Ions In Solution Research Articles

Physiological and molecular responses of the copepods Acartia clausi and Acartia tonsa to nickel nanoparticles and nickel chloride.

Nickel compounds in dissolved form or as nanoparticles may affect planktonic invertebrates in marine ecosystems. Here, we assessed the physiological (naupliar mortality, egg production, egg hatching success) and molecular (quantitative gene expression) responses of the crustacean copepods Acartia clausi (indigenous Mediterranean species) and Acartia tonsa (model organism in ecotoxicology), to nickel nanoparticles (NiNPs) and nickel chloride (NiCl2), over time. We also measured NPs size and the temporal release of Ni ions in aqueous solution, through dynamic light scattering (DLS) and inductively coupled plasma-mass spectrometry (ICP-MS), respectively. Nauplii of A. clausi were highly vulnerable to NiCl2 in the 48 h acute test, with an EC50 in the range of Ni concentrations measured in polluted waters. Females of both species exhibited a decreased egg production and hatching success after the 4-day exposure to NiNPs. Molecular responses in A. clausi incubated in NiNPs and NiCl2 showed a stronger up- or down-regulation, compared to A. tonsa, of genes associated with detoxification (phospholipid-hydroperoxide glutathione peroxidase, glutathione-S-transferase sigma), oxidative stress (superoxide dismutase), nervous system functioning (acetylcholinesterase), and oogenesis (vitellogenin) In conclusion, new information was here obtained on the effects of different forms of nickel on physiological and molecular responses of A. clausi, that could help to identify biomarker genes of exposure to be used as early-warning indicators. Our results also highlighted the need of employing indigenous copepod species to better evaluate the ecotoxicological impact of pollutants in different geographical area.

Reduction of precious metal ions in aqueous solutions by contact-electro-catalysis.

Precious metals are core assets for the development of modern technologies in various fields. Their scarcity poses the question of their cost, life cycle and reuse. Recently, an emerging catalysis employing contact-electrification (CE) at water-solid interfaces to drive redox reaction, called contact-electro-catalysis (CEC), has been used to develop metal free mechano-catalytic methods to efficiently degrade refractory organic compounds, produce hydrogen peroxide, or leach metals from spent Li-Ion batteries. Here, we show ultrasonic CEC can successfully drive the reduction of Ag(ac), Rh3+, [PtCl4]2-, Ag+, Hg2+, Pd2+, [AuCl4]-, and Ir3+, in both anaerobic and aerobic conditions. The effect of oxygen on the reaction is studied by electron paramagnetic resonance (EPR) spectroscopy and ab-initio simulation. Combining measurements of charge transfers during water-solid CE, EPR spectroscopy and gold extraction experiments help show the link between CE and CEC. What's more, this method based on water-solid CE is capable of extracting gold from synthetic solutions with concentrations ranging from as low as 0.196 ppm up to 196 ppm, reaching in 3 h extraction capacities ranging from 0.756 to 722.5 mg g-1 in 3 h. Finally, we showed CEC is employed to design a metal-free, selective, and recyclable catalytic gold extraction methods from e-waste aqueous leachates.

Application of Hydrogen Permeation Techniques to Assess the Effect of Inhibitors in Hydrochloric Steel Pickling of Low‐C Steels and Interstitial‐Free Steels

The acid pickling phase, generally entrusted to HCl‐based solutions, plays a fundamental role in the production of low‐C and interstitial‐free steel coils. Very often, however, pickling operations are challenging due to the possible onset of surface defects (underpickling, overpickling, appearance of surface defects, etc.) linked to complex phenomena involving numerous factors, such as acid concentration, Fe ions in solution, temperature, time, steel type, and scale structure. Moreover, the use of inhibitors, which is essential for controlling the pickling process, represents one of the major challenges. Their dosage, although minimal, must be carefully chosen based on the type of processed coils and other plant engineering variables. The flow of hydrogen that is generated on the surface of the steel during etching causes absorption of hydrogen by the metal and its measurement is strictly linked to the phenomena occurring during scale removal. The correlation of data obtained from a Devanathan double‐cell hydrogen permeation system to results of other techniques, such as weight loss, surface analysis, metallography, and electron microscopy shows that this system can be effectively used to indirectly measure the solution aggressiveness. This experimental approach is applied to two industrial steels: a simple carbon base and an interstitial free Ti steel.

Protector-free, non-plasmonic silver quantum clusters by femtosecond pulse laser irradiation: in situ binding on nanocellulose filaments for improved catalytic activity and cycling performance.

This study introduces a new, facile method to synthesize silver clusters from aqueous silver ion solution by using high intensity femtosecond pulse laser irradiation. The particles obtained in the absence of reducing or capping agents are 1-17 nm in size and presented quantum properties, as characterized by fluorescence, but did not exhibit plasmon signals, which is not a common characteristic of conventional silver nanoparticles. In a further development, small silver quantum clusters (∼1 nm) were bound in situ to wet-spun filaments of cellulose nanofibrils by pulsed laser irradiation. The obtained hybrid filaments as well as free silver quantum clusters revealed a catalytic activity remarkably higher than that of free gold quantum clusters; moreover, the hybrid filaments were found to show improved stability and cycling performance for silver-based catalysis. The present results indicate the potential of femtosecond laser irradiation to generate clusters as well as hybrid systems with excellent performance and reactivity.

Coumarin-Modified Starch Fluorescent Nanoparticles as Sensor of Fe3+ and Zn2+ ions Utilizing Dynamic Quenching and Chelation Mechanisms.

Zinc and iron are two essential trace minerals that play a pivotal role in maintaining optimal health and well-being in the human body. Despite being required in relatively small quantities, their significance can be understated as they participate in a wide array of critical physiological processes such as oxygen transport, DNA synthesis, controlling nutrient availability, etc. Understanding the distribution and behavior of these ions in natural water bodies is essential for assessing water quality, studying ecological processes, and managing environmental impacts. In this study, we have developed a dual fluorescence probe using starch which was functionalized with coumarin derivatives, for efficient detection of Fe3+ and Zn2+ ions. This structure led a self-assembled starch/coumarin (SC) fluorescent nanoparticles with strong fluorescence intensity under ultraviolet light (365nm). The quenching effect of Fe3+ on the SC fluorescent probe enabled efficient specific detection of Fe3+. Furthermore, Zn2+ ions increased fluorescence intensity of coumarin compounds (λemission = 459). This phenomenon occurs when the coumarin compound forms a complex or interacts with the zinc ion, resulting in enhanced fluorescence emission. In summary, the developed fluorescent probe offered a promising approach for sensitive and specific detection of iron and zinc ions in aqueous solutions.

Unlocking Direct Lithium Extraction in Harsh Conditions through Thiol-Functionalized Metal-Organic Framework Subnanofluidic Membranes.

Metal-organic framework (MOF) membranes with high ion selectivity are highly desirable for direct lithium-ion (Li+) separation from industrial brines. However, very few MOF membranes can efficiently separate Li+ from brines of high Mg2+/Li+ concentration ratios and keep stable in ultrahigh Mg2+-concentrated brines. This work reports a type of MOF-channel membranes (MOFCMs) by growing UiO-66-(SH)2 into the nanochannels of polymer substrates to improve the efficiency of MOF membranes for challenging Li+ extraction. The resulting membranes demonstrate excellent monovalent metal ion selectivity over divalent metal ions, with Li+/Mg2+ selectivity up to 103 since Mg2+ should overcome a higher energy barrier than Li+ when transported through the MOF pores, as confirmed by molecular dynamics simulations. Under dual-ion diffusion, as the Mg2+/Li+ mole ratio of the feed solution increases from 0.2 to 30, the membrane Li+/Mg2+ selectivity decreases from 1516 to 19, corresponding to the purity of lithium products between 99.9 and 95.0%. Further research on multi-ion diffusion that involves Mg2+ and three monovalent metal ions (K+, Na+, and Li+, referred to as M+) in the feed solutions shows a significant improvement in Li+/Mg2+ separation efficiency. The Li+/Mg2+ selectivity can go up to 1114 when the Mg2+/M+ molar concentration ratio is 1:1, and it remains at 19 when the ratio is 30:1. The membrane selectivity is also stable for 30 days in a highly concentrated solution with a high Mg2+/Li+ concentration ratio. These results indicate the feasibility of the MOFCMs for direct lithium extraction from brines with Mg2+ concentrations up to 3.5 M. This study provides an alternative strategy for designing efficient MOF membranes in extracting valuable minerals in the future.

Synergistic Effects of Exogenous Nutrient Ions on the Real-Time Cadmium Extraction by an Accumulator

Bidens tripartita L. is a cadmium (Cd) accumulator. However, the real-time influx or efflux of Cd2+ around its root apex has not yet been performed. The object of this experiment was to compare the roles of added ions in solution on dynamic Cd extraction by B. tripartita root tip. Quartz sand was used to grow the seedling of B. tripartite. The Cd concentrations of all samples were determined by using ICP-OES after digestion. The Cd2+ influx around the root apex was measured in vivo, i.e., using non-invasive micro-test technology (NMT). The results showed that the Cd2+ influx was found to be decreased by 35.9%, 43.7%, 20.6%, and 57.5% under 10 μM Cd combined with high content Ca2+, Mg2+, Fe3+, or K+ (16 mM, 8 mM, 0.5 mM, 18 mM, respectively), compared to that under 10 μM Cd stress. But Cd treatments with low content ions with 0.05 mM Fe3+ or 0.5 mM S increased the Cd2+ influx in roots by 20.5% and 34.6%, respectively. It was also found that Cd treatment with high concentrations of Ca2+ or K+ increased the shoot biomass of B. tripartita seedlings. Chl a and b contents were significantly decreased in the Cd treatments with low concentrations of Fe3+ or S compared to those under Cd stress alone, and the dehydrogenase activity of the roots decreased in the treatment of Cd with 0.05 mM Fe3+ or 0.5 mM S. Our results indicate that the addition of 0.05 mM Fe3+ or 0.5 mM S promoted Cd2+ influx and Cd uptake by B. tripartita. Unlike traditional measurement, the Cd2+ movements of three-dimensional space around the B. tripartita root tip had been performed by NMT. It was suggested that the effects of S and Fe3+ on the remediation potential of B. tripartita need to be further researched in the future. The results of this study provided a real-time and micro-dynamic theoretical basis for phytoremediation mechanisms.

Synthesis, Spectral Characteristics, Sensing Properties and Microbiological Activity of New Water-Soluble 4-Sulfo-1,8-naphthalimides

A new water-soluble polyamidoamine (PAMAM) dendrimer modified with 4-sulfo-1,8-naphthalimide (DSNI) and its monomeric structural analogue (MSDI) were synthesized. Their photophysical properties were investigated in organic solvents of different polarities and aqueous solutions. The effect of pH on fluorescence intensity was determined. It was found that the dendrimer emits blue fluorescence in an acidic medium, which is quenched in an alkaline environment. This phenomenon is due to the possibility of suppression of nonradiative photoinduced electron transfer in acidic media. The influence of different metal ions (Cu2+, Pb2+, Sn2+, Sr2+, Mg2+, Ba2+, Co2+, Hg2+, Zn2+, Ni2+, Fe3+, Al3+) and anions (CN−, S2−, S2O52−, HPO42−, H2PO4−, F−, CH3COO−, NO2−, CO32−, SO42−) on the intensity of the emitted fluorescence was studied. Quenching was only found in the presence of Cu2+. This makes the dendrimer suitable for determining copper ions in water solutions in the presence of other metal ions and anions. Additionally, DSNI was used as a ligand to obtain a stable copper complex, the structure of which was investigated by electron paramagnetic resonance (EPR), infrared spectrum, and elemental analysis. Two copper ions were found to form a complex with one dendrimer. The in vitro microbiological activity of the new compounds against bacteria Pseudomonas aeruginosa and two viruses HRSV-2 and HAdV-5 was investigated. With a view to obtaining antibacterial and anti-viral textiles, cotton fabrics were treated with the three compounds, and then their activity against the same microbial strains was investigated. It was found that the microbiological activity was preserved after the application of the new compounds to the cotton fabrics.

Toward Selective Transport of Monovalent Metal Ions with High Permeability Based on Crown Ether-Encapsulated Metal-Organic Framework Sub-Nanochannels.

Achieving selective transport of monovalent metal ions with high precision and permeability analogues to biological protein ion channels has long been explored for fundamental research and various applications, such as ion sieving, mineral extraction, and energy harvesting and conversion. However, it still remains a significant challenge to construct artificial nanofluidic devices to realize the trade-off effects between selective ion transportation and high ion permeability. In this work, we report a bioinspired functional micropipet with in situ growth of crown ether-encapsulated metal-organic frameworks (MOFs) inside the tip and realize selective transport of monovalent metal ions. The functional ion-selective micropipet with sub-nanochannels was constructed by the interfacial growth method with the formation of composite MOFs consisting of ZIF-8 and 15-crown-5. The resulting micropipet device exhibited obvious monovalent ion selectivity and high flux of Li+ due to the synergistic effects of size sieving in subnanoconfined space and specific coordination of 15-crown-5 toward Na+. The selectivity of Li+/Na+, Li+/K+, Li+/Ca2+, and Li+/Mg2+ with 15-crown-5@ZIF-8-functionalized micropipet reached 3.9, 5.2, 105.8, and 122.4, respectively, which had an obvious enhancement compared to that with ZIF-8. Notably, the ion flux of Li+ can reach up to 93.8 ± 3.6 mol h-1·m-2 that is much higher than previously reported values. Furthermore, the functional micropipet with 15-crown-5@ZIF-8 sub-nanochannels exhibited stable Li+ selectivity under various conditions, such as different ion concentrations, pH values, and mixed ion solutions. This work not only provides new opportunities for the development of MOF-based nanofluidic devices for selective ion transport but also facilitates the promising practical applications in lithium extraction from salt-like brines, sewage treatment, and other related aspects.

Adsorption Potential, Speciation Transformation, and Risk Assessment of Hg-, Cd-, and Pb-Contaminated Soils Using Biochar in Combination with Potassium Dihydrogen Phosphate

The objective of this study is to develop a remediation technology for composited heavy metal-contaminated soil. Biochars (BC300, BC400, and BC500) derived from corn were combined with potassium dihydrogen phosphate (KH2PO4) to immobilize and remove heavy metal ions, including mercury (Hg2+), cadmium (Cd2+), and lead (Pb2+). The adsorption kinetics of metal ions in aqueous solutions with different concentrations was tested, and the fitting effects of the two models were compared. The findings demonstrate that the joint application of biochar and KH2PO4 could markedly enhance the immobilization efficacy of Pb2+, whereas the utilization of KH2PO4 on its own exhibited a more pronounced immobilization impact on Cd2+. Furthermore, the present study underscores the shortcomings of various remediation techniques that must be taken into account when addressing heavy metal-contaminated soils. It also emphasizes the value of comprehensive remediation techniques that integrate multiple remediation agents. This study offers a novel approach and methodology for addressing the intricate and evolving challenges posed by heavy metal contamination in soil. Its practical value and potential for application are significant.

Solvation structure design for stabilizing MXene in transition metal ion solutions

AbstractAlthough MXene has attracted great interest in diverse fields, it is susceptible to oxidation in water (H2O) with transition metal ions such as Co2+, Fe2+, and Cu2+, which is pronounced at high temperatures. This impedes the preparation of MXene‐based composites and their functional applications. Here, this study revealed that Co2+ increases the maximum and average atomic charge of H in H2O to improve the reactivity of H2O, which leads to the fact that Co2+ catalyzes the oxidation of Ti3C2Tx MXene. Furthermore, the addition of N,N‐dimethyl formamide (DMF) reduces the H2O activity and improves the oxidation stability of Ti3C2Tx in the presence of Co2+ via preferentially forming coordination bonds with Co2+. This strategy is also effective in enhancing the oxidation tolerance of Ti3C2Tx to Fe2+ in H2O. Moreover, it is feasible to enhance the oxidation stability of Ti2CTx MXene in H2O with the existence of Co2+. By virtue of these, the CoO/Ti3C2Tx composite was successfully prepared without obvious Ti3C2Tx oxidation, which is desirable to harness the advantages of Ti3C2Tx as the complementary component for lithium‐ion batteries. This work provides a straightforward paradigm to enhance the oxidation resistance of MXene in H2O in the presence of transition metal ions and at high temperatures, which opens a new vista to use MXene for target applications.

Quantum sensing of microRNAs with nitrogen-vacancy centers in diamond

Label-free detection of nucleic acids such as microRNAs holds great potential for early diagnostics of various types of cancers. Measuring intrinsic biomolecular charge using methods based on field effect has been a promising way to accomplish label-free detection. However, the charges of biomolecules are screened by counter ions in solutions over a short distance (Debye length), thereby limiting the sensitivity of these methods. Here, we measure the intrinsic magnetic noise of paramagnetic counter ions, such as Mn2+, interacting with microRNAs using nitrogen-vacancy (NV) centers in diamond. All-atom molecular dynamics simulations show that microRNA interacts with the diamond surface resulting in excess accumulation of Mn ions and stronger magnetic noise. We confirm this prediction by observing an increase in spin relaxation contrast of the NV centers, indicating higher Mn2+ local concentration. This opens new possibilities for next-generation quantum sensing of charged biomolecules, overcoming limitations due to the Debye screening.

Hydrothermal Synthesis of Tartaric Acid Functionalized Amino Acid CQD for Sensing of Hg2+ and Fe3+ Ions in Aqueous Medium

AbstractCarbon quantum dots (CQDs) are a type of carbon‐based nanoparticles that are typically smaller than 10 nanometres in size. In this study, L‐tryptophan‐mediated CQDs were synthesized using the hydrothermal carbonization (HTC) technique, which is known for its non‐toxic, environmentally friendly, and cost‐effective nature. The synthesized carbon quntum dot was successfully characterized. The HR‐TEM analysis clearly revealed the formation of specific aggregates with a size distribution ranging from 3.0 to 5.1 nm. These L‐tryptophan‐mediated CQDs exhibited remarkable emission behaviour, displaying strong and stable blue fluorescence. Moreover, they were utilized as a sensor for the sensitive detection of Fe3+ and Hg2+ ions in an aqueous solution, employing a fluorescence quenching mechanism. The limit of detection for Fe3+ sensing was determined to be 1.2×10−5 M, while for Hg2+ sensing, it was found to be 1.9×10−5 M. The sensing of Fe3+ and Hg2+ ions was also confirmed through visual eye detection, as a significant color change of the CQDs was observed. Additionally, a competitive study was conducted to verify the selectivity of the L‐tryptophan‐mediated CQDs towards Fe3+ and Hg2+ metal ions.

Dual function Schiff-base as a selective fluorescence “Turn-on” sensor for Zn2+ and a colorimetric sensor for Cu2+ and Fe3+ ions

A simple and adaptable salen-based Schiff base receptor (L = 6,6′-((1E,1′E)-(cyclohexane-1,2-diylbis(azanylylidene))bis(methanylylidene))bis(2-methoxyphenol))was employed in the current study for colorimetric detection of Cu2+, Fe3+, and fluorescence detection of Zn2+ ions in a semi-aqueous solution. L could identify the three target ions among the many different cations and anions in the solution. The turn-on fluorescence signal of L to Zn2+ ions was boosted by the restriction of the intramolecular charge transfer process, and the resulting chelation enhances the fluorescence signal. The sensing mechanisms were validated using a Job’s plot, Electrospray Ionization Mass Spectrometry (ESI-MS) analysis, Nuclear Magnetic Resonance (NMR) titration experiment, and theoretical calculation investigations. The detection limits for Zn2+ were determined to be 0.038 μM, whereas Cu2+ and Fe3+ detection limits were 0.58 μM and 0.62 μM, respectively. Next, L was used to develop solid silica gel and test strips for instantaneous colorimetric and fluorescent detection of the three target ions in real time. The trace level of Cu2+ and Fe3+ in the tap and drinking water samples could be quantitatively measured using L. Eventually, applications for keypad locks and molecular logic gates were developed utilizing the receptor L.

Metal-phenolic networks-engineered polyimide aerogels for high-efficiency gold extraction and separation from e-waste mixture

Engineering adsorption materials that offer easy handling, efficient, and selective recovery of precious metals, such as gold, from electronic waste (e-waste) are of significant interest, especially given the escalating volume of discarded electronic devices. However, the harsh digested solvents (e.g., aqua regia), ultralow gold concentrations (several ppm), and competitive interference from various metals present significant challenges. Herein, we engineer a porous polyimide (PI) aerogel with chemically reductive, mechanically resilient, and environmentally recyclable capabilities, using biomass-derived metal-phenolic networks (MPNs), for highly selective and efficient gold extraction and separation. The resulting aerogels show a high adsorption efficiency (∼97.4 %), selective extraction of gold ions from 12 metal ions in simulated leached solutions, and superior purity (∼100 %) in the reduced gold particles. The gold ions are reduced, nucleate, and grow into large agglomeration (∼12 μm) as observed in experiments and confirmed by density functional theory (DFT) calculations, facilitating their separation from the aerogels without the need for complex processes (e.g., membrane separation). On application to a central processing unit (CPU), our aerogels effectively extracted > 96 % of gold ions even at ultralow concentrations of 3.6 ppm in aqua regia, generating at least 66 times more profit compared to the cost (profit/cost = ∼52.9/∼0.8 $⋅g−1). These results demonstrated that MPNs-engineered aerogels are promising economical and practical adsorbents for gold recovery in e-waste.

Illuminating the problem of blue verditer synthesis in the early modern English period: chemical characterisation and mechanistic understanding

We present a study into early modern English production of blue verditer, an early synthetic copper-based blue pigment chemically analogous to azurite. Verditers have been identified in numerous wall and easel paintings. While initial documentation occurs in the mid 1500s and production recipes were documented by the 17th c., the synthesis was known to be unreliable. This study replicates historical and recent scientific work on blue verditer and represents a significant advance in our understanding of verditer production and its challenges. Procedures for verditer synthesis are drawn from both 17th c. documentation and 20th c. replication work. The effects of temperature, copper and carbonate sources, solution stirring, copper ion concentration, and atmospheric composition are studied in order to elucidate the mechanism of synthesis and explain its unreliability in early modern refineries. Products are characterised by polarised light microscopy, scanning electron microscopy, Raman spectroscopy, and powder X-Ray diffraction. Rouaite, a green basic copper nitrate, is for the first time confirmed as a product of the refiners’ synthesis and a precursor to blue verditer in laboratory syntheses. This result problematises the blanket identification of green verditer as basic copper carbonate and provides important clues to the mechanism for blue verditer synthesis. Solution chemistry and ion equilibria allow us to explain the route by which rouaite is first formed and then converted to blue verditer. Conditions favouring blue verditer production are also clarified further. Although it is commonly stated that low temperatures are required for blue verditer production, blue verditer is produced here at a range of ambient temperatures. The reaction is found instead to be controlled by solution equilibria and heavily favoured by high partial pressures of carbon dioxide. Alongside archival materials about refining and verditer production, these results are contextualised and explanations for the unreliability of historical synthesis are proposed.

Facile synthesis of lignin/polyethyleneimine foams incorporating zeolitic imidazole framework-8 to efficiently remove tetracycline from aqueous solution

Lignin, as a by-product produced in the biological refining and papermaking processes, is often discarded or burned, resulting in environmental pollution and resource waste. Herein, a novel environmental-friendly ternary hybrid foams adsorbent (SLS/PEI/ZIF-8) was designed for effectively removal TC from aqueous solution. The adsorption properties of the adsorbent were systematically studied. The results show that the adsorption process for TC were fitted well by the pseudo-second-order kinetics model and the Langmuir isotherm model, respectively. The maximum Langmuir monolayer adsorption capacity of SLS/PEI/ZIF-8 for TC was calculated as 1098 mg/g at 30 °C, which was superior to most reported adsorbents. Thermodynamic analysis indicated the adsorption process for TC was spontaneous and endothermic. Moreover, the electrostatic interactions, hydrogen bonding interactions and π–π interactions were proposed as the possible adsorption mechanism. The adsorbent still maintained superior adsorption capacity for TC in ions solution, HA solution and actual water samples, and had good reusability. Therefore, it is a promising adsorbent for the removal of TC from wastewater.

Activated carbon fibers of high surface area from corn husk: Mono and multicomponent adsorption studies of Pb2+ and Cu2+ ions from aqueous solution

The present work reports the preparation of activated carbon fibers (ACF) from corn husk through the slow pyrolysis process in the presence of H3PO4. The ACF were properly characterized, exhibiting morphological characteristics of microfibers, high surface area (SBET = 1824 m2/g), and acidic surface properties (pHpcz = 3.85). Adsorption studies for mono and multicomponent systems of Pb2+ and Cu2+ ions in aqueous solution were carried out and kinetic models of pseudo-first-order, pseudo-second-order, and Elovich, and equilibrium models of Langmuir, Freundlich, and Dubinin-Radushkevich, as well as, multicomponent adsorption models of modified Langmuir, extended Freundlich, and Sheindorf-Rebuhn-Sheintuch were fitted to the experimental data. The results showed the ACF exhibited high adsorption capacity in the monocomponent system (Pb2+= 210.6 mg g−1, Cu2+= 212.9 mg g−1), which decreased for the multicomponent system (Pb2+ = 101.6 mg g−1; Cu2+ = 56.1 mg g−1). Furthermore, the adsorption process involved both physisorption and chemisorption reactions and it was considered spontaneous and endothermic.

Preparation of amidoxime modified covalent organic framework for efficient adsorption of lead ions in aqueous solution

Preparation of amidoxime modified covalent organic framework for efficient adsorption of lead ions in aqueous solution

Effect of Bismuth Doping on Electrodeposition, Physicochemical Properties and Electrocatalytic Activity of Lead Dioxide Electrodes

The bismuth (Bi)-doped PbO2 electrodes were electrodeposited from a nitric plating solution containing Pb (II) and Bi (III) ions by varying the concentrations of Bi (III). Cyclic voltammetry was used to investigate the effect of Bi (III) ions on the kinetics of PbO2 electrodeposition. It is observed that increasing Bi (III) ions in the plating solution reduces the rate of nucleation or formation of PbO2 but does not change the process mechanism. X-ray diffraction confirms that the incorporation of bismuth results in an apparent β (301) texture. Scanning electron microscopic observation reveals that the size of the PbO2-deposit particles gradually decreases by several micrometers as the doping content of Bi (III) increases from 2 to 6mM. Linear scanning voltammograms show that the oxygen overpotential on Bi-PbO2 is much higher than on undoped PbO2 electrodes. Electrochemical degradation of the target pollutant was performed, and HPLC analysis demonstrated that Bi doping significantly improves the electrocatalytic ability of PbO2 electrodes.