Adsorption Of Cadmium Ions Research Articles

Modification of Styrofoam Waste as a Low-Cost Adsorbent for Removal of Cadmium Ion in Aqueous Solution

waste has been modified by sulfonation using sulfuric acid to form its corresponding sulfonated adsorbent and was further used for removing cadmium ion in its aqueous solution. The effect of the styrofoam weight, sulfuric acid concentration, temperature and time on the sulfonation result was evaluated. The prepared adsorbent was characterized by XRD, FTIR, and SEM. The cadmium ion adsorption was conducted by batch technique, where the kinetic parameters were determined. The research results attribute that the sulfonated styrofoam has been successfully prepared, and the highest sulfonation is exhibited by using 18M of the sulfuric acid, at 60 oC for 6 h with 5 g of styrofoam. The cadmium adsorption by the sulfonated styrofoam fits with the pseudo-second-order and the Langmuir isotherm model, while the native styrofoam follows the intraparticle diffusion mechanism and Freundlich isotherm model. The adsorption capacities of the sulfonated and the native styrofoam are 51.6 mg/g and 7.09 mg/g respectively, and their respective adsorption rate are 8.20 10-3 mg. g-1. min-1 and 26.9 10-3 mg.g-1 min-1/2 .

THERMAL EFFECTS UPON SORPTION OF SOME METAL IONS ON CLINOPTIOLITE

The adsorption of lead, cadmium, nickel and copper ions and thermal effects that is accompanying these processes were investigated.Thermal effects and adsorption have been explored in static conditions on the rock of clinoptilolite of the Sokyrnytsa deposit (Ukraine). Thermal effects were measured by calorimetric method. Clinoprotololit was previously transferred to sodium form, treated with 1M sodium chloride solution, for 8 hours at a temperature of 90 degrees Celsius.To study the sorption, a solution of nitrates of the corresponding metals was used, and the initial concentration of solutions was 0.1 mol/l. Mass ratio between clinoptilolite: and solution was 1:30.The maximum sorption capacity of the sodium form of clinoptilolite was observed for the lead ions.Thermal effects accompanying the process of interaction of metal salts solutions with clinoptilolite, take values from 25 (for copper ions) to 70 (for cadmium ions) kJ / mol of sorbent ion.The thermal effects of ion exchange were calculated. The calculation of the thermal effect of ion exchange was carried out on the grounds that the thermal effect of the interaction of clinoptilolite with a solution of metal salt is an algebraic sum of heat effects: dehydration of the adsorbed ion, hydration of the desorbed ion (in this case, the Na+ ion), heat ion exchange effect. In the calculations, it was considered that the ion that is completely absorbed is dehydrated, and the exchange ion undergoes complete hydration after ion exchange. The calculated thermal effects have a negative value for all metals (endothermic process). The calculated heat ion exchange effects range from -1223 kJ/mol for nicole and -647 kJ/mol for lead.It was proven that thermal effects of ion exchange are not determinants in the total thermal effect of the process. Since its value is much less than the thermal effect of hydration of most ions.Correlation between the magnitude of the sorption and the thermal effect of the ion exchange have been established. This dependence is described with the coefficient of correlation R = 0.7.

Mechanism of adsorption of cadmium and lead ions by iron-activated biochar

Heavy metal removal from aqueous matrices may help reduce disease and cancer incidences. In this study, reed biochar (RBC) and RBC modified by ferrous ammonium sulfate addition (1 mol Fe L-1) were compared for potential Cd and Pb removal from varying pH aqueous solutions. Surface functional groups were identified using Fourier transform infrared (FTIR) analysis, and their surface physicochemical structure was observed using scanning electron microscopy-energy dispersive spectrometry (SEM-EDS). Batch experiments showed that the modified-reed biochar (MRBC) had greater Cd and Pb removal capacities over a wide pH range (1 to 8), as well as greater metal sorption capacities compared to RBC. Metal reaction kinetics occurred relatively quickly (i.e., within 60 min), and Langmuir modeling suggested that Cd and Pb removal by MRBC was maximized at 2.97 mg g−1 and 17.5 mg g−1 at 45 °C, respectively. The MRBC effectively sorbed Cd and Pb likely due to associations with functional groups modified by the Fe addition. In the future, MRBC may be used as an efficient and eco-friendly adsorbent for Cd and Pb removal from aqueous solutions and may help reduce water-borne issues associated with metal contamination.

Application Research on the Adsorption of Cadmium Ion in Wastewater by Zeolite Molecular Sieve

In this paper, the synthetic zeolite molecular sieve is used as the adsorbent to study the application of zeolite molecular sieves for the adsorption of cadmium ions in wastewater. It is found that the adsorption of cadmium ions in wastewater by zeolite molecular sieves reaches equilibrium at 90 min. In addition to the factor of time, temperature control is also the key to the adsorption of cadmium ions in wastewater by zeolite molecular sieves. In addition, the Langmuir model and the Freundilich model are used to describe the adsorption isotherm and it is discovered that the maximum adsorption capacity is 197.5 mg/g. When the pH value of the solution is 6, the adsorption capacity of cadmium ions in the wastewater by zeolite molecular sieves reaches the maximum value. In addition, the removal rate of cadmium ions in the wastewater will increase with the temperature. In summary, zeolite molecular sieves can effectively adsorb cadmium ions in wastewater. Therefore, zeolite molecular sieves have important application prospects in the treatment of cadmium ions in wastewater.

Differential Fresnel-reflection-based fiber biochemical sensor with temperature self-compensation for high-resolution measurement of Cd2+ concentration in solution

A fiber biochemical sensor system was developed to measure cadmium (Cd2+) solution based on differential temperature self-compensation, which exhibits high sensitivity in detecting Cd2+. The device only consists of a light source, three couplers, two photodetectors, and two fiber sensing ends. Utilizing the efficient adsorption of cadmium ion by allylthiourea, the sensing head was prepared. The estimated concentration resolution of 4.9 × 10−7 mol/L and the standard deviation of concentration of 4.6 × 10−6 mol/L in large temperature range are achieved. The measured data is fitted to a second-order polynomial equation with good agreement. Moreover, the differential technique of the sensor can effectively eliminate concentration errors resulting from temperature fluctuations and environment effects, and thus real-time monitoring can be obtained.

Preparation of TiO2 incorporated polyacrylonitrile electrospun nanofibers for adsorption of heavy metal ions

This paper describes the adsorption of lead and cadmium ions from an aqueous solution using a composite of titanium dioxide (TiO2)-incorporated polyacrylonitrile (PAN) electrospun nanofibers. Adsorption capacities and the mechanical response of the PAN/TiO2 composite electrospun nanofibers are investigated at different weight percentages of TiO2 (0.5, 1.0, 2.0, and 5.0 wt.%). The adsorption capacities of the composite PAN/TiO2 (2.0 and 5.0 wt.%) for Pb(II) and Cd(II) are remarkably increased by approximately 114 and 47%, respectively, compared to those of pure PAN electrospun nanofibers. Moreover, the adsorption of Pb(II) and Cd(II) by PAN/TiO2 nanofibers reaches an equilibrium within 60 min, and the process can be described using the nonlinear pseudo-second-order kinetic model. The adsorption isotherm study can be represented by the Langmuir model, which suggests the homogeneous distribution of monolayer adsorptive sites on the composite nanofiber surface. Furthermore, the ultimate tensile strength and ductility of all nanofiber membranes are measured through a uniaxial tension test. Mechanical tests reveal a reduction in the tensile strength of the PAN/TiO2 composite nanofibers with increase in TiO2 amount due to the possible formation of agglomerates and voids in the nanofiber structure.

A new combination for the determination of ultratrace cadmium: solid-phase microextraction by stearic acid-coated magnetic nanoparticles prior to batch-type hydride generation atomic absorption spectrometry.

Solid-phase microextraction method based on stearic acid-coated magnetic nanoparticle has been combined with batch-type hydride generation atomic absorption spectrometry (BT-HGAAS) system to determine cadmium at ultratrace levels. After the adsorption of cadmium ions onto stearic acid-coated magnetic nanoparticles, they were easily separated from the aqueous phase by means of a magnet. All the instrumental and experimental parameters such as pH of buffer solution, interaction period, concentration, and volume of NaBH4 were optimized. Under the optimal conditions, limit of quantification (LOQ) and limit of detection (LOD) for the solid-phase microextraction (SPME) based on stearic acid-coated magnetic nanoparticles-BT-HGAAS (SACMNP-BT-HGAAS) method were obtained as 270.8ng/L and 81.7ng/L, respectively. The matrix-matching calibration method was performed in order to improve the accuracy of cadmium quantification in tap water and the recovery results obtained were as follows: 88.56 ± 8.92 and 97.43 ± 9.76, for 6.0 and 8.0ng/mL of cadmium-spiked tap water samples, respectively. Graphical abstract ᅟ.

Adsorption of toxic mercury, lead, cadmium, and arsenic ions on black phosphorous nanosheet: first-principles calculations

The applicability of the black phosphorus monolayer (BPML) material to remove cadmium, lead, mercury, and arsenic ions from contaminated environments was evaluated. The coordination of metal ion varied from two to four. Both expanding and contracting distortions were observed. The bandgap of BPML was enlarged by 0.12–1.10 eV, with the smallest and largest changes for Pb (II) and Hg (II), respectively. After decoration, all decorated BPML nanosheets kept their p-type semiconducting property. The total density of states (TDOS) plots indicated the marked impact of the adatoms on the Fermi level of BPML. The considerably high adsorption energies followed the sequence of Pb (II) < Cd (II) < Hg (II) << As (III), in full correspondence with the remarkable charge transfers (0.440–1.236 e). The localized orbital locator (LOL) profiles revealed the nature of the interactions.

Promotion effects of nitrogenous and oxygenic functional groups on cadmium (II) removal by carboxylated corn stalk

Carboxylated corn stalk was prepared successfully by introducing amide and carboxyl groups into the cellulose structure, and were utilized as an efficient adsorbent to remove cadmium ions from an aqueous solution in batch adsorption process. The maximum adsorption capacity could be achieved 47.17 mg/g at the initial pH 5.8 of aqueous solution, significantly higher than most reported adsorbents. Meanwhile, changing of temperature could not greatly affect during the adsorption process. In addition, this adsorbent had a high selectivity of the cadmium ions in co-existing ions solution, but lead ions exerted obviously a compete effect upon the adsorption of cadmium ions. The adsorption isotherm could be correctly simulated by Langmuir and Freundlich isotherms. Whereas, the adsorption kinetics followed the pseudo-second-order kinetic model. Also, Thermodynamic parameters confirmed that adsorption was exothermic and chemisorption in nature. Based on the results of X-ray photoelectron spectra, the adsorption mechanism was ascribed mainly to the coordination complex between cadmium ions and the oxygen of carbonyl groups, relative to the effect of the nitrogen of amine groups. Regeneration of the adsorbent was performed with 0.1 g/L ethylenediaminetetraacetic acid to provide five cyclical regeneration.

Artificial neural network-based surrogate modeling of multi-component dynamic adsorption of heavy metals with a biochar

This paper reports the application of four neural network surrogate models for the correlation and prediction of asymmetric breakthrough curves obtained from the multi-component adsorption of cadmium, nickel, zinc and copper ions on a biochar. Artificial neural networks namely: Feed forward back propagation neural network, Feed forward back propagation neural network with distributed time delay, Cascade forward neural network and Elman neural network have been assessed and compared where their limitations and capabilities have been discussed. The impact of the architecture of these surrogated models, including the activation functions and training algorithms, has been analyzed using error and residuals analyses in different zones of the adsorption breakthrough curves obtained from single, ternary and quaternary solutions of tested heavy metals. Overall, the bed adsorption capacities for these metals ranged from 2.01 to 5.40, 0.16 to 4.46 and 0.03 to 2.15 mmol/g in single, ternary and quaternary feeds, respectively, at tested operation conditions. Highest adsorption capacities were obtained for copper in single and multi-metallic solutions and they ranged from 2.15 to 5.4 mmol/g. Results of this paper showed that Cascade forward neural network was the best model for multi-metallic adsorption breakthrough curve modeling. This neural network showed the lowest modeling errors for the multi-component adsorption breakthrough curves. This paper introduces new results on the application of ANNs surrogate models for the simulation of multi-component adsorption process involved in water treatment and purification.

Removal of Cadmium (II) from Aqueous Medium Using Vigna radiata Leave Biomass: Equilibrium Isotherms, Kinetics and Thermodynamics

Abstract In the present study, a novel biosorbent Vigna radiata leaves biomass (L. biomass) was utilized for cadmium (II) extraction from aqueous medium. Cadmium (II) free and cadmium (II) loaded L. biomass was analyzed by Fourier transform infrared (FTIR) spectroscopy. Adsorption of cadmium (II) from aqueous medium was studied under various conditions such as adsorbent dose, agitation time, pH and temperature of the medium to optimize the process variables. Different models including Langmuir, Freundlich, Temkin and Dubinin–Radushkevich (DR) were used to elaborate the insight of adsorption process. Best interpretation of biosorption process was given by Langmuir model. Value of maximum adsorption capacity (qm) calculated from Langmuir isotherm model was found to be 13.44 mg/g. Results indicated the establishment of physical interaction between cadmium (II) ions and functional groups of L. biomass. Kinetic study for adsorption of cadmium (II) ions on L. biomass was done by applying pseudo first order, pseudo second order, elovich and intra-particles diffusion models. Biosorption process best followed the pseudo second order kinetics. Value of standard Gibbs energy (ΔG°) and standard enthalpy change (ΔH°) showed the feasibility, spontaneity and endothermic nature of adsorption process. Percentage removal efficiency of L. biomass for cadmium (II) was successfully maintained for four cycles. Biomass has a potential to be used as an efficient adsorbent for the removal of cadmium (II) from different polluted water samples.

Modulation of chromatic reversibility of polydiacetylene Langmuir Schafer (LS) films by cadmium ion Ad/desorption

Although the reversibility of 10, 12-pentacosadiynoic amino meta-acid (PCDA-mBzA) against temperature and pH was reported, the modulation of reversibility by ion adsorption at terminal functional group has not been investigated. In this work, we developed a simple method for modulating the reversibility of PCDA-mBzA films upon a thermal stimulus by cadmium ion adsorption inducing the breakage of the outer hydrogen bonding of two hydrogen bonds, which are responsible for the reversible properties of PCDA-mBzA. External reflection-Fourier transform infrared (ER-FTIR) analyses revealed that the hydrogen bonding between the carboxylic acid groups was broken through ion adsorption and only a single hydrogen bond between the amide groups remained in the PCDA-mBzA polymer. In addition, PCDA-mBzA films could recover their original property through cadmium ion desorption. These results present that the transition between reversibility and irreversibility can be modulated artificially simply through the adsorption and desorption of metal ions.

Highly selective adsorption of cadmium ions by water‐dispersible magnetic thioglycolic acid/graphene oxide composites

A new selective and fast procedure based on magnetic dispersive solid‐phase extraction and zeta potential analysis is proposed for the determination of Cd (II) in some food samples. In the developed method, novel magnetic nanoparticles modified with thioglycolic acid were synthesized/characterized and also applied for quantitative determination of trace amounts of Cd (II) in food samples. The prepared nanoparticles were characterized via infrared spectroscopy, electron microscopy and adsorption–desorption experiments. These magnetic nanocomposites carrying Cd (II) could be easily separated from real samples simply by applying an external magnetic field; no filtration or centrifugation was necessary. Several parameters affecting the analytical performance, such as sample pH, amounts of nanocomposite sample, desorption solution volumes and coexisting ions, were investigated in detail. The detection limit of the method was 0.1 μg l−1 while the relative standard deviation was 1.2% for a Cd (II) concentration of 0.5 mg l−1. The proposed method was successfully applied to food sample analysis and standard reference material samples with satisfactory results, and excellent recoveries were obtained in the range 95–99% even when the matrix, such as sea water, was complex.

Statistical physics modeling of equilibrium adsorption of cadmium ions onto activated carbon, chitosan and chitosan/activated carbon composite

The adsorption ability of activated carbon, chitosan, and chitosan/activated carbon composite for cadmium separation from aqueous solution was analyzed via statistical physical modeling. The equilibrium data were analyzed by Langmuir, Hill, double layer model, and the multi-layer model with saturation isotherm models. Results showed that the multi-layer model with saturation could well describe the data. The number of the adsorbate ions per site, the receiver site density, the number of formed layers, and the energies of adsorption relative to the different layers were estimated by numerical simulation. Results showed that the chitosan/activated carbon has higher receiver site density and the total amount of adsorbed ions than that other two adsorbents. Results showed that the cadmium adsorption onto activated carbon/chitosan composite is a monolayer and exothermic process. With increasing temperature, the amount of cadmium adsorption decreases due to the fact that the number of receiver adsorption sites decreases. Also, the statistical physics modeling indicated the geometry of cadmium ions adsorbed onto the adsorbent surface is parallel.

Adsorption of Cadmium Ions from Aqueous Solutions on Modified Sorbents

Adsorption of Cadmium Ions from Aqueous Solutions on Modified Sorbents

Capacity of Adsorption of Cadmium (II) Ion by Bio-charcoal from Durian Barks

The study examined the adsorption capacity of definite amount of biocharcoal of Durian barks (Durio zibethinus Murr) to adsorb Cadmium ions at various pH. Biocharcoal was made by using pyrolysis method. The adsorption was monitored by measuring the Atomic Absorption of Cd (II) at 228.8 nm. Result shows that the optimum adsorption of Cadmium ion is 93.46% and the weight is 16.62 mg/g with 80 mg biocharcoal. The optimum pH is 7.0 with the percentage uptake of the cadmium ion 97.94%, and the weight is 17.42 mg/g. The optimum concentration is 20 ppm which can adsorb Cadmium ion 91.97%, or 11.42 mg/g. By using Langmuir isotherm equation, the highest adsorption of biocharcoal of Durian’s barks measured is 33.33 mg/g, which is potential as commercial activated carbon.

Double functional polymer brush-grafted cotton fiber for the fast visual detection and efficient adsorption of cadmium ions

In this study, a multi-functional cotton fiber was prepared and investigated for the visual detection and enhanced adsorption of cadmium (Cd) ions in aqueous solutions. SI-ATRP technology was used to graft poly (glycidyl methacrylate) (PGMA) and poly (3-sulfopropyl methacrylate potassium salt) (PSMP) successively on the surface of the cotton fiber. Then, diethylenetriamine (DETA) and 5,10,15,20-tetrakis(1-methy-4-pyridinio)porphyrin tetra(p-toluenesulfonate) (TMPyP) were immobilized onto the PGMA and PSMP polymer brush, respectively, to form the Cotton-PGMA(DETA)-PSMP(TMPyP) (abbreviated as C-PD-PT) material. C-PD-PT showed enhanced Cd ion adsorption with the maximum adsorption capacity of 1.6215 mmol/g derived from the Langmuir model fitting. In addition, The C-PD-PT material exhibited simple visual detection of Cd ions with a remarkable color change from brownish to green. A linear relationship between the light absorbance of C-PD-PT-Cd (C-PD-PT adsorbed with Cd ions) and the initial concentrations of Cd ions was established, which would be used for the fast determination of Cd ion concentrations in aqueous solutions.

Isotherm Studies of Adsorption of Cadmium (II) ion from Aqueous Solution onto Zeolite: Effects of Time, Temperature and pH

Isotherm Studies of Adsorption of Cadmium (II) ion from Aqueous Solution onto Zeolite: Effects of Time, Temperature and pH

Performance of synthesized cast and electrospun PVA/chitosan/ZnO-NH2 nano-adsorbents in single and simultaneous adsorption of cadmium and nickel ions from wastewater.

The performance of synthesized cast and electrospun polyvinyl alcohol/chitosan/zinc oxide/aminopropyltriethoxylsilane (PVA/chitosan/ZnO-APTES) nano-adsorbents were compared in removal of Cd(II) and Ni(II) ions from wastewater. The adsorbents were characterized by SEM, BET, FTIR and TGA analyses. Furthermore, the swelling investigations were carried out to study the adsorbent stability in aqueous solution. The effect of several parameters such as contents of ZnO-NH2, contact time, initial Cd(II) and Ni(II) concentration and temperature on the adsorption capacity was investigated in a batch mode. In comparison with cast adsorbent, nanofiber adsorbent indicated the better adsorption performance. The experimental data well fitted the double-exponential kinetic model. In single metal ion system, the maximum adsorption capacity of nanofiber for Cd(II) and Ni(II) ions is estimated to be 1.239 and 0.851mmol/g, respectively, much higher than qm of cast adsorbent for Cd(II) (0.625mmol/g) and Ni(II) (0.474mmol/g) ions. Thermodynamic parameters were investigated to identify the nature of adsorption process. In binary system of Cd(II)-Ni(II) ions, the inhibitory effect of competitive Cd(II) ion on the Ni(II) adsorption was greater than the inhibitory effect of competitive on the Cd(II) adsorption. The selectivity adsorption of both nanofiber and cast adsorbents was in order of Cd(II) > Ni(II).

The Adsorption of Cadmium Ions on Fly Ash Based Geopolymer Particles

Geopolymer particles from waste coal fly ash were prepared in order to investigate adsorption process of Cadmium ions. The aim of the study is to focus on factors which affect adsorption process of heavy metals on geopolymer materials. The raw fly ash was mixed with sodium hydroxide solution and sodium silicate solution. After that geopolymer was cured at 80 °C for 24 hr. The sample was ground and washed until pH=7. The obtained geopolymer particles were dried at 60 oC. The raw materials and geopolymer were characterized. The XRD results showed a highly amorphous structure in obtained geopolymer. The major components of waste coal fly ash and synthesized geopolymer were SiO2, Al2O3, Fe2O3 and CaO. The BET surface area of fly ash and geopolymer particles were 0.83 m2/g and 85.01 m2/g, respectively. The adsorption conditions (initial concentration from 10-120 mg/L, temperature at 25-45 °C, pH of cadmium ions solution from 1-5, 0.02-0.14 g. of geopolymer and contact time for 5-180 min) were studied. From removal efficiency results, synthesized geopolymer had high removal capacity for cadmium ions (Cd2+). At pH 5 of solution, the highest Cd2+ removal capacity was obtained. In addition, the removal efficiency increases with an increasing geopolymer dosage, contact time and a decreasing of Cd2+ initial concentration. Moreover, both Langmuir and Freundlich models were investigated for studying adsorption isotherm. The result showed Langmuir model is more suitable for geopolymer adsorption of cadmium ion in aqueous solution than Freundlich model.