Amphoteric Supramolecular Nanofiber Separator for High-Performance Sodium-Ion Batteries

The separator is an essential component of sodium-ion batteries(SIBs)to determine their electrochemical performances.However,the separator with high mechanical strength,good electrolyte wettability and excellent electrochemical performance remains an open challenge.Herein,a new separator consisting of amphoteric nanofibers with abundant functional groups was fabricated through supramolecular assembly of natural polymers for SIB.The uniform nanoporous structure,remarkable mechanical properties and abundant functional groups(e.g.-COOH,-NH_(2)and-OH)endow the separator with lower dissolution activation energy and higher ion migration numbers.These metrics enable the separator to lower the barrier for desolvation of Na^(+),accelerate the migration of Na^(+),and generate more stable solid electrolyte interphase(SEI)and cathode electrolyte interphase(CEI).The battery assembled with the amphoteric nanofiber separator shows higher specific capacity and better stability than that assembled with glass fiber(GF)separator.

A micro-crosslinked amphoteric hydrophobic association copolymer as high temperature-and salt-resistance fluid loss reducer for water-based drilling fluids

During ultradeep oil and gas drilling,fluid loss reducers are highly important for water-based drilling fluids,while preparing high temperature-and salt-resistance fluid loss reducers with excellent rheology and filtration performance remains a challenge.Herein,a micro-crosslinked amphoteric hydrophobic association copolymer(i.e.,DADC)was synthesized using N,N-dimethyl acrylamide,diallyl dimethyl ammonium chloride,2-acrylamido-2-methylpropane sulfonic acid,hydrophobic monomer,and pentaerythritol triallyl ether crosslinker.Due to the synergistic effects of hydrogen bonds,electrostatic interaction,hydrophobic association,and micro-crosslinking,the DADC copolymer exhibited outstanding temperature-and salt-resistance.The rheological experiments have shown that the DADC copolymer had excellent shear dilution performance and a certain degree of salt-responsive viscosity-increasing performance.The DADC copolymer could effectively adsorb on the surface of bentonite particles through electrostatic interaction and hydrogen bonds,which bring more negative charge to the bentonite,thus improving the hydration and dispersion of bentonite particles as well as the colloidal stability of the drilling fluids.Moreover,the drilling fluids constructed based on the DADC copolymer exhibited satisfactory rheological and filtration properties(FLHTHP=12 m L)after aging at high temperatures(up to200℃)and high salinity(saturated salt)environments.Therefore,this work provided new insights into designing and fabricating high-performance drilling fluid treatment agents,demonstrating good potential applications in deep and ultradeep drilling engineering.

STUDY ON SYNTHESIS OF AMPHOTERIC POLYACRYLAMIDE IN INVERSE EMULSION

Amphoteric polyacrylamide was prepared first by the copolymerization of acrylamide with sodium acrylate and then through Mannich reaction.The copolymerization was carried out with a redox initiation system using the method of inverse emulsion polymerization.In this paper the reaction conditions and factors that affect emulsion stability were studied.Experiments show that a stable latex can be obtained under the following conditions:anionic degree is five percent,the ratio among acrylamide,formaldehyde and dimethylamine is 1∶1∶1.2,reaction temperature is 45 ℃,reaction time lasts four hours,and pH equals 5.0.The amphoteric copolymer has a higher molecular weight and cationic degree,so it is an ideal filler retention and drainage aid in paper making.

Sorption of Heavy Metal and Organic Pollutants on Modified Soils

Sorption characteristics of both an organic pollutant (phenol) and a heavy metal (cadmium ion) on the clay layer of a Lou soil (Eum-orthic Anthrosol in Chinese Soil Taxonomy) along with the sorption mechanism were investigated using three soil treatments: modification with a cationic surfactant cetyltrimethylammonium bromide added at an amount equivalent to 50% and 100% of the soil CEC (50%CB and 100%CB), modification with an amphoteric surface-modifying agent dodecyldimethylbetaine (commercially known as BS-12) added at an amount equivalent to 50% and 100% of the soil CEC (50% BS and 100%BS), and an unmodified control (CK). Results showed that the BS soil treatments increased sorption of both the heavy metal Cd2+ and the organic pollutant phenol. The equilibrium sorption amount of Cd2+ decreased in the order: 50%BS > 100%BS > CK > 50%CB > 100%CB, with the BS soil treatments being about 1.3 to 1.8 times higher and the CB soil treatments about 23% to 41% lower than CK. Both the single-site and two-site Langmuir models could be applied to describe the sorption of Cd2+ in each soil treatment. The equilibrium sorption amount of phenol on the soil samples decreased in the order: 100%CB > 50%CB > 100%BS > 50%BS > CK, with the CB soil treatments being 41.0 to 79.6 times higher and the BS soil treatments 4.0 to 8.3 times higher than CK. The Freundlich equation could also be used to describe the sorption characteristics of phenol. In the BS soil treatments, both an organophobic long carbon chain and hydrophilic charged groups resulted in a relatively strong sorption ability for both heavy metals and organic pollutants. In addition, the sorption ratio K, the ratio of phenol sorption amount of the modified soil to that of CK, increased initially and decreased later with the amount of phenol added, and the critical sorption ratio KC, the peak value of the sorption ratio curve plotted against the added phenol concentration, was a good index for evaluating the sorption ability of phenol in the soil.

Adsorption/desorption behavior between a novel amphoteric granular lignin adsorbent and reactive red K-3B in aqueous solutions

A novel amphoteric granular lignin adsorbent(AGLA) was prepared using magnesium lignosulfonate as a raw material which was provided by a straw sulfite pulp mill in Guangdong Province, China. A reactive dye(red K-3B) was used as an adsorbate to investigate the adsorption behavior by static and mobile ways. The removal of reactive red K-3B was found to be initially pH and concentration dependent. Moreover, an increase of solution temperature ranging from 5℃ to 60℃ helped to enhance the rate of intraparticle diffusion of adsorbate and changes in the size of the pores of the adsorbent and thus to reduce the adsorption time. The total breakthrough adsorption capacity was 531 mg/g, and the saturated adsorption capacity was 560 mg/g, which prevailed over the activated carbons evidently. The reactive red K-3B adsorbed on AGLA could be recovered with a mixture of alcohol, NaCl and HCl aqueous solutions. The recovery percentage could reach 92.4%.

Hydrogen generation with acid/alkaline amphoteric water electrolysis

To reduce the energy consumption of the electrolytic hydrogen generation process, we propose a novel approach to generate hydrogen with acidic/alkaline amphoteric water electrolysis, wherein hydrogen is produced inside an acidic solution and oxygen evolved under alkaline condition, and a membrane is employed in the middle of the electrolyzer to restrain neutralization. The electrode polarization is greatly reduced due to the specific arrangement of the acidic/alkaline amphoteric electrolyzer. The rate of hydrogen production achieves over four times higher than that of the alkaline aqueous solution at 2.2 V, and the energy consumption is reduced approximately 30% under the current density of 200 m A/cm ^2. The investigation of transmembrane potential drop indicates water splitting on the membrane surfaces, which compensates for acid or alkaline loss on-site and maintains the concentration approximately constant during electrolysis process. The acidic/alkaline amphoteric water electrolysis is promising as an energy saving, clean and sustainable hydrogen production technology.

Adsorption thermodynamics and kinetic investigation of aromatic amphoteric compounds onto different polymeric adsorbents

The adsorption behavior ofp-aminobenzoic acid and o-aminobenzoic acid onto the different polymeric adsorbents was systematically investigated as a function of the solution concentration and temperature. Experimental results indicated that the equilibrium adsorption data of the four polymeric adsorbents fitted well in the Freundlich isotherm. The adsorption capacity of multi-functional polymeric adsorbent NJ-99 was the highest, which might be attributed to the strong hydrogen-bonding interaction between the amino groups on the resin and the carboxyl group of aminobenzoic acid. The adsorption capacity of o-aminobenzoic acid onto any adsorbent was higher than p-aminobenzoic acid. Thermodynamic studies suggested the exothermic, spontaneous physical adsorption process. Adsorption kinetics results showed that the adsorption followed the pseudo-second-order kinetics model and the intraparticle mass transfer process was the rate-controlling step.

Optimization of low-temperature alkaline smelting process of crushed metal enrichment originated from waste printed circuit boards

A novel low-temperature alkaline smelting process is proposed to convert and separate amphoteric metals in crushed metal enrichment originated from waste printed circuit boards. The central composite design was used to optimize the operating parameters,in which mass ratio of Na OH-to-CME, smelting temperature and smelting time were chosen as the variables, and the conversions of amphoteric metals tin, lead, aluminum and zinc were response parameters. Second-order polynomial models of high significance and3 D response surface plots were constructed to show the relationship between the responses and the variables. Optimum area of80%-85% Pb conversion and over 95% Sn conversion was obtained by the overlaid contours at mass ratio of Na OH-to-CME of4.5-5.0, smelting temperature of 653-723 K, smelting time of 90-120 min. The models were validated experimentally in the optimum area, and the results demonstrate that these models are reliable and accurate in predicting the smelting process.

Interface Reversible Electric Field Regulated by Amphoteric Charged Protein-Based Coating Toward High-Rate and Robust Zn Anode

Metallic interface engineering is a promising strategy to stabilize Zn anode via promoting Zn^(2+) uniform deposition.However,strong interactions between the coating and Zn^(2+) and sluggish transport of Zn^(2+) lead to high anodic polarization.Here,we present a bio-inspired silk fibroin(SF)coating with amphoteric charges to construct an interface reversible electric field,which manipulates the transfer kinetics of Zn^(2+) and reduces anodic polarization.The alternating positively and negatively charged surface as a build-in driving force can expedite and homogenize Zn^(2+) flux via the inter-play between the charged coating and adsorbed ions,endowing the Zn-SF anode with low polarization voltage and stable plating/stripping.Experimental analyses with theo-retical calculations suggest that SF can facilitate the desolvation of[Zn(H_(2)O)_(6)]^(2+) and provide nucleation sites for uniform deposition.Consequently,the Zn-SF anode delivers a high-rate performance with low voltage polarization(83 mV at 20 mA cm^(−2)) and excellent stability(1500 h at 1 mA cm^(−2);500 h at 10 mA cm^(−2)),realizing exceptional cumulative capacity of 2.5 Ah cm^(−2).The full cell coupled with Zn_(x)V_(2)O_(5)·nH_(2)O(ZnVO)cathode achieves specific energy of~270.5/150.6 Wh kg^(−1)(at 0.5/10 A g^(−1))with-99.8% Coulombic efficiency and retains~80.3%(at 5.0 A g^(−1))after 3000 cycles.

Tangutidines A-C,Three Amphoteric Diterpene Alkaloids from Aconitum tanguticum

Three new diterpene alkaloids,tangutidines A-C(1-3),and four known alkaloids(4-7)were isolated from the whole plant of Aconitum tanguticum,from which amphoteric diterpene alkaloids(1-3)were obtained for the first time.The structures of 1-3 were elucidated by detailed interpretation of spectroscopic data,including MS and NMR data.All of them were evaluated for their cytotoxic activities.

Facile fabrication of amphoteric semi-interpenetrating network membranes for vanadium flow battery applications

For improvement of vanadium redox flow battery （VRB） performance, novel amphoteric semi- interpenetrating membranes （ASIPN） were prepared using poly（ether ether ketone） （PEEK） and polysul- fone （PSf）, the former bearing sulfonic groups and the latter imidazolium. These two groups form ionic crosslinks between PEEK and PSf; meanwhile, covalent cross links were built between PSf chains with ad- dition of N-（3-aminopropyl）-imidazole. The amphoteric nature of the membrane allows facile proton and anion transport; the IPN structure and the presence of imidazolium cation effectively suppress vanadium ion crossover through the membrane. Therefore, the ASIPN based VRBs show higher Coulombic efficiency and energy efficiency than that assembled with pristine SPEEK and Nation 212 membranes. Our work demonstrates that the ASIPN membranes are promising for VRB applications.

A new long-side-chain sulfonated poly(2,6-dimethyl-1,4-phenylene oxide)(PPO)/polybenzimidazole(PBI)amphoteric membrane for vanadium redox flow battery

A new amphoteric membrane was prepared by blending long-side-chain sulfonated poly(2,6-dimethyl-1,4-phenylene oxide)(S-L-PPO)and polybenzimidazole(PBI)for vanadium redox flow battery(VRFB)application.An acid-base pair structure formed between the imidazole of PBI and sulfonic acid of S-L-PPO resulted in lowered swelling ratio.It favors to reduce the vanadium permeation.While,the increased sulfonic acid concentration ensured that proton conductivity was still at a high level.As a result,a better balance between the vanadium ion permeation(6.1×10^-9 cm^2·s^-1)and proton conductivity(50.8 m S·cm^-1)in the S-L-PPO/PBI-10%membrane was achieved.The VRFB performance with S-L-PPO/PBI-10%membrane exhibited an EE of 82.7%,which was higher than those of pristine S-L-PPO(81.8%)and Nafion 212(78.0%)at 120 m A·cm^-2.In addition,the S-LPPO/PBI-10%membrane had a much longer self-discharge duration time(142 h)than that of Nafion 212(23 h).

Dolomite apatite separation by amphoteric collector in presence of bacteria

Bioflotation represents one of the growing trends to enhance the selectivity of conventional flotation processes. It utilizes the micro-organisms to replace or to interact with the chemical reagents to increase the gap between surface properties of similar minerals and to enhance the separation selectivity. In this work, dolomite-phosphate separation was investigated using amphoteric collector （dodecyl-N-carboxyethyl-N-hyroxyethyl-imidazoline） in presence of bacteria. Two types of bacteria, Corynebacterium- diphtheriae-intermedius （CDI）, and Pseudomonas aeruginosa （PA）, were used. The collector-bacteria interaction was characterized by Fourier transform infra-red （FTIR）, frothing height and Zeta potential. The results show that the collector-bacteria interaction improves the flotation selectivity. Although, the PA positively affects the separation results, the CDI cannot lower the MgO to less than 1%. A phosphate content of 0.7% MgO and 31.77% P205 with a recovery of 68% at pH 11, 3.0 kg/t amphoteric collector, 4× 10^7 cells of PA is obtained.

Synthesis of Mesoporous Silica and Ti-containing Molecular Sieves via A Novel Assembly

Thermally stable mesoporous silica and Ti-containing molecular sieves have been synthesized at mild temperature using low-cost and biodegradable --- amphoteric tetradecyl betaine as template. The physicochemical characterizations proved that Ti(IV) could be incorporated in the mesoporous struture.

SYNTHESIS AND CHARACTERIZATION OF AMPHOTERIC HYDROGELS BASED ON N-CARBOXYETHYLCHITOSAN

New amphoteric hydrogels based on carboxyethylchitosans (CECH) with various degrees of substitution (DS) were prepared using different amounts of epichlorohydrin (ECH) as the crosslinking agent. The equilibrium swelling ratio (SW) was determined as functions of pH and salt concentration. The hydrogels show typical amphoteric character responding to pH change of the external medium. At isoelectric point (IEP), the hydrogels shrink. The DS value has important effect on the swelling properties of the hydrogels. When the DS of N-carboxyethylchitosan increases from 0.32 to 0.72, the equilibrium swelling ratio (SW) of the hydrogel changes from 76 to 290 at pH 7.3 and from 117 to 499 at pH 11.3. A marked volume decrease was observed in hydrogels with increasing salt concentration in the surrounding solution. The viscoelastic properties of the hydrogels were studied by oscillatory shear measurements under small-deformation conditions. The elastic modulus G' of all the samples has no dependence on frequency and is one order of magnitude larger than the loss modulus G '', corresponding to a strong gel behavior.

EFFECT OF pH ON THE ADSORPTION OFp-AMINOBENZOIC ACID ON POLYSTYRENE-BASED ADSORBENTS

In the present study the adsorptive properties of p-aminobenzoic acid with hypercrosslinked and multi-functional polymeric adsorbents at different solution pHs were systematically investigated in accordance with the particular physicochemical characteristics of the aromatic amphoteric compound involving both Lewis acid and Lewis base functional groups. It was found that the equilibrium adsorption data of the three polymeric adsorbents fitted well in the Langmuir and Freundlich isotherm equations. Studies at various pH levels indicate that the capacity of the adsorbents for adsorption of the ionic forms of adsorbate is less than that for the corresponding neutral species. At pH 3.78, the adsorption capacities of the three adsorbents are the highest. Whereas the adsorption property of multi-functional polymeric adsorbent NJ-99 is the largest, which may be attributed to the strong hydrogen-bonding interaction between the amino groups on the resin and the carboxyl group of p-aminobenzoic acid. The trend of the adsorption capacities of the three adsorbents towards p-aminobenzoic acid with the solution pH is in accord with the dissociation curve of the neutral molecular p-aminobenzoic acid. The adsorption forces include π-π interaction, hydrogen-bonding interaction and electrostatic attraction or repulsion when there exist the molecular and ionic adsorbing species at different pHs in aqueous solution.

Effect of Mixed Dispersants on Suppression of the Gel Effect during Aqueous Adiabatic Terpolymerization of AM,NaAA,and DMC

Gelation adversely affects the aqueous adiabatic terpolymerization of acrylamide (AM), sodium acrylate (NaAA),and 2-methacryloyloxyethyl trimethylammonium chloride (DMC). Here, the mixed dispersants sorbitan monooleate (Span80) and polyoxyethylene sorbitan monooleate (Tween 80) were introduced to the terpolymerization system in an attemptto mitigate the gel effect. This enabled the preparation of high-performance amphoteric polyacrylamides, which werecharacterized by Fourier-transform infrared spectroscopy and thermogravimetric analysis. The influences of the dispersanttype and content as well as the hydrophilic-lipophilic balance (HLB) on the gel effect were examined, and the mechanismunderlying the suppression of the gel effect was considered. The obtained results indicated that the gel effect can beeffectively mitigated using an aqueous adiabatic terpolymerization system containing mixed Span 80/Tween 80 dispersantsat various contents. In particular, mixed dispersant contents of 0.6%–0.8% with HLB values of 5.0–6.0 afforded the optimalperformance (e.g., high viscosity, fast aqueous dissolution time, and the like).

THE SPECTROPHOTOMETRIC STUDY ON THE INTERACTION BETWEEN AMPHOTERIC SURFACTANT AND ANIONIC DYE

The interaction of an amphoteric surfactant, N-12alkylbetaine, and an acid dye in aqueous solution was studied by spectrophotometry. The results of the experiments show that the particle of dye interacts with one or several N-12alkylbetaine molecules when the concentration of the surfactant is less than the CMC. The aggregated dyes are disintegrated when the surfactant concentration is more than the CMC, and the individual dye ion interacts with the suffactant micelle.

Transport of Phenol in BS-12 Modified Lou Soil in the Column Experiment: Effect of Concentrations, pH and Ionic Strength

Lou soil was modified by amphoteric surfactant in column experiment which was conducted. This study attempts to explore the transport of phenol to unmodified and modified soil and inquire into the effect of concentrations, pH, and ionic strength on phenol migration in the soil column. The parameters and breakthrough curves (BTCs) of transport were fitted by using the CXTFIT (version 2.1) model. The result of Cl?’s BTCs for non-reactive by determining the equilibrium model (EM) showed the retardation factor which was smaller than 1. The result of phenol’s BTCs by determining non-equilibrium model (NEM) was shown that the R-value increased while modification ratio increased, and the R was in order of CK (1.337) < 50BS-12 (4.085) < 100BS-12 (7.048). The lower to higher concentration of phenol didn’t affect to CK and 100BS-12 was able to block higher concentration. The effect of pH on transport to CK and 100BS-12 didn’t react and the average pore water velocity was decreased at pH = 4. The decreasing ionic strength of phenol migration on CK and 100BS-12 had effect and the average pore water velocity and retardation factor also decreased. The residual retention in soil was in order of CK < 50BS-12 < 100BS-12, and 100BS-12 could hold the amount of phenol than CK 7.21 times. Thus, amphoteric modified lou soil definitely blocks phenol migration and controls groundwater pollution.

INTERACTION MECHANISM OF AMPHOTERIC COLLECTOR-I WITH METALLIC IONS AND MINERALS

The electronic structure and bonding nature of adsorbing bonding complexes which consist of Amphoteric Collector-I and Mg^(2+), Ca^(2+), MgPO_4^-, CaPO_^-4, CaCO_3, as well aa MgCO_3, are studied using quantum chemistry CNDO/2, It is predicted that magnesium salts are more liable to form adsorbing chelates with Amphoteric Collector-I than calcium salts, and all results coincide with that obtained in flotation.