Ion Concentration In Solution Research Articles

Comparison on early hydration of Portland cement and sulphoaluminate cement in the presence of nano ettringite

This paper proposed adopting ettringite-based nucleation seeds to induce ettringite to precipitate in the pore solution, and thus facilitated early hydration reaction. In present work, sulphoaluminate cement (SAC) and Portland cement (PC) paste were considered, and 0 ∼ 5 % nano-ettringite prepared by hydration-wet grinding method was extra incorporated. The hydration kinetic of the blends was studied by hydration heat, chemical shrinkage and setting time. The effects of nano-ettringite on the dissolution behavior were also examined by dynamic conductivity of cement slurry, ion concentration and conductivity of pore solution. Meanwhile, the hydrate assemblage was determined by XRD, TGA, FTIR and 27Al NMR, and the compressive strength was also tested. On this basis, the hydration mechanism was discussed. Results indicated that nano-ettringite significantly hastened ions dissolution and ettringite precipitation, whether it was SAC or PC paste. The initial hydration heat release and chemical shrinkage were obviously promoted, and even cracks were generated in SAC paste; besides, the setting time was also shortened dramatically. In the presence of 1 ∼ 5 % nano-ettringite, the compressive strength of PC pastes at 8 h was increased by 54 ∼ 180 %. However, the strength of SAC paste at all ages was degraded by adding nano-ettringite, due to the appearance of cracks and reduced amount of AH3.

Adsorption of Heavy Metal Ions Copper, Cadmium and Nickel by Microcystis aeruginosa.

To investigate the treatment effect of algae biosorbent on heavy metal wastewater, in this paper, the adsorption effect of M. aeruginosa powder on heavy metal ions copper, cadmium and nickel was investigated using the uniform experimental method, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and TG-DSC comprehensive thermal analysis. The experimental results showed that the initial concentration of copper ion solution was 25 mg/L, the temperature was 30 °C, the pH value was 8 and the adsorption time was 5 h, which was the best condition for the removal of copper ions by algae powder adsorption, and the removal rate was 83.24%. The initial concentration of cadmium ion solution was 5 mg/L, the temperature was 35 °C, the pH value was 8 and the adsorption time was 4 h, which was the best condition for the adsorption of cadmium ion by algae powder, and the removal rate was 92.00%. The initial nickel ion solution concentration of 15 mg/L, temperature of 35 °C, pH value of 7 and adsorption time of 1 h were the best conditions for the adsorption of nickel ions by algae powder, and the removal rate was 88.67%. The spatial structure of algae powder changed obviously before and after adsorbing heavy metals. The functional groups such as amino and phosphate groups on the cell wall of M. aeruginosa enhanced the adsorption effect of heavy metal ions copper, cadmium and nickel. Additionally, M. aeruginosa adsorption of heavy metal ions copper, cadmium, nickel is an exothermic process. The above experiments show that M. aeruginosa can be used as a biological adsorbent to remove heavy metals, which lays a theoretical foundation for the subsequent treatment of heavy metal pollution by algae.

Design of a Novel Nanosensors Based on Green Synthesized CoFe2O4/Ca-Alginate Nanocomposite-Coated QCM for Rapid Detection of Pb(II) Ions.

Pb(II) is a significant contaminant that is known to have negative effects on both humans and animals. Recent industrial operations have exacerbated these consequences, and their release of several contaminants, including lead ions, has drawn attention to the potential effects on human health. Therefore, there is a lot of interest in the rapid, accurate, and selective detection of lead ions in various environmental samples. Sensors-based nanomaterials are a significant class among the many tools and methods developed and applied for such purposes. Therefore, a novel green synthesized cobalt ferrite (CoFe2O4) nanoparticles and functionalized CoFe2O4/Ca-alginate nanocomposite was designed and successfully synthesized for the fabrication of nanoparticles and nanocomposite-coated quartz crystal microbalance (QCM) nanosensors to detect the low concentrations of Pb(II) ions in the aqueous solutions at different temperatures. The structural and morphological properties of synthesized nanoparticles and nanocomposite were characterized using different tools such as X-ray diffraction (XRD), N2 adsorption–desorption isotherm, dynamic light scattering (DLS), zeta potential analyzer (ζ-potential), atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDX). The QCM results revealed that the green synthesized CoFe2O4 nanoparticles and functionalized CoFe2O4/Ca-alginate nanocomposite-coated QCM nanosensors exhibited high sensitivity, stability, and rapid detection of Pb(II) ions in the aqueous solutions at different temperature. The lowest detection limit for Pb(II) ions in the aqueous solutions could reach 125 ng, which resulted in a frequency shift of 27.49 ± 0.81, 23.63 ± 0.90, and 19.57 ± 0.86 Hz (Δf) for the QCM detector coated with green synthesized CoFe2O4 nanoparticles thin films, and 25.85 ± 0.85, 33.87 ± 0.73, and 6.87 ± 0.08 Hz (Δf) for the QCM detector coated with CoFe2O4/Ca-Alg nanocomposite thin films in a real-time of about 11, 13, and 13 min at 25 °C, 35 °C, and 45 °C, respectively. In addition, the resonance frequency change results showed the superiority of functionalized CoFe2O4/Ca-alginate nanocomposite coated QCM nanosensor over CoFe2O4 nanoparticles towards Pb(II) ions detecting, which attributed to the beneficial properties of alginate biopolymer.

Chem-bio interface design for rapid conversion of CO2 to bioplastics in an integrated system

Chem-bio interface design for rapid conversion of CO2 to bioplastics in an integrated system

Study on Mechanical Properties and Weakening Mechanism of Acid Corrosion Lamprophyre.

In order to study the weakening mechanism and mechanical behaviors of hard lamprophyre of Carboniferous Permian coal-bearing strata in China’s mining area, lamprophyre samples were subjected to static rock dissolution experiments with pH values of 0, 2, and 4. The acid corrosion mechanism of lamprophyre was revealed from the weight changes of samples, characteristics of solution ion concentration, and macro-mechanical properties. The experimental results show that reaction occurred between lamprophyre and acid solution. With the increasing concentration of H+, the reaction was more intense, the degree of acid etching was higher, and the weight loss was greater. The internal damage induced by acid etching results in the slow extension of the compaction stage of stress–strain curve of uniaxial compression, and the obvious deterioration of mechanical properties of the lamprophyre. The uniaxial compressive strength of the lamprophyre in the dry state is 132 MPa, which decreased to 39 MPa under the acid etching condition, showing significant mudding characteristics. Dolomite (CaMg(CO3)2 with 19.63%) and orthoclase (KAlSi3O8 with 31.4%) in lamprophyre are the major minerals constituents involved in acidification reaction. Photomicrograph recorded from SEM studies reveals that the dissolution effect was directly related to the concentration of H+ in the solution. The dissolution effect was from the surface to the inside. The small dissolution pores became larger and continuously expanded, then finally formed a skeleton structure dominated by quartz. The content of K+, Ca2+, and Mg2+ in the solution after acid etching reaction indicates that the acidified product of orthoclase is colloidal H2SiO3, which adhered to the surface of samples during acid etching and hinders the further acidification of minerals. The dissolution of dolomite and orthoclase under acidic conditions directly leads to the damage of their structure and further promotes the water–rock interaction, which is the fundamental reason for the weakening of the mechanical properties of lamprophyre.

Evaluation of Green-Synthesized Cuprospinel Nanoparticles as a Nanosensor for Detection of Low-Concentration Cd(II) Ion in the Aqueous Solutions by the Quartz Crystal Microbalance Method.

Cd(II) heavy metal is an extremely dangerous hazardous material for both humans and the environment. Its high toxicity is the reason behind the examination of new techniques for detecting very small concentrations of Cd(II). Recently, Quartz Crystal Microbalance (QCM) has been one of the techniques that have been widely used to detect trace heavy metal ions in solutions. It is a simple, inexpensive, portable, and sensitive gravimetric sensor due to its quality sensitivity lowest to nanograms. In this work, Cuprospinel nanoparticles were synthesized through the green synthesis approach using Psidium guajava L. leaf extract as a reducing agent, which is the first scientific description to report the preparation of these nanoparticles by this method. Subsequently, the synthesized nanoparticles were subjected to the characterization of their crystallinity, structure, and morphology by the XRD, N2 adsorption–desorption, zeta potential, DLS, AFM, SEM, and TEM analyzers. The prepared Cuprospinel nanoparticles were evaluated as a nanosensor for the detection of the very low concentration of Cd(II) ions in aqueous solutions using the QCM technique. The results of the characterization proved that the Cuprospinel nanoparticles have formed in the nanoscale with sub-spherical shapes and particles size ranging from 20 to 80 nm. The BET surface area and pore size analysis revealed that the synthesized Cuprospinel nanoparticles possess a surface area of 47.3 m2/g, an average pore size of 1.5 nm, and a micropore volume of 0.064 cc/g. The QCM results demonstrated the success of the Cuprospinel nanoparticles sensor in detecting the tiny amounts of Cd(II) ions in the aqueous solutions with concentrations reaching about 3.6 ng/L.

Degradation mechanism of cement-based materials under the effects of stray current, chloride and sulfate

When infrastructure is exposed to a complicated environment containing stray current, chloride and sulfate, it may be subjected to severe degradation. In order to analyze the interaction of different factors and the degradation mechanism of cement-based materials in a complicated environment, the blended solution with four molar concentration ratios of Cl-/SO42- (0, 0.5, 1, and 2) were prepared to simulate a range of aggressive medium. Meanwhile, 40 V DC (direct current) electrical field was applied to cement-based materials to simulate stray current. After exposure, the transport properties, macro-properties, and microstructures of specimens were observed and measured. Additionally, the types and amounts of degradation products were tested to further analyze the degradation mechanism of cement-based materials. Experimental results show that chloride in the blended solution could inhibit SO42- transport into cement-based materials, causing the SO42- concentration in a specimen to decrease with the increase of Cl-/SO42- ratio. Therefore, the specimens appeared less degraded in terms of macro-properties. But the results of microstructural analysis showed that degradation products and cracks were generated in the interior of specimens. Friedel’s salt was detected in the specimens exposed to the solutions containing chloride. The formation of Friedel’s salt consumed calcium aluminate hydrate, which caused the amount of Al-phase involved in the formation of ettringite to reduce. Consequently, the amount of ettringite was reduced, and the degradation of compressive strength and appearance was also reduced. Additionally, an electrical field could induce the ion concentration in pore solution to change and even break the ion chemical equilibrium, which resulted in the decomposition of ettringite and Friedel’s salt. However, Friedel’s salt can also transform into ettringite at a specific condition. Therefore, the amounts of ettringite and Friedel’s salt in specimens were changed over the exposure time.

A Simple Contactless High-Frequency Electromagnetic Sensor: Proof of Concept.

We report on the development of a very simple and inexpensive sensor device based on an inductance coil connected to a high-frequency electric field generator. The working principle of this sensor is as follows: liquid sample in a plastic tube is placed inside the inductance coil as its core and this core changes the properties of high-frequency electric current passing through the coil; these changes depend on sample conductivity, dielectric constant, magnetic properties, and capacitance. The electric signal registered after the coil represents a kind of a spectrum that can be effectively treated with chemometric tools. Our studies have shown that such a sensor can be used to distinguish between substances with different physical and chemical properties; different concentrations of ions in aqueous solutions with a linear response in a broad concentration range from 10-3 M to 10-1 M; can quantify the fat content in milk and cream samples with about 2% accuracy; and can distinguish between bacterial cultures and cell line cultures. The measurements are very fast and contactless, and the results show good promise for developing a number of applications of this sensor system.

Selective electrodialysis process for the separation of potassium: Transmembrane transport of ions in multicomponent solution systems

With the development of global agriculture, the demand for potash is growing rapidly. The concentration of K+ in bittern can reach 10 g/L, but the economic benefit of existing extraction methods is still a key concern, and a new extraction method is urgently needed. The monovalent selective electrodialysis was proposed in this study to purify K+. The effects of coexisting ion concentration, voltage, temperature, and ionic strength of dilute solution on the separation of K+ from brine were investigated in ternary system, quaternary system, and quinary system, respectively. Monovalent selective electrodialysis was preliminarily applied to separate K+ from actual bittern. The results showed that monovalent selective electrodialysis can effectively extract K+ and reduce the ratio of Mg2+/K+ from 7.11 to 0.92 with a K+ recovery rate of 74.83%.

Potassium Ion‐selective Electrode with a Sensitive Ion‐to‐Electron Transducer Composed of Porous Laser‐induced Graphene and MoS2 Fabricated by One‐step Direct Laser Writing

AbstractIn this study, an ion‐selective electrode with a sensitive ion‐to‐electron transducer composed of porous laser‐induced graphene (LIG) and MoS2 (LIG‐MoS2/ISE) was fabricated to measure the potassium ion concentration in a greenhouse nutrient solution for soilless culture. Additionally, a more effective and low‐cost method was proposed for the large‐batch production and manufacture of potassium ion‐selective electrodes (K+‐ISEs) using the direct laser writing technique, which differs considerably from existing methods. Moreover, the sensing mechanism of the proposed LIG‐MoS2/ISE for potassium ion detection was investigated. The morphology and physical properties of the LIG‐MoS2/SC‐K+‐ISEs were studied by X‐ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy and energy‐dispersive spectroscopy. Potentiometric measurements, chronopotentiometry, potentiometric water layer tests, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to evaluate the analytical performance of the newly developed K+‐ISEs. A Nernstian slope of 30.1 mV/decade for the activity of potassium ions in a concentration range from 10−7 to 10−2 M was determined. The EIS and chronopotentiometry results revealed that the LIG‐MoS2/SC‐K+‐ISE had a larger resistance and double‐layer capacitance than the LIG/SC‐K+‐ISE. The ion‐selective membrane (ISM) and solid‐contact layer did not have any water film between them, according to the potentiometric water layer test. The results proved that the LIG‐MoS2 nanocomposite could possibly be used as a sensitive ion‐to‐electron transducer to fabricate K+‐ISEs. The K+‐ISE fabrication method using the direct laser writing technique had a higher efficiency, enabling its broad application prospects in agriculture.

Comparative Study of the Adsorption Effects of Activated Carbons from Coconut Shell and Groundnut Shell as Absorbents for Metal Ions

The main objective of this research was to compare the effect of contact time, concentration, and temperature in preparing activated carbon from coconut shells and groundnut shells. The research was carried out at a temperature range of 35 -65 and the maximum adsorption capacities for Pb(II) and Cd(II) ions were respectively 3.61 and 3.34 mg/g for coconut shell, 3.21 and 3.13 mg/g for groundnut shell at the optimum temperature of 35 . Thus the maximum ion adsorption capacities followed the trend: coconut shell>groundnut shell. These results were obtained using the following optimum conditions: initial metal ions concentration of 100 mg/dm3, adsorbents weight of 0.5g, time of 30 min, and pH of 6. The adsorption of the metal ions by the adsorbents was found to decrease with an increase in the initial concentration of the metal ions in an aqueous solution. Also, the adsorption rate increased with temperature. The result of the work revealed that activated carbons derived from coconut shells and groundnut shells can be used as a low-cost alternative to commercial adsorbents in the removal of Pb(II) and Cd(II) ions from water and wastewater.

Effects of cation in sulfate chloride and nitrite on Ca(OH)2 activated ground granulated blast-furnace slag

This study explores the effects of the cations in sulfates, chlorides, and nitrites on calcium-hydroxide activated blast-furnace slag. Using several methods, it was demonstrated that the activators investigated could improve early strength development. Compared with chlorides and nitrites, the type of sulfate has a significant influence on slag hydration. Compared with K2SO4 and Na2SO4, the promotion of slag hydration in MgSO4, at an early age, is limited due to the precipitation of gypsum and brucite which retard the formation of hydrates and limits hydration kinetics during the initial stage. The high concentration of sulfate ions in the pore solution causes some ettringite to remain, promoting strength development. It was observed that the mechanism of pH increase in K2SO4 and Na2SO4 is due to the synergistic reactions between the sulfates and Ca(OH)2, while the low pH of MgSO4 due to the low solubility of brucite inhibits slag dissolution. The critical pH for promoting slag hydration was determined to be 13.1.

Study on improving the activity of mineralized microorganisms by regulating the chemical environment of marine concrete crack area with inorganic minerals

The activity of mineralized microorganisms in concrete crack area, including growth activity and enzyme level, was an important prerequisite to realize the self-healing of concrete cracks. At the same time, Cl− and SO42− in seawater could accelerate the corrosion of marine concrete through cracks. Therefore, the self-healing of marine concrete cracks faced the dual test of improving the activity of mineralized microorganisms and slowing down the erosion of harmful ions. In this paper, improving the activity of mineralized microorganisms by regulating the chemical environment of marine concrete crack area with inorganic minerals was studied systematically. Firstly, the concentration of ions in simulated solution were analyzed, and pH value of solution was studied; Through the deposition of inorganic minerals, Cl−, SO42− and OH− were adsorbed and fixed, and pH value decreased significantly. Secondly, the composition and morphology of inorganic minerals were analyzed by SEM, EDS and XRD. Inorganic minerals presented a laminate structure, which were confirmed as bimetallic hydroxides of calcium and aluminum. Finally, microorganisms were cultured in simulated solution of marine concrete crack area, and the growth performance of microorganisms was tracked and analyzed; microbial growth was significantly improved, which was basically equivalent to that of the control group. The effect of bimetallic hydroxide on improving the environment and promoting the growth of microorganisms was confirmed, and the research provided a new idea for the self-healing of marine concrete cracks.

NMR and Theoretical Study of In-Pore Diffusivity of Ionic Liquid-Solvent Mixtures.

Despite having a lower energy density than common batteries, electric double-layer capacitors (EDLCs) offer several advantages for high-power applications, including high power density, quick charge and discharge time, and long cycle life. Room-temperature ionic liquids (RTILs) have been intensely studied as promising electrolytes for applications in ELDCs because of their wide potential window, low volatility, as well as thermal and chemical stability. The main deficiency of neat RTILs in such applications is the sluggish diffusivity, which restricts the EDLCs' power density. To alleviate the slow diffusivity, RTILs can be used in a mixture with organic solvents. In this study, we applied two-dimensional exchange nuclear magnetic resonance spectroscopy (2D EXSY NMR) and molecular dynamics (MD) simulations to investigate the diffusivity of anions of an RTIL, namely, 1-butyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide (BMIM+-TFSI-), dissolved in five different organic solvents, in the micropores of activated carbon. We determined that the relative concentrations of ions in solutions in the micropores were higher than those in the bulk solutions and were also solvent-dependent. The ion diffusivities in the pores were found to be almost 2 orders of magnitude slower than in the bulk solutions, with methanol showing the largest relative disparity. These results suggested that the interactions of solvents with the activated carbon are critical not only to the power density of EDLCs but also to the energy density. The comparisons of ion diffusivities between the experiments and the MD simulations suggest the need to consider also the surface functionalities of activated carbon for the simulation of ion diffusion in the micropores of activated carbon.

Mechanisms underlying the relationship between electrical resistivity and corrosion rate of steel in mortars

The linear relationship between electrical resistivity of concrete and corrosion rate of steel in logarithmic coordinates (referred as R-C relationship) has been widely reported. However, R-C relationships are not universal but highly dependent on binder chemistry and corrosion environment, and there has been no consensus on the reasons behind the discrepancy of R-C relationships reported in the literature. In this work, the R-C relationships of alkali-activated slag (AAS) mortars are investigated and compared with that of reference ordinary Portland cement (OPC) mortars, aiming at uncovering the fundamental compositional parameters that cause differences in R-C relationships of various cementitious systems. The results show that the hydroxide ion concentration (pH value) of pore solution has a significant and decisive effect on the R-C relationship. With the decrease of pH, the material resistivity increases because of decreased pore solution conductivity while corrosion rate of steel increases due to the drop of [Cl−]/[OH−], leading to a shift of R-C relationship lines. A new mechanism is proposed to explain the differences in the R-C relationship caused by binder chemistry and corrosion type (chloride- versus carbonation-induced corrosion), which is further verified using the published experimental results in the literature.

Tracking the adsorptive effect of nano silicate–ginkgo residue composite for Sr(II) and Cd(II) removal from aqueous solutions

Ginkgo biloba (Ginkgo)/calcium silicate nanocomposite (NG-CSA) was prepared as a novel sorbent. Nanomaterial was characterized using different techniques such as Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, differential thermal analysis and thermal gravimetric analysis (DTA and TG). Adsorption of Sr(II) and Cd(II) ions was performed taking into account significant parameters such as initial pH of the solution, shaking time and initial concentration of metal ions as well as temperature. The acquired results were disclosed that the adsorption of both ions is notably improved using NG-CSA composite. The monolayer capacity of NG-CSA for Sr(II) and Cd(II) from binary system is 122.45 and 64.68 mg/g for Sr(II) and Cd(II), respectively. The kinetic studies exposed that the adsorption process followed nonlinear pseudo-first-order model. The isotherm studies show that the extended Langmuir model is more applicable than Freundlich model for binary system adsorption process. The value of diffusion coefficient for the Sr(II) and Cd(II) is in range 10−10 m2/s which indicates the chemisorption nature of the process. The maximum value of desorption for the Sr(II) and Cd(II) is 98.41% and 97.66 utilized 0.3 M of nitric acid. This indicated that NG-CSA composite can be regenerated and reused for further adsorption of Sr(II) and Cd(II) from wastewater.

Kinetic and equilibrium study of pyrolyzed sugarcane bagesse as adsorbents for Pb2+ and Cd2+ in an aqueous medium

ABSTRACT Sugarcane bagesse was utilised as a low-cost adsorbent for the removal of metal ions. The study was done at a temperature of 35°C, and the maximum adsorption capacities for Pb(II) and Cd(II) ions were 3.02 and 2.90 mg/g, respectively, for sugarcane bagasse. These results were determined using the following optimum conditions: initial metal ion concentration of 100 mg/dm3, adsorbent weight of 0.5 g, time of 30 min and pH of 6. The adsorption of the metal ions by the adsorbents decreased with an increase in the initial concentration of the metal ions in an aqueous solution. The rate of adsorption also increased with temperature. The adsorption showed a good fit to the Langmuir model compared to the Freundlich adsorption model. The Langmuir dimensionless constant (RL) for the adsorption of Pb(II) ion and Cd(II) ion ranged from 0.081 to 0.123 and 0.115 to 0.172, respectively, which confirms favourable adsorption. The adsorption process showed that the pseudo-second-order kinetics was a better fit than the pseudo-first-order kinetics. The result of this work showed a low-cost and efficient potential of sugarcane bagasse to be employed as a good adsorbent for metal ion removal.

New method for recovery of nickel and cadmium from the ”black mass” of spent Ni-Cd batteries by solvent extraction

The paper presents experiments with solid–liquid-liquid extraction of heavy metals from the “black mass” (BM) of waste batteries related to the recycling of nickel and cadmium, as well as cobalt (for several samples) from spent Ni-Cd batteries. The extraction and separation of Ni(II) and Cd(II) from the solid BM with Deep Eutectic Solvents (DESs) and other extractants dissolved in toluene or naphtha (kerosene) have been investigated in detail. It has been shown that the extraction efficiency of DESs, contrary to ionic liquids (ILs), is at the level of 30 wt% Ni(II) and 100 wt% Cd(II) from the BM, without the primary process of leaching with sulphuric acid. Solvent extraction has been proposed with two DESs (choline chloride + lactic acid and choline chloride + malonic acid), with ionic liquids (ILs): trihexyltetradecylphosphonium chloride [P6,6,6,14][Cl] (Cyphos IL 101) and trihexyltetradecylphosphonium thiocyanate [P6,6,6,14][SCN], and with organophosphorous-based acids (OPBAs) such as bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex 272) and di-(2-ethylhexyl) phosphoric acid (D2EHPA). Process factors such as extracting solvents and additives, solvent concentration, holding time, pH and liquid/solid, as well as organic/aqueous (O:A) ratios were studied. For all the systems, the extraction efficiency (E) and the distribution ratio (D) were specified. The metal content in the solid BM was analyzed by the SEM/EDS method and with the use of the UltraWAVE digestion system combined with an atomic absorption spectrometer (FAAS and FAES techniques). An inductively coupled plasma optical emission spectrometer (ICP-OES) was used to determine the concentration of metal ions in aqueous solutions and stripped organic solutions.

An Ion Selective Electrode Based on Ti3C2 Solid‐state Transduction for Rapid Detection of Lead Ion Concentration in Aqueous Solution

Conduction layer plays an important role in ion-selective electrodes (ISEs) with solid-state transduction. Herein, a lead ISE was prepared with Ti3C2 as the conductive layer, which has less water film and good anti-interference ability to O2, CO2 and light. Concentration of lead ions can be quickly determined by detecting the electromotive force of the galvanic cell. In 10−3–10−7 M, the Nernst slope is found to be 28.3±1.02 mV/decade. And the detection limit is 4.4×10−8 M (n=3). It indicates that Ti3C2 is suitable for the conductive layer in solid ISEs.

Mechanochemically prepared Zn–Al LDH precursor for rare earth elements recovery

The ionic rare earth elements (REEs) was mainly recovered by in-situ leaching process. The concentration of rare earth ions in the leaching solution after long-term leaching process would be too low for traditional precipitation process for REEs recovery. The adsorption process was ideal for the low concentration REEs recovery. In this study, Zn–Al LDH precursor were successfully synthesized by mechanochemical method for the adsorption of REEs (including La−, Eu3+ and Er3+). X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron energy spectrometer (XPS), and Zeta potential test was applied for adsorption mechanism illustration. The maximum adsorption capacity of the Zn–Al LDH precursor for La3+, Eu3+ and Er3+ reached 492 mg/g, 346 mg/g, and 1154 mg/g which was significantly higher than other types of adsorbents. The adsorbed REEs on the Zn–Al LDH was hard to be desorbed. The Zn–Al LDH precursor after REEs adsorption could be directly used as high content REEs resources for further process.Therefore, the Zn–Al LDH precursor could be a promising adsorbent for REEs recovery in practical application.