Simple Separation Process Research Articles

Separation and utilization of iron, cerium, and other rare earth elements from rare earth waste by chlorination

Due to the lack of effective screening systems in the rare earth waste recycling industry, the composition of rare earth elements in rare earth waste is complex and difficult to separate. In response to such problems, by studying the reaction behavior between various elements in rare earth waste and cobalt chloride, we propose a process path for the separation and recovery of iron, cerium and other rare earth elements using cobalt chloride roasting. The experiments on simulated wastes show that the leaching rates of the Nd, Sm, Gd, Pr can reach 98.31%, 94.5%, 93.87% and 72.05% under the optimal process conditions, respectively. Ce and iron remain in the leaching residue in the form of CeO2 and CoFe2O4, respectively. And through a simple magnetic separation process, CeO2 and CoFe2O4 can be enriched in non-magnetic leaching residue and magnetic leaching residue, respectively. The cerium content in the leaching residue composed of cobalt ferrite is only 1.95%. Therefore, this method is beneficial to the separation and high-value utilization of iron, cerium, and other rare earth elements in the waste system. The research results can provide theoretical reference for the low-cost and high-value recovery of rare earth secondary resources.

CsCl enrichment during solidification of molten LiCl–KCl–CsCl salt mixture

Metallic alloy fuels from fast reactors will be reprocessed by a non-aqueous electrochemical technique known as electrorefining. Electrorefining of spent metal fuel results in the accumulation of heat generating fission products especially 137Cs in the electrolyte, which is a eutectic salt mixture of 44 wt% LiCl and 56 wt% KCl. The fission products need to be removed from the salt so as to reduce the decay heat load and contamination thereby facilitating reuse of the salt and minimizing waste generation. Melt crystallization technique is a simple separation process being pursued for separation of fission products. This is a single step process which utilizes the difference in solubility of fission products in the solid and liquid phase. Crystallization involves purification of a substance from a liquid mixture by solidification of the desired component. Numerical modeling of separation of CsCl from a LiCl–KCl eutectic mixture by solidification was carried out using ANSYS Fluent (19.2). The enrichment of CsCl during solidification, its distribution in molten salt and segregation time were evaluated. Further, solidification experiments were conducted using the molten salt mixture and the predicted numerical results were validated.

Amphiphilic molecules affording efficient aqueous degradation of unsaturated polyester resin

Enormous challenges have been encountered in the degradation and recycling of unsaturated polyester resin (UPR) in water, primarily due to its water resistance. Herein, a novel, efficient and green catalytic system of methanesulfonic acid (MSA)/sodium laurylsulfonate (SLS) was proposed to aqueously degrade UPR under mild conditions (200°C). This method is considerably milder compared to other reported works based on aqueous hydrolysis (230°C-380°C). What's more, amphiphilic SLS as a phase transfer reagent enhanced the concentration of catalyst at the H2O-UPR interface, which facilitated the mass transfer between organic motifs with inorganic reagents and thus accelerated the reaction. The NMR and FT-IR characterizations indicated the ester bonds were cleaved via hydrolysis with H2O catalyzed by MSA, and high value-added products, i.e., copolymer of styrene and maleic anhydride (SMA) and phthalic acid (PA), were reclaimed by a simple separation process, with the yield of 86.77% and 84.37%, respectively. Furthermore, a viable mechanism for degradation was proposed through the degradation performance of the model compounds. This study provides a practical approach for the chemical degradation and conversion of other resins containing ester bonds.

Selective extraction of 1,3‐propanediol by phenylboronic acid‐based ternary extraction system

AbstractBACKGROUNDConventional methods for the separation of 1,3‐propanediol (1,3‐PDO) are problematic in many ways. The study of simple and efficient separation process was the key to solving the bottlenecks that restricted the large‐scale development of 1,3‐propanediol. In order to solve the difficulty of separating 1,3‐propanediol from fermentation broths, a ternary selective extraction system was constructed to separate 1,3‐propanediol from the simulated solution and fermentation broth.RESULTSIn this study, the quantum chemistry calculation and wave function analysis showed that the reaction between phenylboronic acid and 1,3‐PDO is thermodynamically feasible, stable, and covalently reversible. The ternary extraction system composed of 1‐naphthylboric acid, dichloromethane and Aliquate®336. After optimization of the extraction conditions, a high extraction efficiency of 82.6% could be achieved for 1,3‐PDO. Meanwhile, a stripping recovery of 1,3‐PDO was over 90% with a high purity of 1,3‐PDO (98.6%) from a simulated solution using 0.4 M of hydrochloric acid as stripping solution. The extraction selectivity of 1,3‐PDO to glycerol, acetic acid and butyric acid in the fermentation broth reached to 12.9, 230.6, 233.7, respectively, implying a high selective performance compared with the aldehyde‐based traditional reactive extraction.CONCLUSIONSThe ternary extraction system exhibited good extraction performance which highlighted potential for selective extraction of diol biochemicals from fermentation broths.This article is protected by copyright. All rights reserved.

The sustainable recovery of rare earth in the leaching solution of Baotou minerals with extraction-precipitation strategy based on fatty acids

To research and develop sustainable extraction-precipitation strategy, the recovery of rare earth (RE) was studied by using mono and binary carboxylic acids, namely lauric acid (LA), myristic acid (MA), sebacic acid (SA) and dodecanedioic acid (DA). Compared with the other carboxylic acids, LA has better precipitation performance and selectivity for RE. It was successfully used to concentrate the leaching solution of Baotou minerals to 227 g/L. RE sulfate was also transformed into RE chloride with high solubility. Ca and Mg impurities in the leachate can be effectively eliminated. The particle size of formed RE concentrate is obviously larger than that those produced by industrial precipitants, which helps to improve the separation efficiency. Unlike oxalic acid and ammonium bicarbonate, the extraction-precipitant studied in this article can be reused to avoid the generation of oxalic acid wastewater, ammonia nitrogen wastewater, and carbon dioxide. The obtained RE concentrates have good separation performances and low solubilities in aqueous phase. The mechanism of RE extraction-precipitation by LA was examined by slope analysis, XPS and IR spectra. LA showed good stability during the recovery and recycling processes. Based on the above research, the extraction-precipitation of fatty acid (FA) provides a simple, efficient and sustainable separation process for Baotou minerals.

Reversible assembled gelatin aerogel-based phase change materials for light-to-thermal conversion and management

Employing 3D frameworks to construct composite phase change materials (PCMs) with excellent shape stability and solar-thermal conversion capacity has been proven to be a promising strategy. However, the recycle of effective components in composite PCMs is barely concerned. In this work, reversible assembled composite PCMs are designed by integrating gelatin/CNT (GC) aerogel with paraffin wax (PW), denoted as PGC-x, where x refers to the mass percentage of CNT in GC aerogel. The porous structure of aerogel endows PGC-x with outstanding shape stability until 100 °C and high loading efficiency of PW, enabling the thermal enthalpy of composite PCMs above 164 J/g. In addition, PGC-x demonstrates superior light-to-thermal conversion performance contributed by the wide light absorbance of CNT and phase change of PW, which is further proved by the satisfied conversion efficiency and five highly consistent conversion curves. Moreover, the recovery rate of PW and CNT from PGC-x exceeds 90 % and 80 %, respectively, through simple separation process, disclosing their great potential to reversible assembly, which greatly promotes the large-scale practical application of PCMs.

Efficient separation and coprecipitation for simplified cathode recycling

Hydrometallurgical recycling of spent lithium-ion batteries is among the most promising recovery approaches. The current hydrometallurgical method for battery recycling faces challenges such as complex separation and precipitation processes, and environmental concerns from the use of caustic inorganic acid and hazardous hydrogen peroxide. Our proposed modified method, namely polyol-metallurgy, uses citric acid in ethylene glycol as dual-function green solution to overcome these obstacles. This bifunctional solution leaches valuable metal ions from cathode materials (e.g., LiCoO2), and then acts as chelating agents to selectivxely precipitate cobalt through an esterification reaction, without the need for additional precipitation agents. The leaching efficiency of cobalt and lithium reaches 99.55 % and 97.65 %, respectively, and more than 96 % of cobalt could be directly self-precipitated and recovered. The unique characteristics of the dual-function solution also avoids impurities from Al foils and PVDF/carbon black films, enabling the simple separation process. Therefore, the process can be completed in one-pot system with efficient leaching, separation and coprecipitation, making it more efficient and feasible for operation than existing alternatives.

Pd-Based Nanoparticles as Catalysts for Improved Removal of Florfenicol via Heterogeneous Fenton and Photo-Fenton(-like) Processes

In this work, Fe2O3-Ni, Fe2O3-Ni-Pd, MgO-Ni, and MgO-Ni-Pd nanoparticles were synthesized, characterized, and used for the degradation of florfenicol (FLO). The main goals were to compare the removal capacity of Fe2O3-Ni and MgO-Ni nanocatalysts and evaluate the effect of Pd incorporation on Fe2O3-Ni and MgO-Ni nanoparticles on the degradation of FLO by heterogeneous Fenton(-like) and photo-Fenton(-like) processes. The adsorption and degradation processes of FLO were assessed, determining that the latter process is the principal mechanism for FLO degradation. Through the heterogeneous photo-Fenton process, the antibiotic was 78 and 44% removed using the Fe2O3-Ni and MgO-Ni nanocatalyst, respectively, improving degradation by 22% when Pd is incorporated into both nanostructures. FLO degradation occurs because of the generation of hydroxyl and superoxide radical and holes in the interface and the Fenton reaction with Fe and Mg present in the nanoparticles. Finally, the main organic intermediates produced during the degradation were identified, allowing the proposal of a degradation pathway. Thus, heterogeneous Fenton(-like) and photo-Fenton(-like) processes using nanoparticles as solid phase catalysts are an excellent alternative to FLO degradation from water, especially considering the easy recovery of the nanoparticles through a simple separation process such as filtration.

Magnetic selenium and nitrogen dual‐doped mesoporous carbon for immobilization of Pd nanoparticles: The utilitarian heterogeneous catalyst in Heck‐cross coupling reaction

Pd nanoparticle (Pd NP) immobilized on the magnetic Se and N dual‐doped carbon support was easily fabricated through thermal pyrolysis of glucose, selenium dioxide (SeO2), ammonium chloride (NH4Cl), and Fe3O4 hybridization and followed by chemical reductive reaction. After the successful characterization of prepared Se‐mCN/Fe3O4/Pd by using the various physicochemical techniques, it was used as the heterogeneous magnetic catalyst in the Heck‐cross coupling reaction. The utilization of cost‐effective biomass, high specific surface area, high product conversion, generality in diverse derivative conversion, simple separation process, and four runs reusability are some of the Se‐mCN/Fe3O4/Pd benefits.

Mechanical grinding of FeNC nanomaterial with Fe3O4 to construct magnetic adsorbents for desulfurization

Herein, a series of 3D nitrogen doped porous carbon nanomaterials (FeNC) at different pyrolysis temperature were prepared, followed by a mechanical grinding method to construct magnetically nanocomposite (FeNC/Fe3O4) which was demonstrated for the desulfurization of dibenzothiophene (DBT) in model oils. The FeNC derived from the pyrolysis of iron salt and nitrogen-doped carbon precursors possess abundant porous structure, which is highly active in the physical adsorption of aromatic sulfur derivatives. Impressively, the as-prepared FeNC-700 are evidenced to yield an excellent desulfurization efficiency (95.1% for 200 ppmw), a remarkable estimated adsorption capacity (25.08 mg S/g for 200 ppmw), and a high selectivity for DBT. Theoretical calculation revealed that the adsorption behaviors towards DBT followed the pseudo-second-order kinetic model, displays a better fitting coefficient based on Langmuir isotherm equation. The thermodynamics results indicate that adsorption process over FeNC-700 was spontaneous and exothermic reaction since ΔG, ΔH, ΔS, all shows negative signs. Subsequently, the FeNC-700 was mechanically mixed with 20 nm Fe3O4 to produce magnetically nanocomposite (FeNC-700/Fe3O4) for the adsorption of DBT in a simple separation process by external field and can be regenerated five runs without significant weight loss. Therefore, this strategy greatly simplifies the experimental procedure and favors the regeneration of the adsorbents.

A new method of full resource utilization of copper slag

Copper slags can hardly be utilized because the fayalite in it produces silica gel during the dissolution process. This work proposes a new process on sulfuric acid treatment of copper slag (Jinchuan Group, Gansu Province, China.). The results show that over 98% of recovery efficiency of Cu2+, Co2+, Ni2+ and Zn2+ was achieved through the whole process cycle. Ammonia was used to control the pH of the solution in order to completely precipitate Fe2+, and then produce hematite powder. More than 85% of the non-ferrous metal ions were left in the solution, and the utilization method of stepwise extraction was evaluated. The generation of silica gel during the acid digestion of copper slag was not restricted, and the silica gel in the acid-leach residue was subsequently dissolved with NaOH solution to obtain sodium metasilicate solution. Acidification and other steps were carried out to produce high-purity silica with a purity of 99.9%. Magnetite and pyroxene were obtained by using a simple magnetic separation process to segregate the remaining slag phase. The whole process achieves the full resource utilization of copper slag, and exhibits great potential for the future industrial utilization of copper slag in an economically and environmentally friendly way.

Excellent performance separation of trypsin by novel ternary magnetic composite adsorbent based on betaine-urea- glycerol natural deep eutectic solvent modified MnFe2O4-MWCNTs

The effective trypsin purification methods should be established since trypsin plays a crucial role in biosome. In this work, a novel ternary magnetic composite adsorbent (MnFe2O4-MWCNTs@B–U-G) with the features of strong specific selectivity, good adsorption effect, simple and efficient separation process, no secondary pollution brought in was prepared by integrating the superior physicochemical properties of ternary based natural deep eutectic solvent, multi-walled carbon nanotubes and MnFe2O4. The property, composition and microtopography structure of MnFe2O4-MWCNTs@B–U-G were characterized in detail. Combined with magnetic solid-phase extraction, MnFe2O4-MWCNTs@B–U-G was utilized to adsorb trypsin. Response surface methodology experiment was prepared under Box-Behnken design to optimize the adsorption conditions and the results showed that the practical maximum adsorption capacity for trypsin was 1020.1 mg g−1. Besides, the adsorption isotherms, adsorption kinetics, regeneration studies and method validation studies were investigated systematically to evaluate the established adsorption separation system. Mechanism exploration proved that electrostatic interaction, hydrogen bonding interaction and chelation interaction were the dominant forces for the high-performance adsorption of trypsin. The activity of trypsin after elution had been analyzed by UV–vis spectrophotometer and CD spectrometer with three methods, which illustrated that the enzyme activity, conformation and secondary structure of trypsin did not change significantly during the adsorption-desorption process. In addition, the proposed method was successful and practical applicability to isolation trypsin from crude bovine pancreas. As a result, due to the superiority of the MnFe2O4-MWCNTs@B–U-G, the proposed method not only exhibites high-performance adsorption of trypsin, but also provides a green and sustainable potential value in the adsorption of biomacromolecule.

A simple and feasible separation process of toluene from n-heptane with imidazolium-based switchable solvents

The separation of aromatics and aliphatic hydrocarbons is one of the most challenging and energy consuming operations in the petrochemical industry. In this work, two switchable solvents, 1,8-diazabicyclo[5.4.0]undec-7-ene imidazole ([DBU][Im]) and 1,1,3,3-tetramethylguanidine imidazole ([TMG][Im]), were synthesized and used for phase-change separation of toluene from n-heptane. The structures of these two switchable solvents were analyzed by 1H Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared (FT-IR) spectroscopy. The miscibility of various components in these two ILs before and after treatment with CO2 were studied, the results of which indicated that both these two switchable solvents could be utilized to achieve the effective separation of toluene from n-heptane. Among them, [TMG][Im] was preferable to be used at a low toluene content in the initial toluene/n-heptane system through feasibility study. The effects of extraction time, switchable solvent dosage and molar fraction of toluene on separation performance and the reusability were also investigated, demonstrating that [TMG][Im] could be used simply and feasibly for phase-change separating toluene from n-heptane and showed very good reusability and stability. Finally, the mechanism of reversible phase-change extraction process with [TMG][Im] was explored, indicating that the formation of [TMG][ImCO2] could greatly increase the polarity of the switchable solvent, which is conducive to separating toluene and recovering [TMG][Im] by removing CO2.

Synthesis of Novel Magnetic Carbon Microtube-Based Solid Acid and Its Catalytic Activities for Biodiesel Synthesis

Novel magnetic carbon microtube-based solid acid was synthesized via the carbonization of FeCl3-doped willow catkin and benzenediazoniumsulfonate acid-based sulfonation. The biomass willow catkin provided the special microtube structure and the high surface area of 215 m2/g for the novel solid acid. The microtube structure was well conserved during the mild carbonization (400 °C) and sulfonation process. The large number of acidic sites (2.3 mmol/g) on the microtube surface was quite accessible to reactants. Its magnetic properties offered a simple separation process. The novel solid acid showed very high activity for biodiesel synthesis, using cooking oils as raw material, which gave a total yield of 99% and free fatty acid conversion of 98.7% under mild conditions (70 °C). The facile synthetic process, high activity, high stability, and high recovery simplicity were the main properties of the novel magnetic solid acid, which is one of the best choices for biodiesel synthesis.

Comprehensive Review on Biodiesel Production from Palm Oil Mill Effluent

AbstractBiodiesel synthesis processes including pyrolysis, direct blending, transesterification, and advanced technologies such as microwave‐ and ultrasound‐assisted and supercritical processes from palm oil mill effluent (POME) are reviewed to highlight the significance and advances in terms of process sustainability and cost. POME as the most contaminated waste can be effectively utilized for biodiesel production. Supercritical transesterification offers more advantages over the other processes including higher reaction rate, without catalyst constraint, producing pure glycerol, and simple product separation process. The addition of co‐solvents like CO2 should be investigated for supercritical biodiesel production from POME. Although POME is an inexpensive source to synthesize biodiesel, innovative processes are needed to maximize the oil recovery from POME. Optimization of transesterification parameters is required for high production yields and sustainable processing.

Characterization of metallic particles extracted from fly ash of a thermoelectric plant in Boyacá-Colombia

In this work, it was studied the by-products of fly ashes, obtained from a thermoelectric power station in Boyacá, Colombia, through magnetic separation. The morphological characterization of the particles was performed by a scanning electron microscopy. Its elemental composition and crystalline structure were studied through energy dispersive spectroscopy and an X-ray diffraction, respectively. The results obtained show the presence of ferrospheres and cenospheres, which are irregular and rough compounds with a high iron content. The mineralogical phases present in the samples are mainly magnetite and hematite, with some traces of mullite. These phases can provide magnetic properties and extend the range of applications of these particles using a simple separation process in fly ashes.

Investigation of experimental variables on polyether sulfone (PES) membrane in dehydration of natural gas

This study has been carried out to investigate the dehydration of natural gas of Tabnak sweet gas field by using membrane process, with PES membrane as a new, simple and cheap separation process. The effects of various experimental variables, such as pressure, temperature and nano silica particles in dehydration of natural gas by PES were investigated. PES and its silica nanocomposite membranes were prepared by solution blending in N,N-Dimethylformamide (DMF) and casting-evaporation method.The homogeneity and nano scale distribution of prepared PES-silica membranes were characterized using Fourier transform infra-red spectroscopy (FTIR) and scanning electron microscope (SEM). Dehydration tests were done in pressure range of 2 to 10 bar and temperature range of 20 to 50° C, with nitrogen sweep gas. With an increase in the feed pressure, the permeated water was inhanced. On the other hand decreasing temperature, caused to improve the dehydration on process. Using PES-silica membrane increased water permeation.

Application of Magnetization Treatment in Flotation

With the decrease of mineral resources reserves, the characteristics of “poor, fine and miscellaneous” of mineral resources are becoming more and more obvious. People pay more and more attention to the environmental protection. A simple, green and efficient separation process magnetization flotation has been paid more and more attention by mineral processing workers. Based on the analysis and summary of the development process and advantages of magnetic flotation, the application status of magnetic flotation at home and abroad in the processing of ferrous metal ore, non-ferrous metal ore, rare metal ore, precious metal ore, non-metallic ore, coal, etc. Compared with conventional flotation, it is found that the cost of magnetic flotation is lower than that of conventional flotation. Combining theoretical analysis, computer simulation, experiment and advanced detection methods, the mechanism, influencing factors, process and equipment of magnetic flotation are the development trend in the future.

Flexible and free-standing pristine polypyrrole membranes with a nanotube structure for repeatable Cr(VI) ion removal

The effective removal of toxic Cr(VI) from wastewater remains an important environmental issue. The low adsorption capacity and the complex processes to separate the adsorbents from the treated wastewater are the main scientific and technological challenges. In this study, a flexible and free-standing pristine polypyrrole (PPy) membrane with a nanotube structure (PPy-N) was synthesized via template-assisted interfacial polymerization (TIP) for the selective removal of Cr(VI) through a simple separation and collection process. The superior Cr(VI) adsorption capacity as high as 250.31 mg/g was endowed by the unique structure of the PPy-N membrane. The Langmuir adsorption isotherm model was used to describe the adsorption behavior, with the adsorption kinetics followed a quasi-second-order kinetic model. After four adsorption-and–desorption cycles, the PPy-N membrane adsorption capacity fell by only 8.2%. The mechanism of the selective removal of Cr(VI) was proposed, including electrostatic adsorption, ion exchange and reduction. A combination of the highly attractive material properties, including mechanical processability, large surface area, superior Cr(VI) adsorption capacity and regeneration, makes the single-component PPy-N membrane a good candidate for removing Cr(VI) ions from wastewater.

Efficient direct preparation of antifungal Alteramide B from Lysobacter enzymogenes fermentation broth by macroporous resin adsorption

Alteramide B (ATB) is an antifungal metabolite produced by Lysobacter enzymogenes. However, its separation method has not been explored. This study attempted to directly adsorb ATB from fermentation broth using macroporous adsorption resins (MARs)NKA resin exhibited better adsorption as well as desorption capacities. The static and dynamic adsorption characteristics were assessed to determine the following optimal separation conditions: initial fermentation broth with a pH of 12.0, 2 BV/h flow rate, 8 BV loading volume, and 6 BV 80% aqueous ethanol for elution. After a single treatment, ATB content in the final product was higher by 4.51-fold (i.e, from 12.72 ± 1.21% to 57.35 ± 3.46%), resulting in a recovery yield of 86.20 ± 4.47%. In addition, NKA resin showed superior reusability within eight cycles of adsorption/desorption. The developed method is thus a simple, efficient, and economical process for ATB separation.