Initial Concentration Of Heavy Metal Ions Research Articles

Adsorption of heavy metal ions by carbon-based adsorbent using magnetic nitrogen-doped carbon and graphene oxide

ABSTRACT The adsorption of weighty metal particles from contaminated water sources has garnered significant attention due to its critical role in environmental remediation and ensuring safe drinking water. Heavy metal ions can be removed from water using conventional adsorbents such as activated zeolites; however, these materials have low absorption and slow kinetics. To solve these issues, carbon-based adsorbents that exhibit easy synthesis, high porosity, design ability, and stability have been proposed. In this review, a carbon-based adsorbent, named M-NC, and graphene oxide were created for the particular evacuation of weighty metal particles. To increase the potential for Heavy Metals (HM) immobilization, sulfide-modified biochar was created via a process called synchronous carbon layer epitome. A hypothetical physicochemical and thermodynamic examination of the adsorption of weighty metals Zn2+, Cd2+, Ni2+, Ag2+, Pb2+ and Cu2+ on carbon-based adsorbents was done with factual material science fundaments. The biochar with large surface areas is utilized to eliminate weighty metal particles, quite possibly the most significant heavy metal pollutants, from aqueous solutions. The limit of the adsorbent for eliminating weighty metal ions was concentrated on utilizing Langmuir adsorption isotherm under ultrasound-helped conditions. The Mesoporous Silica Nanoparticles (MNCs) can be applied to the Langmuir model and pseudo-second-order kinetics. It is possible to use the Langmuir and second-order kinetic equations to accurately explain the adsorption method. Thermodynamic limitations were also envisioned because sorption is exothermic when it happens spontaneously. A homogeneous measurable physical science adsorption typically was utilized to describe and analyze the experimental heavy metal removal isotherms at 30°C and pH5 utilizing adsorbents produced by pyrolysis of biomasses (broccoli stalks). The experimental results were investigated in terms of Langmuir and pseudo-2nd-order kinetic equations, Freundlich and isotherm models. The outcome of pH, initial heavy metal ion concentration, contact time, and adsorbent dosage regarding the adsorption capacity and removal efficiency of Pb2+ and Cd2+ on the hydrogel was examined. This study contributes to the advancement of information in the ground of environmentally friendly heavy metal removal techniques, specifically focusing on the usage of biomass-based adsorbents. These findings have the potential to address the need for effective solutions in water purification and environmental cleanup efforts.

Efficient separation of Cd2+ and Pb2+ by Tetradesmus obliquus: Insights from cultivation conditions with competitive adsorption modeling

Microalgae serve as efficient biosorbents for the removal of heavy metals. This study investigates the adsorption and desorption behavior of Tetradesmus obliquus FACHB-14 (T. obliquus) under various culture conditions. Glucose cultivation enhances adsorption, with Pb2+ exhibiting higher capacity than Cd2+, reaching a maximum of 80.24 mg/g at an initial heavy metal ion concentration of 64 mg/L. Kinetic modeling favors the pseudo-second-order kinetics. The Langmuir model is more suitable for describing the adsorption process of Cd2+ in BG11 and Pb2+ in glucose, with maximum adsorption capacities of 6.48 mg/g and 86.29 mg/g, respectively. The Temkin model is more suitable for describing the adsorption process of Pb2+ in BG11 and Cd2+ in glucose. Competitive adsorption reduces the maximum capacity by 42.60 % for Cd2+ and 55.61 % for Pb2+. The Extended Freundlich model fits competitive behavior. Analysis reveals increased extracellular polymer secretion under glucose conditions, which aids adsorption. Na2EDTA achieves up to 97.37 % recovery of heavy metal ions. Overall, T. obliquus cultured with glucose shows promise for heavy metal removal, especially in mixed systems.

Fir sawdust as a low-cost and easily recyclable adsorbent: efficient removal of Pb(II), Cu(II), and Zn(II) contaminants from wastewater.

The main pollution sources of heavy metals are the arbitrary discharge of industrial wastewater and waste residues, which cause serious harm to the water environment, soil environment, and human health. In this study, following the principle of waste utilization, a gel adsorbent (AA-SW-AMPS) was prepared by microwave-assisted chemical cross-linking using fir sawdust as raw material. A scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and swelling dynamic experiments were used to investigate the microstructure, reaction mechanism, and water absorption performance of AA-SW-AMPS. The N2 adsorption-desorption curve shows that the porous structure of AA-SW-AMPS creates 240.75 cm2/g of specific surface area to enable excellent heavy-metal sorption. It was determined by adsorption experiments that the optimal adsorption state was when the dosage of AA-SW-AMPS was 5g/L, the pH of the solution was 5, the adsorption time was 45min, and the initial heavy metal ion concentration was 250mg/L. In addition, the adsorption mechanism was investigated using adsorption dynamics, adsorption isotherm, and Materials Studio simulation. The results show that the maximum adsorption capacities of AA-SW-AMPS for Pb(II), Cu(II), and Zn(II) were 253.49mg/g, 237.29mg/g, and 232.15mg/g, respectively, and the adsorption mechanism is monolayer chemisorption. The adsorbent showed great potential in removing heavy metals from wastewater.

Synthesis of ZIF-8@GO-COOH and its adsorption for Cu(II) and Pb(II) from water: Capability and mechanism

The removal of heavy metal ions from the aqueous environment is an important topic as heavy metal pollution is widely distributed in water bodies, causing serious damage to aquatic ecosystems and worsening the already scarce freshwater resources. In this work, we report the synthesis of novel ZIF-8@GO-COOH composite nanosorbent materials by in situ self-assembly. The physicochemical properties of the composites were investigated using relevant characterisation techniques, and the adsorption capacity of ZIF-8@GO-COOH for copper and lead ions in aqueous solution was tested by batch adsorption experiments. The adsorption behaviour was analysed by combining adsorption kinetics, adsorption isotherm model and Van't Hoff model. The results showed that the adsorption capacities of ZIF-8@GO-COOH for Cu(II) and Pb(II) were 93.26 mg/g and 95.875 mg/g, respectively, when the initial heavy metal ion concentration was 100 mg/L, the adsorption time was 60 min, the temperature was 293 K and the pH conditions were suitable. The high adsorption performance of ZIF-8@GO-COOH was attributed to its surface with abundant oxygen-containing functional groups and excellent specific surface area, which gives it a significant advantage in the removal of heavy metal ions from aqueous solutions.

A graphene-based porous composite hydrogel for efficient heavy metal ions removal from wastewater

A graphene-enhanced supramolecular hydrogel containing poly(acrylic acid)(PAA) and poly(4-vinylpyridine) (P4VP) was fabricated for the wastewater remediation. In this work, P4VP brushes were grown from functionalized graphene oxide (GO) through surface-initiated atom transfer radical polymerization. Then, the P4VP-grafted GO (i.e., GO-g-P4VP) was integrated into PAA matrix to form GO-g-P4VP@PAA hydrogel as a highly efficient adsorbent for extraction of toxic metal ions from wastewater. Due to the introduction of GO-g-P4VP, the GO-g-P4VP@PAA composite hydrogel exhibited good compressive strength, and a special interconnected 3D porous network was formed in the hydrogel. The effect of pH, initial heavy metal ion concentration, contact time, and adsorbent dosage regarding the adsorption capacity and removal efficiency of Pb2+ and Cd2+ on the hydrogel was examined. Under appropriate conditions, the GO-g-P4VP@PAA hydrogel can achieve maximum adsorption capacities of 257.28 mg/g for Pb2+, 175.79 mg/g for Cd2+. The adsorption kinetics of Pb2+ and Cd2+ on the GO-g-P4VP@PAA hydrogel followed a pseudo-second order model and the adsorption isotherms were more consistent with the Langmuir isotherm model. In addition, the GO-g-P4VP@PAA hydrogel exhibited good reusability. After five cycles, the removal efficiency of both Pb2+ and Cd2+ still remained above 80 %. These results demonstrate the GO-g-P4VP@PAA hydrogel serves as a desirable adsorbent in removal of heavy metal cations from wastewater.

Absorption thermodynamic and kinetics of heavy metals by magnetic hydrogel nanocomposite absorbents with semi‐interpenetrating networks structure

AbstractKH570‐modified magnetic hydrogel nanocomposite absorbents (KH570‐mHNAs) with semi‐interpenetrating networks (semi‐IPNs) were synthesized by radical copolymerization based on poly(acrylamide‐co‐acrylic acid), PVP and KH570‐modified magnetic nanoparticles. KH570‐mHNAs with porous and ravine structure have the target structure confirmed by FTIR and XRD results. KH570‐mHNAs have high adsorption capacities of Cu(II) (163 mg/g), Cd(II) (150 mg/g), and Pb(II) (460.8 mg/g), approaching the absorption equilibrium at 60 min. Heavy metal absorption was highly dependent on different process variables, such as pH value, initial heavy metal ion concentration, contact time, and temperature. The endothermic, entropy increasing, and spontaneous nature of heavy metal ion adsorption was revealed from thermodynamic study. Heavy metal ions adsorption isotherms and kinetics were in agreement with the Langmuir model and pseudo‐second‐order kinetic model, respectively. Besides, KH570‐mHNAs had good magnetic responsiveness, desorption, and reusability, which made it a promising adsorbent for removing heavy metal ions from the contaminated wastewater.

Synthesis of ZnO nanoparticles and its application in adsorption

In the present study nanoparticles of zinc oxide (ZnO) were synthesized by simple solution based approach and used as an adsorbent for the removal of Cu(II) ions from aqueous solution. ZnO nanoparticles were characterized by X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and Dynamic Light Scattering (DLS). TEM confirmed the formation of zinc oxide nanoparticles in the size range of 10-11 nm. Adsorption capacity of ZnO for removing Cu(II) ions from aqueous solutions was investigated at different pH, as a function of contact time, metal ion concentration and the amount of adsorbent. Moreover, adsorption isotherms and kinetics was studied to understand the nature and mechanism of adsorption. A high percentage removal (98.71%) of Cu(II) from its aqueous solutions at pH 5 and at initial heavy metal ion concentration of 300 mg/l by ZnO particles was achieved. The adsorption isotherm was well described by Freundlich isotherm model(R2= 0.999). The adsorption kinetics data was well fitted by the pseudo-second-order rate model with a high regression coefficient. The above results suggest that ZnO nanoparticles can be used as potential adsorbent for the efficient removal of heavy metals from aqueous solutions. Copyright © 2017 VBRI Press

Adsorption Features of Loess Calcareous Nodules to Heavy-Metal Ions in Aqueous Solution

This paper explores the use of calcareous tuberculosis as an adsorbent and heavy-metal ions (Cu2+, Zn2+, Cd2+, and Pb2+) as adsorbates, and the influence of varying levels of particle size, adsorption time, pH, adsorbent dosage, and initial concentration of heavy metals is studied through an experiment of single heavy-metal adsorption. In addition, the impact of the temperature and other factors on the adsorption of heavy-metal ions by calcareous nodules is analyzed to identify the optimal conditions for the adsorption of heavy-metal ions by calcareous nodules. As shown by the research findings, the adsorption rates of Cu2+, Zn2+, and Pb2+ gradually declined with the increase in particle size, with no evident effect on Cd2+. In the meantime, with further increases in factors such as the adsorption time, adsorbent dosage, and temperature, the adsorption rates of Cu2+, Zn2+, Cd2+, and Pb2+ experienced gradual increases. The adsorption rates of Cu2+, Zn2+, and Cd2+ gradually declined with the increase in initial concentration of heavy-metal ions, whereas the adsorption rate of Pb2+ experience increased first and then declined. As the pH increased, the adsorption rate of Cd2+ experience increased first and then declined at a slow pace. The adsorption rates of Cu2+, Zn2+, and Pb2+ increased first and then decreased. The adsorption capacity of calcareous nodules toward the four heavy-metal ions was in the order of Pb2+ > Zn2+ > Cu2+ > Cd2+. When the particle size was set to 0.25 mm, the adsorption time was set to 120 min, and the dosage was set to 0.6 g, the calcareous nodules included Pb2+, Zn2+, and Cu2+. Moreover, Cd2+ was able to achieve stronger adsorption capacity, with the adsorption rate able to reach 83.33%, 77.78%, 73.81%, and 81.93% of its maximum level. Therefore, as the particle size of the heavy-metal ions decreased, the adsorption capacity generally became stronger. As the adsorption time increased, the temperature and the amount of adsorbent also increased. The optimal pH value for the adsorption of calcareous nodules toward Pb2+, Zn2+, Cu2+, and Cd2+ was found to be 7, 6, 5, and 8, respectively, and the optimal temperature was 50 °C. In summary, calcareous nodules are a natural, low-cost, and effective adsorbent.

Adsorption of lead, copper and zinc in a multi-metal aqueous solution by waste rubber tires for the design of single batch adsorber

Heavy metal pollution has emerged as one of the most serious environmental challenges facing the world today. The removal of heavy metals from the effluent is of special environmental concern because of their toxicity and persistence in nature. This study presents the suitability of activated carbon from waste rubber tire as a low-cost adsorbent for multiple adsorption of copper, lead and zinc from wastewater. The adsorbent removed heavy metal ions effectively from solution medium in the order of copper > lead > Zinc. The adsorption process was rapid with all metals reaching equilibrium within 120 min. The optimum pH for Lead was achieved at 5 and 6 for copper and Zinc. The removal of heavy metals was discovered to increase with adsorbent dosage and contact time and reduced with initial concentration. The adsorption of multiple heavy metals was modeled using Freundlich and Langmuir adsorption isotherms to assess the experimental findings. The equilibrium data better fitted to the Langmuir isotherm with regression coefficient (R2) of 0.9831, 0.9992 and 0.9953 for lead, copper and zinc respectively. The maximum adsorption capacities (Qmax) at equilibrium were 9.6805 mg/g, 12.4378 mg/g and 4.9950 mg/g for Lead, Copper and Zinc respectively. The adsorption kinetics indicated that pseudo-second-order kinetic model described well the sorption mechanism for multiple adsorption of heavy metals with R2 of more than 0.99 for all metal ions. An empirical model for predicting and designing of a single batch adsorber for 95 % multiple heavy metal ion removal at any given initial heavy metal ion concentration and effluent volume was further developed using activated carbon from waste rubber tires. Waste rubber tire Activated carbon demonstrated an ability for the treatment of wastewater containing these heavy metals in multimetal solutions.

Efficient Removal of Toxic mMetal Ions (Pb(II) and Hg(II) Ions in Single Component Systems by Adsorption on Romanian Clay Material

In this study, a local natural clay material was used for the efficient removal of Pb(II)ions and Hg(II) ions from aqueous media, in batch system. The adsorptive potential of clay material was testes at different initial solution pH, adsorbent dosage, contact time and initial heavy metal ions concentration and room temperature (20  2C). The highest adsorption efficiency of clay material was found at initial pH of 7.0 in case of Pb(II) ions, and 2.0 in case of Hg(II) ions, while the adsorbent dosage had the same value (4 g/L) for both metal ions. The adsorption equilibrium is very fast and was reach within 10 min. The modelling of experimental data showed that the adsorption processes followed the Freundlich isotherm model and pseudo-second order kinetic model. Detailed analysis of the experimental data indicate that the retention of Pb(II) and Hg(II) ions from aqueous solution on clay materials involves two processes, one of adsorption and the other of precipitation, whose succession depends on the speciation form of the metal ion in aqueous solution. However, the high adsorption capacity and short contact time are important characteristics which suggest the potential use of this clay material in environmental remediation processes.

Heavy metal removing by modified bentonite and study of catalytic activity

Due to the high hydrophobicity and surface area, clays are efficient adsorbents for the removal of liquid impurities and purification of gases when they are modified. In this work, bentonite was modified with imidazole and imidazolium groups and resulting clays were characterized by different techniques such as 1H NMR, 13C NMR, TEM, SEM, XPS, TG, and FT-IR. Applications of these clays were studied in the removal of Co, Cu, and Pb in the wastewater. Effects of contact time, pH, initial heavy metal ions concentration, and kinetic were investigated. The catalytic activity of the metals adsorbed by imidazole modified bentonite was studied in A3 coupling reactions of various amines, aldehydes, and alkynes.

Assessment of strength and leaching characteristics of heavy metal-contaminated soils solidified/stabilized by cement/fly ash.

Solidification/stabilization technique has been widely adopted to remediate the heavy metal-contaminated sites. In the present work, the strength and leaching characteristics of the contaminated soils solidified/stabilized by cement/fly ash were systemically investigated. Electrical resistivity was also measured to establish empirical relationships for assessment of remediation efficacy. Tests results showed that the unconfined compressive strength increased and the leached ion concentration decreased with increasing curing time. In contrast, the unconfined compressive strength decreased and the leached ion concentration increased with increasing initial heavy metal ion concentration in the specimen. For the strength characteristic, the most notable detrimental effect was induced by Cr3+ and the least was induced by Pb2+. For the leaching characteristic, the trend was reversed. The electrical resistivity of the tested specimen increased significantly with increasing curing time and with decreasing initial ion concentration. The electrical resistivity of the Pb-contaminated specimen was higher than that of the Zn-contaminated specimen, which in turn was higher than that of the Cr-contaminated specimen. Empirical relationships between the strength, leaching characteristic, and electrical resistivity were established, which could be adopted to assess the remediation efficacy of heavy metal-contaminated soil solidified/stabilized by cement/fly ash.

Efficient Removal of Pb(II) and Cd(II) from Industrial Mine Water by a Hierarchical MoS2/SH-MWCNT Nanocomposite.

In this study, we investigate the adsorption capability of molybdenum sulfide (MoS2)/thiol-functionalized multiwalled carbon nanotube (SH-MWCNT) nanocomposite for rapid and efficient removal of heavy metals [Pb(II) and Cd(II)] from industrial mine water. The MoS2/SH-MWCNT nanocomposite was synthesized by acid treatment and sulfurization of MWCNTs followed by a facile hydrothermal reaction technique using sodium molybdate and diethyldithiocarbamate as MoS2 precursors. Morphological and chemical features of the nanocomposite material were studied using various characterization techniques. Furthermore, the effects of adsorbent (MoS2/SH-MWCNT nanocomposite) concentration, contact time, initial concentration of heavy-metal ions, and reaction temperature were examined to determine the efficiency of the adsorption process in batch adsorption experiments. Kinetics and isotherm studies showed that the adsorption process followed pseudo-second-order and Freundlich adsorption isotherm models, respectively. Thermodynamic parameters calculated using van’t Hoff plots show the spontaneity and endothermic nature of adsorption. MoS2/SH-MWCNT nanocomposite demonstrates a high adsorption capacity for Pb(II) (90.0 mg g–1) and Cd(II) (66.6 mg g–1) following ion-exchange and electrostatic interactions. Metal–sulfur complex formation was identified as the key contributor for adsorption of heavy-metal ions followed by electrostatic interactions for multilayer adsorption. Transformation of adsorbent into PbMoO4–xSx and CdMoO4–xSx complex because of the adsorption process was confirmed by X-ray diffraction and scanning electron microscopy-energy-dispersive spectrometry. The spent adsorbent can further be used for photocatalytic and electrochemical applications; therefore, the generated secondary byproducts can also be employed for other purposes.

Effect of Apricot Stone Activated Carbon Adsorbent on the Removal of Toxic Heavy Metals Ions from Aqueous Solutions

In this work, activated carbon was prepared from apricot stone (ASAC) waste to remove the toxic heavy metal ions (Aluminum ions and zinc ions) from aqueous solutions. The effect of different parameters such as PHs, adsorbent dose, the initial heavy metal ions concentration and contact time were investigated. Adsorption isotherm, kinetics and thermodynamics of metal ions on ASAC were studied. Equilibrium data were fitted to the Langmuir and Freundlich isotherm models. Langmuir isotherm provided the best fit to the equilibrium data with maximum adsorption capacity. Kinetic studies were also undertaken in terms of pseudo-first-order and pseudo-second-order kinetic models for heavy metal ions on ASAC. The adsorption process follows the pseudo- second order kinetic with high coefficients correlation. The thermodynamic parameters ∆G°, ∆H° and ∆S° determined, showed that the adsorption of heavy metal ions onto ASAC was feasible, spontaneous and endothermic. The results showed that ASAC is an efficient adsorbent for the adsorptive removal of heavy metal ions from aqueous solutions.

Competitive removal of heavy metal ions from squid oil under isothermal condition by CR11 chelate ion exchanger

Heavy metal ions (HMIs) are serious threats to the environment. Sub-critical water treatment was used to mimic contamination of squid oil in aqueous, metal-soap and oil phases. Isothermal adsorption of HMIs (Cu2+, Pb2+, Cd2+ and Zn2+) was studied from aqueous phase to oil phase (493, 523, 548, and 573K) for solutions with different initial concentration of HMIs was studied. Decomposition of glycerides into fatty acids was favored at high subcritical temperatures, with metal-soap phase showing the highest chelation ability toward Cu2+ (96%, isotherm 573K). The removal-ability of HMIs from contaminated oil was performed by CR11 chelate ion exchanger, showing facilitated removal from metal-soap and oil phases at low temperatures compared to general-purpose PEI-chitosan bead and PEI-chitosan fiber sorbents. The chelation behavior of Pb2+ and Cd2+ was the same in the OIL, with maximum values of 5.7×10−3 (mol/l) and 5.0×10−3 (mol/l) at 573K, respectively. By contrast, concentration of Zn2+ ion showed a slight increase with increasing temperature due to electrostatic forces between Zn2+ and active sites of glycerides in oil phase. For oil solution, the selectivity of adsorption for CR11, especially for Zn2+, was at least five-fold larger compared to PEI-chitosan bead and PEI-chitosan fiber adsorbents.

Synthesis of Sodium Acrylate and Acrylamide Copolymer/GO Hydrogels and Their Effective Adsorption for Pb2+ and Cd2+

A serial of cross-linked sodium acrylate and acrylamide copolymer/graphene oxide (P(AANa-co-AM)/GO) hydrogels with different mass ratios of acrylic acid (AA) to acrylamide (AM) and different contents of N,N-methylenebis(acrylamide) (MBA) were prepared via dispersive polymerization. The prepared hydrogels were characterized by XRD, FT-IR, TGA, SEM, and BET in detail. The removal efficiency of Pb2+ and Cd2+ on the P(AANa-co-AM)/GO hydrogel have been improved significantly due to the addition of 1.0 wt % of GO. The P(AANa-co-AM)/GO hydrogel with AA/AM = 1 and 0.8 wt % of MBA has the highest removal efficiency for Pb2+ and Cd2+ and a suitable swelling ratio, which was selected as the adsorbent for systematic adsorption of Pb2+ and Cd2+ from aqueous solutions. The adsorption capacity and removal efficiency of Pb2+ and Cd2+ on the P(AANa-co-AM)/GO hydrogel were dependent on pH, initial heavy metal ion concentration, and adsorbent dosage. The presence of 0.01–0.05 M Mg2+ or Ca2+ has an obvious effect on the adso...

Kinetic Modeling of Multiple Adsorption of Heavy Metal Ions Using Activated Carbon from Nigerian Bamboo for Design of Adsorbers

In this study, the kinetics modeling for design of adsorbers for multiple adsorption of heavy metal ions was carried out using activated carbon from waste Nigerian bamboo. The bamboo was cut into sizes, washed, dried and was carbonized at 350°C-500°C. It was then activated at 800°C using nitric acid. Simultaneous batch adsorption of different heavy metal ions (Cd2+, Ni2+, Pb2+, Cr3+,Cu2+and Zn2+) in same aqueous solution using activated carbon from Nigerian bamboo was carried out at different initial concentration till equilibrium was reached. In order to determine the mechanism of sorption for multiple adsorption of these heavy metals ions, the kinetic data were modeled using the pseudo first order, pseudo second order kinetic equations, and intra-particle diffusion models. The pseudo first order did not fit well into the kinetic data. The pseudo second order equation was the best applicable model to describe the sorption process. Hence the pseudo second order kinetic reaction is the rate controlling step with some intra particle diffusion taking place. An empirical model was also developed which can then be used for predicting and designing adsorber for the multiple removal of 99% heavy metal ions at any given initial heavy metal ions concentration and the adsorption time required for any multi-stage adsorption system using Nigerian Bamboo activated carbon.

Metal adsorption by agricultural biosorbents: Adsorption isotherm, kinetic and biosorbents chemical structures

Biosorption of Cu(II), Co(II) and Fe(III) ions from aqueous solutions by rice husk, palm leaf and water hyacinth was investigated as a function of initial pH, initial heavy metal ions concentration and treatment time. The adsorption process was examined by two adsorption isotherms: Langmuir and Freundlich isotherms. The experimental data of biosorption process were analyzed using pseudo-first order, pseudo-second order kinetic models. The equilibrium biosorption isotherms showed that the three studied biosorbents possess high affinity and sorption capacity for Cu(II), Co(II) and Fe(III) ions. Rice husk showed more efficiency than palm leaf and water hyacinth. Adsorption of Cu(II) and Co(II) was more efficient in alkaline medium (pH 9) than neutral medium due to the high solubility of metal ion complexes. The metal removal efficiency of each biosorbent was correlated to its chemical structure. DTA studies showed formation of metal complex between the biosorbents and the metal ions. The obtained results showed that the tested biosorbents are efficient and alternate low-cost biosorbent for removal of heavy metal ions from aqueous media.

Kinetic study of heavy metal ions removal by ion exchange in batch conical air spouted bed

Spouted bed contactor is a hybrid of fixed and fluidized bed contactors, which retains the advantages of each with good hydrodynamic conditions. The aim of the present study is to investigate the performance of a batch conical air spouted vessel for heavy metal removal by strong cation exchange resins (AMBERJET 1200 Na). The effect of various parameters such as type of heavy metal ions (Ni+2 and Pb+2), contact time, superficial air velocity and initial heavy metal ion concentration on % heavy metal ion removal has been investigated. It has been found that under optimum conditions 98% and 99% removal of Ni+2 and Pb+2 were achieved respectively. Several kinetic models were used to test the experimental data and to examine the controlling mechanism of the sorption process. The present results of Ni+2 and Pb+2 well fit pseudo second order kinetic model with a high correlation coefficient. Both film diffusion and intra-particle diffusion contribute to the ion exchange process. The present study revealed that spouted bed vessel may provide an effective alternative for conducting ion exchange reactions.

Rapid and high capacity adsorption of heavy metals by Fe3O4/montmorillonite nanocomposite using response surface methodology: Preparation, characterization, optimization, equilibrium isotherms, and adsorption kinetics study

Fe3O4/montmorillonite nanocomposite (Fe3O4/MMT NC) was synthesized for removal of Pb2+, Cu2+ and Ni2+ ions from aqueous systems. The nanoadsorbent was characterized by X-ray diffraction and transmission electron microscopy and mean diameter of magnetic nanoparticles was about 8.24 nm. The experiments were designed by response surface methodology and quadratic model was used to prediction of the variables. The adsorption parameters of adsorbent dosage, removal time, and initial heavy metal ions concentration were used as the independent variables and their effects were investigated on the heavy metal ions removal. Variance analysis was utilized to judge the adequacy of the chosen models. Optimum conditions with initial heavy metal ions concentration of 510.16, 182.94, and 111.90 mg/L, 120 s of removal time and 0.06 g/0.025 L, 0.08 g/0.025 L, and 0.08 g/0.025 L of adsorbent amount were given 89.72%, 94.89%, and 76.15% of removal efficiency Pb2+, Cu2+ and Ni2+ ions, respectively. Prediction of models was in good agreement with experimental results and Fe3O4/MMT NC was found successful in removing heavy metals from their aqueous solutions.