Adsorption Of Toxic Metal Ions Research Articles

Adsorptive removal of heavy metal ions from aqueous solution by using green synthesized copper oxide nanoparticles

Metal nanoparticles can be synthesized by “green synthesis” methods, an efficient and environmentally friendly process that involves combination of metal salt solution with plant extract. Due to low cost, ideal surface area, plenty of active sites, and high adsorption capabilities, copper oxide nanoparticles (CuO-NPs) have drawn a lot of attention as effective adsorbents. Our present study is primarily concerned about green synthesis route of producing copper oxide nanoparticles (CuO-NPs) from flower extract of Nyctanthesarbor-tristis. The prepared CuO-NPs was used in the adsorption of toxic metal ions including U(VI), Pb(II), Cr(VI), and Cd(II) from water samples was studied. Different analytical techniques like UV-visible spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy and field emission scanning electron microscopy has been used for analyzing the properties of prepared copper oxide nanoparticles. A batch experiment has also been conducted to determine the efficacy of the synthesized copper oxide nanoparticles toward the adsorption of toxic metal ions including U(VI), Pb(II), Cr(VI), and Cd(II) from water samples at various parameters, such as the impact of pH, contact time and adsorbent dosage. According to the results, the adsorption capacity (qmax) of CuO-NPs for U(VI), Pb(II), Cr(VI), and Cd(II) metal ions are 200, 155.27, 131.57 and 90.90 respectively. The kinetic studies showed that the pseudo-second order kinetics model has best fits to the data (R2= 0.85, 0.91, 0.89, 0.92 for U(VI), Pb(II), Cr(VI), and Cd(II) respectively. The study also included pseudo-first order, Elovich models and intra particle diffusion. In light of these findings, copper oxide nanoparticles were found to be a promising nano-adsorbent for the treatment of water.

Adsorption performance of groundnut and sheanut shells biochars in ternary system of toxic metals

The choice of biomass is influenced by its availability, potential characteristics such as abundance of functional groups and large surface area. This study explored the removal of toxic metal ions from aqueous solution using groundnut and sheanut shells biochars. Groundnut and sheanut shells biochars pyrolysed at 350 ± 5ºC and 700 ± 5°C and used to remove lead (Pb), cadmium (Cd) and mercury (Hg) in ternary systems. Initial toxic metal concentrations and residual concentrations after the biochars application were measured using atomic absorption spectrophotometer. The adsorption efficiency of groundnut and sheanut shells biochars pyrolysed at 350 ± 5ºC and 700 ± 5°C in the ternary system ranged from 81.28% to 100% for lead, cadmium ranged from 43.66% to 100% and mercury ranged from 96.38% to 100%. The higher removal rates of Pb, Cd and Hg by the biochars showed the pH solutions were favourable for the adsorption. Langmuir isotherm was the model that best fit the adsorption of toxic metal ions. Groundnut and sheanut shells biochars qualify as a feasible and economic option for toxic metals removal. Hence, studies should be conducted in real polluted water to ascertain the actual effectiveness of these biochar treatments.

Efficient Adsorption of Toxic Heavy Metal Ions on the Surface Engineered Violuric Acid-Reduced Graphene Oxide Nanomaterial

Herein, a surface-engineered violuric acid-functionalized reduced graphene oxide (rGO-VA) has been synthesized and characterized using XRD, FESEM, HRTEM-EDX, FTIR, XPS, Raman, and UV–vis spectroscopy. The surface morphology describes highly exfoliated graphene sheets and uniformly distributed VA showing a topography of average size ∼1.663 nm. The Raman and EDX spectra describe greater defects due to the presence of C, N, and O atoms on the surface of the rGO-VA. Hence, O and N-containing functional groups that are present on the surface and edge of rGO-VA facilitate the efficient adsorption of toxic metal ions. The synthesized rGO-VA efficiently removes metal ions up to 99.9% of Hg2+, Pb2+, and As3+, from their aqueous solutions (40 mg/L) within a short retention time (5–10 min). The removal efficiency results are unaffected even at various interferences like pH, temperature, organic pollutants, cations, and anions. The adsorption process is chemisorption, multilayer, spontaneous, endothermic, and random. During the adsorption process, the residual concentrations were initially analyzed using UV–vis spectroscopy, and the results were verified by AAS. Overall, the present surface-engineered rGO-VA may be crucial for developing an efficient adsorbent to remove toxic metal ions from wastewater.

Preparation of Eco-Friendly Chelating Resins and Their Applications for Water Treatment.

In the present study, two chelating resins were prepared and used for simultaneous adsorption of toxic metal ions, i.e., Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, and Pb2+ (MX+). In the first step, chelating resins were prepared starting with styrene-divinylbenzene resin, a strong basic anion exchanger Amberlite IRA 402(Cl-) with two chelating agents, i.e., tartrazine (TAR) and amido black 10B (AB 10B). Key parameters such as contact time, pH, initial concentration, and stability were evaluated for the obtained chelating resins (IRA 402/TAR and IRA 402/AB 10B). The obtained chelating resins show excellent stability in 2M HCl, 2M NaOH, and also in ethanol (EtOH) medium. The stability of the chelating resins decreased when the combined mixture (2M HCl:EtOH = 2:1) was added. The above-mentioned aspect was more evident for IRA 402/TAR compared to IRA 402/AB 10B. Taking into account the higher stability of the IRA 402/TAR and IRA 402/AB 10B resins, in a second step, adsorption studies were carried out on complex acid effluents polluted with MX+. The adsorption of MX+ from an acidic aqueous medium on the chelating resins was evaluated using the ICP-MS method. The following affinity series under competitive analysis for IRA 402/TAR was obtained: Fe3+(44 µg/g) > Ni2+(39.8 µg/g) > Cd2+(34 µg/g) > Cr3+(33.2 µg/g) > Pb2+(32.7 µg/g) > Cu2+ (32.5 µg/g) > Mn2+(31 µg/g) > Co2+(29 µg/g) > Zn2+ (27.5 µg/g). While for IRA 402/AB 10B, the following behavior was observed: Fe3+(58 µg/g) > Ni2+(43.5 µg/g) > Cd2+(43 µg/g) > Cu2+(38 µg/g) > Cr3+(35 µg/g) > Pb2+(34.5 µg/g) > Co2+(32.8 µg/g) > Mn2+(33 µg/g) > Zn2+(32 µg/g), consistent with the decreasing affinity of MX+ for chelate resin. The chelating resins were characterized using TG, FTIR, and SEM analysis. The obtained results showed that the chelating resins prepared have promising potential for wastewater treatment in the context of the circular economy approach.

Removal of hexavalent chromium ions and mixture dyes by electrospun PAN/graphene oxide nanofiber decorated with bimetallic nickel–iron LDH

The network of electrospun nanofibers modified by layered double hydroxides (LDHs) still needs to be thoroughly investigated in the field of adsorption of toxic metal ions and dyes from its aqueous solution. In the present study, an innovative electrospun nanofiber membrane was fabricated, which was used to eliminate pollutants from water. Polyacrylonitrile/graphene oxide (PAN/GO) composite nanofibrous membranes were fabricated by the electrospinning technique first, and next bimetallic nickel iron layered double hydroxide/PAN/GO (NiFe LDH/PAN/GO) composite nanofibrous membranes were synthesized by via hydrothermal method. The characterizations of the prepared nanofibers membranes were analyzed using FE-SEM, EDS element mapping, XRD, FTIR, AFM, and WCA. The adsorption behavior of binary mixture of Rose Bengal (RB) and Brilliant Blue (BB) dyes and metal ions of hexavalent chromium (Cr(VI)) by NiFe LDH/PAN/GO nanofibers were investigated via batch experiments based on central composite design (CCD) method. According to the Langmuir model, the maximum adsorption capacity of the NiFe LDH/PAN/GO toward mixture of RB and BB dyes and Cr(VI) ions are 6.19, 7.74 and 13.1 mg g−1, respectively. In addition, the fabricated LDH composite membranes after five times sequential adsorption/desorption experiments. The adsorption kinetics of pollutants follows the pseudo-first-order model. The adsorption process is spontaneous, endothermic, and enhancement of randomness. In addition, NaCl salt decreased the mixture of RB and BB dyes and metal Cr(VI) ions removal by the composite membranes.

Simultaneous adsorption of toxic metals in binary systems using peanut and sheanut shells biochars

Converting peanut and sheanut shells into biochar is a smart strategy for recycling agricultural waste. Biochar was produced from peanut and sheanut shells at temperatures of 350 ± 5 °C and 700 ± 5 °C. The adsorption capacities for lead (Pb2+), cadmium (Cd2+) and mercury (Hg2+) in the binary systems were evaluated. In the binary systems with concentrations of 5 : 5 mg/L, 10 : 10 mg/L, 25 : 25 mg/L and 50 : 50 mg/L the removal efficiencies of GB350, SB350, GS350, GB700, SB700 and GS700 were 100% for Pb2+ and 88.70%–99.46% for Cd2+, 98.20%–100% for Pb2+ and 100% for Hg2+, 79.30%–100% for Cd2+ and 99.96%–100% for Hg2+. The higher adsorption percentages of Pb2+, Cd2+ and Hg2+ by the biochar in the binary systems indicated that the pH values of the solutions were good and suitable for adsorption. The biochar from peanut and sheanut shells showed excellent capacity to remove Pb, Cd and Hg in the binary systems. The Langmuir model (0.3351 ≤ R2 ≤ 0.9901) was more suitable than the Freundlich model (0.0014 ≤ R2 ≤ 0.9994) for the adsorption of toxic metal ions onto the biochar in the binary systems. The interactive effects of the binary mixtures in the aqueous solution of Pb2+, Cd2+, and Hg2+ were found to be either antagonistic or synergistic. Peanut and sheanut shell biochar were rich in calcium, potassium, magnesium, and sodium, and phosphates affected the mechanisms of Pb and Cd adsorption. The high sulphur content might have influenced the mechanism of Hg adsorption in the aqueous solutions on peanut and sheanut shell biochar. These results suggest that peanut and sheanut shell biochar have enormous potential and are suitable for adsorption of Pb2+, Cd2+ and Hg2+ in wastewater and polluted soil. Therefore, their effectiveness should be further tested in an actual water polluted environment.

Optimization of toxic metal adsorption on DEA-calix[4]arene appended silica resin using a central composite design

An assessment of central composite design (CCD) for the optimization of the adsorption of toxic metal ions using a DEA-calix[4]arene (DEA-C4) based silica resin.

Adsorption performance of activated carbon synthesis by ZnCl2, KOH, H3PO4 with different activation temperatures from mixed fruit seeds

ABSTRACT In this study, new activated carbons (ACs) were synthesized from a mixture of lemon and orange seeds (LOS) for toxic metal removal from aqueous solutions. Adsorbents have been produced by chemical activation with different activation agents (with H3PO4, ZnCl2 and KOH) and activation temperature (600°C, 700°C, 800°C). The elemental analysis, FT-IR, XRD and SEM analyses were performed to determine the characterization of the ACs. A series of batch adsorption experiments were done to research the influence of various parameters such as pH, adsorbent dosage, contact time, temperature, the complexing agents on the toxic metal ions (Cu(II), Cr(III) and Ni(II)) removal capacity of ACs. Adsorption equilibration time was 60 min, the adsorption capacity was 118.02 mg/g for Ni(II) ions, 146.03 mg/g for Cr(III) ions and 150.45 mg/g for Cu(II) ions. The adsorption of toxic metal ions was observed as a maximum at pH = 5 on AC-ZnCl2 (600°C) produced under N2 atmosphere. The adsorption process was fitted with a Langmuir isotherm model and a pseudo-second-order kinetic equation, showing the metal ions adsorption on AC was monolayer coverage. Thermodynamic studies show that the adsorption is endothermic and spontaneous in nature. AC produced from the LOS mixture has not been encountered in the literature. A simple, easy-to-apply method has been developed for a new adsorbent prepared from a mixture of LOS with environmentally friendly, easy to produce, reusable, cost-effective, non-toxic and with good adsorption-desorption capacity. Therefore, this study will contribute to the world economy in terms of environmental and wastewater cleaning.

Review on toxic metal ions removal by using activated carbon prepared from natural biomaterials

Heavy metals has wide range of applications including industrial, domestic, medical, agricultural and technological field. Due to industrialization and urbanization variety of heavy metal ions are released in the environment. Toxicity of heavy metal ions depends on the route of exposure, media of exposure and its dose. Some of the metals, due to its high degree of toxicity are incorporated in CERCLA (Comprehensive Environmental Response, Compensation and Liability Act) priority list of hazardous substances. According to CERCLA, arsenic is the top most toxic metal followed by lead and mercury. These metals are proven to be carcinogens for human beings even at lower concentration. Contamination of water resources by toxic metal ions is a common problem since past years. There exists different methods for removal of toxic metal ions from waste water but adsorption is the most widely used and effective method. There are several adsorbents used for adsorption of toxic metal ions but, adsorbents prepared from low-cost and ecofriendly raw materials like coconut shells, rice husk, sugarcane bagasse, banana peels, potato peels, corncob, wheat straw, neem barks, almond shells and others are capturing researcher’s attention due to its easy availability and effective removal efficiency. This review highlights low cost adsorbents used for elimination of heavy metal ions from waste water and its other usage possibilities based on the literature study. This paper also highlights emerging potential bio-adsorbents which can provide maximum removal efficiency.

Binary Adsorption Studies of Toxic Metal Ions of Lead and Copper from Aqueous Solution by Modified Foeniculum vulgaris Seeds (Fennel Seeds)

Discharge of copper(II) and lead(II) ions into rivers and streams by industries and other human activities has gained serious consideration from regulatory bodies. These toxic metals are harmful to human beings and aquatic life when in high concentrations. Therefore, their removal from wastewater is very important. Hence, this work reports the binary adsorption of toxic metal ions of Cu(II) and Pb(II) from aqueous solution by pristine and modified fennel seeds. Pristine fennel seeds (PFS) were treated with acidic and alkaline solutions to develop modified adsorbents designated ATFS and BTFS, respectively. SEM images revealed that PFS had an amorphous surface with irregular cavities. However, upon acid and base treatment, the surface was more refined. The ATFS had interconnected pores while BTFS had somewhat honeycomb pores. The UV-Vis results confirmed that some of the components were removed from PFS during acid and base pre-treatment. FTIR spectra revealed that the adsorbents had functional groups such as (-OH) and (-C=O), which were involved in the uptake of the metal ions. It was observed that the uptake of Cu(II) and Pb(II) ions onto all adsorbents progressively increased when the initial concentration of the solution was increased. The maximum adsorption capacity was obtained when the initial concentration of the solution was 100 mg/L. The uptake of Cu(II) and Pb(II) on PFS was 3.345 and 11.524 mg/g. While for ATFS 3.78 and 13.07 mg/g and BTFS 8.143 and 14.85 mg/g, respectively. It was observed that the isotherm data fitted Freundlich better for the uptake of both metal ions onto all adsorbents. It was observed that there was a rapid uptake when contact time increased from 5 to 60 min. However, when time increased above 60 min the uptake stabilized and reached equilibrium this was due to the saturation of active sites on the surface for all adsorbents. The kinetics study revealed that PSO fitted the data better than PFO. IPD data revealed that the uptake of metal ions was controlled by the synergistic of ESA and EPA. The ΔHº values for Cu(II) and Pb(II) uptake onto all adsorbents were all negative. This suggested that the reactions were exothermic.

Preparation of carbon spheres/lignin materials and adsorption of toxic metal ions

Preparation of carbon spheres/lignin materials and adsorption of toxic metal ions

Carbon Nanotubes-Based Nanomaterials and Their Agricultural and Biotechnological Applications.

Carbon nanotubes (CNTs) are considered a promising nanomaterial for diverse applications owing to their attractive physicochemical properties such as high surface area, superior mechanical and thermal strength, electrochemical activity, and so on. Different techniques like arc discharge, laser vaporization, chemical vapor deposition (CVD), and vapor phase growth are explored for the synthesis of CNTs. Each technique has advantages and disadvantages. The physicochemical properties of the synthesized CNTs are profoundly affected by the techniques used in the synthesis process. Here, we briefly described the standard methods applied in the synthesis of CNTs and their use in the agricultural and biotechnological fields. Notably, better seed germination or plant growth was noted in the presence of CNTs than the control. However, the exact mechanism of action is still unclear. Significant improvements in the electrochemical performances have been observed in CNTs-doped electrodes than those of pure. CNTs or their derivatives are also utilized in wastewater treatment. The high surface area and the presence of different functional groups in the functionalized CNTs facilitate the better adsorption of toxic metal ions or other chemical moieties. CNTs or their derivatives can be applied for the storage of hydrogen as an energy source. It has been observed that the temperature widely influences the hydrogen storage ability of CNTs. This review paper highlighted some recent development on electrochemical platforms over single-walled CNTs (SWCNTs), multi-walled CNTs (MWCNTs), and nanocomposites as a promising biomaterial in the field of agriculture and biotechnology. It is possible to tune the properties of carbon-based nanomaterials by functionalization of their structure to use as an engineering toolkit for different applications, including agricultural and biotechnological fields.

Synthesis, Crystal Structure, and Excellent Selective Pb2+ Ion Adsorption of New Layered Compound (NH4)In3(SO4)2(OH)6

(NH4)In3(SO4)2(OH)6, a new indium incorporated synthetic compound belonging to the alunite supergroup, is successfully prepared by hydrothermal reaction. The crystal structure is determined by single‐crystal X‐ray diffraction. (NH4)In3(SO4)2(OH)6 crystallizes in space group R3m of a = b = 7.69(8) Å, c = 17.71(2) Å and Z = 3, and it adopts a layered structure with alternating corrugated two‐dimensional 2∞[In3(SO4)2(OH)6–] anionic network and interstitial NH4+ ions. The measurements of X‐ray powder diffraction pattern, Fourier transform infrared spectroscopy spectrum, differential Scanning Calorimeter and X‐ray photoelectron spectroscopy have been performed on this new compound. The title compound is air‐ and water‐stable and starts thermal decomposition to In2O3 at 620 K. Interstitial NH4+ ions between two‐dimensional 2∞[In3(SO4)2(OH)6–] layers are exchangeable by cations like Pb2+. The maximum adsorption capacity of Pb2+ ions reaches 990 mg/g at pH 6.5, and the selectivity is observed with a very high distribution coefficient Kd of 1.1 × 106 mL/g compared with other completive cations. The unique layered framework composed of [InO6]9– octahedra and [SO4]2– tetrahedra is chemically stable to enable excellent cycling performance. This investigation will advocate the alunite supergroup minerals for efficient and recyclable adsorption of toxic metal ions in contaminated water.

Rapid removal of toxic metals Cu2+ and Pb2+ by amino trimethylene phosphonic acid intercalated layered double hydroxide: A combined experimental and DFT study

Abstract Phosphonates are environmental friendly materials, and can be potentially employed to improve the removal efficiency of the clay materials. In the present work, Zn-Al layered double hydroxide (LDH) intercalated with amino trimethylene phosphonic acid (ATMP) by a facile technique and employed as an adsorbent for Cu2+ and Pb2+ from wastewater. The adsorption characteristics and microscopic mechanism of ATMP in the interlayer space were explored by a combination of experimental and density functional theory (DFT). The adsorption capacity for Cu2+ and Pb2+ could reach 42.02 mg.g−1 and 84.06 mg.g−1, respectively. The adsorption kinetics curves were matched well with the pseudo-second-order model, indicating chemical adsorption via electrostatic interaction mechanism. Based on Multiwfn and VMD program calculation, the ways of electrostatic potential and average local ionization energy were firstly applied to predict reactive sites of ATMP molecule and corresponding anion, suggesting that anion state was more easily to provide lone pair electrons for electrophilic reaction. The weak interaction analysis indicated that interactions among ATMP and LDH are mainly dominated by H-bond. These results recommended that modified LDH can be a promising adsorbent for the adsorption of toxic metal ions in practical applications.

Selective adsorption of toxic heavy metal ions using guanine-functionalized mesoporous silica [SBA-16-g] from aqueous solution

Abstract The removal of toxic metal ions e.g. Pb2+, Hg2+ and Cd2+ from aqueous solution were explored using guanine functionalized SBA-16 [SBA-16-G]. Nitrogen sorption isotherm, HRXRD, FESEM, HRTEM, EDA-X analysis were performed to investigate the changes in the surface morphology and chemical characteristics of [SBA-16-G] before and after the adsorption of toxic metal ions. Owing to the presence of large number of active functional groups of –NH, –C O on the surface, this adsorbent demonstrated proficient toxic metal ions removal capacities (maximum adsorption capacity, q m a x : 289.9 mg g−1 for Pb2+ at 303 K, 259.9 mg g−1 for Hg2+ at 308 K and 228.8 mg g−1 for Cd2+ at 313 K, respectively) from aqueous medium. The isotherm study dictated that the adsorption data better comply to Langmuir isotherms with R L value

Mathematical modelling of Pb2+, Cu2+, Ni2+, Zn2+, Cr6+ and Cd2+ ions adsorption from a synthetic acid mine drainage onto chitosan derivative in a packed bed column

ABSTRACTStudies on the adsorption of toxic metal ions in batch mode using modified chitosan beads have been reported by several authors in literature; for large-scale operations, packed bed column studies are performed to generate data that are directly applicable in real wastewater treatment. In this work, the application potential of chitosan derivative for the uptake of Pb2+, Cu2+, Ni2+, Zn2+, Cr6+, and Cd2+ ions from aqueous solution in a packed bed adsorption column was investigated. On this note, the adsorbent was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Scanning electron microscope (SEM); the effect of breakthrough parameters such as influent concentration, bed height, and feed flow rate was determined. The experimental data were fitted to mathematical column models, namely Bed Depth Service Time (BDST), Yoon-Nelson and Thomas model. The removal efficiency, breakthrough and exhaustion time increased with an increase in bed height but decreased with an increase in the flow rate and influent concentration. The mathematical models applied in this study were successful in describing experimental data. Desorption studies were performed with no loss in the mass of the beads, and the breakthrough and exhaustion time were found to be the same on reusing the beads.Abbreviations: Ch-b: chitosan coated bentonite; GXXB: grafted cross-linked chitosan beads; MMBB: multi metal binding biosorbent; PFOLG: panosized ferric oxide loaded glycidyl; MPSD: Marquardt’s percent standard deviation

Effect of annealing on the spectral and optical characteristics of nano ZnO: Evaluation of adsorption of toxic metal ions from industrial waste water

The present work accentuates an unexploited and environmentally benign method of synthesizing ZnO nanomaterials using Sugar cane juice. The synthesized nanomaterials were characterized by XRD, SEM, TEM, BET, EDS and FTIR. UV–visible and photoluminescence studies were also carried out to understand the absorption properties of synthesized nanomaterial. From the adsorption studies, it would be clear that synthesized ZnO should be used as an effective adsorbent for Pb(ll) and Cd(ll) removal. The kinetic data followed the pseudo-second-order model. The equilibrium attained at 120min and isotherm follows the order Sips>Langmuir>Freundlich. The adsorption–desorption studies conducted over 6 cycles illustrate the viability and repeated use of the adsorbent for the removal of Pb(ll)and Cd(ll) from aqueous solutions. The practical efficiency and usefulness of the adsorbent was tested using real industrial wastewater also. Cytotoxicity result shows that, ZnO was biocompatible at lower concentrations, and it was used as an ecofriendly nanoadsorbent for industrial and environmental applications.

Removal of toxic zinc from water/wastewater using eucalyptus seeds activated carbon: non-linear regression analysis.

In the present study, a novel activated carbon was prepared from low-cost eucalyptus seeds, which was utilised for the effectively removal of toxic zinc from the water/wastewater. The prepared adsorbent was studied by Fourier transform infrared spectroscopy and scanning electron microscopic characterisation studies. Adsorption process was experimentally performed for optimising the influencing factors such as adsorbent dosage, solution pH, contact time, initial zinc concentration, and temperature for the maximum removal of zinc from aqueous solution. Adsorption isotherm of zinc removal was ensued Freundlich model, and the kinetic model ensued pseudo-second order model. Langmuir monolayer adsorption capacity of the adsorbent for zinc removal was evaluated as 80.37 mg/g. The results of the thermodynamic studies suggested that the adsorption process was exothermic, thermodynamically feasible and impulsive process. Finally, a batch adsorber was planned to remove zinc from known volume and known concentration of wastewater using best obeyed model such as Freundlich. The experimental details showed the newly prepared material can be effectively utilised as a cheap material for the adsorption of toxic metal ions from the contaminated water.

Removability Efficiency of Heavy Metals with Modified Humate from Aqueous Media

<p>The main aim of this work was to study the possibility of using amine-modified humate as a sorbent for the purification of water from heavy metal ions (Cu&Co). One of the effective methods of creating new sorbents of humic acids is chemical modification based on the high reactivity of the functional groups in the composition of humic acids. The possibility of modification of humic acid with bis(3-aminopropyl) amine was illustrated. Modification was carried out with the aim of increasing its sorption capacity. Metal-humate complexes were also obtained by an ion-exchange procedure with modified humate (Mod-Hum) by employing metal salts such as Cu(CH<sub>3</sub>COO)<sub>2</sub>·H<sub>2</sub>O, Co(CH<sub>3</sub>COO)<sub>2</sub>·4H<sub>2</sub>O. Maximum sorption percentages of Mod-Hum achieved were about 99.2% for Cu (II) and 90% for Co (II). The sorption degree depending on pH changes was studied in the range of 2 to 8, the sorption ability of the sorbents was stated to increase with the increase in pH. The degree of sorption of copper (ІІ) on Mod-Hum in the studied range of рН 5 was higher and of cobalt (II) for which the sorption is optimal at higher values (рН 7-8). It is stated that sorption degree increases with the increase in time from 15 min to 2 h. The adsorption of toxic metal ions with Mod-Hum was measured by atomic absorption spectroscopy (AAS). The experimental results on determination of the adsorption isotherm were evaluated with the Langmuir equation. It is shown that the sorbent develops a high sorption capacity in regard to ions of Cu (18.42 mg/g) and Со (16.25 mg/g). All the obtained complex compounds were analyzed and characterized by FT infrared spectroscopy (FTIR), scanning electron microscopy (SEM).</p>

Adsorption of toxic metal ions onto activated carbon: Study of sorption behaviour through characterization and kinetics

This paper presents the physico-chemical characteristics of coconut-based activated carbon of commercial grade (ACC) and the sorption behaviour and kinetics of adsorption of toxic metal ions onto ACC. The proximate and CHN analysis of the ACC showed the presence of ∼41% carbon, ∼16% hydrogen and ∼2% nitrogen in ACC. Bulk density and heating value of ACC were found to be 599.32 kg/m 3 and 18.81 MJ/kg, respectively. The BET surface area was 171.05 m 2/g whereas the BET average pore diameter was 31.03 Å. The meso-porous surface area was found to be 76% and the micro-porous surface area was 24% of the total pore surface area. The polar groups present on the ACC surface impart considerable cation exchange capacity to it. ACC worked as a very good adsorbent at an optimum initial pH (pH 0) of 6.0 and at a dose of 20 g/dm 3 for the adsorption of cadmium (Cd(II)), nickel (Ni(II)) and zinc (Zn(II)) metal ions at a concentration of 100 mg/dm 3. The adsorption of metal ions onto ACC was found to be a gradual process and the quasi-equilibrium condition reached in 5 h. The adsorption followed pseudo-second-order kinetics. The effective diffusion coefficient was of the order of 10 −12 m 2/s.