Presence Of Competitive Metal Ions Research Articles

Competitive sequestration behavior and mechanism of Cd2+, Pb2+and Ni2+ ions from single, binary and ternary metal laden solution by Hevea brasiliensis wood sawdust (HBS)

HeveaBrasiliensis wood sawdust (HBS), a lignocellulosic material, was employed for the eradication of Cd(II), Pb(II), and Ni(II) from synthetic single and multi-metalsystem. In the realm of multimetal adsorption, HBS exhibited the most substantial adsorption capacities for heavy metals, in the order: Pb(II) > Cd(II) > Ni(II). Experiments involving batch process were carried out to explore the rolesofpH, contact duration, HBS quantity, and preliminary metal concentrations on the adsorption capacity. Optimal conditions for biosorption of metal ions were determined as pH 5.0, dosage of 7 gL−1, and an equilibrium time of 90 min. The pseudo-second-order kinetics andLangmuirisotherm had a favorable alignment with the biosorption of all individual metal ions. Adsorption capacity was 8.45, 13.01 and 6.04 mg g− 1 for Cd, Pb and Ni respectively in single metal system. In binary and ternary system the capacity and adsorption percentages decreases significantly due the presence of competitive metal ions. HBS demonstrated effectiveness in treating real wastewater containing Cd2+, Pb2+and Ni2+ ionsin both single and mixed metal solutions, highlighting the necessity of thoroughly considering the impact of competitive adsorption. SEM with EDS results indicated single metal fixing in a multi-ion solution followed complex mechanisms. The surface area and functional group studies were conducted utilizing BET and a FTIR Spectrometer. Electrostatic attraction and complexation mechanisms were identified as responsible factor for capturing metal ions to the active surfaces of the bio sorbent. Cost analysis reflected the adsorbent cost was $0.021 per liter of mixed contaminated ternary effluent (30 mg L−1).

Synthesis of phosphonic acid and amide functionalized core–shell magnetic composite and its mechanisms for synergistic adsorption of thorium from strongly acidic solution

To develop adsorbents for the preeminent extraction of thorium in strongly acidic solutions is very imperative, due to strong inorganic acids are frequently used in the fuel cycle of thorium. Herein, a robust core–shell magnetic nanocomposite Fe3O4@SiO2/P (MBA-VPA-AM) possessing phosphonic acid and amide was developed via distillation-precipitation copolymerization of N, N'-methylene diacrylamide (MBA), vinylphosphonic acid (VPA) with acrylamide (AM) employing Fe3O4 decorated by SiO2 (Fe3O4@SiO2) as magnetic core. Due to the synergistic effect of phosphonic acid and amide ligand, the sorbent could capture thorium from concentrated HNO3 media efficiently, and the maximum adsorption capacity (qmax) at 4 mol L−1 of HNO3 solution reached up to 232.5 mg g−1, superior to that of all magnetic sorbents reported previously. Furthermore, the sorbent displayed good selectivity towards thorium in the presence of competitive metal ions including La3+, Nd3+, and Ce3+. The excellent thorium sorption behavior in strong hydrogen nitrate solution was merely ascribed to the complexation of thorium with phosphonic acid ligand, and the amide ligand could not complex with thorium, evidenced by XPS, FT-IR and DFT method. However, the presence of amide ligand could enhance the hydrophilicity of the sorbent and the free movement degree of phosphonic acid ligand to a certain extent, both of which could help to promote the thorium sorption on the sorbent in strong HNO3 media. Besides, due to its core–shell structure and superparamagnetism, the sorbent not only exhibited excellent acidic resistance in strong acid medias, but could be magnetically recouped, which could avoid tedious centrifugation or filtration of traditional adsorbents. This work provides a novel strategy to develop magnetic sorbent for the preeminent entrapment of thorium from strong acid solutions.

Sulfurized bimetallic biochar as adsorbent and catalyst for selective co-removal of cadmium and PAHs from soil washing effluents

Although biosurfactant enhanced soil washing is effective to remediate Polycyclic Aromatic Hydrocarbons (PAHs)-Heavy metals (HMs) co-contaminated soil, the treatment of soil washing effluents containing pollutant and biosurfactant remains a critical challenge. In this study, the sulfurized Fe–Mn bimetallic biochar, named FMSBC was prepared, which exhibited excellent performance in activating sodium percarbonate (SPC) to degrade phenanthrene and the good adsorption capacity of cadmium. A simple system using FMSBC adsorption and SPC oxidation (FMSBC/SPC) is thus developed to remove phenanthrene and cadmium from soil washing effluents.Although there was antagonistic behavior between PAHs and HMs in the FMSBC/SPC system, over 80% phenanthrene and cadmium can be simultaneously removed from soil washing effluents. Adsorption of cadmium was mainly driven by complexation and precipitation. Free radical quenching studies and electron paramagnetic resonance (EPR) analyses verified that the dominant radical in the FMSBC/SPC system was hydroxyl radical (·OH). The performances of adsorption and catalyst were stable across a wide pH range and in the presence of competitive metal ions or natural organic matters. The recovered biosurfactants could be further reused for three washing cycles. This study has suggested biosurfactant enhanced soil washing coupled with FMSBC/SPC system is a promising method for remediation of HMs-PAHs co-contaminated soil.

Fluorescence Behavior and Mechanisms of Poly(ethylene glycol) and Their Applications in Fe3+ and Cr6+ Detections, Data Encryption, and Cell Imaging

In contrast to conventional fluorescent polymers featured by large conjugation structures, a new class of fluorescent polymers without any conjugations is gaining great interest in immerging applications beyond the possibility to achieve by the conjugated polymers. Poly(ethylene glycol) (PEG), widely used in biomedical fields for a long time owing to its nontoxicity and nonimmunogenicity, is found to be fluorescence emissive in the solid state and in aqueous solution, though deemed as not fluorescent in numerous reports. Through systematic study under different conditions, the emission is ascribed to the cluster formation of its chains; thereby the blue-shift of the emission with the excitation wavelength was interpreted through the Forster resonance energy transfer. The clusterization was ascertained through size measurements, Fourier transform infrared spectroscopy, NMR analyses, and the dependence on temperature, pH, and nonsolvent presence. Tested in the presence of competitive metal ions, selective emission quenching by Fe³⁺ and Cr⁶⁺ was observed. PEG was used as a sensor for the detection of Cr⁶⁺, Fe³⁺, and H₂O₂, outperforming most of the reported sensors alike. Its uses for data encryption and cell imaging were also presented. This work provides therefore a novel face of PEG with great potential in a variety of emerging applications, in particular, as sensors in the biomedical area.

A thiol-functionalized zirconium metal–organic cage for the effective removal of Hg2+ from aqueous solution

The mercury ions in waste water have threatened public health and environmental protection. In this sense, novel materials with outstanding performances for removal of Hg2+ are imperative. Herein, we demonstrate a thiol-functionalized zirconium metal–organic cage (MOC-(SH)2) with excellent dispersion displays ideal properties for Hg2+ capture. MOC-(SH)2 exhibits the ability of removing Hg2+ in aqueous solutions with a capacity of 335.9 mgHg2+/gMOC-(SH)2, which surpasses that of classical Zr-based metal–organic framework Uio-66-(SH)2 by 1.89 folds. The higher loading capacity of MOC-(SH)2 is probably owing to the excellent dispersion of the discrete cage, which makes the accessibility of binding sites (thiol) easier. Additionally, 99.6% of Hg2+ can be effectively captured by MOC-(SH)2 with the concentration decreased from 5 to 0.02 ppm reaching the permissible limit for Hg2+, outperforming the performance of Uio-66-(SH)2. The excellent absorption property of MOC-(SH)2 is also achieved in terms of superior selectivity under the presence of competitive metal ions. Meanwhile, the regenerated MOC-(SH)2 can be reused without apparent loss of Hg2+ loading capacity. UV–vis absorption spectra, IR spectra and emission spectra further verified the strong chemical affinity between Hg2+ and the thiol of MOC-(SH)2. The study lays the groundwork for using Zr-MOCs in the removal of toxic metal ions and environmental sustainability.

Super rapid removal of copper, cadmium and lead ions from water by NTA-silica gel.

Copper (Cu2+), cadmium (Cd2+) and lead ions (Pb2+) are toxic to human beings and other organisms. In this study, a silica gel material modified with nitrilotriacetic acid (NTA-silica gel) was sensibly designed and prepared via a simple amidation procedure for the removal of Cu2+, Cd2+ and Pb2+ from water. The NTA-silica gels showed rapid removal performances for the three metal ions (Pb2+ (<2 min), Cu2+ and Cd2+ (<20 min)) with relatively high adsorption capacities (63.5, 53.14 and 76.22 mg g−1 for Cu2+, Cd2+ and Pb2+, respectively). At the same concentration of 20 mg L−1, the removal efficiencies of the three metals by the adsorbent ranged from 96% to 99%. The Freundlich and Langmuir models were utilized to fit the adsorption isotherms. The adsorption kinetics for the three metal ions was pseudo-second-order kinetics. The removal performance of the NTA-silica gels increased in a wide pH range (2–9) and maintained in the presence of competitive metal ions (Na+, Mg2+, Ca2+ and Al3+) with different concentrations. In addition, the NTA-silica gels were easily regenerated (washed with 1% HNO3) and reused for 5 cycles with high adsorption capacity. This study indicates that the NTA-silica gel is a reusable adsorbent for the rapid, convenient, and efficient removal of Cu2+, Cd2+, and Pb2+ from contaminated aquatic environments.

Efficient and selective separation of U(VI) and Th(IV) from rare earths using functionalized hierarchically mesoporous silica

The separation and recovery of U(VI) and Th(IV) from rare earths are very important to avoid environmental pollution. A functional fibrous hierarchically bimodal mesoporous silica (F-SiO2-DP) as an high efficient adsorbent for selective adsorption of uranium and thorium, which had hierarchically bimodal mesoporous structure and specific surface area of ca. 474.1 m2 g−1, was prepared by post-modification method using 2,9-diamide-1,10-phenanthroline. The synthesized adsorbent was characterized by HR-TEM, SEM, FT-IR, N2 adsorption–desorption, TGA techniques, XRD and NMR spectroscopy. The effects of pH, contact time, initial U(VI) and Th(IV) concentration, temperature and the presence of competitive metal ions on U(VI) and Th(IV) adsorption behavior were studied in detail. The hierarchically bimodal mesoporous structure endows F-SiO2-DP with faster adsorption rate, which can reach equilibrium within 10 min, as well as higher adsorption capacities for U(VI) and Th(IV) compared with unimodal mesoporous silica like MCM-41 functionalized with 2,9-diamide-1,10-phenanthroline. The maximum adsorption capacities reach 416 mg g−1 for U(VI) at pH 5.0 and 277 mg g−1 for Th(IV) at pH 3.8, which are much higher than most of previously reported mesoporous silica-based adsorbents. The selectivity coefficient of U(VI) and Th(IV) over Ce(III), Nd(III), Sm(III), Eu(III), Gd(III), Y(III) and Yb(III) is all larger than 9 at pH 3.8, indicating that F-SiO2-DP possesses a good simultaneously selective adsorption performance for U(VI) and Th(IV). This work demonstrates that F-SiO2-DP with hierarchically bimodal mesoporous structure has promising application in adsorption and separation of actinides from lanthanides, which is crucial to the environmental protection.

Simultaneous removal of PAHs and metal contaminants from water using magnetic nanoparticle adsorbents

Many industrial wastewaters are contaminated with both heavy metal ions and organic compounds, posing a major threat to public health and the environment. In this study, magnetic nanoparticle adsorbents, namely Mag-PCMA-T, which contain a maghemite core and a silica mesoporous layer that permanently confines surfactant micelles within the mesopores, were synthesized to achieve simultaneous removal of polycyclic aromatic hydrocarbons (PAHs) (1mg/L) and metal contaminants (1mg/L). The individual removal efficiency of Cd2+ and acenaphthene using Mag-PCMA-T was evaluated under a range of initial ion concentrations and adsorbent dosages, as well as the competitive adsorption with Cd2+ and acenaphthene simultaneously present. The isotherms and kinetics of Cd2+ and acenaphthene sorption onto Mag-PCMA-T were determined. Mag-PCMA-T removed >85% of the acenaphthene in <30min, with relatively high sorption capacity (up to 1060mg/kg). Mag-PCMA-T also exhibited high sorption capacity for Cd2+ (up to 2250mg/kg). The simultaneous sorption performance was stable across a wide pH range (4–9) as well as in the presence of competitive metal ions (Ca2+ and Mg2+) or natural organic matters. The Mag-PCMA-T can be regenerated and reused, providing a sustainable, fast, convenient, and efficient approach for water treatment.

EDTA functionalized magnetic nanoparticle sorbents for cadmium and lead contaminated water treatment

Cadmium (Cd2+) and lead (Pb2+) are toxic to human beings and other organisms, and the U.S. Environmental Protection Agency (EPA) has classified both as probable human carcinogens. In this study, a regenerable magnetic ligand particle (Mag-Ligand) which includes a metal-binding organic ligand (EDTA) attached to an iron oxide nanoparticle was developed for rapid removal of Cd2+ and Pb2+ as well as other metals from contaminated water. Mag-Ligand showed fast removal ability for both Cd2+ (<2 h) and Pb2+ (<15 min) with relatively high sorption capacity (79.4 and 100.2 mg/g for Cd2+ and Pb2+, respectively). The removal performance of Mag-Ligand was high across a wide pH range (3–10) as well as in the presence of competitive metal ions (Ca2+ and Mg2+). In addition, Mag-Ligands can be easily regenerated (washed by 1% HCl) and reused several cycles with high sorption capacity. This study indicated that Mag-Ligand is a reusable sorbent for rapid, convenient, and efficient removal of Cd2+ and Pb2+ from contaminated aquatic systems.

Preparation and characterization of surface imprinted polymer for selective sorption of uranium(VI)

A new surface ion-imprinted polymer for the selective sorption of U(VI) from aqueous solution was prepared by copolymerization of a binary complex of U(VI) with methacrylic acid. The adsorption behavior of U(VI) onto the imprinted polymer was investigated by batch experiments and the results demonstrated that the maximum adsorption capacity of U(VI)-imprinted and non-imprinted polymers was found to be 35.92 and 22.58 mg g(-1), respectively. The selectivity study revealed that the U(VI)imprinted polymer exhibited excellent selectivity and affinity toward U(VI) in the presence of competitive metal ions.

Magnetic mesoporous silica hybrid nanoparticles for highly selective boron adsorption

Novel core–shell magnetic mesoporous silica hybrid nanoparticles were synthesized and functionalized further with a glycidol reagent to produce boron-specific cis-diol, chelating functional derivatives. The resulting core–shell hybrid nanoparticles were found to be a better alternative to the existing boron adsorbents that had been modified with large molecular weight saccharide moieties and polymer functionalities. The magnetic mesoporous silica hybrid nanoparticles had a surface area, diameter, pore size, and saturation magnetization of 629 m2 g−1, 200–300 nm, 2.5 nm, and 33.25 emu g−1, respectively. The glycidol-modified nanoparticles with cis-diol functional groups showed high adsorption affinity and excellent selectivity towards boron in an aqueous solution, even in the presence of competitive metal ions (Ni2+, Cu2+, Cr2+ and Fe2+) and sulphates and chlorides of Na+, K+, Ca2+ and Mg2+ ions. Adsorption equilibrium could be established within 15–20 min, and the level of boron adsorption was 2.37 mmol g−1, which is much higher than the values previously reported for other boron adsorbent materials. The synthesized magnetic mesoporous silica hybrid nanoparticles showed approximately 97% boron removal capacity from a H3BO3 solution (100 mg L−1), and the used adsorbent particles could be separated easily from the aqueous suspensions by an external magnetic field. The adsorbent could be used repeatedly after a simple acid treatment (0.1 M HCl) and regenerated by an aqueous ammonia solution (3% NH3·H2O).

Design and synthesis of rhodamine based chemosensors for the detection of Fe3+ ions

The number and nature of coordinating entities as well as the size of chelating cavity in rhodamine based chemosensors were tuned to enhance the selectivity and sensitivity for Fe 3+ ions. An intense pink color development and enhancement in fluorescence emission intensity of chemosensor 5 upon complex formation at pH 7·4 enabled the detection of Fe 3+ ions in the presence of other competitive metal ions like Li + , Na + , K + , Cs + , Mg 2+ , Ca 2+ , Sr 2+ , Cr 3+ , Mn 2+ , Fe 2+ , Cu 2+ , Co 2+ , Ni 2+ , Zn 2+ , Cd 2+ , Hg 2+ , and Pb 2+ . A plausible application of chemosensor 5 in the imaging of live fibroblast cells exposed to Fe 3+ ions is also demonstrated. ► Number and orientation of chelating atoms for detection of Fe 3+ ions is explored. ► Probe 5 selectively detects Fe 3+ even in the presence of competitive metal ions. ► Mechanistic aspects of Fe 3+ selective sensing have been demonstrated. ► Distorted octahedral geometry of 5 -Fe 3+ complex is proposed. ► Imaging of live fibroblast cells exposed to Fe 3+ ions is presented.

Highly Fluorescent Conjugated Polyelectrolyte Nanostructures: Synthesis, Self‐Assembly, and Al3+ Ion Sensing

AbstractA highly fluorescent triazine‐bridged polymer, poly[(diphenylamino‐s‐triazine)‐co‐(2‐methoxy‐5‐propyloxysulfonate‐1,4‐phenylene vinylene)] (DTMSPV), is synthesized from Wittig polycondensation of a triazine monomer with a water‐soluble p‐phenylene vinylene monomer. The fluorescent amphiphilic polymer in aqueous solution self‐assembled into nanoassemblies of micelle‐like nanostructure (MS) and π stacking nanostructure (πS), which have average sizes of 93 to 270 nm, depending on the concentration of DTMSPV. The micelle‐like nanostructure of DTMSPV (MS) shows blue emission at 457 and 488 nm with a high emission quantum yield (ΦE) of 31% in aqueous solution. On the other hand, the ΦE of π stacking structures (πS), formed in a highly concentrated solution, is lower than the MS. The MS exhibits fluorescence quenching as well as color change from blue to green/yellow, depending on the kinds of metal ions. The metal ion sensitivity is larger in the order of the main group ions (Na+, K+) &lt; dicationic transition metal ions (Zn2+, Cd2+, Pb2+, Cu2+, Pd2+) &lt; trivalent transition metal ions (Fe3+, Ru3+), with an exception of Al3+. In particular, the fluorescence of MS is dramatically quenched with color change to yellow in response to Al3+ concentrations. The selectivity and sensitivity of MS to Al3+ are unusually high even in the presence of competitive metal ions, which can be attributed to the specific interaction of triazine units with Al3+.

Effect of operating conditions on the removal of Pb 2+ by microporous titanosilicate ETS-10 in a fixed-bed column

The breakthrough behavior of Pb 2+ in an ETS-10 fixed bed was experimentally examined at various operating conditions. Results showed that the adsorption amount of Pb 2+ ions per unit mass of ETS-10 particles in a column is about 1.68 mmol/g under the experimental conditions. This amount was not markedly affected by the operating conditions because of the rapid adsorption rate of Pb 2+ ions on ETS-10. In the presence of competitive metal ions, the amount of Pb 2+ adsorbed on ETS-10 was slightly reduced. An overshoot of the effluent concentrations of competitive metal ions Cu 2+ and Cd 2+ was observed in the adsorption systems of binary and ternary solutions. This is ascribed to the replacement of pre-adsorbed Cu 2+ and Cd 2+ ions by Pb 2+ ions. The ETS-10 column broken up by Pb 2+ ions can be regenerated by using an EDTA-Na 2 solution and the regenerated column can be reused.

Elucidation of Interactions between Metal Ions and Ca Alginate-Based Ion-Exchange Resin by Spectroscopic Analysis and Modeling Simulation

In this study, a cost-effective calcium alginate-based ion-exchange resin (CABIER) was employed for treatment of metal waste streams. pH, concentration, and presence of competitive metal ions played important roles in the removal. The X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR) analysis indicated that the functional groups on the carbohydrate backbone (i.e., C−O−R and COO-1) were responsible for the binding of metals. It was found that the lead abstraction was driven by the ion exchange between Ca2+ and Pb2+. On the contrary, the Cu2+ ion was stripped via both ion exchange with Ca2+ and coordination of the other functional groups. A new mathematical model based on ion exchange (between metal and calcium) and elementary coordination (among metals and functional groups) reactions successfully described and predicted the metal removal under various conditions (e.g., pH, concentration, and existence of competitive metal ions). It was found from the modeling that metal binding follows a decreasing order of Pb2+ > Cu2+ > Ca2+.

CHARACTERIZATION OF A Ca-ALGINATE BASED ION-EXCHANGE RESIN AND ITS APPLICATIONS IN LEAD, COPPER, AND ZINC REMOVAL

Characterization of a novel ca-alginate based ion-exchange resin and its application in metal removal were investigated. The metal removal percentages increased from almost 0 to nearly 100% for metal concentrations < 0.1 mmol/L at pH 1.2 to 4, and a plateau was established at pH > 4. The removal percentages were in the following order: Pb2+ > Cu2+ > Zn2+ at pH < 4. Lower initial concentrations and ionic strengths slightly enhanced the removal percentage. The maximum metal removal capacities (q max) were 2.01 and 2.04 mmol/g for lead and copper, respectively, which are much higher than activated carbons and other reported biosorbents. Competitive effects were important for zinc removal, but less significant for lead and copper uptake. Organic chemical leaching from the resin was negligible. The single- and multiple-species metal ions were removed completely within approximately 90 and 130 minutes, respectively. The lead removal became much faster when its concentration was decreased and in the absence of other metal ions. Presence of competitive metal ions significantly reduced the metal uptake rate. Removal process kinetics were controlled by the mass transfer, while the local equilibrium followed an ion-exchange relationship.

Synthesis, characterization and ion exchange properties of the framework sodium titanium germanate Na3H(TiO)3(GeO)(GeO4)3·7H2O

Sodium titanium germanate with a semicrystalline framework (STG) of the formula Na3H(TiO)3(GeO)(GeO4)3·7H2O was synthesized under mild hydrothermal conditions and its proton form, H4(TiO)3(GeO)(GeO4)3·8H2O (STG-H), was prepared by acid treatment of the sodium compound. The STG was characterized by elemental analysis, TGA, FT-IR, and X-ray powder diffraction. A comparative ion exchange examination of the STG-H towards alkali and alkaline earth metals in a broad pH and concentration range was carried out. It was found that the STG is a moderately weak cation exchanger, possessing high ion exchange capacity (up to 4.0 meq/g) and showing preference for heavy alkali and alkaline earth metals. The STG selectivity towards Cs+ and Sr2+ ions in the presence of competitive metal ions and certain organic compounds was also studied. The data obtained suggest that the sodium titanium germanate is a more selective exchanger for Sr2+ ion than its titanium silicate analogue, K3H(TiO)4(SiO4)3·4H2O.