Separation Of Metal Ions Research Articles

Separation of Copper and Nickel Metal Ions from Electroplating Wastewater by Ultrafiltration with Tartaric Acid and Sodium Citrate Reinforced Sodium Polyacrylate Complexation

In this study, sodium polyacrylate (PAAS) and ultrafiltration membranes were used to extract and separate Cu2+ and Ni2+ ions from electroplating wastewater. The effects of pH, the P/M ratio (mass ratio of sodium polyacrylate to metal ions), tartaric acid, and sodium citrate on the complexation of Cu2+ and Ni2+ by sodium polyacrylate were investigated. The retention of Cu2+ and Ni2+ by PAAS in single metal solutions with a P/M ratio = 4 and pH = 5 differed by 45.36%. When the complexation system of PAAS with a single metal contained tartaric acid and sodium citrate, the retention of PAAS for Cu2+ and Ni2+ increased to 80.36% and 58.84%. PAAS retention for Ni2+ decreased, but retention for Cu2+ remained the same. All the results indicated that there was competition between tartaric acid, sodium citrate, and PAAS for the adsorption of Cu2+ and Ni2+. Some of the Ni2+ complexed with PAAS were detached from PAAS complexed by tartaric acid and sodium citrate and permeated through the membrane pores, while the Cu2+ complexed with PAAS was not complexed by tartaric acid and sodium citrate and could not permeate through the membrane pores. Therefore, this study helps to provide a theoretical basis for the separation of Cu2+ and Ni2+ in electroplating wastewater.

Enrichment of lithium ions for battery application by electrolysis through a nanoporous membrane

In recent years, lithium (Li) has become a valuable commodity widely used in rechargeable batteries. The present study aims to extract battery-grade lithium-ion, as lithium hydroxide (LiOH), from lithium chloride (LiCl) solution by the membrane electrolysis process. Experiments are performed using a commercial cation exchange membrane and an indigenous High flux-Nanofiltration 300 alkali resistant (HF-NF 300 AR) nanoporous membrane. The dual-chamber electrolytic cell incorporates a selective membrane to separate the feed and concentrate chambers containing LiCl solution and deionized water. These two chambers are connected with titanium electrodes through the external circuit. The in-situ design of the compact two-chambered acrylic electrolytic cell helps to separate metal ions from ionizable salts of sodium, lithium, magnesium, potassium, etc. The experiment is conducted on a laboratory scale by varying the LiCl concentration at voltages of 24 V and 36 V. The feed and concentrate solutions are analyzed for pH, conductivity, and total dissolved solids. Inductively coupled plasma-optical emission spectrometry evaluates the presence of metal ions in the solution. The study shows effective metal ion recovery and separation to achieve battery-grade Li.

Modulating metal-centered dimerization of a lanthanide chaperone protein for separation of light lanthanides

Elucidating details of biology's selective uptake and trafficking of rare earth elements, particularly the lanthanides, has the potential to inspire sustainable biomolecular separations of these essential metals for myriad modern technologies. Here, we biochemically and structurally characterize Methylobacterium (Methylorubrum) extorquens LanD, a periplasmic protein from a bacterial gene cluster for lanthanide uptake. This protein provides only four ligands at its surface-exposed lanthanide-binding site, allowing for metal-centered protein dimerization that favors the largest lanthanide, LaIII. However, the monomer prefers NdIII and SmIII, which are disfavored lanthanides for cellular utilization. Structure-guided mutagenesis of a metal-ligand and an outer-sphere residue weakens metal binding to the LanD monomer and enhances dimerization for PrIII and NdIII by 100-fold. Selective dimerization enriches high-value PrIII and NdIII relative to low-value LaIII and CeIII in an all-aqueous process, achieving higher separation factors than lanmodulins and comparable or better separation factors than common industrial extractants. Finally, we show that LanD interacts with lanmodulin (LanM), a previously characterized periplasmic protein that shares LanD's preference for NdIII and SmIII. Our results suggest that LanD's unusual metal-binding site transfers less-desirable lanthanides to LanM to siphon them away from the pathway for cytosolic import. The properties of LanD show how relatively weak chelators can achieve high selectivity, and they form the basis for the design of protein dimers for separation of adjacent lanthanide pairs and other metal ions.

Covalent organic framework membranes with vertically aligned nanorods for efficient separation of rare metal ions

Covalent organic frameworks (COFs) have emerged as promising platforms for membrane separations, while remaining challenging for separating ions in a fast and selective way. Here, we propose a concept of COF membranes with vertically aligned nanorods for efficient separation of rare metal ions. A quaternary ammonium-functionalized monomer is rationally designed to synthesize COF layers on porous substrates via interfacial synthesis. The COF layers possess an asymmetric structure, in which the upper part displays vertically aligned nanorods, while the lower part exhibits an ultrathin dense layer. The vertically aligned nanorods enlarge contact areas to harvest water and monovalent ions, and the ultrathin dense layer enables both high permeability and selectivity. The resulting membranes exhibit exceptional separation performances, for instance, a Cs+ permeation rate of 0.33 mol m−2 h−1, close to the value in porous substrates, and selectivities with Cs+/La3+ up to 75.9 and 69.8 in single and binary systems, highlighting the great potentials in the separation of rare metal ions.

Spatial Size Manipulation of 1D/2D Channels in Covalent Organic Framework Membranes Through Dopamine Chemistry for Ion Separations

AbstractCovalent organic framework (COF) membranes feature with well‐developed 1D in‐plane pores and parallelly arranged 2D interlayer gallery, presenting promising platform for precise separations. However, it remains a formidable challenge to construct and regulate membrane channels at angstrom scale. Herein, pH‐sensitive dopamine is taken advantage to elaborately engineer the spatial size of 1D/2D channels in COF membranes for the separations of alkali metal ions. Acid treatment allows monomolecular dopamine to segment 1D in‐plane pores of COF membrane, achieving ultramicroporous regulation from 1.25 nm to 0.71 nm, which enables high selectivity of 18.7 for K+/Li+ separation. Molecular dynamics simulations reveal the higher dehydration degree, weaker channel‐cation interaction and faster diffusion coefficient of K+ than Li+. For alkaline treatment, dopamine self‐polymerizes to form nanoparticles between COF layers, which enlarges the 2D interlayer channels from 0.33 nm to 0.45 nm in COF membrane, enabling high‐permeance ion/molecule separations. The water permeance increases 86.7% to 404 L m−2 h−1 bar−1, without the sacrifice of membrane sieving ability. Both cation separation and ion/molecule separation performances outperform the current state‐of‐the‐art membranes. This dopamine‐mediated channel engineering strategy may provide the new insights for the design of membrane channels in precise separations.

Selective extraction of lead from chelator-rich effluents using a biomass-based sorbent

The efficient removal of lead (Pb) from waste streams containing chelators presents a significant challenge due to the high stability and mobility of Pb-chelator complexes. This study investigates a novel approach utilizing a biomass-based sorbent, proline-incorporated dithiocarbamate-modified cellulose with epoxy-cross-linkage (DMC-Pro-Epo6), to extract Pb from effluents with excess chelators. DMC-Pro-Epo6 exhibited exceptional Pb(II) sorption performance under controlled and various chelator-rich conditions. The sorbent maintained high sorption efficiency even with 100-fold excess chelator concentration and competing metal ions. DMC-Pro-Epo6 also outperformed commercially-available ion-selective sorbents in terms of separation efficiency. The sorption kinetics followed a pseudo-second order model, demonstrating rapid sorption with equilibrium reached within 20 min. The maximum sorption capacities of DMC-Pro-Epo6 obtained from the Langmuir isotherm model were 1267 and 659 µmol g−1 in Pb(II)-containing aqueous solution and Pb(II)-containing EDTA solution, respectively. X-ray photoelectron and absorption spectroscopy analyses, along with sorption parameters, confirmed a chemisorption mechanism for Pb(II) sorption onto DMC-Pro-Epo6. Validation of the protocol using real waste samples with complex chelator and base metal ion matrices resulted in a quantitative and selective extraction of 92 to 99 % of Pb(II). This success suggests the potential for scaling up the developed process. Compared to conventional treatment methods, the proposed technique offers a more efficient and streamlined process for separating metal ions and chelators from effluents.

Rapid and selective separation of heavy metal ions from aquatic medium using a bidentate functionalized hybrid material

Low-cost mesoporous silica material, functionalized with a bidentate pyrazolyl pyridine metal acceptor and presenting a high specific surface area of 417 m²/g, was synthesized (mSi-L3) using a two-step procedure and characterized in detail to confirm the successful covalent binding onto silica surface. Notably, mSi-L3 exhibited strong selectivity for PbII among CdII and CuII ions, and displayed rapid metal ion removal, typically less than 10 min, from water samples.The influence of various environmental parameters on the adsorption process, such as pH, contact time and temperature, was systematically investigated. Optimal adsorption of metal ions was achieved at pH 6, as lower pH values reduced the availability of active sites due to competitive hydronium ion presence. Kinetic studies indicated that the adsorption process adhered to the pseudo-second-order model, suggesting a chemisorption mechanism. Temperature significantly influenced the adsorption capacity, with increased temperatures enhancing metal ion removal and confirming the endothermic nature of the process. The isotherm study suggests that the Langmuir model accurately describes the adsorption process, confirming that CuII, CdII and PbII ions are adsorbed as a monolayer on the homogeneous surface of m-SiL3 material, implying that the material has uniform adsorption sites where each metal ion occupies a distinct site without interaction with neighbouring ions. These findings underscore the importance of optimizing environmental conditions to maximize the efficiency of mSi-L3 for heavy metal removal. Also, mSi-L3 demonstrated excellent stability, with only a slight (∼1−3 %) decrease in functional groups on its surface after multiple regeneration cycles. Extensive analytical studies conducted with real water samples provided further evidence of the stability and effectiveness of mSi-L3 for the separation of metal trace elements of lead, copper and cadmium.

Advanced Sorbents for Separation of Metal Ions

Effective, sustainable, and selective methods for recovering or removing metals from various media, such as mining leachates, recycling waste, industrial effluents, and natural water, are necessary due to the increasing demand for metals and stringent environmental constraints [...]

Modelling of a mechanically enhanced PTFE-PVC composite polymer inclusion membrane for highly selective separation of several transition metal ions

Conventional polymer inclusion membranes (PIMs) exhibit suboptimal mechanical properties. Consequently, new composite PIMs were prepared by a modified solvent evaporation method using a PTFE base membrane, a PVC polymer, and an organic phosphonate extractant. Their chemical compositions and microstructures were analyzed by ATR-FTIR and FESEM. The mechanical and mass transfer properties of the composite PIMs were systematically investigated. The composite PIMs exhibited significantly higher tensile strength (36.86 MPa to 52.77 MPa), reduced tensile strain (76.49 % to 118.49 %), and enhanced bursting strength exceeding 0.2 MPa, compared to conventional PIMs. The Zn2+/Cu2+ were separated with a high separation coefficient of 2003.19 by a retardant-enhanced composite PIM system. A new mass transfer model was developed by analyzing the multilayered structure of composite PIMs in depth. The apparent diffusion coefficient of Zn2+ within PTFE-PVC composite layer (7.76 × 10−14 m2/s) was found to be lower than that within polymer inclusion layer (3.18 × 10−13 m2/s). The optimal regions of polymer inclusion layer thickness, contact area, and time were selected by model calculation for a certain separation task (e.g., purity ≥ 0.97 and yield ≥0.80 for Zn2+ or Cu2+). Finally, the retardant-enhanced composite PIMs were successfully used for selective separation of several other transition metal ions.

Sorption, kinetic and separation studies of transition and heavy metal ions using cerium amino tris-(methylene phosphonic acid)

ABSTRACT In the present study, the ion exchange behaviour of cerium (IV) amino tris-(methylenephosphonic acid) (CeATMP) towards transition and heavy metal ions has been studied by determining the values of distribution coefficient (Kd) and breakthrough capacity (BTC). Various kinetic models such as pseudo-first-order, pseudo-second-order, and intra-particle diffusion have been applied to determine ion exchange efficiency and compared with the reported works. As a result, CeATMP was found to be an efficient ion exchange material in term of a very short equilibrium time to for a metal ion to occupy an exchange site. Among the separation studies, elution behaviour of these metal ions has been executed using various acids and electrolytes media. A few binary and ternary metal ion separations also have been performed with consideration of Kd values. A study on regeneration shows that material can be reused without loss of the performance ability in term of cation exchange capacity. The present work reveals a significant use of CeATMP as an effective cation exchange material for removing and separation of inorganic contamination as environmental cleaning applications.

Synthesis of Some Eco-Friendly Materials for Gold Recovery.

The aim of this study was to develop new materials with adsorbent properties that can be used for the adsorption recovery of Au(III) from aqueous solutions. To achieve this result, it is necessary to obtain inexpensive adsorbent materials in a granular form. Concomitantly, these materials must have a high adsorption capacity and selectivity. Other desired properties of these materials include a higher physical resistance, insolubility in water, and materials that can be regenerated or reused. Among the methods applied for the separation, purification, and preconcentration of platinum-group metal ions, adsorption is recognised as one of the most promising methods because of its simplicity, high efficiency, and wide availability. The studies were carried out using three supports: cellulose (CE), chitosan (Chi), and diatomea earth (Diat). These supports were functionalised by impregnation with extractants, using the ultrasound method. The extractants are environmentally friendly and relatively cheap amino acids, which contain in their structure pendant groups with nitrogen and sulphur heteroatoms (aspartic acid-Asp, l-glutamic acid-Glu, valine-Val, DL-cysteine-Cys, or serine-Ser). After preliminary testing from 75 synthesised materials, CE-Cys was chosen for the further recovery of Au(III) ions from aqueous solutions. To highlight the morphology and the functionalisation of the material, we physicochemically characterised the obtained material. Therefore, the analysis of the specific surface and porosity showed that the CE-Cys material has a specific surface of 4.6 m2/g, with a porosity of about 3 nm. The FT-IR analysis showed the presence, at a wavelength of 3340 cm-1, of the specific NH bond vibration for cysteine. At the same time, pHpZc was determined to be 2.8. The kinetic, thermodynamic, and equilibrium studies showed that the pseudo-second-order kinetic model best describes the adsorption process of Au(III) ions on the CE-Cys material. A maximum adsorption capacity of 12.18 mg per gram of the adsorbent material was achieved. It was established that the CE-Cys material can be reused five times with a good recovery degree.

Ultra-hydrophilic MOF-303 on electrospun nanofibers with Burr Puzzles structure for the purification of oily wastewater containing heavy metal ions

The current oil-water separation field is extremely complex and the material system is variable. Therefore, the full process applicability of membrane technology is extremely demanding, both in terms of high oil-water separation efficiency and the treatment of soluble substances in wastewater, such as heavy metal ions. The high demand for membrane performance is accompanied by the complexity of the membrane manufacturing process, resulting in the development of membrane technology being hindered. If we can purify heavy metal ions from wastewater while meeting the conditions of oil-water treatment, and simplify the process flow, it is an innovation that we are happy to see. Herein, the use of a seed pre-embedded growth strategy is taking polyacrylamide (PEI) as a breakthrough point, we take advantage of blending to introduce embedding sites in polyacrylonitrile (PAN) membranes. Uniform growth of MOF-303 with Burr Puzzle structure on membrane surface using in situ hydrothermal growth method. The Burr Puzzles structure on the membrane surface is not only able to effectively deal with nanoscale stabilized oil-water mixture and effectively adsorb heavy metal ions, but also enables the MOF-303 crystals to grow more firmly on the membrane surface, so that the modified membrane still maintains good performance in harsh environments. The separation fluxes of the oil-in-water emulsions were all higher than 6987 L m−2 h−1 for oil-in-water emulsion with a separation efficiency of 98.4 %, and the adsorption efficiency of heavy metal ions was also as high as 98.3 %. After 20 cycles, the membrane maintains its promising performance. Due to its simple preparation process and excellent efficiency of emulsions separation and heavy metal ions separation, simplifies complex membrane processes while meeting the rigors of wastewater treatment. it has great prospects for development in the current complex wastewater treatment process.

Ketone-based conjugated microporous poly(aniline)s for the ultradeep separation of heavy metal ions

The heavy-metal contamination of aquatic environments presents imminent threat. Herein, we report a class of dual-heteroatomic conjugated microporous poly(aniline)s showing high-affinity separation performance toward heavy metals. The prepared keto-CMPA shows monolayer adsorption capacity for Hg (II) as high as 980 mg g−1 according to the Langmuir model, and ultra-rapid kinetic with h reaching 30.41 mg g−1 that could be described by the pseudo-second-order model. It maintains excellent stability across six reuses under harsh conditions, and furthermore demonstrates ultradeep separation efficiency that could adsorb almost all of heavy metals to ppb level with low usage. For further industrialization, a competent adsorption device was developed to remove heavy metals down to 1 ppb with a remarkable breakthrough over 20,000 BV. Characterizations and DFT calculation showed that the triangular synergistic region formed by the N-O-sites in the singular CMPA structure provided a feasible binding energy to enable the above impressive performance.

Interfacial effect of coexisting salt cations on extraction of erbium using gas bubble-supported organic liquid membrane

The conventional understanding about the specific ion effect from the coexisting electrolyte salts on the extraction and separation of target metal ions during liquid-liquid solvent extraction cannot explain some abnormal phenomena when more than one kind of background ions coexisting in the aqueous feed solutions to be separated. In this work, the specific ion effect of coexisting ions, Mg2+ and Al3+ as the example here, on extraction of Er3+ ion was investigated using gas bubble-supported organic liquid membrane. A very interesting phenomenon was noticed that, the difference in Er3+ extraction percentage was only 11.7 % in the Er-Mg solution system with addition of Al3+ ions or not, while it could reach 18.0 % in that of Er-Al with addition of Mg2+ ions or not. When Mg2+ and Al3+ coexisted simultaneously in the feed solutions, their specific ion effect on improving the extraction percentage of Er3+ was not equal to the sum of that when only single Mg2+ or Al3+ exists, respectively. Furthermore, a thinner organic liquid membrane supported by gas bubbles was in favor of enhanced interfacial enrichment of Er3+ and its diffusion mass transfer near the interface. During gas bubble-supported organic liquid membrane extraction, Mg2+ ions exhibited more obvious specific ion effect due to a weaker interaction with P507 molecules. However, a stronger hydration ability of Al3+ than Mg2+ ions induces a stronger competition of Al3+ with P507 molecules. Therefore, the coexistence of Mg2+ and Al3+ ions could play a synergistic role in enhancing enrichment of Er3+ on the basis of the mutual interference from the synergistic specific ion effect of coexisting Al3+ and Mg2+ ions. The research helps thoroughly understand the regulation mechanism on the synergistic specific ion effect for selective extraction of specified ions from the complex solutions containing multiple coexisting background ions.

Simulation of Magnetic Separation of Metal Ions in Aqueous Electrolytes

The magnetic separation of metal ions provides an alternative solution to traditional separation techniques such as pyrometallurgy, hydrometallurgy, biometallurgy or electrodialysis. Compared to traditional techniques that either use large amounts of chemicals (usually inorganic acids combined with reducing agent), produce large amounts of sludge as solid waste, consume a large amount of energy, or are difficult to separate ions of different charges [1], the magnetic separation of the metal ions can separate ions based on their magnetic susceptibility. This method is environmentally friendly [2] and consumes a small amount of energy (particularly when the system is designed using permanent magnets instead of electromagnets). The goal of this presentation is twofold. First, we derive the set of transport equations that need to be used to simulate the magnetic separation of metal ions in aqueous solutions. Then, we use these transport equations to simulate the magnetic separation process in various magnetic systems and predict the efficiency of magnetic separation of different systems.The mathematical model developed here is based on coupling the three-dimensional Navier-Stokes equations for flow transport with the drift (migration)-diffusion equations of ion transport [3] in the presence of magnetic field gradients. Both the drift-diffusion model and the Navier-Stokes equations include the magnetic force term as an additional driving force. By solving the entire system of equations self-consistently we analyze the effect of the diffusivity, concentration gradients, magnetic field gradients and fluid velocity over the capturing properties of the system. A detailed presentation of the mathematical model, underlying assumptions of the model, limiting cases, numerical implementation in three-dimensional structures, and simulations results will be presented at the meeting. In addition, we will present predictions for the magnetic separation of Li, Fe, Ni, Mn, and Co from the solution phase. Fortunately, these ions have significantly different magnetic susceptibility, which vary over more than 3 orders of magnitude, and which allows for the efficient extraction and separation of the elements from the solution and from each other.

Accelerated de-chelation of EDTA-metal complexes: A novel and versatile approach for wastewater and solid waste remediation

Industrial waste, including wastewater and solid waste, often contains toxic heavy metals that necessitate extraction and separation prior to safe disposal or reusing them. Sewage sludge incineration ash (SSIA), a non-incinerable waste, holds significant amounts of heavy metals such as iron, zinc, copper, nickel, chromium, and lead. Recovery and reuse of heavy metals from SSIA and further application of treated SSIA sludge remain challenging. Ethylenediaminetetraacetic acid (EDTA) is widely used for heavy metals chelation in different applications. While its chelation with heavy metals is rapid and easy to achieve, the de-chelation of the metal complexes is otherwise slow (∼3 days) and challenging due to their high stability constants. In this study, we investigate the recovery of heavy metals from SSIA through chelation using EDTA, and develop, for the first time, a method to rapidly de-chelate the EDTA-metal complexes through the facile chilling process (1 – 3 h) that accelerates the separation of EDTA and metal ions. A sequential precipitation of high-purity heavy metals from the EDTA-metal complexes was demonstrated with and without de-chelation. This novel and versatile method allows the separation of many valuable compounds from the treated SSIA, including regenerated EDTA, potassium hexafluorosilicate, iron phosphate, iron(III) hydroxide, iron silicate, titanium phosphate, calcium phosphate, copper(I) thiocyanate, nickel bis(dimethylglyoximate), lead(II) sulfate, and zinc sulfide. This approach opens doors for more sustainable waste management and the recovery of valuable resources from industrial waste.

Benzo-12-crown-4 and β-diketone bi-functionalized ionic liquids for highly selective lithium extraction from alkaline solution

Indeed, the efficient and sustainable recovery of lithium from highly concentrated sodium-containing mother liquors of Li2CO3 and salt-lake brines remains a significant challenge. Herein, two typical Li+ recognition receptors, namely benzo-12-crown-4 and thenoyltrifluoroacetone, were separately introduced into the cationic and anionic parts to successfully synthesize novel bi-functionalized task-specific ionic liquids [(B12C4)Cnim][TTA] (n = 4, 6, 8). A new, green, and high-efficiency extraction system has been developed by dissolving [(B12C4)C6im][TTA] in commercial room-temperature ionic liquid 1-hexyl-3-methyl-imdazolium bis(trifluromethylsulfonyl)imide [C6mim][NTf2], without the addition of any other co-extractants. The newly developed [(B12C4)C6im][TTA]-[C6mim][NTf2] extraction system exhibited a wide pH working range (4.0–11.0), high lithium extraction efficiency (95.4 %), as well as superior separation factors of Li/Na (βLi/Na = 2154.0) and Li/K (βLi/K=757.2). The extraction mechanism involving cation exchange was determined through slope analysis, ion chromatography, UV–vis spectroscopy and FT-IR spectra measurement, indicating that one [(B12C4)C6im][TTA] molecule can interact with two lithium ions and form a 1:2 complex. Moreover, the [(B12C4)C6im][TTA]-[C6mim][NTf2] extraction system also demonstrated fast extraction kinetics, facile stripping and regeneration, along with good cycling performance. Furthermore, a multi-stage countercurrent extraction process to extract lithium from the simulated mother liquor of Li2CO3 was evaluated. When the volume ratio (O/A) of oil phase (O) to water phase (A) was 1.0, only two theoretical extraction stages were needed to extract 91.4 % of lithium into the organic phase. Thus, the [(B12C4)C6im][TTA]-[C6mim][NTf2] extraction system is promising for lithium extraction from mother liquor of Li2CO3 and salt-lake brines. This study also opens the avenue for designing cationic and anionic bi-functionalized ionic liquids for metal ion separation.

Development of an Efficient Process for the Separation of Co(ii), Mn(ii), and Ni(ii) from Chloride Solution by Precipitation

ABSTRACT The demand for nickel, cobalt, and manganese is increasing owing to their critical role in the performance of lithium-ion batteries. Precipitation is simpler to operate than solvent extraction in the separation of metal ions. In this work, precipitation-based procedures were developed to separate Co(II), Mn(II) and Ni(II) from synthetic chloride solutions. Dimethylglyoxime (DMG) was effective in selectively precipitating Ni(II) from the chloride solutions containing Co(II) and Mn(II). Solution pH greatly affected the precipitation of Ni(II) by DMG. In the first procedure, Ni(II) was first precipitated using DMG from solution with initial pH 6 at a DMG/Ni(II) molar ratio of 3, a reaction time of 30 min and then Co(II) was separated from the filtrate by precipitation with Na2S, with optimal conditions being an initial pH of 6, a Na2S/Co(II) molar ratio of 2 and a reaction time of 15 min. In the second procedure, both Ni(II) and Co(II) was simultaneously precipitated with Na2S, leaving Mn(II) in the filtrate. Then the mixed sulfides of Co(II) and Ni(II) were dissolved by using HCl solution containing NaClO as an oxidizing agent. From the leaching solution, Ni(II) was separated by precipitation with DMG. Optimum conditions for the separation conditions were obtained. In both procedures, the separation degree among the three metal ions was higher than 99%. The developed procedures were simple and effective for the separation of the three metal ions compared to solvent extraction.

Construction of heterogeneously connected cobalt-based MOF-COF and its application in highly selective separation of trace lead ions

As a new type of porous crystalline composite material, MOF-COF has shown great advantages in metal separation. Herein, a CoMOF-COF was designed for highly selective separation of trace Pb2+ ions. The designed CoMOF-COF has a high density of nitrogen-oxygen functional groups and can selectively separate metal ions. There is a strong affinity between the designed CoMOF-COF material and metal Pb2+ ions, which can be attributed to the ordered heterogeneous porous structure and large amounts of nitrogen-and oxygen-containing functional groups. The composite showed high adsorption selectivity for Pb2+ ions and had adsorption capacity of 33 mg g−1, with high chemical stability. Based on this solid phase extraction material, a high sensitivity detection method for Pb2+ ions was established, which has the detection limit of 37.3 ng L−1, precision of 1.9 %. Linear detection range is 0.2–10 ng mL−1, and the detection of Pb2+ ions in actual water samples was realized. Through this study, it is proved that the strong affinity between the designed CoMOF-COF materials and metal Pb2+ ions can be attributed to the soft and hard acid-base theory, which reveals the structure-activity relationship between the porous heterostructure of such materials and metal separation, providing a highly selective separation material for the separation of other environmental pollutants.

Based on proteomics probing into the deterioration mechanism of pork batter gel caused by different cooking temperatures

The purpose of this experiment was to explore the influence of different cooking temperatures on the deterioration characteristics of pork batter gel by using proteomics, gel electrophoresis, size and chemical bond of aggregates. The results showed that the protein molecules of the pork batter gel was degraded during heating cooking and the protein aggregates were composed of many degraded protein fragments; compared with the control group 75 °C (0 min), the significant degradation of cytoskeleton showed at 110 °C (30 min) and 121 °C (30 min) and the significant degradation of myosin complexonly appeared at 121 °C (30 min). As the heating temperature points increased, compared with the control group 75 °C (0 min), the different temperatures could promote the separation of metal ions with proteins especially at 110 °C (30 min) and 121 °C (30 min), which could ultimately influence quality of pork batter gel by the size of particle. As the increase of heating temperature points, the recombination of aggregates composed of different proteins was not conducive to the retention of capillary water, which reduced the texture of pork batter gel. This research provided theoretical support for improving the process property of the meat products.