Metal Ions In Aqueous Solution Research Articles

PREPARATION OF ACTIVATED CARBON ADSORBENT FROM COCONUT HUSK FOR THE ADSORPTION OF LEAD (II) IONS FROM AQUEOUS SOLUTION

Heavy metals contamination of water and wastewater is a common phenomenon. Industrial wastewaters are usually the cause of heavy metals pollution of the environment. In this work, the adsorptive removal of lead metal ions in aqueous solution is investigated using an activated carbon derived from coconut husk. The activated carbon was modified with NaOH and characterized for functional group, micro-structure and textural properties. The activated carbons have a surface area of 304.38 m 2 /g from 600 °C activation with NaOH modification and 281.19 m 2 /g (300 °C) without modification. FTIR demonstrated the different functional groups present and the SEM images showed the pores on the surface of the activated carbon due to the NaOH modification. The maximum adsorption capacity of 91.70 and 73.90 mg/g were obtained for the coconut husk modified and unmodified adsorbents respectively. The adsorption kinetics for lead metal ions onto both adsorbents can be described by a pseudo-second-order rate model and are well fitted to the Langmuir adsorption isotherm. The results indicated that coconut husk in modified and unmodified forms can be used for the efficient removal of lead (II) ions from water and wastewater.

A novel 2D metal–organic framework probe: a highly sensitive and visual fluorescent sensor for Al3+, Cr3+ and Fe3+ ions

A novel 2D MOF Tb-DBA was constructed. Tb-DBA could detect Al3+, Cr3+ and Fe3+ ions rapidly, sensitively, selectively, reversibly and visually. Tb-DBA represents a promising material for the quick detection of metal ions in aqueous solution.

Effect of Aqueous Metal Ion Solutions Containing Copper on Cyanobacterial Cells: Behavior of Metal Ions and Changes in Cell Structure

Effect of Aqueous Metal Ion Solutions Containing Copper on Cyanobacterial Cells: Behavior of Metal Ions and Changes in Cell Structure

Zein adsorbents with micro/nanofibrous membrane structure for removal of oils, organic dyes, and heavy metal ions in aqueous solution

Developing multi-functional media for effectively removing different contaminants coexisted in wastewater system is highly desired. Herein, zein, a natural protein possessing abundant functional groups in molecule, is chosen to be fabricated into micro/nanofibrous membranes as adsorbents and separation media. Zein fibers with novel groove ribbon structures, which possess better structural characteristics, are designed for obtaining good adsorption performance. The adsorption performances of zein fiber membranes are evaluated. The results show that zein fiber membranes have the adsorption capacities up to 94 g/g for motor oil, 168 mg/g for Congo red, and 189 mg/g for Pb2+ ion for 1000 mg/L initial solution concentration, showing considerable competitiveness as compared with the reported adsorbents. The zein membrane with groove ribbon fiber morphology exhibits optimal adsorption capability and can be attractive multi-functional separation media.

Improving the adsorption of poly(o-phenylenediamine) to heavy metal ions in aqueous solution through its composite with carbon dots

Improving the adsorption of poly(o-phenylenediamine) to heavy metal ions in aqueous solution through its composite with carbon dots

A terpyridine-based chemosensor for detection transition metal ions in aqueous solution: Synthesis and characterization

A hydrophilic terpyridine-based copolymer chemosensor containing acrylic acid and fluorescence fragments to detect transition metal ions in aqueous solution were synthesized and well characterized. Characteristic color changes, which were resulted from chelating with specific metal ions and visible to the naked eye under natural and ultraviolet light provided possibility for real-time monitoring. Absorption and luminescence properties were adopted for further study, which exhibited unique response when treated with various metal ions. Intensity of absorption peak at 284 nm decreased with the increase of all kinds of metal ions while the secondary absorption peak at 335 nm increased with a certain concentration range. Different metal ions bring fluorescence enhancement or quenching response to the copolymer in aqueous solution. The unique fluorescence enhancing resulting from coordination of terpyridine and Zn2+ endows the polymer excellent detection ability. In particular, owing to metal-ligand charge transfer (MLCT) process, a new absorption peak appeared at 570 nm with the addition of Fe2+, and the polymer showed obvious color change.

A novel fluorescent metal-organic framework based on porphyrin and AIE for ultra-high sensitivity and selectivity detection of Pb2+ ions in aqueous solution

Lead (Pb2+) ion, as a heavy metal pollutant in water, is harmful to human health, and may cause various diseases. Therefore, it is of great necessity for people to find a new and quick way to detect Pb2+ ions in water. Based on this condition, a zinc porphyrin-based metal-organic framework (ZnTCPP-MOF) with aggregation-induced emission (AIE) was successfully synthesized via coordination polymerization of zinc (Zn2+) ions, H2TCPP and TPE-2COOH, and shows a great fluorescent phenomenon which can be used as a fluorescent probe to detect metal ions in aqueous solution. So, the ZnTCPP-MOF with a highly selective and sensitive property can be employed to detect Pb2+ ions. The experiment results exhibit that the color change of ZnTCPP-MOF could be directly discovered from bright red to colorless after adding Pb2+ ions by naked eyes. Meanwhile, the quenching curves, at lower concentrations of Pb2+ ions, exhibited an excellent linear relationship between fluorescence quenching efficiency and concentrations. The highlight of this study is that the ZnTCPP-MOF could explore Pb2+ ions in water, at very low concentrations, as well as the limit of detection (LOD) is 4.99 × 10−8 M which is an excellent data, compared with other MOFs.

Preparation of recyclable materials for removing heavy metal ions in aqueous solution and wastewater applications

AbstractBACKGROUNDTwo functionalized nano‐adsorbents were prepared by modifying carbon nanotubes and graphene oxide with active carboxyl groups, and used to remove Pb(II) heavy metal ions in aqueous solutions. The adsorbent combines the advantages of the active groups that can easily capture heavy metal ions and the high specific surface area of nanomaterials, has high adsorption capacity and affinity and is easily separated from the sample solution by centrifugation.RESULTSBoth scanning and transmission electron microscopy images show that the walls of the carbon tubes are oxidized and the ports at both ends are also opened, and the graphene oxide surface has more folds, producing more active groups such as carboxyl and hydroxyl groups, which provide suitable active sites for the attachment of heavy metals. X‐ray photoelectron spectroscopy shows that characteristic peak of lead appears in the energy spectrum after adsorption. Raman and infrared spectra show that the surface defects of the two materials have increased. The adsorption capacity calculated using the Langmuir equation was 118.82 and 178.23 mg g−1 at pH = 5, and equilibrium adsorption capacity was reached at 120 min. The adsorption capacity of the materials for Pb2+ reaches the equilibrium concentration value when the concentration is 50 mg L−1. Wastewater experiments were carried out to prove that the materials can meet the relevant national standards for lead ions in actual wastewater.CONCLUSIONSThe adsorption results for the two materials demonstrated that the materials prepared in the optimum conditions exhibited strong adsorption ability and high stability and with promise for practical applications. © 2021 Society of Chemical Industry

Synthesis and Self-Assembling Properties of Peracetylated β-1-Triazolyl Alkyl D-Glucosides and D-Galactosides

Carbohydrate-based low-molecular-weight gelators (LMWGs) are useful classes of compounds due to their numerous applications. Among sugar-based LMWGs, certain peracetylated sugar beta-triazole derivatives were found to be effective organogelators and showed interesting self-assembling properties. To further understand the structural influence towards molecular assemblies and obtain new functional materials with interesting properties, we designed and synthesized a library of tetraacetyl beta-1-triazolyl alkyl-D-glucosides and D-galactosides, in which a two or three carbon spacer is inserted between the anomeric position and the triazole moiety. A series of 16 glucose derivatives and 14 galactose derivatives were synthesized and analyzed. The self-assembling properties of these new triazole containing glycoconjugates in different solvents were analyzed. Several glucose derivatives were found to be effective LMWGs, with compound 7a forming gels in a variety of organic solvents as well as in the presence of metal ions in aqueous solutions. The organogels formed by several compounds were characterized using optical microscopy, atomic force microscopy (AFM) and UV-vis spectroscopy, etc. The co-gels formed by compound 7a with the Fmoc derivative 7i showed interesting fluorescence enhancement upon gelation. Several gelators were also characterized using powder X-ray diffraction and FT-IR spectroscopy. The potential applications of these sugar-based gelators for drug delivery and dye removal were also studied.

Facile fabrication of PVB-PVA blend polymer nanocomposite for simultaneous removal of heavy metal ions from aqueous solutions: Kinetic, equilibrium, reusability and adsorption mechanism

The available poly (vinyl butyral) (PVB)-based materials are potential media for wastewater treatment, however, their high butyral contents and low quantity of hydroxyl groups cause their low adsorption efficiency for heavy metals removal. Here, a new polymer blend nanocomposite of PVB-poly (vinyl alcohol), (PVB-PVA), incorporated with different contents of stearic acid-grafted epsilon-manganese oxide nanoflowers, (PVB-PVA/SA-ε-MnO2), was prepared through blending, solution casting and solvent evaporation techniques. According to the results, PVB-PVA/SA-ε-MnO2 nanocomposite containing 6 wt% SA-ε-MnO2 showed the maximum efficiency of 99.88%, 94.26% and 87.12%, respectively, for the adsorptive removal of Cu2+, Cd2+ and Pb2+ metallic ions from aqueous solutions. The binary and ternary adsorption of the heavy metal ions in aqueous solutions indicated a high adsorption affinity towards Cu2+. Kinetic modeling revealed that the adsorption of Cu2+, Cd2+ and Pb2+ ions follow the diffusion–chemisorption model (R2 = 0.99, RMSE = 0.31–0.56). The adsorption isotherms modeling confirmed that the Langmuir isotherm well-fitted the adsorption data of the target ions on the nanocomposite surface (R2 = 0.96–0.99, RMSE = 3.20–9.68), suggesting a homogeneous monolayer surface adsorption with the maximum adsorption capacity of 172.54, 112.89 and 111.23 mg/g for Cu2+, Cd2+ and Pb2+ ions, respectively. The reusability of PVB-PVA/SA-ε-MnO2 nanocomposite presented the removal efficiency of 94.50%, 92.05% and 88.60%, respectively, for Cu2+, Cd2+ and Pb2+ ions after five successive sorption/desorption cycles. The great adsorption performance of PVB-PVA/SA-ε-MnO2 towards the heavy metal ions could be attributed to the important role of various types of physicochemical interactions (e.g., electrostatic interactions and surface complexation) in the adsorptive removal process.

Efficient activation of peroxymonosulfate by copper supported on polyurethane foam for contaminant degradation: Synergistic effect and mechanism

The occurrence of tetracycline (TTC) in the environment can exacerbate microbial selection pressure and trigger bacterial resistance, raising potential risks to the ecosystem and public health. Here, we report that copper supported polyurethane foam (Cu-NC) can efficiently activate PMS to degrade TTC. Results demonstrated that the degradation rate of TTC was 91.3% and the pseudo first-order kinetic constant of 0.0762 min−1 was achieved after 40 min reaction at pH 5.0. Activation of PMS by Cu-NC was proposed to proceed via two sequential processes, which was different from the conventional mechanism for sulfate radical generation. Cu0 initially reacts with dissolved oxygen to generate H2O2 and Cu(I)(s) in situ in the solid form. Then Cu(I)(s) solves the relative instability of low-valent transition metal ions in aqueous solution, thus improving the activation efficiency of PMS. A novel mechanism for Cu(I)(s) activation of PMS to generate HO• was proposed and elucidated through outer-sphere interaction (electrostatic bonding) and acid-base theory. Superoxide radical and Cu0 accelerate the Cu(II)/Cu(I) redox, overcoming the rate-limiting step in Fenton-like reaction. Cu-NC showed an excellent cycling stability (80.8% removal efficiency after fifth run) in PMS activation with low Cu ion leaching (＜0.2 mg/L). The Cu-NC/PMS system also exhibited satisfactory removal of TTC in the presence of various water matrices. This study can deepen the understanding of the generation of HO• in the PMS activation process and provide a promising strategy for pollutants degradation in wastewater treatment.

Combining plug-in devices for reconfigurable removal of trichloroethylene and heavy metal ion in aqueous solution: Application and biosafety of iron-iron sulfide and its composites

The development of artificial intelligent (AI) planning for smart water treatment and the exploration of digitizable continuous-flow fabrication platform comprising electrically operable reactions for reconfigurable contaminant removal are two important challenges in future water purification technology. Most research and development efforts as well as the investment in water purifying materials have been focusing on the dimensions, compositions, or architectures containing highly adsorptive and catalytic components for effective combinatorial contaminant removal. However, limited attempts have been made to secure a digital system for adjusting the supply of existing adsorbents and chemicals to respond to transient or nonuniform distribution of contaminant load. To utilize AI planning in a more practical manner, developing a plug-in platform is necessary for reconfigurable fabrication that enables in situ supply of different water purifying materials. Therefore, a platform suitable for handling different material architectures was constructed by selecting different operation modes of plug-in reactionware (spark ablation, droplet generation, and photon supply) to modulate the architectures of water purifying materials. First, iron-iron sulfide (Fe–FeS) was fabricated using Fe nanoparticles and thiol vapors under photoirradiation, followed by combining the resulting Fe–FeS with metal (cobalt, nickel, or palladium) nanoparticles or graphene nanosheets to enhance the trichloroethylene (from 0.135 to 0.221 h−1 in removal kinetics) or heavy metal ion (from 299 to 592 mg g−1 in adsorption capacity) removal. Finally, in vitro toxicological analyses were conducted to determine biosafety of the resulting materials. The results of cell viability and reactive oxygen species profiles indicated that further investigation is required to realize the safe-by-design concept.

Removal of cadmium and lead from aqueous solutions using iron phosphate-modified pollen microspheres as adsorbents

Abstract Iron phosphate-modified pollen microspheres (pollen@FePO4) were prepared and applied as sorbents for the removal of heavy metals (Cd2+ and Pb2+) from the aqueous solution. Batch sorption studies were conducted to investigate the effects of solution pH, contact time, sorbent dosage, and metal concentration on the adsorption process. The sorption of Cd2+ and Pb2+ ions on pollen@FePO4 corresponds to the pseudo-second-order model and Langmuir isotherm, which is similar to the unmodified pollen. At pH 5.92, pollen@FePO4 offers maximum adsorption capacities of 4.623 and 61.35 mg·g−1 for Cd2+ and Pb2+, respectively. The faster sorption kinetics and higher adsorption capacities of Cd2+ and Pb2+ ions onto pollen@FePO4 than pollen indicates that it might be a promising material for the removal of heavy metal ions in aqueous solutions. The possible adsorption mechanism involves electrostatic and chemisorption for Cd2+ and mainly complexion for Pb2+.

Electrochemically Synthesized Bis(diimino)metal Coordination Nanosheets as Ultrastable Electrocatalysts for Hydrogen Evolution Reaction

Bis(diimino)metal (MDI) nanosheets (M = Ni, Co, Cu) are synthesized within a few minutes on indium tin oxide (ITO), glassy carbon (GC), and carbon paper (CP) by electro-oxidation of an aqueous solution of metal ions, hexaaminobenzene trihydrochloride, and ammonia. Thin films of these materials are firmly immobilized directly on the substrate. Their PXRD patterns are similar to those prepared by chemical oxidation, indicating considerable crystallinity. Electrocatalytic activities of MDIs on GC in hydrogen evolution reaction were investigated using rotating disk voltammetry. NiDI affords the lowest overpotential for HER among known coordination nanosheet (CONASH) catalysts and offers high catalytic robustness.

Hydrophilic graphene quantum dots as turn-off fluorescent nanoprobes for toxic heavy metal ions detection in aqueous media

Efforts are being made to develop fast, cost-effective and sensitive sensor to detect water contamination by toxic heavy metal ions. The oxygenated functional groups decorated graphene quantum dots (GQDs) effectively enhances the aqueous solubility and considered as a more desirable and simple sensing material with high sensitivity. Here, photoluminescence (PL) property of GQDs has been employed to devise an optical nanosensor for the detection of toxic heavy metal ions in aqueous media. Hydrothermal method was employed to synthesize highly fluorescent and water soluble GQDs. The fluorescence intensity reduces with the increase in toxic heavy metal ions concentration. The observed PL was analyzed by the Stern-Volmer equation to study the fluorescent quenching mechanism of the system. Nonlinear behavior of Stern-Volmer plot suggests that the reduction in the fluorescent intensity is due to the combination of dynamic and static processes. The fluorescence quenching results showed that, the as synthesized GQDs are an efficient fluorescent probe for heavy metal ions viz. Hg2+, Cd2+ and Pb2+ with the detection limit of 1.171 μM, 2.455 μM and 2.011 μM respectively. This study shows the viability of GQDs as promising material for sensing the heavy metal ions in aqueous solution.

Artificial neural networks modeling for lead removal from aqueous solutions using iron oxide nanocomposites from bio-waste mass

Heavy metal ions in aqueous solutions are taken into account as one of the most harmful environmental issues that ominously affect human health. Pb(II) is a common pollutant among heavy metals found in industrial wastewater, and various methods were developed to remove the Pb(II). The adsorption method was more efficient, cheap, and eco-friendly to remove the Pb(II) from aqueous solutions. The removal efficiency depends on the process parameters (initial concentration, the adsorbent dosage of T-Fe3O4 nanocomposites, residence time, and adsorbent pH). The relationship between the process parameters and output is non-linear and complex. The purpose of the present study is to develop an artificial neural networks (ANN) model to estimate and analyze the relationship between Pb(II) removal and adsorption process parameters. The model was trained with the backpropagation algorithm. The model was validated with the unseen datasets. The correlation coefficient adj.R2 values for total datasets is 0.991. The relationship between the parameters and Pb(II) removal was analyzed by sensitivity analysis and creating a virtual adsorption process. The study determined that the ANN modeling was a reliable tool for predicting and optimizing adsorption process parameters for maximum lead removal from aqueous solutions.

Piperidine based effective chemosensor for Zn(II) with the formation of binuclear Zn complex having specific Al(III) detection ability in aqueous medium and live cell images

A schiff base chemosensor HL [4-chloro-(((2-(piperidine-1-yl)imino)methyl)phenol], constructed by one step condensation of 2-aminoethyl piperidine and 5- Chloro Salicylaldehyde is illustrated to have its usefulness for selective and sensitive detection of Zn(II) among other metal ions in aqueous solution (HEPES buffer) displaying the colour changes from light blue to turquoise under UV light. The specific detection phenomena of Zn (II) is monitored by the remarkable fluorescence enhancement and notable change in NMR spectral data of fluorescence active HL after addition of Zn(II) to it. The impressive high binding constant in 106 orders, determined by electronic spectral titration after introduction of Zn(II) to HL assure the formation of a Zinc complex during sensing phenomena. In order to check whether the nuclearity of the constructed complex can be increased or not fluorescence enhancement phenomenon is further monitored in presence of different bridging ligands and the results display that only in presence of azide a significant enhancement of Zn(II)-HL domain is exposed where as for other bridging ligand the spectra remain unaltered. This observation insists to conduct the reaction between HL and ZnCl2 in presence of sodium azide which lead the formation of a Zn complex [Zn2(HL)2(N3)4] (complex 1) employing azide as the secondary anionic residue instead of bridging. The single crystal structure of the complex unveils the unique protonation of the piperidine N during the crystallization of the dinuclear motif of the complex 1. Furthermore the Zn complex due to the presence of remarkable luminescence property have been effectively used for selective sensing of Al(III) ion as metalloreceptor in HEPES buffer solution via turn of fluorescence with remarkable fluorescence quenching constant. In aqueous solution, complex 1 induces a 1:2 complex formation with Al(III) ion indicated by Job’s plot analysis. The DFT study suggests the formation of bimetal complex during sensing of Al(III) with complex 1 as metalloreceptor. The in vitro cell imaging study gives a authentic hints for in vivo biomedical application of HL as a selective and easy Zn(II) sensor. The two step sensing phenomena of HL and complex 1 is further established by advanced molecular logic gate formation.

Unmodified Green Silver Nanoparticles as Multisensor for Zn2+ and Catalyst for Environmental Remediation

AbstractThis paper details the selective optical, fluorescent and electrochemical detection of Zn2+ among various divalent metal ions in aqueous solution by the green synthesized silver nanoparticles (AgNP) using the fresh extract of Myristica fragrans (MF) with the aid of microwave energy. The synthesized silver nanoparticles stabilized with MF were analysed using UV‐vis., Fourier‐transform infrared (FT‐IR), X‐ray diffraction (XRD), and transmission electron microscopy (TEM) techniques. Due to the effective complexation between silver nanoparticles and metal ions, absorbance of AgNP‐MF diminished with increasing concentration of Zn2+. This is visually identified through the color changes. Fluorescent sensing studies involved the changes in fluorescent intensity of AgNP‐MF in the presence of Zn2+. Electrochemical sensing of Zn2+ was carried through cyclic and differential pulse voltammetric techniques using AgNP‐MF modified platinum electrode (AgNP‐MF−Pt). The developed electrochemical sensor showed a limit of detection (LOD) of 0.6148 μM and its good sensing ability was checked for the detection of Zn2+ in environmental water samples. Recoveries of Zn2+ in the various real water samples were obtained in the range from 100.2 % to 100.6 %. The multi‐functional utility of the AgNP‐MF as a catalyst towards the reduction of two environmentally toxic contaminants such as o/p‐nitroanilines through NaBH4 was also evaluated. The complete degradations were achieved within few minutes and the reactions followed pseudo first order kinetics. The effect of catalytic dosage on the rate of reduction reactions was also studied.

The participation of cyanobacteria in reducing the concentration of fusariotoxins and heavy metal ions in aqueous solutions (model experiments)

Aim. The goal was to establish the effect of soil cyanobacteria (CB) Fischerella muscicola, Nostoc paludosum and Nostoc linckia on change in the concentration of heavy metal ions (HM) and fusariotoxins in aqueous media.Material and Methods. In order to plot the kinetics of sorption by dry biomass of CB Fischerella muscicola and Nostoc paludosum of copper(II), lead(II) and cadmium ions from solutions with a concentration of 10‐4mol/L, the method of potentiometry with ion‐selective electrodes was used. The concentration of fusariotoxins in the filtrate of the contact medium of Fischerella muscicola CB and Nostoc linckia with F. culmorumwas determined by HPLC.Results. The kinetics of sorption of TM ions by dry biomass of the CB isbest described by a modified second‐order model. According to the model, the sorption process limits the ion exchange reaction. In the presence of CB Fischerella muscicola and Nostoc linckia with a titer of 1.8∙106 cells/mL (1:100 dilution), a decrease in toxin and lycomarasmin in T‐2 medium occurs. However, this increases the concentration of fusaric acid and deoxynivalenol. In the variant where the titer of CB is equal to 1.8∙107cells/mL, the concentration of lycomarasmin is significantly reduced, while there is no change in the concentration of other fusariotoxins.Conclusion. Dry biomass of CB, having a high bisorption potential, can act as a good biosorbent with respect to copper(II), lead(II) and cadmium ions. A decrease in the concentration of fusariotoxins indicates the possibility of isolating active CB substances that can inhibit the biosynthesis of certain toxins of micromycetes of the genus Fusarium, reducing both the phytotoxicity of plant growth media and increasing the safety of crop production.

Parametrization of Trivalent and Tetravalent Metal Ions for the OPC3, OPC, TIP3P-FB, and TIP4P-FB Water Models.

Commonly seen in rare-earth chemistry and materials science, highly charged metal ions play key roles in many chemical processes. Computer simulations have become an important tool for scientific research nowadays. Meaningful simulations require reliable parameters. In the present work, we parametrized 18 M(III) and 6 M(IV) metal ions for four new water models (OPC3, OPC, TIP3P-FB, TIP4P-FB) in conjunction with each of the 12-6 and 12-6-4 nonbonded models. Similar to what was observed previously, issues with the 12-6 model can be fixed by using the 12-6-4 model. Moreover, the four new water models showed comparable performance or considerable improvement over the previous water models (TIP3P, SPC/E, and TIP4PEW) in the same category (3-point or 4-point water models, respectively). Finally, we reported a study of a metalloprotein system demonstrating the capability of the 12-6-4 model to model metalloproteins. The reported parameters will facilitate accurate simulations of highly charged metal ions in aqueous solution.