Mixed Metal Ion Solutions Research Articles

Enhanced removal of lead ions from wastewaters by electrochemical adsorption using nitrogen-doped Ti3C2Tx MXene

As a two-dimensional material containing transition metal carbides and nitrides, MXene is often used in capacitive deionization for its excellent hydrophilic and pseudocapacitive properties. Nitrogen doping is widely used to improve the adsorption properties of certain materials. However, the effect of nitrogen doping on the electrochemical adsorption properties of MXene remains unclear. In this work, nitrogen-doped Ti3C2Tx MXene was synthesized using a simple hydrothermal method to achieve highly selective and efficient removal of Pb(II) at a constant cell voltage. The concentration of Pb(II) decreased from 4.95 to 0.02 mg L−1 in a 100 mg L−1 NaCl supporting electrolyte after electrosorption. The removal efficiency of Pb(II) reached 99.5%, whereas it was only 15.2% for Na+. The introduction of nitrogen functional groups increased the electrical conductivity and layer spacing of MXene, thereby improving the pseudocapacitive adsorption performance in the presence of Pb(II). The complexation function of the Ti-OH group on nitrogen-doped Ti3C2Tx surface increased and contributed to the selective adsorption of Pb(II). The removal efficiency of Pb(II) increased with increasing solution pH and cell voltage, reaching the maximum value at pH 5.0 and 1.5 V, respectively. The effect of supporting electrolyte type on the removal of Pb(II) was negligible. In addition, the removal efficiency for mixed heavy metal ion solutions, including Cu(II), Ni(II), and Pb(II), exceeded 79.0%. It exhibited the highest removal efficiency for Pb(II) at 97.9%. After five cycles of electrochemical adsorption–desorption, the nitrogen-doped Ti3C2Tx maintained a stable Pb(II) removal efficiency of 97.0%. This work provides a promising material for the electrochemical removal of low-concentration heavy metal ions from wastewaters.

A Remarkable Strategy to Hijack U(VI) from Mixed Metal Ion Solutions Using 1-Hydroxy-2-pyridone.

The present work envisages a chelation driven, facile, selective, and rapid method for uranium(VI) separation from a (U, Th) mixture using 1-hydroxy-2-pyridone (1,2-HOPO). Herein, U(VI) was selectively precipitated as the neutral [UO2(HOPO)2(H2O)]·nH2O (orange colored) complex while Th(IV) and other metal ions remained in the solution. The pH of the medium played a key role in facilitating the separation process.

Corrective protocol to predict interference free sensor response for paper-based solution sampling coupled with heavy metal sensitive ion-selective electrodes.

Paper-based microfluidics combined with potentiometric measurement has emerged as an attractive approach for detecting various chemical ionic moieties. Detection of heavy metal ions, using paper substrates as solution sampling and delivery systems remains challenging despite efforts to introduce several physico-chemical paper substrate modifications to stop adsorption of ions onto the paper substrates. This study quantitatively investigates the adsorption of heavy metal ions on the paper substrates during paper-based potentiometric measurements and explains the super-Nernstian response of potentiometric sensors through local depletion of heavy metal ions from the solution. Consequently, based on the investigated ion adsorption, a corrective potential protocol was established for the electrodes coupled with paper-based solution sampling by predicting interference free sensor response from paper-based measurement. Furthermore, the ion adsorption was also recorded for mixed metal ion solutions to understand competitive primary/interfering ions adsorption onto the paper substrates and establish corrective measures to predict interference free sensor response. In this method, no modifications of the paper substrates are necessary before actual potentiometric measurements. The proposed corrective protocol allows prediction of sensor response based on the paper-based solution sampling potentiometric measurement, providing a simple methodological approach based on correction of potential readout of the potentiometric sensor, thus completely resigning from the need of modifying paper substrate for measurements of heavy metal ions.

An Effective Mercury Ion Adsorbent Based on a Mixed-Matrix Polyvinylidene Fluoride Membrane with Excellent Hydrophilicity and High Mechanical Strength

Improving the hydrophilicity and mechanical strength of membranes in water treatment applications remains challenging. In this study, modified vermiculite (VT-M) and a hydrophilic polyvinylpyrrolidone (PVP) were introduced into a polyethyleneimine-functionalized polyvinylidene fluoride composite membrane (PVDF/PEI) to prepare a comprehensively modified mixed-matrix PVDF composite membrane adsorbent that exhibited high mechanical strength and excellent hydrophilicity. The modified composite membrane featured good tensile properties, with a maximum tensile strength of 2.093 MPa, which was 2.5 times that of the PVDF/PEI membrane. After 7 s, the water contact angle of the composite membrane decreased to 0°, leading to significantly improved hydrophilicity. The modified composite membrane exhibited excellent adsorption selectivity for mercury ions, with a fitted maximum adsorption capacity of 807 mg/g. In a mixed-metal ion solution, the selectivity of the membrane for Hg(II) ions was 1.2 × 105 times that for Cd(II) ions. The adsorption mechanism of Hg(II) ions involved chelation, electrostatic attraction, and crystal growth processes. The present work suggests the great potential of mixed-matrix PVDF composite materials in the remediation of mercury-polluted water environments.

Ultra-clean ternary Au/Ag/AgCl nanoclusters favoring cryogenic temperature-boosted broadband SERS ultrasensitive detection.

Exploring multifunctional surface-enhanced Raman scattering (SERS) substrates with high sensitivity, broadband response property and reliable practicability should be required for ultrasensitive molecular detection in complex environments, which is heavily dependent on the photo-induced charge transfer (PICT) efficiency realized on the desirable nano-architectures. Herein, we introduce ultra-clean ternary Au/Ag/AgCl nanoclusters (NCs) with broadband resonance crossing the visible light to near-infrared region created by one step laser irradiation of mixed metal ion solution. Interestingly, the surface defects and interaction among these unique cluster-like ternary nanostructures would be further enhanced by thermal annealing treatment at 300°C, providing higher broadband SERS activities than the reference ternary nanoparticles under 457, 532, 633, 785, and 1064 nm wavelengths excitation. More importantly, the further promoted SERS activities of the resultant Au/Ag/AgCl NCs with achievable ∼5-fold enhancement than the initial one can be conventionally realized by simplistically declining the temperature from normal 20°C to cryogenic condition at about -196°C, due to the lower temperature-suppressed non-radiative recombination of lattice thermal phonons and photogenerated electrons. The cryogenic temperature-boosted SERS of the resultant Au/Ag/AgCl NCs enables the limit of detection (LOD) of folic acid (FA) biomolecules to be achieved as low as 10-12 M, which is obviously better than that of 10-9 M at room temperature condition. Overall, the smart Au/Ag/AgCl NCs-based broadband SERS sensor provides a new avenue for ultrasensitive biomolecular monitoring at cryogenic condition.

Microwave-assisted solvothermal synthesis of cube-shaped MOF-COF composites for copper detection and capture

A novel metal organic framework-covalent organic framework (IRMOF3-TzDa) composite was prepared by microwave-assisted solvothermal methods. The designed IRMOF3-TzDa was integrated with dual function of copper ion detection and removal, and characterized by FTIR, XRD, SEM, TEM and XPS et al. The adsorption capacity of Cu2+ by IRMOF3-TzDa was 86 mg g−1 by Langmuir isotherm model fitting. In a mixed metal ions solution, IRMOF3-TzDa demonstrated high adsorption selectivity to Cu2+. The strong affinity between IRMOF3-TzDa and Cu2+ and the rapid transfer of the π electrons of the material to the lowest unoccupied molecular orbital of Cu2+ provided the chance for Cu2+ fluorescence sensing by IRMOF3-TzDa. A linear range of 10–500 μM was obtained, with a limit of detection of 2.2 μM (n = 11) and a precision of 3.3% (50 μM, n = 9), respectively. Water samples were analyzed by the detection platform, with satisfactory recoveries of 94% to 107%. Benefiting from the high density of adsorption groups and excellent fluorescence properties, the facile synthetic MOF-COF composite provided an alternative material for copper ion removal and detection.

Triazine-Based Functionalized Activated Carbon Prepared from Water Hyacinth for the Removal of Hg2+, Pb2+, and Cd2+ Ions from Water.

A novel chelating adsorbent, based on the functionalization of activated carbon (AC) derived from water hyacinth (WH) with melamine thiourea (MT) to form melamine thiourea-modified activated carbon (MT-MAC), is used for the effective removal of Hg2+, Pb2+, and Cd2+ from aqueous solution. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) theory confirm the successful functionalization of AC with the melamine thiourea chelating ligand through the amidation reaction between the carboxyl groups of oxidized activated carbon (OAC) and the amino groups of melamine thiourea (MT) in the presence of dicyclohexylcarbodiimide (DCC) as a coupling agent. The prepared MT-MAC exhibited extensive potential for the adsorption of the toxic metal ions Hg2+, Pb2+, and Cd2+ from wastewater. The MT-MAC showed high capacities for the adsorption of Hg2+ (292.6 mg·g–1), Pb2+ (237.4 mg·g–1), and Cd2+ (97.9 mg·g–1) from aqueous solution. Additionally, 100% removal efficiency of Hg2+ at pH 5.5 was observed at very low initial concentrations (25–1000 ppb).The experimental sorption data could be fitted well with the Langmuir isotherm model, suggesting a monolayer adsorption behavior. The kinetic data of the chemisorption mechanism realized by the melamine thiourea groups grafted onto the activated carbon surface have a perfect match with the pseudo-second-order (PSO) kinetic model. In a mixed solution of metal ions containing 50 ppm of each ion, MT-MAC showed a removal of 97.0% Hg2+, 68% Pb2+, 45.0% Cd2+, 17.0% Cu2+, 7.0% Ni2+, and 5.0% Zn2+. Consequently, MT-MAC has exceptional selectivity for Hg2+ ions from the mixed metal ion solutions. The MT-MAC adsorbent showed high stability even after three adsorption–desorption cycles. According to the results obtained, the use of the MT-MAC adsorbent for the adsorption of Pb2+, Hg2+, and Cd2+ metal ions from polluted water is promising.

Preparation of SBA-15 mesoporous silica grafted with bis-salicylaldehyde Schiff base for uptake of Pb(II) and Cu(II) from water

SBA-15 type mesoporous silica modified with bis-salicylaldehyde Schiff base (SBA-DSA) was developed for the Pb(II) and Cu(II) ions removal from water. The adsorption properties of SBA-DSA were also compared with SBA-15 decorated with mono-Schiff base (SBA-SA). Sorption of Pb(II) and Cu(II) on SBA-DSA and SBA-SA was pH-dependent and the optimum pH for adsorption was selected at pH 5.0. The pseudo-second-order kinetic model described the sorption process well. Besides, adsorption isotherm data were better represented by the Langmuir model, confirming the adsorption processes occurred on the monolayer. Maximum adsorption capacities of SBA-DSA were 60.9 mg g−1 for Pb(II) and 36.6 mg g−1 for Cu(II), which were higher than adsorption performance of SBA-SA. The synthesized SBA- DSA showed excellent adsorption selectivity for Pb(II) in mixed metal ions solution. Considering the good reusability and regeneration of the adsorbent, SBA-DSA prepared here is promising for decontamination of water solutions from heavy metal ions.

TiO2/PKSAC functionalized with Fe3O4 for efficient concurrent removal of heavy metal ions from water

An effective material to assist in the elimination of heavy metal contaminants in the water system is necessary, as they persist for a long period in the environment. A novel multifarious TiO2/PKSAC/Fe3O4 composite with combined properties namely adsorption, photocatalytic and magnetic was successfully synthesized and applied for the simultaneous removal of mixed heavy metals, Pb(II), Cu(II), and Ni(II) under various conditions. Characterizations confirmed the fabrication of TiO2/PKSAC/Fe3O4 composite. An optimal adsorbent dosage of 0.9 g/L allowed >80% removal efficiency in 10 ppm of mixed metal ions solution. Among all three catalyst ratios, the equivalent mass ratio of 1:1:1 (TiO2/PKSAC/Fe3O4) demonstrated the best performance (>72%) in removing Pb(II), Cu(II), and Ni(II) ions, even after the addition of coexisting ions (Ca2+, Na+, Cl−, Br−) during the treatment. A recycling study confirmed the materials' regenerative stability. The fabricated TiO2/PKSAC/Fe3O4 composite can be applied as an effective material for heavy metals removal in wastewater.

Modeling Loop Composition and Ion Concentration Effects in RNA Hairpin Folding Stability

The ability to accurately predict RNA hairpin structure and stability for different loop sequences and salt conditions is important for understanding, modeling, and designing larger RNA folds. However, traditional RNA secondary structure models cannot treat loop-sequence and ionic effects on RNA hairpin folding. Here, we describe a general, three-dimensional (3D) conformation-based computational method for modeling salt concentration-dependent conformational distributions and the detailed 3D structures for a set of three RNA hairpins that contain a variable, 15-nucleotide loop sequence. For a given RNA sequence, the new, to our knowledge, method integrates a Vfold2D two-dimensional structure folding model with IsRNA coarse-grained molecular dynamics 3D folding simulations and Monte Carlo tightly bound ion estimations of ion-mediated electrostatic interactions. The model predicts free-energy landscapes for the different RNA hairpin-forming sequences with variable salt conditions. The theoretically predicted results agree with the experimental fluorescence measurements, validating the strategy. Furthermore, the theoretical model goes beyond the experimental results by enabling in-depth 3D structural analysis, revealing energetic mechanisms for the sequence- and salt-dependent folding stability. Although the computational framework presented here is developed for RNA hairpin systems, the general method may be applied to investigate other RNA systems, such as multiway junctions or pseudoknots in mixed metal ion solutions.

Multithiol functionalized graphene bio-sponge via photoinitiated thiol-ene click chemistry for efficient heavy metal ions adsorption

Heavy metals contamination in the natural waters remains an unresolved environmental challenge pressing for the development of purification technologies. This paper presents the green engineering of a new bio-sponge for heavy metals adsorption composed of alginate bio-polymeric network encapsulated with reduced graphene oxide (rGO) modified with iron oxide nanoparticles and covalently attached multithiol (pentaerythritol tetrakis-mercaptopropionate) molecules using photoinitiated thiol-ene click chemistry. The multithiol functionalized graphene bio-sponge (SH-Graphene bio-sponge) is designed to enhance adsorption performances of heavy metals including structural approach combined with oxygen functionalities and high density of sulfur-containing groups (10.2 at % S, confirmed by X-ray Photoelectron Spectroscopy, XPS) with high binding affinity towards specific heavy metals (Cd and Pb). It was shown that the level of thiol functionalization on the graphene structure within the bio-sponge can be controlled by tuning the Ultraviolet (UV) irradiation time without adjusting the concentration of the precursors. SH-functionalized graphene bio-sponge showed outstanding adsorption capacity for Pb (II): 101.01 mg/g and Cd (II): 102.99 mg/g, outperformed commercial and literature reported adsorbents in highly competitive selectivity studies using co-existing heavy metal ions (Cu, Co, Pb and Cd) spiked- sea water. The multithiol modified bio-sponge also showcased an excellent stability and reusability feature with only 0.015 mg/L Pb (II) detected, conforming the strict United States Environmental Protection Agency (US EPA) maximum contaminant level (MCL) for lead, after five recurring cycles using mixed heavy metal ions solution and acidic eluent. The outcomes from this work present valuable and promising contribution towards the development of a scalable and sustainable adsorbents for efficient remediation of heavy metals from waters.

Fluorescence quenching of photoluminescent organic polymer nanofilms by ferric ions

There are considerable reports on fluorescent detection of ferric ions, which were universally simplified as Fe3+, by using carbon dots-based sensors. Although several mechanisms have been proposed for the fluorescence quenching of the host, it deserves deep understanding on this topic because the hydrolysis of Fe3+ has not been considered in previous reports. In this contribution, we report on fluorescent detection of ferric ions in mixed metal-ion solution and in real water with organic polymer nanofilms (PNFs)-based sensor. The limit of detection of PNFs towards ferric ions is 44 nM. In particular, we focus on demonstration of the fluorescence quenching mechanisms through instrumental analysis and theoretical computations. The electron transfer from the LUMO level of PNFs to the LUMO level of Fe2(OH)24+ and the HOMO levels of Fe(OH)2+ is suggested to be responsible for the impressive fluorescence quenching of PNFs by ferric ions with concentration lower than 80 µM.

Tetrabromothiophene-Derived Sulfur-Containing Polymer Dots with Deep-Blue Luminescence and High Sensitivity to Fe3+

Polymer dots are extensively studied in the fields of catalysis, energy storage, light-emitting devices, biomedicine and engineering, and fluorescent sensors. In this paper, we report on synthesis of a new type of sulfur-containing polymer dots (SPDs) through an atomic transfer radical polymerization method. The SPDs exhibit a maximum photoluminescence at 378 nm under excitation wavelength of 280 nm. The deep-blue luminescence of SPDs may be attributed to self-passivation of SPDs by polyethylene glycol oligomers which create surface states between π* band and π energy level. Also, the SPDs show a highly selective sensitivity to Fe3+ in a mixed metal-ion solution containing Ag+, Cu2+, Hg2+, Cd2+, Pb2+, Cr3+, and Fe3+ with every metal-ion concentration set at 50 μmol L‒1. The detection limit of Fe3+ by SPDs is determined to be 1.7 μM at a signal-to-noise ratio of 3, lower than the maximum of Fe3+ tolerance (5.4 μM) in drinking water permitted by the U.S. Environmental Protection Agency.

Selective Recovery of Metal Ion by Using Hydrogel With Different Inner pH

New metal ion recovery method with hydrogels as a reaction and separation media has been investigated. Hydrogels based on copolymers of 2‐(Dimethylamino)ethyl methacrylate, N‐3‐(Dimethylamino)propyl acrylamide, and N,N‐dimethylacrylamide are prepared. Diethyleneglycol dimethacrylate is used as a crosslinker. The hydrogel with tertiary amino group exhibited high pH value inside of them when they swelled in water because the tertiary amino group was protonated by water and produced hydroxide ion was retained in the hydrogel. When the hydrogel is immersed in the metal ion aqueous solution, the metal ion diffused into the hydrogels to produce metal hydroxide in the hydrogel. The metal hydroxide within hydrogel is easily separated from the solution. The recovery amount of the metal in the hydrogel is increased with the concentration of the metal ions in the solution. The pH value of the hydrogel could be controlled by the concentration monomers at the preparation. The selective recovery of a certain metal ion from the mixed metal ion solution is attained by controlling the pH value of the hydrogel. The results obtained here suggest the possibilities of the novel metal ion recovery method replacing the coagulation and/or adsorption methods.

Highly selective adsorption of Hg(II) by the monodisperse magnetic functional chitosan nano-biosorbent

Aminothiourea functionalized magnetic chitosan nano-biosorbent (AT-MCS), a new kind of bio-adsorbent, has been first synthesized by covalently linking the chitosan and NH2-Fe3O4 with glutaraldehyde and functionalized with aminothiourea group. The resulting bio-absorbent was characterized by means of the Fourier transform infrared spectra (FT-IR), transmission electron microscope (TEM), X-ray diffraction (XRD), elemental analysis, and vibrating sample magnetometer (VSM). With the excellent mono-dispersive ability in aqueous phase, the obtained bio-sorbent showed not only the good adsorption capacity for Hg(II) on high initial concentration, but also the strong removal ability on low concentration. The maximum adsorption amount was up to 246 mg g−1, and the removal percentage reached 98.7% at initial concentration of 10 mg L−1. Moreover, the nano-biosorbent has a unique selectivity for Hg(II) among the mixed metal ions solution and exhibits good regeneration performance.

Co-precipitation preparation of LiNi0.5Mn1.5O4 hollow hierarchical microspheres with superior electrochemical performance for 5 V Li-ion batteries

In this work, a NH4HCO3 co-precipitation method was used to prepare the precursor of LiNi0.5Mn1.5O4 (LNMO). An orthogonal experiment method was applied to analyze the effects of synthetic conditions such as concentration and molar ratio of Mn2+ and Ni2+ in initial solution, reaction temperature, concentration of NH4HCO3, addition speed of NH4HCO3 on the molar ratio of Mn/Ni in the sediments, through which the co-precipitation process was also optimized. It was found that both Mn and Ni are not completely precipitated from the NH4HCO3 solution, and the precipitation rate of Ni2+ is much lower than that of Mn2+. Among these synthetic conditions, the molar ratio of Ni/Mn in the mixed metal ion solution has the greatest impact on the molar ratio of Mn/Ni in the precursor. A LNMO spinel with precise stoichiometric Ni/Mn and classic Fd3¯m structure was obtained by using a precursor prepared under the optimal synthesis conditions. Additionally, the prepared LNMO has a spherical hierarchical morphology, composed of submicron primary particles with a chamfered polyhedral structure. This LNMO shows superior electrochemical performance. It delivers a high reversible capacity of ∼110 mAh/g and superior capacity retention of 68.2% after 900 cycles at 1 C. Even at a higher discharge rate of 10 C, the LNMO material still shows a reversible capacity of 84 mAh/g.

Extraction of gold, palladium and silver ions using organically modified silica-coated magnetic nanoparticles and silica gel as a sorbent

Two new adsorbents were synthesized by covalently grafting 2,3-Bis(2-formylphenoxy)-propan-1-ol (BH) onto the surface of silica-coated magnetic nanoparticles and silica gel by a conventional method and a vice-versa method. The morphology and properties of the adsorbents were characterized by FT-IR, XRD, SEM, TEM, VSM, TGA, UV-Vis, Optical microscope and DLS. The materials are shown to be effective adsorbents for the selective extraction of the ions of Au(III), Pd(II) and Ag(I) from aqueous mixed metal ions solution also containing Cu(II), Co(II), Ni(II), Zn(II) and Pb(II). Syringe and batch techniques are compared. The ions can be desorbed with 0.5 M HCl and quantified by FAAS. The maximum adsorption capacity of the MN-Si-NH2-BH and Si-NH2-BH were determined to be 257, 197 mg·g−1 for Au(III), 311, 191 mg·g−1 for Ag(I) and 301, 222 mg·g−1 for Pd(II), respectively. The detection limits (for n = 15 and at an S/N ratio of 2 blank standard deviations) are 0.12, 0.28, and 0.17 μg·L−1 for Au(III), Pd(II) and Ag(I), respectively.

Highly Efficient Adsorption of Heavy Metals onto Novel Magnetic Porous Composites Modified with Amino Groups

A novel porous magnetic composite CoFe2O4–SiO2 (CF–S) was prepared by a simple template method. After facile amino-functionalization, it exhibited bigger adsorption capacity and higher removal efficiency (>90%) for all the heavy metal ions (Cu(II), Mn(II), Cd(II), and Pb(II)) in single or mixed metal ions solution. The adsorption affinity for heavy metal ions was not much impacted by the presence of competitive ions. Moreover, effects of experimental parameters, including adsorbent dosage, solution pH, initial concentration, reaction temperature and time, were discussed. The isothermal adsorption results were well described by the Langmuir model, and the maximum adsorption capacities were 429.18 mg·g–1 (25 °C), 500.00 mg·g–1 (35 °C), 523.56 mg·g–1 (45 °C), and 555.51 mg·g–1 (55 °C) for Cu(II) ions. The adsorption kinetics fitted well with pseudo-second order kinetic model. Analysis of thermodynamic study for Cu(II) showed that the process of adsorption was spontaneous and endothermic in nature. The result...

Novel Metal Ion Removal Method Using Protonated Hydrogel

SummaryHydrogels based on copolymers of N‐[3‐(dimethylamino)propyl] acrylamide (DMAPAA), N,N‐dimethylacrylamide (DMAA) and N,N’‐methylenebis(acrylamide) (MBAA) were prepared as selective metal ion removal media. MBAA was used as a crosslinking agent for the DMAPAA and DMAA monomers. Polymerization mixtures were polymerized to create cylindrical shapes. The hydrogels were protonated when they were swelled in water and exhibited higher pH value inside than surrounding water because of Donnan effect. The pH value of the hydrogel could be changed by the concentration of DMAPAA monomers at the preparation. Metal ion removal experiments were carried out by swelling the hydrogels in metal ion aqueous solutions. The metal ions diffused in to the hydrogels to produce metal hydroxide in the hydrogel. The hydrogel with metal hydroxide in them were easily separated from the solution. The removal ratio of the metal increased with increasing the swelling time. The removal amount of the metal in the hydrogel was increased with the concentration of the metal ions in the solution. The selective removal of a certain metal ion from the mixed metal ion solutions was attained by controlling the pH value of the hydrogel. The results obtained here suggest the possibilities of the novel metal ion removal method replacing the coagulation and/or adsorption methods.

Ultrasound irradiation promoted synthesis of bispyrimidine and bispyrazolines as selective adsorbents for the selective removal of Ag(I) and Pb(II) from aqueous solutions

In this paper, a new series of five-membered heterocyclic compounds containing pyrazoline and pyrimidine nucleus were synthesized under both conventional and ultrasonic irradiation conditions. In the first step, bischalcone derivatives were prepared by Claisen-Schmidt condensation of bisaldehydes and acetophenone in alkaline ethanol under conventional and ultrasonic conditions. In the second step, bispyrimidine and bispyrazolines were synthesized by the condensation reaction of bischalcones with thiourea/phenyl hydrazine in an alkaline medium. The ultrasound-assisted synthesis provides excellent yields in short reaction times at room temperature. The structures of the newly synthesized compounds were characterized by IR, 1H NMR, 13C NMR, mass and elemental analysis. The new synthesized bispyrimidine and bispyrazoline were used as new adsorbents for the excellent selective removal of silver and lead ions from aqueous mixed metal ion solution containing Cu(II), Co(II), Ni(II), and Zn(II) by batch technique. Also, the quantitative desorption was achieved for lead and silver ions with 0.5 M of HNO3 and HCl solutions, respectively.