Adsorbent For Removal Of Heavy Metals Research Articles

Environmental remediation of heavy metal ions from aqueous solution through hydrogel adsorption: a critical review.

Heavy metal ions such as Cd(2+), Pb(2+), Cu(2+), Mg(2+), and Hg(2+) from industrial waste water constitute a major cause of pollution for ground water sources. These ions are toxic to man and aquatic life as well, and should be removed from wastewater before disposal. Various treatment technologies have been reported to remediate the potential toxic elements from aqueous media, such as adsorption, precipitation and coagulation. Most of these technologies are associated with some shortcomings, and challenges in terms of applicability, effectiveness and cost. However, adsorption techniques have the capability of effectively removing heavy metals at very low concentration (1-100 mg/L). Various adsorbents have been reported in the literature for this purpose, including, to a lesser extent, the use of hydrogel adsorbents for heavy metal removal in aqueous phase. Here, we provide an in-depth perspective on the design, application and efficiency of hydrogel systems as adsorbents.

Removal of heavy metal ions in water by starch esters

Corn starch has been modified with naturally occurring compounds, maleic acid (MA) and itaconic acid (IA), by esterification in an aqueous medium catalyzed by NaOH to produce adsorbents for heavy metals removal in water. The ester formation has been confirmed by wide angle x‐ray scattering (WAXS), thermogravimetric analysis (TGA), Fourier Transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The effect of the mono and di‐substitution with both acids, on the solubility and the swelling capacity of the modified starch have been investigated. The materials modified with maleic acid exhibited high water solubility, fact that made difficult their characterization and thus their application as adsorbents. In contrast, itaconate esters derivatives demonstrated superabsorbent characteristics and a typical polyelectrolyte behavior. Semiester derivative with greater content of carboxylic acid groups underwent the highest water uptake (H∞ = 1292%). Additionally, the capability of the modified starches with itaconic acid to adsorb aqueous metal cations such as Ni2+, Zn2+, Cd2+, and Pb2+ was investigated and the results were compared with the native corn starch. The modified and native starches exhibited reasonable adsorption capacity for all the cations. It was demonstrated that the native starch does not exhibit selectivity for any of the cations, whereas the itaconate starches remove higher content of Pb2+ with the lowest hydration radius in comparison with other ions.

Sustainable natural adsorbents for heavy metal removal from wastewater: lead sorption on pine bark (Pinus radiataD.Don)

Aqueous Pb(II) adsorption on pine bark (Pinus Radiata D.Don), an inexpensive and sustainable natural sorbent material, has been evaluated and the mechanism of metal retention characterized by scanning electron microscopy (SEM), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and X-ray photoelectron spectroscopy (XPS). Bark pulp densities >1.5 g l−1 achieve near 100% Pb(II) removal from aqueous solutions containing 100 mg l−1 Pb(II). Adsorption rates increased with pulp density, although adsorption capacity diminished at high densities because of blockage of adsorption sites. The effects of washing and sulfuric acid activation were assessed and found to be less important than in previous metal sorption studies. Pb(II) sorption takes place mainly at the lignocellulosic C―O groups, with adsorption at phenolic sites appearing to be most significant. © 2016 The Authors. Surface and Interface Analysis published by John Wiley & Sons, Ltd.

Eggshell: A green adsorbent for heavy metal removal in an MBR system

Presence of heavy metals as well as different metal ions in treated wastewater is a problem for the environment as well as human health. This paper aims to investigate the possibility to combine an MBR (membrane biological reactor) with an adsorption process onto powdered eggshell and eggshell membrane in order to improve metal removal from wastewater. The first step of the experimental analysis consists of the evaluation of the compatibility between the two processes. Then, a study about sorbent concentration and size effect on fouling was conducted, because the use of this kind of sorbent could affect membrane performance. The second step of the work concerns the check up of eggshell removal capacity as a function of sorbent size, achieved treating an aqueous solution containing Al3+, Fe2+ and Zn2+ as water pollutants. Finally, synthetic wastewater, containing the metal species, was treated by two alternative process schemes: one of them performs the metal uptake in a dedicated adsorption unit, before the MBR. In the second, the two processes take place in the same unit. Results demonstrate that the optimization of the first option could be a solution to MBR upgrading.

Characterization of potassium hydroxide (KOH) modified hydrochars from different feedstocks for enhanced removal of heavy metals from water.

Hydrochars produced from different feedstocks (sawdust, wheat straw, and corn stalk) via hydrothermal carbonization (HTC) and KOH modification were used as alternative adsorbents for aqueous heavy metals remediation. The chemical and physical properties of the hydrochars and KOH-treated hydrochars were characterized, and the ability of hydrochars for removal of heavy metals from aqueous solutions as a function of reaction time, pH, and initial contaminant concentration was tested. The results showed that KOH modification of hydrochars might have increased the aromatic and oxygen-containing functional groups, such as carboxyl groups, resulting in about 2-3 times increase of cadmium sorption capacity (30.40-40.78 mg/g) compared to that of unmodified hydrochars (13.92-14.52 mg/g). The sorption ability among different feedstocks after modification was as the following: sawdust > wheat straw > corn stack. Cadmium sorption kinetics on modified hydrochars could be interpreted with a pseudo-second order, and sorption isotherm was simulated with Langmuir adsorption model. High cadmium uptake on modified hydrochars was observed over the pH range of 4.0-8.0, while for other heavy metals (Pb(2+), Cu(2+), and Zn(2+)) the range was 4.0-6.0. In a multi-metal system, the sorption capacity of heavy metals by modified hydrochars was also higher than that by unmodified ones and followed the order of Pb(II) > Cu(II) > Cd(II) > Zn(II). The results suggest that KOH-modified hydrochars can be used as a low cost, environmental-friendly, and effective adsorbent for heavy metal removal from aqueous solutions.

Copper, lead and zinc removal from metal-contaminated wastewater by adsorption onto agricultural wastes

The use of agricultural wastes (groundnut shell, orange and banana peel, rice husk, coconut husk and Wawa tree saw dust) as potential cost-effective adsorbent for heavy metal removal from wastewater was evaluated. The effect of pH (2.0–6.0), adsorbent dosage (0.6–2.2 g), contact time (10–130 min) and initial concentration (Pb: 5–105 mg/L, Cu and Zn: 2.5–52.7 mg/L) on the metal removal efficiency and uptake capacity were investigated using response surface methodology to optimize the process conditions. Groundnut shell showed a high potential to remove Cu, Pb and Zn from synthetic wastewater. The highest removal efficiencies with groundnut as the adsorbent were 85% at pH 5.0 for Cu and 98% at pH 3.0 for Pb and Zn. The optimum conditions obtained were 2.5 g adsorbent with 40.7 mg/L Cu at pH 4.4 and 64 min contact time, 2.5 g adsorbent with 196.1 mg/L Pb at pH 5.6 and 60 min contact time and 3.1 g adsorbent with 70.2 mg/L Zn at pH 4.3 and 50 min contact time, for Cu, Pb and Zn, respectively. The regeneration of the groundnut shell was possible for a maximum of three cycles using 0.2 M HCl as the desorbing solution without any significant change in the adsorbing efficiency.

Adsorption of Cu2+, Cd2+ and Ni2+ from aqueous single metal solutions on graphene oxide membranes

Novel, highly ordered layered graphene oxide (GO) membranes with larger interlayer spacing were prepared by induced directional flow and were used as adsorbents for the removal of Cu2+, Cd2+ and Ni2+ from aqueous solutions. The effects of pH, ionic strength, contact time, metal ion concentration and cycle time on Cu2+, Cd2+ and Ni2+ sorption were investigated. The results indicated that the adsorption of Cu2+, Cd2+ and Ni2+ onto GO membranes was greatly influenced by the pH and weakly affected by the ionic strength. The adsorption isotherms for Cu2+, Cd2+ and Ni2+ were well fitted by the Langmuir model. The maximum adsorption capacities of the GO membranes for Cu2+, Cd2+ and Ni2+ were approximately 72.6, 83.8 and 62.3mg/g, respectively. The adsorption kinetics of Cu2+, Cd2+ and Ni2+ onto GO membranes followed the pseudo-second-order model. The adsorption equilibrium was reached in a shorter time. The GO membranes can be regenerated more than six times based on their adsorption/desorption cycles, with a slight loss in the adsorption capacity. The results demonstrated that the GO membranes can be used as effective adsorbents for heavy metal removal from water.

Development of novel adsorbent-mangrove-alginate composite bead (MACB) for removal of Pb(II) from aqueous solution

This study described a preparation of novel composite adsorbent for heavy metal removal by immobilized mangrove bark into alginate as supporting matrix. The removal of Pb(II) ions from aqueous solution by mangrove-alginate composite bead (MACB) was investigated by performing batch adsorption studies to evaluate the performances of the bead. It was found that the adsorption of Pb(II) ions by MACB beads was pH dependent, as the maximum percentage removal was obtained at pH 5.0. The results revealed the superior parameters of MACB beads had attained about 99.15% efficiency in conditions of 7 g L−1 MACB concentration, 150 min contact time, 5.0 as the initial pH, and 250 rpm agitation speed. The adsorption kinetic data can be well described using pseudo-second-order model and the equilibrium data were fitted well by Freundlich isothermal model, respectively. Thermodynamic parameters were calculated and revealed that the adsorption process is an exothermic and spontaneous reaction within range of temperature of 35–65 °C. This indicates that the MACB beads can be used as a promising adsorbent for removal of heavy metals from aqueous solutions.

Adsorptive removal of heavy metals from water using sodium titanate nanofibres loaded onto GAC in fixed-bed columns

Heavy metals are serious pollutants in aquatic environments. A study was undertaken to remove Cu, Cd, Ni, Pb and Zn individually (single metal system) and together (mixed metals system) from water by adsorption onto a sodium titanate nanofibrous material. Langmuir adsorption capacities (mg/g) at 10−3M NaNO3 ionic strength in the single metal system were 60, 83, 115 and 149 for Ni, Zn, Cu, and Cd, respectively, at pH 6.5 and 250 for Pb at pH 4.0. In the mixed metals system they decreased at high metals concentrations. In column experiments with 4% titanate material and 96% granular activated carbon (w/w) mixture at pH 5.0, the metals breakthrough times and adsorption capacities (for both single and mixed metals systems) decreased in the order Pb>Cd, Cu>Zn>Ni within 266 bed volumes. The amounts adsorbed were up to 82 times higher depending on the metal in the granular activated carbon+titanate column than in the granular activated carbon column. The study showed that the titanate material has high potential for removing heavy metals from polluted water when used with granular activated carbon at a very low proportion in fixed-bed columns.

Modeling and Mechanism of the Adsorption of Proton and Copper to Natural Bamboo Sawdust Using the NICA–Donnan Model

Bamboo sawdust represents an attractive low-cost adsorbent for heavy metal removal from contaminated waters. In the present study, the binding of protons and copper (Cu) ions to purified natural bamboo sawdust was investigated through acid–base titrations and Cu adsorption isotherms. The experimental data were modeled with the nonideal competitive adsorption (NICA)–Donnan equation (the NICA–Donnan model) to account for the heterogeneity of binding sites, stoichiometry of ion binding, as well as electrostatic interaction. Our results showed that the NICA–Donnan modeling of acid–base titration curves provided more accurate fitting results than the two-site surface complexation model. The stoichiometry parameters of the adsorption for Cu were both mono-dentate and binuclear, with the latter existing mainly under low ionic strength and high pH conditions. The contribution of low proton affinity and high proton affinity sites to Cu binding was dependent on pH. For high proton affinity sites, the partial inclusion of CuOH+ species adsorption led to an increase in the Cu ion affinity constant, whereas the incorporation of species adsorption decreased the affinity constant.

Banana Peduncle Biochar: Characteristics and Adsorption of Hexavalent Chromium from Aqueous Solution

Aims: Biochar produced from different waste biomass has been documented as an adsorbent for heavy metal removal from contaminated water . In present study, Banana peduncle which considered as waste, but abundantly available and have high biomass was selected for production of biochar to investigate its adsorption capacity for hexavalent chromium. Place and Duration of Study: Environment and Sustainability Department, CSIR - Institute of Miner als and Materials Technology (CSIR - IMMT), Bhubaneswar, India, between April 2014 and October 2014. Methodology: Banana peduncle pyrolysed at 300 ° C and 500 ° C temperature and characterized by proximate, total carbon, FE - SEM, FTIR and XPS analysis. The adsorp tion of Cr (VI) studied through the batch experiment at different pH, adsorbent dose, and initial concentration. Results: The banana pedun cle biochar yield was 66 and 40 % at 300 ° C and 500 ° C respectively.

Adsorptive removal of heavy metals by magnetic nanoadsorbent: an equilibrium and thermodynamic study

An efficient and new magnetic nanoadsorbent photocatalyst was fabricated by co-precipitation technique. This research focuses on understanding metal removal process and developing a cost-effective technology for treatment of heavy metal-contaminated industrial wastewater. In this investigation, magnetic nanoadsorbent has been employed for the removal of Zn(II) ions from aqueous solutions by a batch adsorption technique. The adsorption equilibrium data fitted very well to Langmuir and Freundlich adsorption isotherm models. The thermodynamics of Zn(II) ions adsorption onto the magnetic nanoadsorbents indicated that the adsorption was spontaneous, endothermic and physical in nature. Surface morphology of magnetic nanoadsorbent by scanning electron microscopy (SEM) and elemental analysis by EDX technique. The structural and photocatalytic properties of magnetic nanoadsorbent were characterized using X-ray diffraction (XRD) and FTIR techniques. Also, the magnetic properties of synthesized magnetic nanoadsorbent were determined by vibrating spinning magnetometer (VSM).

Adsorption of chromium from aqueous solutions using crosslinked chitosan–diethylenetriaminepentaacetic acid

Chitosan (CH) and its derivatives have been the focus of attention for researchers as potential adsorbents for heavy metal removal. The adsorption potential of chitosan cross-linked with diethylenetriaminepentaacetic acid (CD) for Cr6+ was investigated. CD was characterized by FTIR, XRD, TGA, XPS and ESR techniques. Batch experiments were conducted to optimize the parameters affecting the adsorption of chromium. The optimum pH was found to be 3 and the adsorption process was found to be exothermic. Adsorption isotherms were determined and the maximum adsorption capacity of CD for chromium was found to be 192.3mg/g which was higher than the adsorption capacity of the adsorbents reported in literature. The thermodynamic parameters, such as Gibbs free energy, changes in enthalpy and changes in entropy change were also evaluated. XPS and ESR studies revealed that Cr6+ adsorbed onto CD was reduced to Cr3+. The efficacy of CD for removal of Cr6+ from chrome plating effluent was demonstrated.

Chemically activated phosphate slime as adsorbent for heavy metals removal from polluted water

Phosphate slime was activated by chemical activators (0.5 M HNO3, 1 M HNO3, 2MHNO3, 0.5MHNO3: 0.5M NaOH, 1MHNO3: 1M NaOH, and 2MHNO3: 2M NaOH) to use as a cost-effective adsorbent for removal of heavy metals (Pb, Ni, Cd, Zn and Cu) from solution. The influence of pH, adsorbent dosage, contact time, initial metal concentration, and temperature on metals adsorption were investigated. Results revealed that slime phosphate activated by 2MHNO3 was an effective adsorbent for the removal of all metals from aqueous solution. Metal removal was affected by pH, adsorption dosage, initial metal concentration and solution temperature, while it shows less significant for effect of contact time. Metal adsorption was in a good correspondence with the Langmuir isotherm. The order for the maximum adsorption using the adsorbent was Zn (43.47 mg/g) > Cu (38.46 mg/g) > Ni (34.47 mg/g) > Pb (33.3 mg/g) > Cd (26.31 mg/g).

Heavy Metal Removal from Wastewater Using Low Cost Adsorbents

With the onset of industrialization mankind has witnessed various environmental issues in the society. This industrialization has not only brought development and prosperity but eventually disturbed the ecosystem. One of the impacts is visible, in form of water pollution. In the present study heavy metal contamination of water bodies has been discussed. Effluents from large number of industries viz., electroplating, leather, tannery, textile, pigment & dyes, paint, wood processing, petroleum refining, photographic film production etc., contains significant amount of heavy metals in their wastewater. The conventional methods of treatment of heavy metal contamination includes chemical precipitation, chemical oxidation, ion exchange, membrane separation, reverse osmosis, electro dialysis etc. These methods are costly, energy intensive and often associated with generation of toxic byproducts. Thus, the adsorption has been investigated as a cost effective method of removal of heavy metals from wastewater. In the present study various low cost adsorbent has been reviewed as an abatement of heavy metal pollution from wastewater. These adsorbent includes materials of natural origin like zeolites, clay, peat moss and chitin are found to be an effective agent for removal of toxic heavy metals like Pb, Cd, Zn, Cu, Ni, Hg, Cr etc. Apart from these various agricultural wastes like rice husk, neem bark, black gram, waste tea; Turkish coffee, walnut shell etc. were also established as a potent adsorbent for heavy metal removal. Beside that low cost industrial by products like fly ash, blast furnace sludge, waste slurry, lignin, iron (III) hydroxide and red mud, coffee husks, Areca waste, tea factory waste, sugar beet pulp, battery industry waste, sea nodule residue and grape stalk wastes have been explored for their technical feasibility to remove toxic heavy metals from contaminated water.

Evaluation of an activated carbon from olive stones used as an adsorbent for heavy metal removal from aqueous phases

Abstract The performance of a microporous activated carbon prepared chemically from olive stones for removing Cu(II), Cd(II) and Pb(II) from single and binary aqueous solutions was investigated via the batch technique. The activated carbon sample was characterized using N 2 adsorption–desorption isotherms, SEM, XRD, FTIR, and Boehm titration. The effect of initial pH and contact time were studied. Adsorption kinetic rates were found to be fast and kinetic experimental data fitted very well the pseudo-second-order equation. The adsorption isotherms fit the Redlich–Peterson model very well and maximum adsorption amounts of single metal ions solutions follow the trend Pb(II) > Cd(II) > Cu(II). The adsorption behavior of binary solution systems shows a relatively high affinity to Cu(II) at the activated carbon surface of the mixture with Cd(II) or Pb(II). An antagonistic competitive adsorption phenomenon was observed. Desorption experiments indicated that about 59.5% of Cu(II) and 23% of Cd(II) were desorbed using a diluted sulfuric acid solution.

Synthesis and Characterization of Chitosan/Polyvinylpyrrolidone/Zeolite Composite by Solution Blending Method

Polymer/clay composites have been studied for several decades; in the study, polymer/zeolite composite beads have been prepared by a simple solution blending method using chitosan, polyvinylpyrrolidone and zeolite particles as organic and inorganic components, respectively. Different techniques, such as SEM, FTIR spectroscopy, and thermogravimetry have been used to characterize the composite beads. Chitosan/polyvinylpyrrolidone/zeolite (CH/PVP/Z) beads are expected to have a potential as an adsorbent for wastewater treatment. To investigate its applicability, copper (II) was selected as a model compound. The results showed that the composite beads had effective loading capacity and it is a promising adsorbent for heavy metal removal.

Highly efficient co-removal of heavy metals in wastewater from chemical oxygen demand testing instrument by cysteine-functionalized magnetic nanoparticles

Wastewater discharged from chemical oxygen demand(COD) testing instrument was generally difficult to treat due to its high content of heavy metals and very low pH. In this study, a kind of cysteine-functionalized magnetic narioparticles(MNPs-Cys) was synthesized and used to treat the wastewater. The synthesized MNPs-Cys as the adsorbent for heavy metal removal from aqueous solutions were systematically investigated. The adsorption dynamic process fit the Langmuir isotherms well with a maximum adsorption capacity of 76.92 mg/g for Cu(II). The adsorbent could be easily regenerated by 0.1 mol/L HNO3, which exhibited a high adsorption performance within 10 cycles. This adsorbent, combined with a developed pretreatment approach, could make Cr(III), Hg(II) and Ag(I) in the wastewater discharged from COD testing instrument effectively removed and the removal efficiency is more than 99%. This work gave a new insight into the design and synthesis of high-performance materials for treating wastewater with heavy metals.

ADSORPTION STUDIES OF ZINC (II) IONS ON BIOPOLYMER COMPOSITE BEADS OF ALGINATE-FLY ASH

Normal 0 Normal 0 The gelling and metal-chelating properties of alginate were combined to develop an adsorbent for heavy metal removal. Biopolymer beads composed of fly ash and sodium alginate proved to be an effective adsorbent for removal of Zn(II) ions from aqueous solutions. The effect of initial pH (2–10), bead dose (10–80), agitation time (1–24 h), beads composition (0.1g–0.7 g fly ash) and Zn(II) ions initial concentration (5–30 mg L -1 ) on the adsorption process, as well as to what extent the adsorption data obey Langmuir and Freundlich adsorption isotherms were investigated. The maximum adsorption was found 84.20 % within 8 h and after that reaches equilibrium. The adsorption of Zn(II) ions is quite sensitive to pH of the suspension and shows an optimum uptake value at pH 6.0. Maximum adsorption occurred for 40 beads and in case of composition, beads composed of 0.5 g fly ash has shown good results. It is clear from the experimental results that the pH plays an important role in adsorption of zinc ions. The average size, bulk density and swelling ratio of beads calculated are; 0.12 cm, 0.34 g mL -1 and 28.65 respectively. The synthesized beads were also characterized by FTIR, XRD, SEM, TGA/DTA and other methods.

Biosorption of zinc ions onto Corylus avellana L.

Hazelnut is one of the most important agricultural products of Turkey. North coasts of Turkey are so suitable to grow hazelnut that approximately 80% of the total hazelnut production in the world is supplied from this region. There is a great potential of woody hazelnut shell (obtained from species of Corylus avellana L.) to use in some applications in that region. Sorption studies are one of these. For this reason in this paper, batch adsorption of Zn2+ ions onto ground and sieved hazelnut shells was studied in comparable with sawdust of various species of wood and in order to explore the potential use of this material as low cost adsorbent for heavy metal removal in industrial effluents. The capacity of the adsorption for the removal of zinc ions from aqueous solution was investigated under different conditions such as solution contact time (1–360 min), particle size (–75, 75–150 and 150–200 μm), temperature of solution (25 °C–60 °C) and solution pH (3–7). Moreover, zeta potential of particles at different initial pHs (2–10) was measured. The equilibrium data were processed according to Langmuir and Freundlich’s isotherm models and higher adsorption capacity values towards Zn2+ ions were shown. The adsorption kinetics was investigated and the best fit was achieved by a pseudo-second-order equation.