Synergistically constructed lamination-like network of redox-active polyimide and MXene via π-π interactions for aqueous NH_(4)^(+) storage

As a nonmetallic charge carrier,ammonium ion(NH_(4)^(+))has garnered significant attention in the construction of aqueous batteries due to its advantages of low molar mass,small hydration size and rapid diffusion in aqueous solutions.Polymers are a kind of potential electro-active materials for aqueous NH_(4)^(+)storage.However,traditional polymer electrodes are typically created by covering the bulky collectors with excessive additives,which could lead to low volume capacity and unsatisfactory stability.Herein,a nanoparticle-like polyimide(PI)was synthesized and then combined with MXene nanosheets to synergistically construct an additive-free and self-standing PI@MXene composite electrode.Significantly,the redox-active PI nanoparticles are enclosed between conductive MXene flakes to create a 3D lamination-like network that promotes electron transmission,while theπ-πinteractions existing between PI and MXene contribute to the enhanced structural integrity and stability within the composite electrode.As such,it delivers superior aqueous NH_(4)^(+)storage behaviors in terms of a notable specific capacity of 110.7 mA·h·cm^(–3) and a long lifespan with only 0.0064%drop each cycle.Furthermore,in-situ Raman and UV–Vis examinations provide evidence of reversible and stable redox mechanism of the PI@MXene composite electrode during NH_(4)^(+)uptake/removal,highlighting its significance in the area of electrochemical energy storage.

Effects of Hydroxyl Groups in Organic Ammonium Counterions on the Properties of Fluorinated Surfactants

The surface tension, foaming and viscosity for C7F15COO^-N^＋H（C2H4OH）χ（C2Hs）3-x and C8F17SO3- N^＋H（C2H4OH）χ（C2H5）3-χ （x = 0, 1, 2, 3） were measured to systematically study the effects of hydroxyl groups in organic ammonium counterions on the properties of perfluorooctanoates and perfluorooctanesulfonates. The results showed that the critical micelle concentration （cmc） and the surface tension at cmc （γcmc） were both increased with the increase of number of hydroxyl groups （χ） in the two series. The perfluorooctanesulfonate had smaller cmc but higher γ=cmc than perfluorooctanoate with the same counterion. The minimum molecular area of surface adsorption （Amin） of C8F17zSO3^-N^＋H（C2H4OH）χ（C2H5）3-χ were 0.64, 0.57, 0.63 and 0.72 nm^2 while the Amin values of C7F15COO^-N^＋H（C2H4OH）χ（C2H5）3-χ were 0.61, 0.62, 0.61 and 0.71 nm^2 when χ = 0, 1, 2 and 3, respectively. For the investigated systems of surfactants, the results of foam expansion ratio agreed with those of surface activity, while the 25% drainage time were consistent with the results of viscosity.

Determination of Ammonium Ion in Lake Water by Voltammetry

An electroanalytical method for the determination of ammonium ion using a platinized platinum electrode is described. Under optimized analytical conditions, the linear range of the calibration graphs for ammonium ion is 3.0×10?5?5.0×10?3 mol·L?1 with a detection limit of 5.0×10?6 mol·L?1. The method has been applied to the determination of ammonium ion in lake water samples and recoveries of 100%–103% are obtained. The results obtained are found to be in good agreement with spectrophotometric results. Key words ammonium ion - voltammetry - platinized platinum electrode CLC number O 657.1 Foundation item: Supported by the National Natural Science Foundation of China (60171023)Biography: Wu Yun-hua (1971-), female, Ph. D candidate, research direction: bioelectrochemistry.

Migration process of ammonium ion in saturated silty sand and sandy loam

ＭｉｇｒａｔｉｏｎｐｒｏｃｅｓｏｆａｍｍｏｎｉｕｍｉｏｎｉｎｓａｔｕｒａｔｅｄｓｉｌｔｙｓａｎｄａｎｄｓａｎｄｙｌｏａｍＺｈｕＷａｎｐｅｎｇ，ＹａｎｇＺｈｉｈｕａ，ＪｉａｎｇＺｈａｎｐｅｎｇＤｅｐａｒｔｍｅｎｔｏｆＥｎｖｉｒｏｎｍｅｎｔａｌＥｎｇｉｎ...

Chemiluminescence flow Sensor for determination of the Ammonium ion

A novel chemiluminescence (CL) sensor for NH4+ combined with flow injection analysis is presented in this paper. It is based on the inhibition effect of NH4+ on the CL reaction between luminol, immobilized electrostatically on an anion-exchange column, and hypochlorous acid electrogenerated on-line. The sensor responds linearly to NH4+ concentration in 1.0x10(-6)-4.0x10(-9) g/ml range. A complete analysis could be performed in 1 min. The system is stable for 200 determination.

Switching Optimally Balanced Fe-N Interaction Enables Extremely Stable Energy Storage

The interaction between electrode materials and charge carriers is one of the central issues dominating underlying energy storage mechanisms.To address the notoriously significant volume changes accompanying intercalation or formation of alloy/compounds,we aim to introduce and utilize a weak,reversible Fe-N interaction during the(de)intercalation of ammonium ions(NH_(4)^(+))within iron(Ⅲ)hexacyanoferrate(FeHCF),inspired by manipulating the electrostatic adsorption between N and Fe in the early stages of ammonia synthesis(Bosch-Harber Process,Chemical Engineering)and steel nitriding processes(Metal Industry).Such strategy of switching well-balanced Fe-N interaction is confirmed in between the nitrogen of ammonium ions and highspin Fe in FeHCF,as observed by using X-ray absorption spectroscopy.The resulting material provided an extremely stable energy storage(58 mAh g^(-1) after 10000 cycles at current density of 1 A g^(-1))as well as high-rate performance(23.6 mAh g^(-1) at current density of 10 A g^(-1)).

Rocking-chair ammonium ion battery with high rate and long-cycle life

Aqueous rechargeable ammonium-ion batteries(AIBs)have drew considerable attention because of their capacity for high rates,low cost,and high safety.However,developing desired electrodes requiring stable structure in the aqueous fast ammoniation/de-ammoniation becomes urgent.Herein,an ammonium ion full battery using Cu_(3)[Fe(CN)_(6)]_(2)(CuHCF)acting to be a cathode and barium vanadate(BVO)acting to be an anode is described.Its excellent electrochemical behavior of Prussian blue analogs and the perfectly matched lattice structure of NH_(4)^(+)is expected.And the open structure of vanadium compounds satisfies the fast ammoniation/de-ammoniation of NH4+is also achieved.As a result of these synergistic effects,the BVO//CuHCF full cell retains 80.5 percent of its capacity following 1000 cycling.These achievements provide new ideas for developing low-cost and long-life AIBs.

Cu-substituted nickel hexacyanoferrate with tunable reaction potentials for superior ammonium ion storage

In this work,a variety of Cu_(x)Ni_(2-x)Fe(CN)_(6)(x=0,0.4,0.8,1.2,1.6,2)cathodes for ammonium ion batteries are prepared and their electrochemical performances are investigated.During the introduction of copper in nickel hexacyanoferrate,the electrochemical performance varies without changing the structure of nickel hexacyanoferrate.The increase of Cu content in nickel hexacyanoferrate leads to the enhancement of reaction potential and capacity.Electrochemical results suggest that the substitution of Cu for Ni has a positive effect on improving the cycling stability and rate capacity of nickel hexacyanoferrate when x in Cu_(x)Ni_(2-x)Fe(CN)_(6)is less than 0.4.Therefore,Cu_(0.4)Ni_(1.6)Fe(CN)_(6)exhibits the best cycling per-formance(capacity retention of 97.54%at 0.3 C)and the highest rate capacity(41.4 mAh g^(-1)at 10 C)in Cu_(x)Ni_(2-x)Fe(CN)_(6).Additionally,the X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS)tests also reveal that the structural evolution of Cu_(0.4)Ni_(1.6)Fe(CN)_(6)is highly reversible upon NH_(4)^(+)storage.Therefore,this work proposes a candidate material for ammoniumion batteries and offers a novel avenue for adjusting the operating potential of the material.

Etching-courtesy NH_(4)^(+) pre-intercalation enables highly-efficient Li^(+) storage of MXenes via the renaissance of interlayer redox

Inspired by a well-known architecture notion that load-bearing walls enable maintaining a highly-stable multiple-floored building,superior advantages are afforded via fabricating the NH_(4)+ions pre-intercalated Mo_(2)CT_(x) MXene(Mo_(2)CT_(x)-N)in a mixed solution of NH_(4)F and HCl via a simple one-step hydrothermal method.As a result of the synergistic effects of pillared structure,immobilizing-F groups and unlocking Mo-based redox,the Mo_(2)CT_(x)-N remarkably delivered a reversible capacity of 384.6 mAh ^(g-1) at 200 mA g^(-1) after 100 cycles.Our work lays a foundation for fully packaging its optimal performance via carding and architecting the chemistry of the MXene layers and between them.

Hydrogen Bond-Assisted Ultra-Stable and Fast Aqueous NH_(4)^(+)Storage

Aqueous ammonium ion batteries are regarded as eco-friendly and sustainable energy storage systems.And applicable host for NH_(4)^(+)in aqueous solution is always in the process of development.On the basis of density functional theory calcula-tions,the excellent performance of NH_(4)^(+)insertion in Prussian blue analogues(PBAs)is proposed,especially for copper hexacyanoferrate(CuHCF).In this work,we prove the outstanding cycling and rate performance of CuHCF via electrochemical analyses,delivering no capacity fading during ultra-long cycles of 3000 times and high capacity retention of 93.6%at 50 C.One of main contributions to superior performance from highly reversible redox reaction and structural change is verified during the ammoniation/de-ammoniation progresses.More importantly,we propose the NH_(4)^(+)diffusion mechanism in CuHCF based on con-tinuous formation and fracture of hydrogen bonds from a joint theoretical and experimental study,which is another essential reason for rapid charge transfer and superior NH_(4)^(+)storage.Lastly,a full cell by coupling CuHCF cathode and polyaniline anode is constructed to explore the practical application of CuHCF.In brief,the outstanding aqueous NH_(4)^(+)storage in cubic PBAs creates a blueprint for fast and sustainable energy storage.

强碱阴离子交换树脂及碱性洗脱剂的离子排阻/阴离子交换色谱法同时测定NH_4^+，NO_2^-和NO_3^-(英文)

Ion-exclusion/anion-exchange chromatography(IEC/AEC) on a combination of a strongly basic anion-exchange resin in the OH——form with basic eluent has been developed.The separation mechanism is based on the ion-exclusion/penetration effect for cations and the anion-exchange effect for anions to anion-exchange resin phase.This system is useful for simultaneous separation and determination of ammonium ion(NH+4),nitrite ion(NO-2),and nitrate ion(NO-3) in water samples.The resolution of analyte ions can be manipulated by changing the concentration of base in eluent on a polystyrene-divinylbenzene based strongly basic anion-exchange resin column.In this study,several separation columns,which consisted of different particle sizes,different functional groups and different anion-exchange capacities,were compared.As the results,the separation column with the smaller anion-exchange capacity(TSKgel Super IC-Anion) showed well-resolved separation of cations and anions.In the optimization of the basic eluent,lithium hydroxide(LiOH) was used as the eluent and the optimal concentration was concluded to be 2 mmol/L,considering the resolution of analyte ions and the whole retention times.In the optimal conditions,the relative standard deviations of the peak areas and the retention times of NH+4,NO-2,and NO-3 ranged 1.28%-3.57% and 0.54%-1.55%,respectively.The limits of detection at signal-to-noise of 3 were 4.10 μmol/L for NH+4,1.87 μmol/L for NO-2 and 2.83 μmol/L for NO-3.

Enabling nickel ferrocyanide nanoparticles for highperformance ammonium ion storage

Prussian blue and its analogs are extensively investigated as a cathode for ammonium-ion batteries.However,they often suffer from poor electronic conductivity.Here,we report a Ni_(2)Fe(CN)_(6)/multiwalled carbon nanotube composite electrode material,which is prepared using a simple coprecipitation approach.The obtained material consists of nanoparticles with sizes 30-50 nm and the multiwalled carbon nanotube embedded in it.The existence of multiwalled carbon nanotube ensures that the Ni_(2)Fe(CN)_(6)/multiwalled carbon nanotube composite shows excellent electrochemical performance,achieving a discharge capacity of 55.1 mAh·g^(-1)at 1 C and 43.2 mAh·g^(-1)even at 15 C.An increase in the ammoniumion diffusion coefficient and ionic/electron conductivity based on kinetic investigations accounts for their high performance.Furthermore,detailed ex situ characterizations demonstrate that Ni_(2)Fe(CN)_(6)/multiwalled carbon nanotube composite offers three advantages:negligible lattice expansion during cycling,stable structure,and the reversible redox couple.Therefore,the Ni_(2)Fe(CN)_(6)/multiwalled carbon nanotube composite presents a long cycling life and high rate capacity.Finally,our study reports a desirable material for ammonium-ion batteries and provides a practical approach for improving the electrochemical performance of Prussian blue and its analogs.

Adsorption behavior of ammonium by a bioadsorbent-Boston ivy leaf powder

The adsorption behaviors of ammonium ions from aqueous solution by a novel bioadsorbent, the Boston ivy （Parthenocissus tricuspidata） leaf powder （BPTL） were investigated. The SEM images and FT-IR spectra were used to characterize BPTL. The mathematical models were used to analyze the adsorption kinetics and isotherms. The optimum pH range for ammonium adsorption by BPTL was found to be 5-10. The adsorption reached equilibrium at 14 b.r, and the kinetic data were well fitted by the Logistic model. The intraparticle diffusion was the main rate-controlling step of the adsorption process. The high temperature was favorable to the ammonium adsorption by BPTL, indicating that the adsorption was endothermic. The adsorption equilibrium fitted well to both the Langmuir model and Freundlich model, and the maximum monolayer adsorption capacities calculated from Langmuir model were 3.37, 5.28 and 6.59 mg N/g at 15, 25 and 35~C, respectively, which were comparable to those by reported minerals. Both the separation factor （RL） from the Langmuir model and Freundiich exponent （n） suggested that the ammonium adsorption by BPTL was favorable. Therefore, the Boston ivy leaf powder could be considered a novel bioadsorbent for ammonium removal from aqueous solution.

Removal of ammonium ion from water by Na-rich birnessite:Performance and mechanisms

Na-rich birnessite（NRB） was synthesized by a simple synthesis method and used as a high-efficiency adsorbent for the removal of ammonium ion（NH＋4） from aqueous solution.In order to demonstrate the adsorption performance of the synthesized material,the effects of contact time,pH,initial ammonium ion concentration,and temperature were investigated.Adsorption kinetics showed that the adsorption behavior followed the pseudo second-order kinetic model.The equilibrium adsorption data were fitted to Langmuir and Freundlich adsorption models and the model parameters were evaluated.The monolayer adsorption capacity of the adsorbent,as obtained from the Langmuir isotherm,was 22.61 mg NH＋4-N/g at283 K.Thermodynamic analyses showed that the adsorption was spontaneous and that it was also a physisorption process.Our data revealed that the higher NH＋4adsorption capacity could be primarily attributed to the water absorption process and electrostatic interaction.Particularly,the high surface hydroxyl-content of NRB enables strong interactions with ammonium ion.The results obtained in this study illustrate that the NRB is expected to be an effective and economically viable adsorbent for ammonium ion removal from aqueous system.

Material conversion from paper sludge ash in NaOH solution to synthesize adsorbent for removal of Pb^(2+),NH_4^+and PO_4^(3-) from aqueous solution

Material conversion from paper sludge ash （PSA） in NaOH solution was attempted to synthesize the adsorbent for removal of inorganic pollutants, such as Pb^2＋, NH^4＋ and PO4^3- from aqueous solution. PSA of 0.5 g was added into 10 mL of 3 mol/L NaOH solution, and then heated at 80, 120, and 160℃ for 6-48 hr to obtain the product. PSA mainly composed of two crystalline phases, gehlenite （Ca2Al2SiO7） and anorthite （CaAl2Si2O8）, and amorphous phase. Hydroxysodalite （Na6Al6Si6O24-8H2O） was formed at 80℃, and anorthite dissolved, whereas gehlenite remained unaffected. Katoite （Ca3Al2SiO4（OH）8） was formed over 120℃, and hydroxycancrinite （Nas（OH）2Al6Si6O24·2H2O） was formed at 160℃, due to the dissolution of both gehlenite and anorthite. Specific surface areas of the products were almost same and were higher than that of raw ash. Cation exchange capacities （CECs） of the products were also higher than that of raw ash, and CEC obtained at lower temperature was higher. Removal abilities of products for Pb^2＋, NH4＋, and PO4^3- were higher than that of raw ash. With increasing reaction temperature, the removal efficiencies of Pb^2＋ and NH4＋ decreased due to the decrease of CEC of the product, while removal efficiency for PO4^3- was almost same. The concentrations of Si and AI in the solution and the crystalline phases in the solid during the reaction explain the formation of the product phases at each temperature.