Competitive Adsorption Of Cadmium Research Articles

Fabrication of biocompatible chitosan/graphene based nanocomposite for the competitive adsorption of heavy metal ions from wastewater in binary and ternary systems: Scale-up and upgradation studies

Coexistence of multiple metal ions in the wastewater alters the adsorption behavior compared to single metal ion system using the existing adsorbents which are chemically driven, requires harsh operating conditions and additional energy. The present study evaluates the performance of Chitosan/Graphene based nanocomposite for the competitive adsorption of heavy metals in single, binary and ternary systems. Maximum removal efficiency was 89.35 % (As), 90.41 % (Cu), 93.22 % (Ni), 96.47 % (Cd), 95.45 % (Pb) and 88.65 % (Cr) under optimum conditions (pH 4, Temperature = 25 °C, Equilibrium Time = 90 min, Adsorbent Dosage = 1.25 g and Initial Metal Ion Concentration = 150 mg/L) in a single system. A detailed investigation on the competitive adsorption of Cadmium, Copper, and Chromium ions was performed in binary. Maximum adsorption capacity was 1.55 mg/g and 1.48 mg/g (CuCd); 2.98 mg/g and 3.21 mg/g (CuCr) and 2.21 mg/g and 1.90 mg/g (CdCr system) at 4 mM concentration. The constructed mathematical models accurately forecast the adsorption behavior and shows a good match with the experimental data. Also, fixed-bed column studies were performed for the large-scale upgradation and optimum flow rate and bed height was 1 L/h and 15 cm at 25 °C. The study proposes the fabrication of natural-polymer based composite which can significantly reduce the dependency on synthetic and chemical-based adsorbents which poses severe negative impacts such as high-cost, poor selectivity and rapid saturation due to their low recyclability or sludge generation. Such application can effectively transform wastewater into contamination free water that could be valuable to society.

Non-competitive and competitive adsorption of cadmium and zinc by nano-iron and titanium oxides from aqueous solution

Non-competitive and competitive adsorption of cadmium and zinc by nano-iron and titanium oxides from aqueous solution

Mono-/competitive adsorption of cadmium(II) and lead(II) using straw/bentonite-g-poly(acrylic acid-co-acrylamide) resin

We investigated the adsorption of Cd2+ and Pb2+ using straw/bentonite-g-poly(acrylic acid-co-acrylamide) resin as an adsorbent in single and binary-component systems. The resin was characterized by various analytical techniques. Adsorption experiments were conducted by varying the pH, adsorbent dosage, initial concentration and temperature. Adsorption data for Cd2+ and Pb2+ fitted the Langmuir isotherm in the single-component system. Kinetic data for Cd2+ and Pb2+ followed the pseudo-second-order kinetic in a single-component system. A maximum adsorption for Cd2+ occurred at pH 5, whereas for Pb2+, the maximum Cd2+ adsorption occurred at pH 3. The maximum Cd2+ and Pb2+ adsorption capacities were 315.1 mg g−1 and 355.5 mg g−1, respectively. In the binary-component system, the presence of Cd2+ could improve the adsorption capacity of Pb2+ and the presence of Pb2+ could reduce the adsorption capacity of Cd2+ when the Cd2+ concentration was high. This study provides realistic and valid data on resin use to remove heavy metal ions from aqueous solutions.

Interpretation of single and competitive adsorption of cadmium and zinc on activated carbon using monolayer and exclusive extended monolayer models.

In this work, a modeling analysis based on experimental tests of cadmium/zinc adsorption, in both single-compound and binary systems, was carried out. All the experimental tests were conducted at constant pH (around neutrality) and temperature (20°C). The experimental results showed that the zinc adsorption capacity was higher than that of cadmium and it does not depend on cadmium presence in binary system. Conversely, cadmium adsorption is affected by zinc presence. In order to provide good understanding of the adsorption process, two statistical physics models were proposed. A monolayer and exclusive extended monolayer models were applied to interpret the single-compound and binary adsorption isotherms of zinc and cadmium on activated carbon. Based on these models, the modeling analysis demonstrated that zinc is dominant in solution and more favorably adsorbed on activated carbon surface. For instance, in single-compound systems, the number of ions bound per each receptor site was n (Zn2+)=2.12>n (Cd2+)=0.98. Thus, the receptor sites of activated carbon are more selective for Zn2+ than for Cd2+. Moreover, the determination of adsorption energy through the adopted models confirmed that zinc is more favored for adsorption in single-compound system (adsorption energies equal to 12.12 and 7.12kJ/mol for Zn and Cd, respectively) and its adsorption energy does not depend on the cadmium presence in binary system. Finally, the adsorption energy values suggested that single-compound and binary adsorption of zinc and cadmium is a physisorption.

Competitive adsorption of cadmium and phenol on activated carbon produced from municipal sludge

Competitive adsorption of Cadmium (Cd2+) and phenol from binary aqueous solutions were investigated using activated carbon (AC) produced from municipal sewage sludge. The produced AC was characterized using different techniques that included Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and Porosity and Surface Area Analysis. The results showed that produced AC samples had a specific surface area of 319.5m2/g when 5.0M ZnCl2 was used as the activating agent at activation temperature and time of 700°C and 60min, respectively. Effects of various operational parameters such as initial pH, initial concentration, adsorbent dosage and contact time were investigated. The produced AC was found to have higher affinity to phenol than Cd2+, where removal efficiencies of 28 and 53% for Cd2+ and phenol, respectively, were achieved from binary solutions at optimum conditions of pH (5.5), AC dosage (0.15g/50mL) and contact time (120 and 480min for Cd2+ and phenol, respectively). Experimental data on adsorption of Cd2+ and phenol was found to best fit the Freundlich isotherm model. Moreover, adsorption mechanism of both components was attributed to chemisorption, which was demonstrated by the equilibrium data that best fitted the pseudo-second order kinetic model.

Competitive Adsorption of Cadmium(II) and Mercury(II) Ions from Aqueous Solutions by Activated Carbon from Xanthoceras sorbifolia Bunge Hull

This paper presents low-cost and recyclable activated carbon (XLAC) derived from Xanthoceras sorbifolia Bunge hull for high-efficiency adsorption of Cd(II) and Hg(II) ions in industrial wastewater. XLAC was prepared through H3PO4 activation and was characterized using N2 adsorption-desorption, scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDX), and Fourier transform infrared (FTIR) spectroscopy. In single-metal-system adsorption experiments, the maximum adsorption capacities for Cd(II) and Hg(II) obtained under different experimental conditions were 388.7 and 235.6 mg·g−1, respectively. All adsorption equilibrium data fit perfectly with the Langmuir isotherm model. In a binary metal system, competitive studies demonstrated that the presence of Cd(II) significantly decreased the adsorption of Hg(II), but the adsorption of Cd(II) showed a little change in the presence of Hg(II). In addition, XLAC can be regenerated with a 0.01 mol·L−1 HNO3 solution and reused at least four times. The FTIR spectra revealed that a chemical interaction occurs between functional groups containing lone electron pairs in XLAC and metal ions. Overall, these results suggest that XLAC may be suitable as an adsorbent for heavy metal removal from wastewater streams.

Competitive Adsorption of Cadmium (II) from Aqueous Solutions onto Nanoparticles of Water Treatment Residual

There is increasing interest in using water treatment residuals (WTRs) for heavy metals removal from wastewater due to their low cost, availability, and high efficiency in removing various pollutants. In this study, novel water treatment residuals nanoparticles (nWTRs) were prepared using high energy ball milling and used for efficient removal of Cd(II) in single- and multi-ion systems. The WTR nanoparticles demonstrated high removal efficiency for Cd from aqueous solution as the adsorption capacities of nWTR were 17 and 10 times higher than those of bulk WTR in single- and multielement systems, respectively. Noticeably, Cd(II) adsorption was clearly suppressed in the multi-ion system as Cu and Pb form the most stable monohydroxo complexes. Fourier transmission infrared (FTIR) analyses suggested the participation of OH−, O-Al-O, FeOH, and FeOOH entities in the adsorption process. The stability of Cd-nWTR surface complexes is evident as less than 0. 2% of adsorbed Cd(ll) was released at the highest Cd(II) concentration load after 4 consecutive desorption cycles. Moreover, the real efficiency of nWTR for Cd(II) removal from wastewater samples studied was calculated to be 98.35%. These results highlight the potential of nWTR for heavy metals removal from wastewater.

Modeling of single and competitive adsorption of cadmium and zinc onto activated carbon

This paper describes an experimental and modeling analysis of cadmium and zinc adsorption from aqueous solutions in single and binary systems on activated carbon. Batch tests were performed at constant pH (6.8 ± 0.3) and temperature (20 °C), in order to assess the adsorption capacity in experimental conditions simulating real wastewater. In particular, binary tests were carried out at same pH and temperature, with different initial concentration ratios of the two analytes (\(C_{Zn}^{0}\):\(C_{Cd}^{0}\)), in order to emphasize the competition phenomena while minimizing the effect of pH. Experimental results indicate that zinc is adsorbed to a greater extent than cadmium, both in single and binary systems. In binary systems, zinc adsorption capacity is not influenced by the presence of cadmium, regardless of its concentration. On the contrary, an increase in zinc concentration in solution brings about a decrease in cadmium adsorption capacity. The experiments were interpreted by using both the rigorous and the extended Langmuir multicomponent adsorption isotherms and the Vacancy Solution Theory. The latter provided a satisfactory and simultaneous description of the experimental data for both zinc and cadmium adsorption, also accounting for the possible interactions between the two analytes and between the solvent (water) and the single analyte.

Competitive adsorption of cadmium and aluminum onto fresh and oxidized biochars during aging processes

Fresh biochar was shown to effectively reduce concentrations of heavy metal in soil, but the influences of the aging processes of biochar and competitions from other elements are warranted to precisely evaluate the long-term effect of biochar. This work investigated the effects of water washing, oxidation, and coexistence of aluminum (Al) on cadmium (Cd) adsorption by biochars and oxidized biochars. The Cd adsorption and the competitive adsorption of Cd and Al to rice straw-derived biochars, before and after oxidation by HNO3/H2SO4, were investigated. Meanwhile, the structural characteristics and surface charges of primary and oxidized biochars, with and without Cd loading, were analyzed by scanning electron microscopy, fourier-transform infrared spectroscopy, and zeta potential. The adsorption of Cd onto fresh biochars was dominated by surface complexation of oxygen-containing functional groups via esterification reactions, which was regulated by solution pH. Oxidization (aging) introduced carboxylic functional groups to biochar surfaces, which served as additional binding sites for Cd. The Cd binding to biochars was significantly affected by the coexistence of Al via acidification and competition for adsorption sites. The biochars exhibited high sorption capacities of Cd in soil, but soil acidification led to a counteractive of biochar’s liming effect and a reduction of Cd-binding sites; thus, the long-term effect of biochar for heavy metal immobilization should be paid more attention in acidic soil.

Comparative and competitive adsorption of cadmium, copper, nickel, and lead ions by Iranian natural zeolite

The competitive adsorption behavior of cadmium (Cd2+), copper (Cu2+), nickel (Ni2+), and lead (Pb2+) ions using Iranian natural zeolite has been studied in order to determine its applicability in treating industrial wastewater. Tests to determine both the rate of adsorption and the uptake at equilibrium were performed under batch conditions from single- and multi-component solutions. The optimum conditions for the treatment process were investigated by observing the influence of pH levels, the presence of competing ions, varying the mass of zeolite and different contact time. Adsorption kinetics of the zeolite followed first-order kinetics, showing about 100 % of Pb2+ removal within 40 min and reaching an equilibrium state within 24 h for Cd2+, Cu2+, and Ni2+. The results indicated that removal of metals from single- and multi-component solutions is best described by a Freundlich isotherm, in which the distribution coefficient was in the following order: Pb2+ > Cu2+ > Cd2+ > Ni2+. In the multi-component solutions, metals exhibit competitive adsorption on the zeolite. The adsorption is reduced to 90, 53, 30, and 22 % of single component of Cu2+, Ni2+, Cd2+, and Pb2+, respectively. However, the total adsorption was higher than single component. Finally, soil solution saturation indices and speciation of metals was assessed using Visual MINTEQ 2.6 software, and probability of precipitation of minerals supported by scanning electron microscopy. The research indicates that Cd2+ and Ni2+ retention by zeolite can be viewed as the result of ion exchange reaction, but Pb2+ and Cu2+ retention is both due to ion exchange and precipitation. These results show that Iranian natural zeolite particularly effective in removing cationic heavy metal species from industrial wastewater.

Competitive adsorption of cadmium(II) and nickel(II) metal ions from aqueous solution onto rice husk ash

The present study deals with the competitive adsorption of cadmium (Cd(II)) and nickel (Ni(II)) ions from aqueous solution onto rice husk ash (RHA). Non-competitive Redlich–Peterson (R–P) and Freundlich models represent the single metal ion equilibrium sorption data. The adsorption capacities for the binary mixtures–RHA system are in the order Ni(II) > Cd(II). The combined equilibrium sorption of Cd(II) and Ni(II) ions onto RHA is found to be antagonistic in nature and the extended Freundlich model was found to best represent the binary equilibrium isotherm data.

Modelling Individual and Competitive Adsorption of Cadmium(II) and Zinc(II) Metal Ions from Aqueous Solution onto Bagasse Fly Ash

The present study deals with the competitive adsorption of cadmium (Cd(II)) and zinc (Zn(II)) ions onto bagasse fly ash (BFA) from binary systems. BFA is a waste obtained from the bagasse‐fired boilers of sugar mills. The initial pH≈6.0 is found to be the optimum for the individual removal of Cd(II) and Zn(II) ions by BFA. The equilibrium adsorption data were obtained at different initial concentrations (C 0 = 10–100 mg/l), 5 h contact time, 30°C temperature, BFA dosage of 10 mg/l at pH 0 = 6. The Redlich–Peterson (R–P) and the Freundlich models represent the single ion equilibrium adsorption data better than the Langmuir model. The adsorption capacities in the binary‐metal mixtures are in the order Zn(II)>Cd(II) and is in agreement with the single‐component adsorption data. The equilibrium metal removal decreases with increasing concentrations of the other metal ion and the combined action of Cd(II) and Zn(II) ions on BFA is found to be antagonistic. Equilibrium isotherms for the binary adsorption of Cd(II) and Zn(II) ions on BFA have been analyzed by non‐modified Langmuir, modified Langmuir, extended‐Langmuir, Sheindorf–Rebuhn–Sheintuch (SRS), non‐modified R–P and modified R–P adsorption models. The isotherm model fitting has been done by minimizing the Marquardt's percent standard deviation (MPSD) error function using MS Excel. The SRS model satisfactory fits for most of the adsorption equilibrium data of Cd(II) and Zn(II) ions onto BFA.

Equilibrium modelling of single and binary adsorption of cadmium and nickel onto bagasse fly ash

Abstract The present study deals with the competitive adsorption of cadmium (Cd(II)) and nickel (Ni(II)) ions onto bagasse fly ash (BFA) from single component and binary systems. BFA is a waste material obtained from the flue gas of the bagasse-fired boilers of sugar mills. Equilibrium adsorption is affected by the initial pH (pH0) of the solution. The pH0 ≈ 6.0 is found to be the optimum for the individual removal of Cd(II) and Ni(II) ions by BFA. The pH of the system, however, increases during the initial sorption process for about 20 min and, thereafter, it remains constant. The equilibrium adsorption data were obtained at different initial concentrations (C0 = 10–100 mg/l), 5 h contact time, 30 °C temperature, BFA dosage of 10 mg/l at pH0 6. The single ion equilibrium adsorption data were fitted to the non-competitive Langmuir, Freundlich and Redlich–Peterson (R–P) isotherm models. The R–P and the Freundlich models represent the equilibrium data better than the Langmuir model in the studied initial metal concentration range (10–100 mg/l). The adsorption capacity of Ni(II) is higher than that for Cd(II) for the binary metal solutions and is in agreement with the single-component adsorption data. The equilibrium metal removal decreases with increasing concentrations of the other metal ion and the combined action of Cd(II) and Ni(II) ions on BFA is generally found to be antagonistic. Equilibrium isotherms for the binary adsorption of Cd(II) and Ni(II) ions onto BFA have been analyzed by using non-modified Langmuir, modified Langmuir, extended Langmuir, extended Freundlich and Sheindorf–Rebuhn–Sheintuch (SRS) models. The competitive extended Freundlich model fits the binary adsorption equilibrium data satisfactorily and adequately. Desorption with various solvents showed that the hydrochloric acid is the best solvent; the maximum elution being about 65% for Cd(II) and about 42% for Ni(II). Since BFA is a waste material obtained at almost no cost, the spent BFA can be combusted to recover its energy value and the bottom ash can be blended with cementitious mixture for making building blocks.

木質系炭化物のカドミウム（ＩＩ），鉛（ＩＩ），水銀（ＩＩ）の混合水溶液中における吸着特性

To clarify the differences in the mechanism of adsorption among cadmium (II), lead (II), and mercury (II) by wood charcoal produced from sugi (Cryptomeria japonica D. Don), the adsorption characteristics of these heavy metals in mixed aqueous solutions were examined.In the case cadmium (II) and lead (II) are present in the same aqueous solution system, the adsorption of each of them by sugi wood charcoal decreases. It is therefore assumed that the same mechanism of adsorption is involved in the adsorption of cadmium (II) and lead (II) by sugi wood charcoal, and that these heavy metals compete for this adsorption. Because the presence of mercury (II) does not affect the adsorption of cadmium (II) and lead (II), it is assumed that a different mechanism of adsorption is involved in the adsorption of mercury (II), and that mercury (II) does not take part in the competitive adsorption of cadmium (II) and lead (II).Regarding the mechanism of adsorption of cadmium (II) and lead (II) by sugi wood charcoal in an acidic solution, we inferred that when the cadmium (II) and lead (II) ions come in contact with the sugi wood charcoal surface in an aqueous solution, hydroxides are formed by a high concentration of alkali on the charcoal surface and deposited and stabilized on the surface or in the micro pores of the charcoal. It is assumed that the adsorption of mercury (II) by sugi wood charcoal occurs on the basic surface oxide, and that such chemical species of mercury as the complex anions [HgCl4]2- and [HgCl3]- and the non-charged complex [HgCl2] are adsorbed by sugi wood charcoal.Almost the entire quantity of the cadmium (II) and lead (II) adsorbed to sugi wood charcoal was desorbed at pH1.2, the recovery rate being 99% for cadmium (II) and 97% for lead (II). The mercury (II) adsorbed to sugi wood charcoal was not desorbed in the pH range from 1.2 to 9.0; its desorption characteristic was found to be quite different from that of cadmium (II) and lead (II). The difference in desorption characteristic is attributable to a difference in the mechanism of adsorption between mercury (II) and cadmium (II) or lead (II). The adsorption of mercury (II) by sugi wood charcoal is assumed to be much more irreversible than that of cadmium (II) and lead (II).

Single and competitive adsorption of Cd and Zn onto a granular activated carbon

Single and competitive adsorption of cadmium and zinc onto granular activated carbon DARCO 12–20 mesh has been investigated. This activated carbon has been shown as an effective adsorbent for both metals. Cadmium and zinc removals increased with pH and decreased with molar metal/carbon ratio. Surface precipitation phenomena have been detected for the higher pHs and molar ratios. The adsorption process has been modelled on the surface complexation Triple Layer Model (TLM). For this purpose, the amphoteric nature of the activated carbon has been studied. Single metal adsorption data have been used to calibrate TLM parameters. A dependence of the adsorption constants on pH and molar metal/carbon ratio has been observed, and a correlation for log K ads has been determined. In the competitive system, the removal efficiency of the activated carbon decreased for both metals. The TLM model, using surface complexation constants determined from single adsorption experiments, successfully predicted cadmium and zinc removal from the two metal solutions.