Adsorption Of Cadmium Ions Research Articles

Preparation of the Carbonized Zif-8@PAN Nanofiber Membrane for Cadmium Ion Adsorption.

The zeolitic imidazolate framework (ZIF−8)@polyacrylonitrile (PAN) nanofiber membrane was prepared and carbonized for heavy metal cadmium ion (Cd2+) adsorption in aqueous medium. Zinc oxide (ZnO) was first sputtered onto the surface of the PAN electrospun nanofiber membrane to provide a metal ion source. Then, the ZIF−8@PAN nanofiber membrane was prepared via in situ solvothermal reaction and carbonized in a tube furnace at 900 °C under a N2 atmosphere to enhance adsorption performance. The synthesized ZIF−8 particles with polyhedral structure were uniformly immobilized on the surface of the PAN electrospun nanofiber membrane. After being heated at 900 °C, the polygonal ZIF−8 shrank, and the carbonized ZIF−8@PAN nanofiber membrane was obtained. Compared with the nanofiber membrane without being carbonized, the adsorption capacity of the carbonized ZIF−8@PAN nanofiber membrane reached 102 mg L−1, and its Cd2+ adsorption efficiency could be more than 90% under the adsorption temperature of 35 °C and solution of pH = 7.5 conditions. According to the adsorption thermodynamics analysis, the Cd2+ adsorption process of the carbonized ZIF−8@PAN nanofiber membrane was spontaneous. The whole Cd2+ adsorption process was more suitably described by the pseudo second-order adsorption kinetics model, indicating that there exists a chemical adsorption mechanism besides physical adsorption.

The design of SnO2-crosslinked-chitosan nanocomposite for microwave-assisted adsorption of aqueous cadmium and mercury ions

Modern day worldwide industrial activities have negatively affected the environment due to daily pollutant accumulation. Evidence of this is seen in the heavy metal deposits found in water resources from mining, well drilling, electroplating, and heavy metals production. Mercury and cadmium ions are among the most hazardous heavy metals of significant concern. The removal of these two toxic metals from wastewater requires effective, low-cost techniques, and, therefore, this current study looks at the design and fabrication of SnO2-formaldehyde-chitosan to facilitate the rapid microwave-assisted elimination of Hg(II) and Cd(II) ions. This paper explores the microwave-assisted removal of Hg(II) and Cd(II) ions, a highly efficient process which establishes 1050 μmol g−1 and 600 μmol g−1 capacity values at pH 6, at 10 s and 15 s, respectively. The application of SnO2-formaldehyde-chitosan for the microwave-assisted elimination of Hg(II) and Cd(II) ions from natural water and wastewater is also explored. In this respect, the microwave-assisted removal values of Cd(II) achieved were 95.6%, and 99.2% from tap water and wastewater, respectively. In addition, Hg(II) removal percentages were found to be 94.2% and 98.4% from the same two water samples.

Adsorption and removal studies of cadmium ion onto sulphonic/phosphonic acid functionalization resins

AbstractCadmium is a persistent bio‐accumulative toxic metallic element, which causes hazardous impacts on living species, water, and the environment. This paper presents the study of cadmium ion removal from aqueous solutions in batch experiments using 22 ion exchange resins with different functional groups. It was found that Dowex G‐26 resin with a sulphonic functional group and Puromet™ MTS9570 resin with sulphonic and phosphonic functional groups had excellent performance for Cd (II) ion removal. The effects of resin dosage, adsorption time, initial concentration of cadmium, and initial pH of solution on cadmium removal were investigated systematically using Dowex G‐26 and Puromet™ MTS9570 resins. Maximum cadmium removal rates of 99.2% and 98.9% were achieved for G‐26 and MTS9570, respectively, at an initial cadmium concentration of 1000 mg/L, an initial solution pH of 5.0, an adsorption time of 30 min, and a 0.01 mg/L resin dosage for G‐26, and a 0.025 mg/L resin dosage for MTS9570. The ion‐exchange adsorption process was fast, and it reached equilibrium after 30 min of adsorption. The results obtained show that both resins performed well for the removal of Cd (II) ions from weakly acidic solutions. Langmuir, Freundlich, and Temkin isotherms models were employed to investigate and understand the adsorption characteristics. The results showed that the studied adsorption processes fitted well to the Langmuir adsorption isotherm. From the Langmuir adsorption isotherm, the maximum adsorption capacities of Cd (II) were found to be 78.125 and 51.020 mg/g for G‐26 and MTS9570, respectively. This research provides an efficient systemic approach for cadmium ion removal from aqueous solutions.

A comparative analysis of the adsorption kinetics of Cu2+ and Cd2+ by the microalgae Chlorella vulgaris and Scenedesmus obliquus

The ability of microalgae to adsorb heavy metals from their environment has been well documented, with numerous previous studies documenting their metal binding ability. This ability has brought interest of the water treatment industry as metal removal to ppb concentrations is an expensive undertaking using conventional methods.To date, few researchers have focussed on the kinetics of adsorption, with the majority of publications focussing primarily on equilibrium data and the production of adsorption isotherms. This current study investigates the adsorption of heavy metal ions onto the surface of microalgae biomass from dilute solutions, with the performance of adsorption of copper and cadmium ions by C. vulgaris and S. obliquus being compared by fitting the Lagergren and second-order kinetic models.Kinetic studies were able to fit the Lagergren model and the second-order model to reflect the experimental data closely. The Lagergren model required fitting using a non-linear least squares algorithm, whereas the second-order model reflected experimental data closely by obtaining parameters by linearising the model. C. vulgaris had a greater second-order uptake rate for both copper (0.33 g·mg−1·s−1) and cadmium (0.17 g·mg−1·s−1) compared to S. obliquus. The capacity of C. vulgaris was greater than that of S. obliquus 10.02 mg·g−1 for copper and 9.12 mg·g−1. When the metal ions were adsorbed from a binary metal solution, copper was preferably adsorbed compared to cadmium.Analysis of equilibrium data concluded that the Freundlich Isotherm was the more appropriate isotherm compared to the Langmuir Isotherm when representing the current experimental data. The value for adsorption at equilibrium was determined to be function of the initial concentration of adsorbate and adsorbent in solution.

Biosorption of Rubber Seed Shell as a Waste Material in the Removal of Cadmium Ion from Contaminated Water

Heavy metal ion contamination in industrial wastewater is a major source of concern. Among the numerous approaches, biosorption has attracted the greatest attention in the removal of heavy metal ions from water. In particular, cadmium is bio-accumulative that poses a threat to our health when it exists in excess in our bloodstream. Here, the elimination of Cd (II) ions from wastewater using adsorbent derived from rubber seed shell (RSS). Further, thermogravimetric analysis was performed to determine the stability of materials. According to the hard and soft acids and bases (HSAB) principle, the rubber seed shell as novel bioadsorbent creates hard surface sites for cadmium ion adsorption. Batch experiments were carried out to determine the effects of pH, contact time, initial metal ions concentration, and biosorbent dosage on the removal efficiencies of Cd2+ ion using rubber seed shell. Adsorption isotherms and kinetics models were also performed for the elimination of Cd2+ ion. The optimum conditions was conducted and achieved 96% removal efficiencies of Cd2+ ion from water (pH 5.6, temperature 60°C, and initial metal concentration of 150 mg/L, the adsorption dosage 180 mg/g). The outcome of the present investigations indicated that the increasing use of bioadsorbent materials due to their low cost, regeneration ability, high adsorption efficiency, and higher removal percentage of metal ions from water sources.

A novel Sulfur-functionalized alkynyl carbon material for highly efficient removal of Hg(II) from water

In this work, a novel sulfur-functionalized alkynyl carbon materials (SACMs) were synthesized by mechanochemical reaction of CaC2 and CS2 with rich sulfur and alkynyl functional groups, as well as high porosity and surface area. Their sulfur content varies from 4.1 % to 39.8 %, depending on the stoichiometric ratio of the reactants used. The SACM-2 exhibits extremely high mercury uptake capacity (500 mg-Hg⋅g−1 at ca. 2 μg.g-1 of equilibrium Hg(II) concentration), being one of the best adsorbents, and it showed favorable recyclability after 5 cycles. The adsorption behavior follows the Freundlich and the pseudo second-order kinetic model, respectively. The SACM-2 was examined for aqueous phase adsorption of mercury, cadmium, lead, and copper ions. Its affinity for neat heavy metals was in the order of Hg(II) > Cd (II) > Pb(II) > Cu(II). The high-efficiency adsorption of Hg(II) was mainly attributed to the sulfur and alkynyl functional groups as well as their synergestic effect for specific soft acid-soft base interaction between adsorbent and the heavy metal ions. Overall, our work not only reports a promising material for removal of heavy metals-containing wastewater, but inspires the value-added utilization of CS2 in preparing other highly sulfureted materials.

Gels based on calcium alginate/pillared bentonite: structural characterization and their use as cadmium removal agent

In this work, calcium alginate hydrogels with natural and pillared bentonites (0.5 and 5% w/w) were synthetized in two geometries (disks and beads) and their capacity to adsorb cadmium ion from aqueous media was evaluated. Pillarization effect on bentonite morphology was evidenced by SEM, XRD, LD and BET isotherms. Structure and swelling capacity of hydrogels were determined, showing that hydrogels beads with pillared clays presented the higher ability to retain water. Regarding cadmium adsorption capacity, the effect of pH media (3, 5 and 7), the contact time (0 to 320 min.) and the initial cadmium ion concentration (6 to 42 mg/L) were studied employing hydrogel beads. Regardless bentonite type and concentration, the optimal pH cadmium adsorption was 7, reaching the highest adsorption capacity (93%) for hydrogel with 0.5% natural bentonite. Besides, the equilibrium adsorption time was reached at 120 min for all studied hydrogels and experimental data fitted with a pseudo-second order kinetic model.

Cellulose from Tamarix aphylla’s stem via acetocell for cadmium adsorption

This study emphasized the efficiency of unconventional delignification treatment “Acetocell” as a basic pretreatment to isolate cellulose fiber from Tamarix aphylla’s stem. Chemical proprieties of obtained cellulose were determined and its efficiency for cadmium ions adsorption was evaluated subsequently. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis, thermogravimetric analysis (TGA), Scanning Electron Microscopy (SEM), fluorescence microscope and Morfi were used to analyze the thermochemical and morphological characteristics of the fibers before and after treatment. Cellulose was used as a biosorbent to remove cadmium ions from polluted water. The effects of many parameters on the efficiency removal of cadmium were investigated; the amount of cellulose, the contact time, pH and the initial concentration of cadmium ions. The optimum conditions were 45 mg of adsorbent, 45 mg L−1, 1200 min and pH 8 which provide best adsorption capacity equal to 44.21 mg g−1. The energy value E = 6.65 kJ mol−l which confirm the physical interaction between cellulose-cadmium ions. Then Langmuir, Freundlich, Temkin and Dubinin-Radushkevich models were followed for modeling adsorption. Langmuir isotherm and the pseudo-second order model seems the most suitable which describe better the adsorption of cadmium ions with best R2 values which equal to 0.9937 and 0.9979, respectively.

Single and binary adsorption of lead and cadmium ions in aqueous solutions and river water by butylamine functionalized vermiculite: performance and mechanism

ABSTRACT Lead and cadmium are toxic to human, animal, and plant health; they enhance oxidative stress indirectly while simultaneously acting through other toxicodynamic mechanisms. In this study, pristine vermiculite (VER) was functionalized with butylamine (BUT) and a novel organoclay (BUT-VER) adsorbent material was produced for simultaneous removal of Pb(II) and Cd(II) in aquatic medium. The adsorbents were characterized by spectroscopic, microscopic, spectrometric, and potentiometric techniques. The adsorption affecting parameters, including pH, time, initial concentration, temperature, and co-existing cations were investigated and optimized. The kinetic data results were in better agreement with pseudo-second-order (PSO) model (R 2 > 0.992). Multiple isotherm models were used to study the adsorption system and results showed that adsorption was monolayer. The BUT-VER showed an improvement in adsorption capacity in a single system (Pb(II): from 134.2 to 160.6 mg g−1) and (Cd(II): from 51.1 to 58.9 mg g−1) while in binary system (Pb(II): from 107.3 to 114.5 mg g−1) and (Cd(II): from 33.7 to 39.7 mg g−1), respectively. Furthermore, BUT-VER was tested in real river water and removed efficiency of >99% was achieved in just 1 h. The dominant mechanisms were electrostatic attraction and complexation. BUT-VER was regenerated for five consecutive cycles and showed >90% removal efficiency. These findings suggest that the proposed inexpensive adsorbent has the potential for practical applications of toxic metals removal from water.

Adsorption of Cd and Cr ions from industrial wastewater using Ca doped Ni–Zn nanoferrites: Synthesis, characterization and isotherm analysis

Removal of heavy metals (Cd and Cr) from industrial wastewater by adsorption onto a series of Ca substituted nickel zinc nanoferrites (CaxNi0.4Zn0.6-xFe2O4 (x = 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6)) (CNZNFs) was studied in detail. The effect of calcium doping and contact time over adsorption of cadmium and chromium ions was investigated and maximum uptake of Cd (98.25%) and Cr (51%) ions were marked by prepared nanoadsorbents. Structural studies confirmed the formation of spinel structured nanoparticles with crystallite size ranging from 24 to 38 nm while porosity was observed to vary from 52% to 58% with calcium concentration. Pseudo second order (PSO) kinetic model for adsorption of both heavy metals (cadmium and chromium) was observed to be better fitted with adsorption data. Maximum adsorption efficiencies for Cd (128.20 mg/g) and Cr (23.54 mg/g) were found by the data fit of Langmuir isotherm model. Additionally, the adsorption data was found to obey Langmuir isotherm model for both heavy metals due to higher values of correlation coefficients (R2 = 0.94131 for cadmium and 0.91091 for chromium) than Freundlich isotherm model (R2 = 0.5865 for cadmium and 0.4599 for chromium).

Adsorption of Cd(II), Pb(II) and Ni(II) onto natural sediments from the Gulf of Aqaba Jordan

ABSTRACT Carbonate and silicate natural sediments from the gulf of Aqaba-Jordan have been used to study adsorption of nickel(II), lead(II) and cadmium(II) ions, separately, from aqueous solutions. Both sediment types were characterised by FTIR, XRD and SEM. Adsorption of these metal ions were investigated using batch technique as a function of initial concentration of metal cations, adsorbent dosage, initial pH, contact time and temperature. The metal uptake enhanced with increasing pH until a maximum removal at pH 8.0 for Ni, 5.0 for Pb and 6.0 for Cd. Kinetic study shows that the adsorption obeys a pseudo-second-order kinetic model. The adsorption isothermal behaviour of the metal ions uptake onto carbonate and silicate sediments were examined using Langmuir, Freundlich and Dubinin–Radushkevich (D-R) adsorption isotherms. The maximum adsorption capacity obtained by Langmuir isotherm model (25°C) onto carbonate sediments was 2.64, 4.41 and 4.15 mg/g for Ni(II), Pb(II) and Cd(II), respectively. While the adsorption onto silicate sediments was 2.57, 3.56 and 3.15 mg/g, respectively. These adsorption values on carbonate sediments comparing to silicate sediments were attributed to some physical and chemical properties of both sediments, especially the higher permeability and porosity for carbonate sediments. Thermodynamic functions, ΔG*, ΔH* and ΔS* were determined. Negative ΔG* values show that the adsorption process of these metal ions onto both sediments is spontaneous. While the positive ΔH* values indicate that adsorptions are endothermic, and the positive values of entropy ΔS* suggest that the adsorption is driven by increasing of randomness. Conservative calculations using the data in this study and some other from the literature shows that the shallow sediments would adsorb roughly 7 × 10 16 kg of heavy metals that may be introduced into the sea through different anthropogenic activities.

Adsorption of cadmium ion from water using activated carbon produced from palm kernel shell

Carbon produced from agricultural wastes could be a great adsorptive material in removal of metals from water. This study was conducted to remove Cadmium ion from water using activated carbon produced from palm kernel shell (PKS). Cd ion were adsorbed using various masses of PKS for a varied temperature, time and pH. The concentration of Cd adsorbed were determined using Atomic Absorption Spectrophotometer (AAS). The results showed that the adsorption of Cd can be optimize within 2hrs when allowed to equilibrate with gentle agitation (80 rpm) at pH 2. The results obtained were further subjected to Langmuir, Freundlich and Temkin adsorption isotherms. It was found that the value for qm were 2000, 2.203 and 0.906 respectively indicating that the most suitable isotherm for Cd adsorption is Langmuir. This study indicates another way of utilizing PKS which is a common waste in rural area.

Adsorption of cadmium ion from water using activated carbon produced from palm kernel shell

This study was carried out to evaluate the phytochemical, antioxidant potentials, and proximate composition of extracts of Citrullus lanatus rind (CLR) in different solvents. Chloroform, n-hexane, ethyl acetate, ethanol, and aqueous extracts of CLR were prepared after which they were subjected to phytochemical, antioxidants, and proximate analysis using standard methods. The ethanol and aqueous extracts of Citrullus lanatus rind were rich in alkaloids, saponins, and terpenoids, while the chloroform and ethanol extract were rich in flavonoids. It was observed that the ethyl acetate, chloroform and ethanol extracts of Citrullus lanatus rind had the highest concentration of total phenolic substances when compared with other extracts considered. The DPPH antioxidant scavenging activity was significantly higher in the ethyl acetate, hexane, and chloroform extracts. The aqueous extract Citrullus lanatus rind was richer in moisture content, but chloroform and hexane extracts were richer in calorie or carbohydrate a relatively high percentage of crude protein in the ethanol extract. With prescence of alkaloids, saponins, terpenoids, and phenolic compounds in ethanol and aqueous extracts of CLR. They may be beneficial in reducing cardiovascular diseases. Also, with improvement in quality of Citrullus lanatus rind, it may be of high medicinal value to man and livestock.

Remediation of Cd (II) Ion from an Aqueous Solution by a Starch-Based Activated Carbon: Experimental and Density Functional Theory (DFT) Approach

Heavy metal ion pollution is a serious threat for aquatic and terrestrial living beings. Adsorption is a facile process to encounter heavy metal pollution. Various types of adsorbents have been developed and used for environmental remediation. Activated carbon is one of the cheapest adsorbents derived from various biomass. In this work, the adsorption of cadmium ions (Cd (II)) with starch-based activated carbon (AC) having a specific surface area of 1600 m2 g−1 was investigated in a series of batch laboratory studies. The effective operating parameters, such as initial pH (pH0), initial concentration of metal ions, contact time, and temperature on the adsorption, were investigated. Validation of the kinetic study shows that the adsorption process is better predicted by the pseudo-second-order model. The extended Freundlich and Langmuir isotherms were applied to the study. The results show that the metal ion adsorption capacities of activated carbon increased with increasing pH, and it was found that maximum adsorption (284 mg g−1) of Cd (II) was achieved at pH solution of 5.5–6. The thermodynamic parameters, such as ∆G, ∆H, and ∆S, were found to be −17.42 kJ mol−1, 8.49 kJ mol−1, and 58.66 J mol−1 K−1, respectively, revealing that the adsorption mechanism is endothermic, spontaneous, and feasible. Furthermore, the density functional theory simulations demonstrated that the activated carbon strongly interacted with toxicity and mobility, so it is very urgent to remove this species from industrial wastewater before it is discharged into the environment. The adsorption energy calculated for all interactive sites was negative (−43.41 kJ mol−1 to −967.74 kJ mol−1), showing effective interaction between the adsorbate and adsorbent. The PDOS clearly shows that there is a stronger overlapping at the Femi level between the d orbital of the Cd ion and the p orbital of the O atom, showing a strong interaction and confirming the chemical bond formation between the Cd (II) ion and O atom.

Functionalized Cu-based metal oxide nanoparticles with enhanced Cd+2 adsorption capacity and their ecotoxicity assessment by molecular docking

In the present study, synthesis of eco-friendly Cu-based metal oxides nanoparticles [CuO, Cu2O, and CuO&Cu2O nanoparticles (NPs)] without and with functionalization with Diethylene glycol (DEG) has been demonstrated. The synthesized NPs were screened for their ability to adsorb multiple heavy metal ions from an aqueous solution. Based on the maximum Cadmium (Cd+2) ion adsorption capacity, functionalized Cu2O (fCu2O) NPs were selected for the detailed characterization and batch studies. The average size of fCu2O NPs was found to be 57.4 ± 6.14 nm in comparison to NPs without capping (72.6 ± 5.19 nm). The experimental parameters viz. contact time, initial pH, and initial concentration were optimized, and the obtained results were interpreted using standard isotherms and kinetic models. The maximum Cd+2 adsorption on fCu2O NPs was observed at initial solution pH 7. The adsorption of Cd+2 was found to be decreased at acidic pH due to the protonation of functional groups present on the NPs surface. A maximum Cd+2 adsorption capacity of 204 ± 6.2 mg g−1 was obtained from the Langmuir adsorption isotherm. The crystal structure of NPs was prepared and docked with the protein targets of selected soil microbes in order to determine their ecotoxicity. The obtained results showed that NPs exhibited low affinity towards protein targets in comparison to the standard used. It suggests that NPs have less impact on the functionality of soil microbes and are thus safe for their disposal into the soil micro-environment.

Adsorption of cadmium ions on silica coated metal organic framework

Heavy metal ions are commonly encountered pollutants that are toxic to both marine and human life, even at low concentrations. Adsorption is one of the most suited processes for heavy metal ions removal from aqueous solutions owing to its simplicity and efficacy at even low metal ion concentrations. TMU-5 Metal Organic Framework (MOF) was sonochemically synthesized and coated with a silica layer to improve its hydrophobicity. Cadmium found in landfills, especially from exhausted cell batteries, was chosen as the model solute to demonstrate adsorption with TMU-5. The chosen MOF was found to have a good affinity towards cadmium but leaked zinc ions into the water. Though its adsorption capacity was relatively high, the MOF did not possess water stability especially at low pH. When the silica layer coating was applied to the MOF, the adsorption capacity was reduced to 634 mg/g for cadmium. However, the water stability of the MOF was considerably improved even at moderate pH and beyond the point of zero charge, where the adsorbent was conducive for electrostatically adsorbing the cadmium ions. The silica coated MOF could be effectively used at relatively moderate metal ion concentrations and close to natural pH condition of the contaminated aqueous solution. The coated MOF could be reused without decrease in its adsorption capacity.

Preparation of a Novel Hydrogel of Sodium Alginate Using Rural Waste Bone Meal for Efficient Adsorption of Heavy Metals Cadmium Ion

Preparation of a Novel Hydrogel of Sodium Alginate Using Rural Waste Bone Meal for Efficient Adsorption of Heavy Metals Cadmium Ion

Adsorption of Iron(II) and Cadmium(II) Ions Separately using Carbon Materials from Hazelnuts and Walnuts Waste Shells

An inexpensive and efficient carbon materials as adsorbents were obtained from hazelnuts and walnuts waste shells. Their adsorption capacity with respect to iron(II) and cadmium(II) ions was studied. The results show that the carbonaceous material obtained from hazelnut shells has the best adsorption capacity with respect to Fe2+ & Cd2+, which is not inferior to commercial activated carbon. Studies of iron (II) and cadmium(II) of various concentrations showed that within 20-30 min, the best extraction rate and adsorption for both metal ions were achieved with a solution of 0.0025 M. For Fe2+ ions, the adsorption value and extraction rate have achieved good results at pH = 3-5, and for Cd2+ ions at pH = 5-6. Furthermore, the prepared adsorbent exhibited the excellent adsorption abilities even in the presence of various metal ions and successfully used as sorbents for drinking and wastewater treatment without modification and activation.

Fabrication and Characterization of Xanthan Gum-cl-poly(acrylamide-co-alginic acid) Hydrogel for Adsorption of Cadmium Ions from Aqueous Medium.

The present research demonstrates the facile fabrication of xanthan gum-cl-poly(acrylamide-co-alginic acid) (XG-cl-poly(AAm-co-AA)) hydrogel by employing microwave-assisted copolymerization. Simultaneous copolymerization of acrylamide (AAm) and alginic acid (AA) onto xanthan gum (XG) was carried out. Different samples were fabricated by changing the concentrations of AAm and AA. A sample with maximum swelling percentage was chosen for adsorption experiments. The structural and functional characteristics of synthesized hydrogel were elucidated using diverse characterization tools. Adsorption performance of XG-cl-poly(AAm-co-AA) hydrogel was investigated for the removal of noxious cadmium (Cd(II)) ions using batch adsorption from the aqueous system, various reaction parameters optimized include pH, contact time, temperature, and concentration of Cd(II) ions and temperature. The maximum adsorption was achieved at optimal pH 7, contact time 180 min, temperature 35 °C and cadmium ion centration of 10 mg·L−1. The XG-cl-poly(AAm-co-AA) hydrogel unveiled a very high adsorption potential, and its adsorption capacities considered based on the Langmuir isotherm for Cd(II) ions was 125 mg·g−1 at 35 °C. The Cd(II) ions adsorption data fitted nicely to the Freundlich isotherm and pseudo-first-order model. The reusability investigation demonstrated that hydrogel retained its adsorption capacity even after several uses without significant loss.

Effect of hydrothermal treatment of zirconium phosphate xerogel on its surface groups properties and affinity adsorption to Cd (II) ions from acidic solutions

The paper presents the kinetics of Cd (II) ions adsorption as well as adsorption of Cd (II) ions as a function of pH on the hydrothermally modified zirconium phosphate samples. Zirconium phosphate was synthesized using zirconium oxy-chloride and ammonium phosphate. The hydrothermal modification was carried out using dried xerogel of zirconium phosphate at temperature 150, 200 and 250 °C. The hydrothermal modification increases the specific surface area, the content of mesoporous as well as promotes creation of more acidic sites in the surface. Cadmium ions adsorption studies on these adsorbents showed practically complete removal of Cd (II) from aqueous solutions with an initial concentration of ≤0.0001 mol dm−3 and a pH> 3 within a few minutes.