibility to develop gentle, environmentally safe and cost-effective method for heavy metal removal.

An eco-friendly method for heavy metal removal from mine tailings.

One of the serious environmental problems that society is facing today is mine tailings. These byproducts of the process of extraction of valuable elements from ores are a source of pollution and a threat to the environment. For example, mine tailings from past mining activities at Giant Mines, Yellowknife, are deposited in chambers, stopes, and tailing ponds close to the shores of The Great Slave Lake. One of the environmentally friendly approaches for removing heavy metals from these contaminated tailing is by using biosurfactants during the process of soil washing. The objective of this present study is to investigate the effect of sophorolipid (SL) concentration, the volume of washing solution per gram of medium, pH, and temperature on the efficiency of sophorolipids in removing heavy metals from mine tailings. It was found that the efficiency of the sophorolipids depends on its concentration, and is greatly affected by changes in pH, and temperature. The results of this experiment show that increasing the temperature from 15 to 23°C, while using sophorolipids, resulted in an increase in the removal of iron, copper, and arsenic from the mine tailing specimen, from 0.25, 2.1, and 8.6 to 0.4, 3.3, and 11.7%. At the same time, increasing the temperature of deionized water (DIW) from 15 to 23°C led to an increase in the removal of iron, copper, and arsenic from 0.03, 0.9, and 1.8 to 0.04, 1.1, and 2.1%, respectively. By increasing temperature from 23 to 35°C, when using sophorolipids, 22% reduction in the removal of arsenic was observed. At the same time while using DI water as the washing solution, increasing temperature from 23 to 35°C resulted in 6.2% increase in arsenic removal. The results from this present study indicate that sophorolipids are promising agents for replacing synthetic surfactants in the removal of arsenic and other heavy metals from soil and mine tailings.

An investigation of heavy metal adsorption by hexa-dentate ligand-modified magnetic nanocomposites

ABSTRACTAdvancement of an efficient and cost-effective method for heavy metal removal from contaminated water utilising Fe3O4–APTES–EDTA (FAE) nanocomposite, a productive reusable adsorbent, is explained in this study. The novel FAE nanocomposite was prepared and characterised using different techniques such as FTIR, XRD, TEM, EDS, BET, TGA, EDX and Zeta potential techniques. FAE is found to be a good adsorbent for Pb2+, Cd2+, Ni2+, Co2+ and Cu2+ removal with a higher adsorption capacity. The maximum adsorption capacity of Pb2+, Cd2+, Ni2+, Co2+ and Cu2+ are found to be 11.31, 13.88, 7.64, 4.86 and 78.67 mg/g, respectively. The adsorption and desorption cycle was studied for five cycles with minimal loss of efficiency.

Effectiveness of Mg–Al-layered double hydroxide for heavy metal removal from mine wastewater and sludge volume reduction

Health hazards from heavy metal pollution in water systems are a global environmental problem. Of similar concern is sludge that results from wastewater treatment due to unsatisfactory sludge management technology. Therefore, the effectiveness of using Mg–Al-layered double hydroxide in the removal of heavy metals from mine wastewater was tested and compared with that of calcium hydroxide [Ca(OH)2], which is a common treatment method for heavy metal removal. Initially, the mine wastewater contained cations of the heavy metals iron (Fe), zinc (Zn), copper (Cu), and lead (Pb). The Mg–Al-layered double hydroxides were able to remove 371, 7.2, 121, and 0.4 mg/L of these pollutants, respectively, using the co-precipitation method. The removal of these metals is most effective using 0.5 g Mg–Al-layered double hydroxide (Mg/Al molar ratio 4) and 20 min of shaking. Zn was removed by the formation of Zn(NO3)(OH)·H2O and Zn5(NO3)2(OH)8 when LDH, Mg/Al molar ratios of 4 and 2, respectively, were used. Similarly, Fe, Cu, and Pb were removed by the formation of Fe–Al-layered double hydroxide, Cu2(OH)3·NO3 and Pb4(OH)4(NO3)4, respectively. While Ca(OH)2 is also capable of reducing the heavy metal concentrations below the Japanese recommended values, this analysis shows that using 0.5 g Mg–Al-layered double hydroxide is a better treatment condition for mine wastewater, because it generates lower sludge volumes than 0.1 g of Ca(OH)2. The measured sludge volume was 1.5 mL for Mg–Al-layered double hydroxide and 2.5 mL for Ca(OH)2, a nearly twofold further reduction.

Positively charged nanofiltration membrane fabricated by poly(acid–base) complexing effect induced phase inversion method for heavy metal removal

Abstract Poly(arylene ether ketone)s with carboxylic groups (PAEK-COOH) is a good membrane fabrication material, a kind of polyacids, while polyethylenimine (PEI) is a weak organic base, a kind of polybases. Those polyacids and polybases would form ionic complexation at the interface of two liquid phases. In this paper, PAEK-COOH/ N -methyl pyrrolidone (NMP)/1,4-dioxane (DO) mixture, employed as polymer casting solution and aqueous solution of PEI, used as coagulation bath, respectively. Then ion complexation induced phase inversion process is applied to prepare positively charged nanofiltration membrane with thinner but denser separation skin layer. The complexing reaction at the interface of two liquid phases has great influence on the kinetic aspects of phase inversion process, which in accordance would affect the morphology and performance of the membrane. The obtained membrane, fabricated via the ion complexation induced phase inversion method, is positively charged, has high water permeability, and possesses high rejection towards divalent cations, such as Mg 2 + , Ca 2 + , Pb 2 + etc. , which could be used for removal of heavy metals from polluted water. At the optimal condition, the pure water flux of the PAEK-COOH-PEI nanofiltration membrane is 24.3 L·m − 2 ·h − 1 , with MgCl 2 rejection of 92.2%.

A Review on Elimination of Heavy Metals from Wastewater Using Agricultural Wastes as Adsorbents

In this article, the potential of various low-cost adsorbents for the removal of heavy metals from contaminated water has been reviewed. There are various conventional methods for heavy metal removal from wastewater such as precipitation, evaporation, electroplating and also ion-exchange have been applied since previous years. However, these methods have several disadvantages such as only limited to certain concentrations of metals ions, generation large amount of toxic sludge and the capital costs are much too high to be economical. Adsorption is the alternative process for heavy metal removal due to the wide number of natural materials or agricultural wastes gathering in abundance from our environment. In this review, a list of adsorbent has been compiled to provide available information on a wide range of low cost adsorbents for removing heavy metals from wastewater.

Methodologies for removal of heavy metal ions from wastewater: an overview

Heavy metal is a serious problem nowadays. These heavy metals are discharged into water from various chemical industries. They are harmful for living organisms and it is necessary to eliminate these heavy metals to minimise risk of uptake by plants, animal and human. In the last few decades, several methods have been developed and extensively investigated for heavy metal removal. There are several methods for heavy metal removal: chemical precipitation, adsorption, ion exchange, membrane filtration, coagulation-flocculation and floatation. In this paper, an attempt is made to review various methodologies for heavy metal removal from wastewater with their advantages and disadvantages. It is evident from the literature survey that adsorption method is widely used over conventional methods, (i.e., chemical precipitation, ion exchange, membrane filtration, coagulation-flocculation and floatation) because of its low cost, availability and eco-friendly nature.

Direct application of sodium alginate solution via dripping technique for effective copper removal and recovery from aqueous solution

This study introduces the direct application of a sodium alginate solution via a dripping technique to induce effective metal recovery by the formation of crosslinked Cu2+‐alginate capsules. The experimental results demonstrated that the performance of Cu2+ removal was highly dependent on the concentration of alginate, dose ratio of alginate to Cu2+ (Al/Cu ratio), and the solution pH condition as these factors immensely affect the mass transfer of Cu2+ into the crosslinking sites in alginate, structural alternations of Cu2+‐alginate capsule, and electrostatic relationship among Cu2+ and the functional groups present in alginate. The maximum Cu2+ removal efficiency of 93.1 ± 1.3% was achieved using 2.0% alginate solution, an Al/Cu ratio of 10:1, and solution pH of 4.5. Thermal treatment (calcination) for metal recovery indicates that a single‐phase monoclinic CuO crystal was the sole product after a simple calcination process. Therefore, it can be concluded that the newly introduced dripping method is a potent alternative technique to provide an abridged and efficient method for heavy metal removal and recovery. © 2016 American Institute of Chemical Engineers Environ Prog, 36: 489–493, 2017

Removal of Pb(II) by adsorption onto Chinese walnut shell activated carbon.

The excessive discharge of Pb(II) into the environment has increasingly aroused great concern. Adsorption is considered as the most effective method for heavy metal removal. Chinese walnut shell activated carbon (CWSAC) was used as an adsorbent for the removal of Pb(II) from aqueous solution. Batch experiments were conducted by varying contact time, temperature, pH, adsorbent dose and initial Pb(II) concentration. Adsorption equilibrium was established within 150 min. Although temperature effect was insignificant, the Pb(II) adsorption was strongly pH dependent and the maximum removal was observed at pH 5.5. The Pb(II) removal efficiency increased with increasing CWSAC dosage up to 2.0 g/L and reached a maximum of 94.12%. Langmuir and Freundlich adsorption isotherms were employed to fit the adsorption data. The results suggested that the equilibrium data could be well described by the Langmuir isotherm model, with a maximum adsorption capacity of 81.96 mg/g. Adsorption kinetics data were fitted by pseudo-first- and pseudo-second-order models. The result indicated that the pseudo-first-order model best describes the adsorption kinetic data. In summary, CWSAC could be a promising material for the removal of Pb(II) from wastewater.

Adsorption of copper by magnetic graphene oxide-supported β-cyclodextrin: Effects of pH, ionic strength, background electrolytes, and citric acid

Elucidating the influence mechanism of surrounding environmental conditions on the adsorption process is essential in application of adsorption method for heavy metal removal from wastewater. In the present work, the magnetic graphene oxide-supported β-cyclodextrin (MGO/β-CD) was synthesized and characterized by FESEM, TEM, TG–DSC, FT-IR, and zeta potential. The effects of pH, ionic strength, background electrolytes, and citric acid on the adsorption behavior of Cu(II) by MGO/β-CD were investigated. The results showed that Cu(II) adsorption was strongly dependent on solution pH and could be affected by ionic strength, background electrolytes and citric acid. The Cu(II) adsorption was increased as the NaNO3 concentration increased from 0 to 0.1M at pH<8. The presence of LiNO3, NaNO3, KNO3, NaCl, and NaClO4 enhanced the Cu(II) removal slightly. The Cu(II) adsorption was also improved by citric acid. Adsorption kinetics of Cu(II) was found to follow pseudo-second-order rate equation, and the adsorption rate was controlled by film diffusion. The adsorption data showed good correlation with the Freundlich and Temkin isotherm models. The results of this work are of great significance for the application of MGO/β-CD as a promising adsorbent material for Cu(II) removal from aqueous solution.

Fe&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt; and TiO&lt;sub&gt;2&lt;/sub&gt; Embedded Sodium Alginate Beads of Composite Adsorbent for Pb(II) Removal

In this study, Fe3O4 and TiO2 nanocomposites embedded sodium alginate (SA) beads were synthesized, which exhibited a robust performance of efficient adsorption in Pb (II) removal. Effects of lead ion concentration, initial pH , Pb (II) of contact time and no Tio2 in mixture on final removal efficiency were also evaluated. The results showed that Pb2+concentration increased from 25 to 200 mg/L, beads of adsorption capacity increased from 25 to 95 mg/g, the optimum pH for adsorption is located at 6.2 and the adsorption balance is around 240 minutes in 298K. The effect of the synthetic materials to add light catalyst is better, and removal efficiency can reach more than 95%.This work provides a practical and high-efficient method for heavy metal removal from water and sediment. Particles can be used to effectively handle containing low concentration of Pb2+ (&lt; 200 mg/L) of water and sediment pollution.

A Study on Biosorption Potential of &amp;lt;i&amp;gt;Aspergillus&amp;lt;/i&amp;gt; sp. of Tannery Effluent

Chromium toxicity is one of the major environmental pollutants. As conventional methods for heavy metal removal are very expensive, bioremediation using fungi is extensively explored. Therefore in the present investigation, out of 23 fungi isolated from tannery effluent, 4 Aspergillus species namely A. terreus, A. tamarii, A. flavus and A. niger were selected for evaluating chromium tolerance and biosorption potential. Growth of the fungi was tested using various concentrations of Potassium dichromate (Cr VI) viz., 1 mM, 3 mM and 5 mM amended in potato dextrose agar. For all the fungi, growth was observed only in 1 mM and 3 mM. No growth was observed in 5 mM. Biosorption efficiency of both live and alkali pretreated Aspergillus species was compared. In the present study, alkali pretreated form exhibited highest biosorption efficiency than the live biomass in which A. terreus showed highest chromium biosorption potential compared to the other fungi.