NH4HCO3 Solution Research Articles

Integration of surface swab with optical microscopy for detection and quantification of bacterial cells from stainless-steel surfaces.

Swab sampling is a common method for recovering microbes on various environmental surfaces. Its successful application for a specific target depends on the proper swab method and the following detection assay. Herein, we evaluated critical factors influencing surface swab sampling, aiming to achieve the optimal detection and quantification performance of optical detection for bacterial cells on stainless-steel surfaces. Our results showed the recovery rate of Salmonella enterica (SE1045) cells from the 10×10cm2 stainless-steel surface reached up to 92.71±2.19% when using ammonia bicarbonate-moistened polyurethane foam swabs for gentle collection, followed by ultrasound-assisted release in NH4HCO3 solution. Among the six different foam swabs, the Puritan™ Sterile Large Foam Swab contributed the lowest background noise and highest recovery efficiency when integrated with the optical detection assay. Notably, our method exhibited a strong linear relationship (r2=0.9983) between the detected cell numbers and the theoretical number of SE1045 cells seeded on surfaces in the range of 104-107 Colony Forming Units (CFU), with a limit of detection of 7.2×104 CFU 100cm-2. This integration was completed within 2 h, exhibiting the applicable potential in various settings.

A reverse electrodialysis cell-modified photocatalytic fuel cell for efficient electricity and hydrogen generation from the degradation of refractory organic pollutants.

Wastewater treatment is typically energy-intensive. To achieve carbon neutrality, new wastewater treatment technologies that have high efficiency and low energy consumption must be developed. In this study, a reverse electrodialysis (RED) cell-modified photocatalytic fuel cell (PRC) for efficient electricity and hydrogen generation from the degradation of refractory organic pollutants is developed and evaluated. A hydrogen evolution cathode was developed and optimized by doping 1.53wt. % Ni-N-C on CoP/NF. The bias voltage generated from the RED stack accelerated the separation of photoinduced holes and electrons on the photoanode, which enhances ampicillin (AMP) degradation and hydrogen production. The RED stack and electrode reactions respectively contribute 72.3 % and 27.7 % to the electricity production of PRC. The output current and cumulative hydrogen generation reach 2.2-3.0mA and 500 μmol/L respectively with 81.8 % AMP removal. Increasing high concentration (HC), flow rate of NH4HCO3 solutions and AMP concentration could increase the electricity and hydrogen generation. Acidic environment is helpful to improve the reaction rate of hydrogen evolution. We believe this study would provide a promising option for wastewater remediation.

Effective and Low-Cost In Situ Surface Engineering Strategy to Enhance the Interface Stability of an Ultrahigh Ni-Rich NCMA Cathode.

Ultrahigh Ni-rich quaternary layered oxides LiNi1-x-y-zCoxMnyAlzO2 (1 - x - y - z ≥ 0.9) are regarded as some of the most promising cathode candidates for lithium-ion batteries (LIBs) because of their high energy density and low cost. However, poor rate capacity and cycling performance severely limit their further commercial applications. Herein, an in situ coating strategy is developed to construct a uniform LiAlO2 layer. The NH4HCO3 solution is added to a NaAlO2 solution to form a weak alkaline condition, which can reduce the hydrolysis rate of NaAlO2, thus enabling uniform deposition of Al(OH)3 on the surface of a Ni0.9Co0.07Mn0.01Al0.02(OH)2 (NCMA) precursor. The LiAlO2-coated samples show enhanced cycling stability and rate capacity. The capacity retention of NCMA increases from 70.7% to 88.3% after 100 cycles at 1 C with an optimized LiAlO2 coating amount of 3 wt %. Moreover, the 3 wt % LiAlO2-coated sample also delivers a better rate capacity of 162 mAh g-1 at 5 C, while that of an uncoated sample is only 144 mAh g-1. Such a large improvement of the electrochemical performance should be attributed to the fact that a uniform LiAlO2 coating relieves harmful interfacial parasitic reactions and stabilizes the interface structure. Therefore, this in situ coating approach is a viable idea for the design of higher-energy-density cathode materials.

Highly efficient preconcentration using anodically generated shrinking gas bubbles for per- and polyfluoroalkyl substances (PFAS) detection.

Here we report a highly efficient PFAS preconcentration method that uses anodically generated shrinking gas bubbles to preconcentrate PFAS via aerosol formation, achieving ~ 1400-fold enrichment of PFOS and PFOA-the two most common PFAS-in 20min. This new method improves the enrichment factor by 15 to 105% relative to the previous method that uses cathodically generated H2 bubbles. The shrinking gas bubbles are in situ electrogenerated by oxidizing water in an NH4HCO3 solution. H+ produced by water oxidation reacts with HCO3- to generate CO2 gas, forming gas bubbles containing a mixture of O2 and CO2. Due to the high solubility of CO2 in aqueous solutions, the CO2/O2 bubbles start shrinking when they leave the electrode surface region. A mechanistic study reveals two reasons for the improvement: (1) shrinking bubbles increase the enrichment rate, and (2) the attractive interactions between the positively charged anode and negatively charged PFAS provide high enrichment at zero bubble path length. Based on this preconcentration method, we demonstrate the detection of ≥ 70ng/L PFOA and PFOS in water in ~ 20min by coupling it with our bubble-nucleation-based detection method, fulfilling the need of the US Environmental Protection Agency.

Simultaneous retention of organic and inorganic contaminants by a ceramic nanofiltration membrane for the treatment of semiconductor wastewater

The semiconductor manufacturing industry produces large amounts of ammonia-contaminated wastewaters which require costly and energy-intensive treatments. This study demonstrates the application of a commercially available ceramic nanofiltration (NF) membrane for the control of organic and inorganic contaminants as well as ammonium retention in the treatment of semiconductor wastewater. Analysis of the hydrodynamic pore transport model based on the direct measurement of membrane thickness in the active layer indicated that the ceramic NF membrane has an average pore radius of ≈0.65 nm. Zeta potential measurements of the ceramic NF membrane showed that the membrane surface was negatively charged at neutral pH. The ammonium retention capacity of the ceramic NF membrane was evaluated using a single symmetric ammonium salt solution (1.8 mM NH4HCO3; i.e., the average ammonium concentration in semiconductor wastewater) and combined salt solutions (mixtures of 1.8 mM NH4HCO3 and either 2.0 mM of Na2SO4, CaSO4, or CaCl2). The combined NH4HCO3 and Na2SO4 solution rendered a remarkably high ammonium retention rate of 88.7%, which was attributed to higher valency co-ions (SO42-) in this solution with the same negative surface charge of the ceramic NF membrane. In contrast, the calcium ions (Ca2+) in different combined salt solutions containing CaSO4 and CaCl2 interfered with ammonium retention. We further employed the ceramic NF membrane to treat semiconductor wastewater samples taken from a full-scale semiconductor wastewater treatment plant and demonstrated that this proposed treatment method could effectively retain organic and inorganic contaminants with a low fouling propensity. Our results highlight the promising potential of ceramic NF membranes for the treatment of industrial wastewaters with diverse organic and inorganic contaminants.

Investigation of the effect of equal and unequal feeding time intervals on process stability and methane yield during anaerobic digestion grass silage

The effects of equal and unequal feeding intervals, organic loading rates (OLR) and operating temperatures on specific methane production (SMP) during the anaerobic digestion (AD) process were investigated using three pairs of continuously stirred tank reactors (CSTRs). The Pair 1, 2 and 3 CSTRs were operated at psychrophilic (25 ± 2 °C), mesophilic (40 ± 3 °C) and thermophilic (60 ± 2.5 °C) conditions, respectively. After acclimatization, the reactors were fed at an OLR of 1.0 and 1.5gVS/L.d at selected intervals, while maintaining their pH 6.8–7.2 with NH4HCO3 solution. The results showed that during uneven feeding regime (day 8–93), the mean SMP from Pair 1, 2 and 3 reactors were 294.5, 433.5 and 370.2 N mLCH4/gVS fed, respectively. At failing state (day 60–93), the mean concentrations of free ammonia nitrogen (FAN) in the psychrophilic, mesophilic and thermophilic CSTRs were 19.1, 33.7 and 127.2 mg/L; VFAs of 6940.1, 6852.3 and 4694.9 mg HAc/L; which reduced their SMPs to 140, 273.8 and 231.1 N mLCH4/gVS, respectively. Therefore, uneven feeding, trace elements (TEs) deficiency, VFAs accumulation and FAN (for thermophilic) led to CSTRs failure. An even (24-hourly) feeding regime with daily biomass ash-extracts supplement enhanced the recovery of the failed CSTRs. Although, uneven daily feeding conditions led to AD process instability, it favoured SMP in mesophilic CSTRs compared to psychrophilic and thermophilic. These results strongly indicate that the soluble TEs and alkalinity contained in ash-extracts facilitated the recovery of the failed AD reactors and therefore can be used to revive failed AD processes.

Pom-pom-like nanowire clusters prepared by potentiostatic oxidation of copper in NH4HCO3 solution

Formation of hemispherical pom-pom-like clusters of nanowires during potentiostatic oxidation of copper in NH 4 HCO 3 is reported. High-purity copper was oxidized in a three-electrode setup at constant electrode potential ranging from 200 mV to 1000 mV vs. Ag|AgCl|sat. KCl for 14 h. The obtained clusters of nanwires were examined using FE-SEM, XRD and XPS techniques. The diameter of nanowires, composed mainly of CuO, Cu 2 O, Cu(OH) 2 , and Cu 4 O 3 , was ca. 50–70 nm. The diameter of the clusters strongly depends both on the applied potential and the time of electrooxidation, and was found to be in the range of 1–3 μm. The mechanism for the formation of such nanowires clusters is proposed. • Clusters of nanowires form on copper during potentiostatic oxidation in NH 4 HCO 3 . • The outer layer of nanowires is composed of mostly Cu(OH) 2 and CuO. • Cu 2 O, CuO, Cu(OH) 2 , Cu 4 O 3 and Cu 2 CO 3 (OH) 2 are present in internal layer. • The cluster diameter depends on the applied potential and time of oxidation.

Fabrication of MOF-808(Zr) with abundant defects by cleaving Zr[sbnd]O bond for oxidative desulfurization of fuel oil

Creation of defects in metal–organic frameworks (MOFs) has been demonstrated to be of significance for many potential applications. MOF-808(Zr), as an important member of MOFs, has attracted extensive attention due to its advantages such as high stability, large surface area and pore size. Therefore, the development of defective MOF-808(Zr) is of great interest. In this contribution, we report that MOF-808(Zr) with abundant defects can be fabricated by the fracture of partial ZrO bonds in its structure by the treatment of NH4HCO3 solution. During the treatment, the effect of NH4HCO3 concentration and treatment time on the structural properties of MOF-808(Zr) was investigated. The catalytic performance of obtained materials was evaluated by the oxidative desulfurization reaction of dibenzothiophene. The results revealed that MOF-808(Zr) obtained under the conditions of 0.08 M NH4HCO3 and treatment time of 10 min exhibited superior catalytic activity (124.8 mmol/h/g) at 60 °C due to the formation of rich defect sites in MOF-808(Zr).

Increasing the production of gas condensate by using ammonium carbonate salts

The work is devoted to the problem of increasing gas condensate production in gas condensate fields. It was found that ammonium carbonate salts, in the absence of calcium chloride type waters, interact with carbonate rocks, increase the permeability of reservoirs. Solutions of ammonium carbonate salts when interacting with formation water of the calcium chloride type form chemically precipitated chalk in the pore space, while the permeability of carbonate rocks decreases. A set of experimental studies was carried out to study the displacing and washing properties of ammonium carbonate salts. It was found that ammonium carbonate salts have high displacing properties, the displacement ratio of kerosene by NH4HCO3 solution is 0.75-0.80, while reservoir water – 0.55-0.58. According to the results of laboratory studies of the displacing and washing characteristics of ammonium carbonate salts, conclusions were made about the effect of bicarbonate solution (ammonium carbonate salts) on the production characteristics of a well in reservoir conditions at temperatures of 80-100 °C and above. Industrial tests of ammonium carbonate salts showed an increase in gas flow by 30-50% at wells № 23 of Opishnia, № 115 of Mashivka, № 3 of Tymofiivka gas condensate fields. The effect of formation treatment with ammonium carbonate salts is achieved due to clearing of well bottom zone and increasing the formation permeability. At wells № 56, 108 of Yablunivka and № 58 of Tymofiivka gas condensate fields, an increase in the condensate ratio was observed by 22-35%. The effectiveness of this treatment is associated with the simultaneous bottomhole zone cleaning from asphalt-resinous contaminants and permeability increase, as well as with the hydrophilization of the pore space and mobility increase of condensate precipitated as a result of carbon dioxide effect, which was rejected as a result of decomposition of ammonium carbonate. Thus, experimental and industrial tests in Opishnia, Mashivka, Tymofiivka, Yablunivka gas condensate fields of Poltava region confirmed the effectiveness of using ammonium carbonate to increase hydrocarbon production. The prospect of further research is aimed at developing a technology for increasing the production of liquid hydrocarbons by using ammonium carbonate salts.

NOx Emission Reduction by Advanced Reburning in Grate-Rotary Kiln for the Iron Ore Pelletizing Production

The NOx reduction in the iron ore pelletizing process becomes an important environmental concern owing to its role in the formation of photochemical smog and acid rain. Thus, it is essential to develop new technologies for reducing NOx emissions in order to contribute to the cleaner production of pellets. In this paper, NOx reduction by advanced reburning ingrate-rotary kiln for oxidized pellet production was performed on a laboratory-scale gas kiln. Temperature and NH3/NOx molar ratio (NSR) were the key factors affecting the reduction of NOx. A better denitrification effect can be obtained on flus gas with higher initial NOx concentration, at temperature = 900 °C, NSR = 1.2, and reaction time exceeds one second. NOx reduction rate had reached 55–65% when the initial NOx concentration was above 400 ppm, and exceeds 70% when the initial NOx concentration was around 680 ppm. Urea solution has the best denitrification effect compared with NH3·H2O and NH4HCO3 solution. As for additives, the denitrification effect of the vanadium-titanium catalyst was better than that of ethanol and NaCl, while NaCl plays a promotive role at low NSR. Finally, a series of denitrification measures that include advanced reburning technology for achieving NOx ultra-low emission in the oxidation pellet production was proposed.

Low-grade heat energy driven microbial electrosynthesis for ethanol and acetate production from CO2 reduction

Microbial reverse-electrodialysis electrosynthesis cell (MREC) is an attractive strategy for wastewater treatment and valuable chemicals production from CO2 reduction. Herein, one innovative MREC is proposed to drive CO2 conversion to ethanol and acetate with low-grade waste heat energy coupled with thermolytic solutions (e.g., NH4HCO3 solution) as driven power sources. In such MREC, the maximum ethanol and acetate accumulated concentration of 5.23 ± 0.35 and 2.85 ± 0.38 mM are obtained, catalyzed by Clostridium ljungdahlii ERI-2 with production rates of 130.75 ± 8.75 and 137.92 ± 7.92 mmol m−2 d−1, respectively. Moreover, the current as the key parameter for the CO2 conversion, which can be controlled by the salinity ratios of NH4HCO3 solutions and medium of Clostridium ljungdahlii ERI-2. This work for the first time proves the potential of the MREC for simultaneous biofuels production, CO2 reduction, wastewater treatment and waste heat energy utilization.

Thermolytic osmotic heat engine for low-grade heat harvesting: Thermodynamic investigation and potential application exploration

The osmotic heat engine is a promising technology for harvesting low-grade heat from different heat sources. However, a better understanding of the system performance, thermodynamic efficiencies, and suitable application circumstances (type of heat sources, system energy generation capacity, etc.) is needed before the transition can be made from conceptual design to practice. Firstly, the energy efficiency (ƞth) and exergy efficiency (ƞX) of a thermolytic osmotic heat engine (NH4HCO3 solution as the working fluid) were investigated in this study. It was found that the osmotic heat engine performs better when the operating temperature (heat source temperature) is lower (323 K). Additionally, a higher draw solution concentration and a lower feed solution concentration can increase both ƞX and ƞth. Subsequently, the energy return on investment with either low-grade industrial waste heat or solar thermal energy acting as the heat source was calculated. It was found that different energy return on investment values can be obtained with different heat sources. The results show that when industrial waste heat is used as the heat source, a much higher energy return on investment value (approximately 55) can be obtained. This finding indicates that it is suitable to generate electricity from industrial waste heat using the osmotic heat engine. When solar thermal energy is used as the heat source the energy return on investment value is 1.3–2.2 because there is a large amount of embodied energy in the flat-plate solar collector. This study represents a step forward towards the practical application of the osmotic heat engine.

Preparation of Small-Particle and High-Density Cobalt Carbonate Using a Continuous Carbonate Precipitation Method and Evaluation of Its Growth Mechanism.

Spherical CoCO3 powder with a small particle size and high density was successfully prepared using a continuous carbonate liquid precipitation method with a raw material of cobalt chloride solution, a precipitant of NH4HCO3, and without a template. The effects of the concentration of ammonium carbonate, process pH, and feeding rate on the tap density and apparent density of cobalt carbonate were investigated. It was found that the apparent and tap density values of 4.4 µm of cobalt carbonate were 1.27 g/cm3 and 1.86 g/cm3, respectively, when the initial concentration of NH4HCO3 solution was 60 g/L, the pH was 7.15–7.20, and the feeding rate of cobalt chloride was 2 L/h. The anisotropic growth process of the crystal lattice plane of CoCO3 under the aforementioned optimal conditions were studied. The results demonstrated that the crystal grew fastest along the (110) facet orientation, which was the dominant growth surface, determining the final morphology of the primary particles. The scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HR-TEM) results demonstrated that the primary particle morphology of the cobalt carbonate was a nanosheet. The unit cell of cobalt carbonate, of a hexagonal structure in the horizontal direction, grew horizontally along the (110) facet orientation, while 20–35 unit cells of the carbon carbonate were stacked along the c-axis in the thickness direction. Finally, the sheet-shaped particles were agglomerated into dense spherical secondary particles, as presented through the crystal re-crystallization model.

Effects of hydrophilic/lipophilic nanoparticles on the decomposition of NH4HCO3 solution

Aqueous ammonia is a potential absorbent for post-combustion carbon capture. Desorption of carbon dioxide (CO2) from ammonium bicarbonate (NH4HCO3) solution is one of key reactions of regeneration of the absorbent. Experimental studies on decomposition of NH4HCO3 solution with and without nano-TiO2 at different temperatures were conducted. Additions of nano-TiO2 into ammonium bicarbonate solutions decrease the apparent activation energy of overall decomposition reaction and accelerate the decomposition of ammonium bicarbonate solutions. Moreover, compared to hydrophilic nano-TiO2, hydrophilic lipophilic nano-TiO2 exerts more significant promoting effects on the decomposition reaction.

Energy-efficient mineral carbonation of CaSO4 derived from wollastonite via a roasting-leaching route

Mineral carbonation is an important technique for the sequestration of carbon dioxide (CO2) on a large scale. In this article, indirect carbonation of abundant wollastonite [CaSiO3] mineral combined with the use of a CO2 mineralization cell (CMC) for the recovery of mineralization energy has been proposed. The results of thermodynamic analysis reveal that the described process consumes 73% less energy than that required for the route, in which serpentine is utilized as the mineralization agent. During this process, calcium sulfate (CaSO4) was first derived with recyclable ammonium sulfate (AS) via a roasting-leaching route. The gaseous ammonia produced during the roasting stage was used to capture CO2 from a mixture of flue gases and simultaneously generate ammonium bicarbonate (NH4HCO3) and electricity by the CMC. The obtained NH4HCO3 solution reacted directly with the leaching slurry to mineralize CO2 and regenerate AS at the same time. In this study, process parameters of this route were investigated in detail, and the related extraction mechanism was discussed. It was found that 94.5% of calcium species in wollastonite was converted into CaSO4, 94.8% of which was subsequently carbonated. The extraction efficiency of the roasting stage did not exceed 39% due to its low mass transfer rate resulting from the high viscosity of liquid ammonium bisulfate and presence of silicon dioxide (SiO2) and CaSO4 species on the surface of unreacted wollastonite. Preliminary energy analysis showed that a net reduction of CO2 emission of about 347 kg could be achieved for the mineralization of 1000 kg of CO2.

Ventilatory sensitivity to ammonia in the Pacific hagfish (Eptatretus stoutii), a representative of the oldest extant connection to the ancestral vertebrates.

Ventilatory sensitivity to ammonia occurs in teleosts, elasmobranchs and mammals. Here, we investigated whether the response is also present in hagfish. Ventilatory parameters (nostril flow, pressure amplitude, velar frequency and ventilatory index, the last representing the product of pressure amplitude and frequency), together with blood and water chemistry, were measured in hagfish exposed to either high environmental ammonia (HEA) in the external sea water or internal ammonia loading by intra-vascular injection. HEA exposure (10 mmol l-1 NH4HCO3 or 10 mmol l-1 NH4Cl) caused a persistent hyperventilation by 3 h, but further detailed analysis of the NH4HCO3 response showed that initially (within 5 min) there was a marked decrease in ventilation (80% reduction in ventilatory index and nostril flow), followed by a later 3-fold increase, by which time plasma total ammonia concentration had increased 11-fold. Thus, hyperventilation in HEA appeared to be an indirect response to internal ammonia elevation, rather than a direct response to external ammonia. HEA-mediated increases in oxygen consumption also occurred. Responses to NH4HCO3 were greater than those to NH4Cl, reflecting greater increases over time in water pH and PNH3 in the former. Hagfish also exhibited hyperventilation in response to direct injection of isotonic NH4HCO3 or NH4Cl solutions into the caudal sinus. In all cases where hyperventilation occurred, plasma total ammonia and PNH3 levels increased significantly, while blood acid-base status remained unchanged, indicating specific responses to internal ammonia elevation. The sensitivity of breathing to ammonia arose very early in vertebrate evolution.

Facile and cost-efficient indirect carbonation of blast furnace slag with multiple high value-added products through a completely wet process

Mineral carbonation of blast furnace slag (BFS) has been proposed as a comprehensive method for carbon capture and storage and utilization of the industrial solid waste. However, the challenge for this technology to be applied practically is how to reduce the cost of process. A completely wet process combining a CO2-mineralization cell for CO2 capture and membrane electrolysis for recovery of carbonated mother liquor is proposed to simultaneously fix CO2 and produce multiple value-added products. In this process, Ca, Mg, Al, and Si are extracted from BFS with an NH4HSO4 solution prepared from H2SO4 and (NH4)2SO4 with extraction ratios of 97.3%, 98.8%, 96.4%, and 94.3% under optimized conditions, respectively. The extracted Al and Si are then recovered as NH4Al(SO4)2·12H2O (99.59 wt%) and SiO2 (97.70 wt%) with 93% and 98.1% yield, respectively. The CaSO4-rich leaching residue and MgSO4-rich leachate after complete depletion of the residual Al and Si are successively carbonated with an NH4HCO3 solution obtained from a CO2-mineralization cell with total CO2 capacity up to 361 kg-CO2 per tonne BFS. The preliminary economic evaluation shows that the present carbonation route is a cost-efficient method to comprehensively utilize BFS and reduce CO2 emissions.

Oxygen consumption by splanchnic tissues of sheep under mesenteric load of N compounds

Four Corriedale castrated male sheep (42 ± 3.4 kg body weight (BW)) surgically implanted with chronic indwelling catheters into the mesenteric, portal and hepatic veins, housed in metabolism cages and fed oat-ryegrass hay at maintenance level were used in a trial conducted to evaluate the effect of the mesenteric load of N compounds on oxygen consumption by the liver. After 17 days of a pre-experimental period, treatments were applied throughout four days following a 4 × 4 Latin Square design, which consisted of mesenteric vein infusion of either NaCl (0.15 M, Control), NH4HCO3 (0.25 M), alanine (0.25 M) or arginine (0.125 M) solution. All solutions were infused continuously at a rate of 2 ml/min during six hours in each experimental period, as to provide a mesenteric N load of 500 umol/min. Blood flow across portal and hepatic veins were estimated through downstream dilution of p-aminohippurate also continuously infused into the mesenteric vein. The blood flow across the portal vein was not affected by treatments whereas the blood flow across the hepatic vein tended (P = 0.09) to be higher in the control treatment. Oxygen consumption by the portal-drained viscera was similar for all treatments whereas oxygen consumption by the liver was higher (P < 0.05) in the control treatment. In conclusion, energy expenditure by the liver was not directly impacted by ammonia or amino acids load. Instead, the blood flow across the liver seems to have a key role in its oxidative metabolism.

HDEHP-CMPO/SiO2-P: a promising solid-phase extractant for uranium recovery from different acidic media

A novel macroporous silica-based HDEHP-CMPO impregnated polymeric solid-phase extractant showed an excellent uranium adsorption efficiency from HNO3, HCl, and H2SO4 media with the wide concentration range from the near neutral to high acidic conditions. The adsorption equilibrium data were well described with the Redlich–Peterson isotherm with the relatively high uranium adsorption capacity. Furthermore, the HDEHP-CMPO/SiO2-P showed a significant selectivity for U(VI) among the coexisting elements while the co-extraction of Fe(III) with U(VI) was observed. In desorption process, Fe(III) and U(VI) were separated and desorbed efficiently using the 1 M H2SO4 solution at 55 °C and 1 M NH4HCO3 solution at 25 °C, respectively.

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

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