Adsorption Of Anions Research Articles

Magnetic porous Ag2O/Chitin nanostructure adsorbent for eco-friendly effective disposing azo dyes

Water treatment is as much important as it is to satisfying 11 worldwide sustainable development goals out of 17. The removal of Azo is much important as they are toxic and their existence in water, air and food can easily affect humans by triggering allergies, forming tumours etc. Azo contained Dyes Production was banned in many countries. This research aims to synthesize composite Nanorods and Nanospheres and characterize and test to remove Azo dyes from the wastewater. This research used a previously reported method to rapidly synthesize chitin magnetite nanocomposites (ChM) by co-precipitation while irradiating with ultrasound (US). Detailed structural characterization of ChM revealed a crystalline phase analogous to magnetite and spherical morphologies; extending the reaction time to 8 min yielded a “nanorod” type morphology. Both the morphologies displayed a nanoscale limit with particles averaging between 5 and 30 nm in size, resulting the superparamagnetic performance and saturation magnetization values between 45 and 58 emu/g. The nitrogen adsorption-desorption isotherms showed that the surface modification of ChMs resulted in a rise of specific surface area and pore size. Anionic azo dyes (methyl orange (MO) and reactive black 5 (RB5)) adsorption on the surface of nanocomposites was also demonstrated to be pH-dependent, with the reaction favoured for surface-modified samples at pH 4 and unmodified samples at pH 8. Adsorption capacity studies showed that molecule size effect and electrostatic attraction were two distinct adsorption processes for unmodified and modified ChMs. Chitin Magnetite nanoparticles appear to be a substitute for traditional anionic dye adsorbents. Additionally, the two key materials sources, chitin, and magnetite are inexpensive and easily accessible.

Influence of Salts on the Photocatalytic Degradation of Formic Acid in Wastewater.

Conventional wastewater treatment technologies have difficulties in feasibly removing persistent organics. The photocatalytic oxidation of these contaminants offers an economical and environmentally friendly solution. In this study, TiO2 membranes and Ag/TiO2 membranes were prepared and used for the decomposition of dissolved formic acid in wastewater. The photochemical deposition of silver on a TiO2 membrane improved the decomposition rate. The rate doubled by depositing ca. 2.5 mg of Ag per 1 g of TiO2. The influence of salinity on formic acid decomposition was studied. The presence of inorganic salts reduced the treatment performance of the TiO2 membranes to half. Ag/TiO2 membranes had a larger reduction of ca. 40%. The performance was recovered by washing the membranes with water. The anion adsorption on the membrane surface likely caused the performance reduction.

A general strategy to synthesize single-atom metal-oxygen doped polymeric carbon nitride with highly enhanced photocatalytic water splitting activity

Polymeric carbon nitride (PCN) is a prospective photocatalyst in water splitting to produce H2, but its overall water splitting (OWS) activity is suppressed by the sluggish oxygen evolution reaction (OER). Herein, a general strategy involving electrostatic adsorption of oxometallate anions on protonated amorphous melon was proposed to synthesize single-atom metal-oxygen doped PCN (MO-PCN). MO-PCN exhibits highly enhanced photocatalytic OER and thereby OWS activity, benefitting from the MO structure functioning as OER active centers and enhancing photoexcited charge separation by introducing hole-trapping doping levels in bandgaps. This work provides a universal strategy to enhance OER activity of PCN-based photocatalysts.

Balancing the anions adsorption and intercalation in carbon cathode enables high energy density dual-carbon lithium-ion capacitors

The mismatch in kinetics and capacity of electrodes restricts the further improvement of lithium-ion capacitors (LICs). In specific, carbon cathode with a high specific capacity plays a crucial role in achieving the high energy density of LICs devices. Herein, the ordered-disordered hybrid carbon structure was designed and different anions storage behaviors were revealed. Benefiting from this novel method, the specific capacity of carbon cathode reached 130.1 mAh g−1 at 0.1 A g−1 in the range of 2–4.6 V with anions adsorption and intercalation mechanism. Moreover, the specific capacity still stabilized at 62.3 mAh g−1 even after 500 cycles at 5.0 A g−1 (vs. 17.6 mAh g−1 of commercial activated carbon). When assembled into dual-carbon LICs with the modified anode, the energy density was as high as 231.5 Wh kg−1 at a power density of 40.6 W kg−1, which was much superior to the present LICs devices. The energy density was still maintained at 86.2 Wh kg−1 at 5.0 A g−1 after 1000 cycles. The improved carbon cathode tactic by regulating the anions storage behavior provides a new approach for high-performance LICs.

Electrostatic interaction and surface S vacancies synergistically enhanced the photocatalytic degradation of ceftriaxone sodium

ZnIn2S4 ultrathin 2D nanosheets with a positive surface charge are synthesized by a hydrothermal method and different contents of surface S vacancies are induced via heat treatment of as-prepared ZnIn2S4 (ZIS). As the S vacancies contents increased, the photocatalytic degradation efficiency of ceftriaxone (CTRX) sodium is promoted. Especially, ZIS-300 shows the best degradation efficiency (88.8%) for an initial CTRX concentration of 10 mg L−1 in 2 h. It is found that S vacancies cause the electron density of surface metal atoms (Zn, In) to be decreased, which makes the effective adsorption and activation of ceftriaxone anions through electrostatic adsorption interactions. Meanwhile, S vacancies also serve as active centers to promote the absorption of O2 and gather electrons to form •O2− species. The photogenerated holes quickly transfer to the surface of the catalyst to directly degrade the adsorbed CTRX. Thus, the photocatalytic CTRX degradation efficiency is significantly improved. Finally, a possible mechanism for over defective ZIS is proposed. This work provides a feasible strategy for the efficient degradation of antibiotics from the perspective of electrostatic adsorption and molecule activation.

Design of bionic amphoteric adsorbent based on reed root loaded with amino-functionalized magnetic nanoparticles for heavy metal ions removal

Renewable and cheap reed roots are rich in polysaccharide and lignin and naturally possesses wastewater purification ability. However, if applied as industrial adsorbent, the active sites of reed roots need further enhancement to fit realistic amphoteric ion adsorption requirement and its recovery also request for optimization to avert secondary pollution caused by adsorbent residues. Under this background, a novel adsorbent based on reed root loaded with magnetic amino-functionalized nanoparticles (RrH@Fe3O4 @SiO2-NH2) with a bionic dendritic structure and a pleated surface was designed. The reed roots were firstly pretreated with hydrogen peroxide solution with strong oxidizing properties under UV light irradiation to expose more oxygen-containing functional groups, which then condensed with the amino groups on the surface of Fe3O4 @SiO2-NH2 nanoparticles, leading to the formation of the final adsorbent. The carboxyl, hydroxyl and methoxy and amino groups on the surface of the adsorbent synergistically contribute to the adsorption of both anions and cations. The maximum adsorption capacity for Pb (II) and Cr (VI) ions per unit mass of reed root in RrH@Fe3O4 @SiO2-NH2 reached 99.1 and 106.5 mg g− 1, much higher than those obtained with raw reed roots (24.8 and 30.6 mg g−1). The superior adsorption performance was ascribed to its physicochemical properties as characterized by a series of characterization methods. The adsorption process followed pseudo-second-order kinetic and Freundlich isotherm model, indicating a chemical multi-layer endothermic adsorption process. The addition of magnetic Fe3O4 endows the easy recovery of the adsorbent by applying a magnetic field, and after five cycles, the adsorption capacity can still reach 82% of that of the first time. In summary, the desirable adsorption performance, easy recovery, and low cost make the bionic RrH@Fe3O4 @SiO2-NH2 a promising amphoteric adsorbent for eliminating heavy metal ions from wastewater.

Adsorption of croconic acid anions at silver electrodes in sodium fluoride solutions. Interplay of DFT calculations and in situ ATR-SEIRAS measurements for the interpretation of experimental spectra of adsorbed species

The adsorption of species coming from the disodium salt of croconic acid (4,5-dihydroxy-4-cyclopentene-1,2,3-trione, H2C5O5) at chemically deposited silver electrodes was studied in aqueous sodium fluoride solutions by combining in situ ATR-SEIRAS (Surface-Enhanced Infrared Reflection Absorption Spectroscopy experiments under Attenuated Total Reflection conditions) and Density Functional Theory (DFT) calculations. Voltammetric experiments suggest the existence of reversible adsorption processes in the potential range between −0.55 and −0.20 V vs Ag/AgCl (KCl 1 M), whereas irreversible reduction is observed for potentials below-0.55 V. ATR-SEIRA spectra show potential-dependent adsorbate bands in the potential range for reversible adsorption, that were assigned according to DFT calculations. Calculated optimized geometry of adsorbed croconate and bicroconate correspond to bonding to the silver surface in a bidentate configuration through two oxygen atoms with the molecular plane perpendicular to the metal surface. The broadening and splitting at high electrode potentials of the CO stretching bands for adsorbates coming from croconic acid can be explained by invoking the existence of collective vibrational modes appearing at high coverage. In overall, the ATR-SEIRA spectra obtained with Ag thin layer electrodes resembles that reported for Au thin layers. As a difference, higher adsorbate coverage seems to be obtained in the case of silver. Moreover, a strong feature at ca. 1580 cm−1 is experimentally observed, that was much weaker on gold samples. The calculated frequencies for adsorbed croconate and bicroconate do not change significantly with the adsorption bonding sites for the optimized geometries. Taking into account the calculated frequencies of both types of species, a better agreement with the experimental behavior (including the splitting/shifting caused by dipole–dipole coupling in high-coverage collective modes) is obtained in the case of bicroconate. The coexistence with some adsorbed croconate species cannot be ruled out.

Mandarin Biochar-TETA (MBT) prepared from Citrus reticulata peels for adsorption of Acid Yellow 11 dye from water

Dehydration technique with 80% sulfuric acid was used to create a novel biochar from mandarin peel wastes followed by condensate with triethylenetetramine (TETA) to give Mandarin Biochar-TETA (MBT). BJH, BET, FTIR, SEM, DSC, TGA, and EDX studies were used to characterise the MBT. The capacity of the newly developed biochar to remove Acid Yellow 11 (AY11) dye from a water solution was studied. The pH of AY11 dye adsorption was found to be best at pH 1.5. Using 100 ppm AY11 dye as a beginning concentration and 1.75 g L–1 MBT dose, the greatest percent of AY11 dye removal by MBT was 97.83%. The MBT calculated maximum adsorption capacity (Qm) was 384.62 mg g–1. Langmuir (LIM), Freundlich (FIM), Tempkin (TIM), and Dubinin–Radushkevich (DRIM) isotherm models were applied to analyse the experimental data. Furthermore, the results of these isotherm models were investigated by various known error function equations. The MBT experimental data was best suited by the LIM. Pseudo-first-order (PFO), pseudo-second-order (PSO), Elovich kinetic model (EKM), intraparticle diffusion (IPD), and film diffusion (FD) models were used to calculate kinetic data. A PSO rate model with a high correlation (R2 > 0.990) was used to assess the adsorption rate. The main mechanism of the MBT adsorption method of the AY11 dye’s anions adsorption is the electrostatic attractive forces that arise with the increase of positively charged sites in an acidic medium. The obtained data suggest that the prepared MBT adsorbent has the potential to be an effective material to remove the AY11 dye from water and that it may be used repeatedly without losing its adsorption efficiency.

Effective removal of fluorine ions in phosphoric acid by silicate molecular sieve synthesized by hexafluorosilicic acid

Silicone zeolite prepared from hexafluorosilicic acid is a good adsorbent for fluoride removal. The morphology and structure of the prepared composites were characterized by XRD, FT-IR and BET. XRD images showed that fluorine was adsorbed on the surface of zeolite and the FT-IR spectra showed that there are different kinds of silicon and aluminum in silica-based zeolite. Therefore, through the studied of regeneration-adsorption cycle of zeolite, fluoride desorption and regeneration mechanism of zeolite defluorination was explained, and the adsorption performance and regeneration adsorption performance of zeolite defluorination were evaluated. The effects of phosphoric acid concentration, operating condition and specific surface area of zeolite and Si/Al ratio of zeolite on adsorption performance were investigated. Silicate molecule sieve shows strong adsorption capacity for fluoride (F-), and the adsorption capacity reached 352.46 mg/g under the optimal conditions. The Freundlich and Langmuir isotherm models for aluminosilicate MCM-41 and NaA zeolite which experimental data of F- adsorption on in phosphoric acid were fitted to investigate the adsorption mechanism. In the mechanism of anion adsorption, F- or SiF62- is bound by electrostatic adsorption of hydroxyl on the surface of adsorbent with anion adsorption. The adsorbed SiF62− ions can be regenerated when the environmental pH increases to value higher than that of zero charge point of zeolite. There is a competitive adsorption between OH– and F- with negative charge, which reduces the adsorption efficiency of adsorbent for F-. The NaA zeolite regenerated with NH3·H2O showed better fluorine re-adsorption performance.

Active ion-exchangeable Bi2O(OH)2SO4 synthesized by ball milling for effective iodine enrichment: Insight into the pathway

Effective capture of radioactive iodine and iodine enrichment from dilute source are highly desirable but still remain as significant challenges. Based on mechanochemical activation of Bi oxide (Bi2O3) toward iodine incorporation by forming BiOI, we report a new approach to functionalize Bi2O3 with several anion groups just by simply co-milling with Bi sulfate. Several analytical methods were used to characterize the reaction products and its high efficiency for iodine enrichment inside. Compared with activation just for α-Bi2O3 itself, formation of Bi2O(OH)2SO4 was confirmed to allow a tremendous increase in adsorption capacity up to 335.57 mg/g towards iodine with the product, due to effect by ion-exchange with three anion groups (SO42−, CO32−, OH−) to form BiOI with a stable structure of Bi-O layer, demonstrating obvious advantages as a newly developed typical anionic adsorbent. Iodine can be recovered by heating BiOI to give back Bi2O3 for recycling. As a cost-effective and environmental-friendly process to produce an efficient material for iodine enrichment, this research may open a promising way to effectively remove radioactive iodine and recover iodine resources.

On the mechanisms of ion adsorption to aqueous interfaces: air-water vs. oil-water

The adsorption of ions to water-hydrophobe interfaces influences a wide range of phenomena, including chemical reaction rates, ion transport across biological membranes, and electrochemical and many catalytic processes; hence, developing a detailed understanding of the behavior of ions at water-hydrophobe interfaces is of central interest. Here, we characterize the adsorption of the chaotropic thiocyanate anion (SCN-) to two prototypical liquid hydrophobic surfaces, water-toluene and water-decane, by surface-sensitive nonlinear spectroscopy and compare the results against our previous studies of SCN- adsorption to the air-water interface. For these systems, we observe no spectral shift in the charge transfer to solvent spectrum of SCN-, and the Gibb's free energies of adsorption for these three different interfaces all agree within error. We employed molecular dynamics simulations to develop a molecular-level understanding of the adsorption mechanism and found that the adsorption for SCN- to both water-toluene and water-decane interfaces is driven by an increase in entropy, with very little enthalpic contribution. This is a qualitatively different mechanism than reported for SCN- adsorption to the air-water and graphene-water interfaces, wherein a favorable enthalpy change was the main driving force, against an unfavorable entropy change.

Operando X-Ray Absorption Spectroscopic Study on Influence of Specific Adsorption of Sulfo Group in Perfluorosulfonic Acid Ionomer Towards ORR Activity of Pt/C Catalyst

Polymer electrolyte fuel cells (PEFCs) are clean energy devices with polymer electrolytes and are expected to play an important role in the development of a global renewable energy system and a pure hydrogen energy society in the future. PEFCs have already been applied for small-scale energy systems such as fuel cell vehicles (FCVs). Pt-based catalysts are basically used due to the relatively inefficient reaction kinetics and catalyst degradation under strong acidic conditions during the oxygen reduction reaction (ORR). However, there are still many difficulties in realizing acceptable cost-effective FCVs. It is known that the ORR activity of Pt-based catalysts is reduced by specific adsorption of anionic species. Perfluorosulfonic acid ionomers such as Nafion® are commonly included in the catalyst layers of PEFCs to provide protonic pathways for promoting the ORR1. However, direct observation of anion adsorption on practical Pt nanoparticle/C catalysts for perfluorosulfonic acid ionomers using X-ray absorption spectroscopy (XAS) still has less report. In this study, to achieve specific adsorption over a higher potential range that is at least equal to the ORR active potential (around 0.90 V vs. RHE), operando XAS measurements were performed; the electronic status and local structural change of Pt atoms induced by the specific adsorption of anions at any potential were observed2.Pt/C (29.1 wt.%; TEC10V30E) catalyst supported was purchased from TKK. Nafion® solution was employed to prepare Pt/C catalyst ink with I/C ranging from 0.0 to 1.0. And the amount of Pt/C was adjusted to form a 20 µgcarbon cm-2 catalyst layer after dropping 10 μL on a glassy carbon RDE. The electrochemical cell was constructed using a model electrode fabricated in the working electrode, a Pt mesh for the counter electrode, a reversible hydrogen electrode for the reference electrode, and 0.1 M HClO4 aq for the electrolyte. operando XAS measurement of Pt L-edge was carried out in SPring-8 (Japan).The specific activity decreased as the I/C ratio increased from 0.0 to 0.20. We utilized many methods to evaluate the adsorption species separately, including the measurements of ECSA and oxygen coverage, CO stripping voltammetry, operando X-ray absorption fine structure, and analysis of 5d orbital vacancy. The ECSA and oxygen coverage did not change with increasing ionomer content, indicating that the Pt/C catalyst activity was affected by other adsorption species. A comparison of the CO displacement charge and 5d orbital vacancies of the Pt/C catalysts with I/C = 0.0 and 1.0 suggests that the ionomer-specific adsorption increases when the I/C ratio of the Pt/C catalyst is 1.0; active sites on the surface of the Pt/C catalyst are occupied, resulting in lower catalyst activity. Acknowledgment This work was supported by the project (JPNP20003) and a NEDO FC-Platform project commissioned by the New Energy and Industrial Technology Development Organization (NEDO).

Insights into Cu Surface Chemistry Via in-Operando nanoparticle Enhanced Vibrational Spectroscopy and Mass Spectrometry Measurements

Copper electrodeposition is a central process in the metallization of microelectronics and more recently has found use as an important electrocatalyst in the conversion of CO2 to hydrocarbons. Gaining mechanistic insight into the nature of the respective reactions requires in situ and better still in operando measurements. Herein the utility of shell-isolated nanoparticle enhanced Raman spectroscopy (SHINERS) and electrochemical mass spectrometry (EC-MS) to study the potential dependent anion adsorption and hydride formation on low index Cu single crystals surface will be detailed. SHINERs enables monitoring of competitive adsorption between Cl- and SO4 2- on Cu(100) and Cu(111) surfaces (Figure 1a). Saturated ordered halide adlayers are formed at potentials slightly below the open circuit potential while moving to more negative values halide is disrupted resulting with the emergence of a sulfate mode near 970 cm-1. In the case of Cu(111) the desorption of the halide adlayer is coupled to the formation of a hydride phase (Figure 1b) as evident in both SHINERS and EC-MS measurements. SHINERS was also employed to examine the adsorbate dynamics associated with superconformal electrodeposition of Cu. Specifically, competitive adsorption between Cl- and sulfonate terminated thiol/disulfide accelerators molecules was examined during Cu deposition on planar and patterned surfaces (Figure 1c). The ability of the nanoparticle reporters to float on the advancing surface is demonstrated and used to probe the additive evolution on the growth front associated with superconformal electrodeposition. This work demonstrates the capabilities of operando electrochemical measurements and their importance in achieving future technological breakthroughs.Figure 1. Capturing Cu interfacial chemistry with operando SHINERS (a) on a c(2x2)-Cl covered Cu(100) surface, (b) coupling to EC-MS to reveal the existence of hydride on Cu(111) in Cl containing electrolyte and (c) to track accelerator coverage on electrodeposited pattern surfaces. Figure 1

Impact of Sulfate Adsorption on Particle Morphology during Precipitation of Ni-Rich Precursors for Li-Ion Cathode Active Materials

Current standard industrial manufacturing of lithium layered transition metal oxides (LiMO2) as cathode active material (CAM) can be divided into two major process steps: The first step involves coprecipitation of mixed transition metal hydroxide (M(OH)2) particles (M consisting mainly of Ni, Co, and Mn) by mixing a transition metal sulfate solution (MSO4(aq.)) and a sodium hydroxide solution (NaOH(aq.)) in a stirred tank reactor. The resulting hierarchally structured secondary particles are composed of many primary particles which are used as precursors for CAMs (referred to as pCAM). Subsequently, the obtained pCAM is mixed with a lithium source such as Li2CO3 or LiOH and calcined at elevated temperatures to yield LiMO2.1 Recently, reports in the literature have shown clear correlations of CAM morphology with their electrochemical performance in a battery cell.2 Furthermore, it has been demonstrated that the electrochemical performance of a CAM is affected by the morphology of the associated pCAM.3, 4 However, a detailed understanding of the impact of the process parameters on the course of precipitation reaction and on the physical properties of the pCAM precipitate is still lacking.In order to gain a mechanistic understanding of the M(OH)2 pCAM particle formation, ten distinctive Ni0.8Co0.1Mn0.1(OH)2 particle lots were prepared by the coprecipitation method in a stirred tank reactor. The precipitation pH-value was systematically varied between pH = 8.6-12.7, while all other process parameters were kept constant. The S-content of the resulting pCAM powders, representing the residual sulfate (SO4 2-) content, was investigated by S-combustion and is depicted as a function of precipitation pH-value in Figure 1a. In the pH-value range between 8.57 and 10.27 (red), a slight increase in residual SO4 2- from 10.29 mol% to 12.60 mol% is observed until it decreases again to 11.10 mol%. Between pH = 10.27 and pH = 10.74, a sharp transition takes place and residual SO4 2- is reduced by a factor of 4 from 11.10 mol% to 2.60 mol%, which even decreases further with increasing pH-value, namely from 2.60 mol% at pH = 10.74 to 0.35 mol% at pH = 12.69 (green). Interestingly, the turning point in S-content between pH = 10.27 and pH = 10.74 (dashed blue line in Figure 1a) coincides with the point-of-zero-charge (pzc) of Ni(OH)2, which is reported to be at pH = 10.50-10.60.5 This result is rationalized by a pH-dependent SO4 2- adsorption equilibrium that is governing the SO4 2- uptake during the precipitation reaction, as depicted schematically in Figure 1b. For a precipitation below the pzc, positive charged surface hydroxyl-groups of Ni0.8Co0.1Mn0.1(OH)2 attract SO4 2-, resulting in high SO4 2- uptake during M(OH)2 formation and vice versa.In light of these results, it is further demonstrated by x-ray diffraction analysis that SO4 2- adsorption not only governs the crystallinity of the Ni0.8Co0.1Mn0.1(OH)2 material, but also suppresses the vertical crystal growth in the 001-direction during particle formation. This in turn seems to affect the vertical primary particle size as well as the secondary particle porosity, both observable by SEM imaging. The morphological trend is quantitatively verified by extracting the primary particle size distribution from SEM images and by measurements of the secondary particle porosity via nitrogen physisorption. As proof-of-concept for the proposed adsorption mechanism, precipitation reactions at pH = 12.0 with different metal feed sources (MX(aq.), with X = SO4 2-, (NO3 -)2, (CH3COO-)2) were conducted. The resulting clearly distinct physical properties of the Ni0.8Co0.1Mn0.1(OH)2 particles obtained from the different anion systems with different anion adsorption affinities can be well understood based on the Fajans-Paneth-Hahn law for crystallization.6 Finally, desorption experiments indicate options to reduce the residual SO4 2- amount after the Ni0.8Co0.1Mn0.1(OH)2 particle formation has been completed.Based on the results of this study, guidelines for pCAM design are formulated and discussed with respect to composition and subsequent manufacturing steps in industrial CAM production.

Interfacial Chemistry and Electrolyte Approaches for Enabling Metal Anode Batteries

Continuous solid electrolyte interphase (SEI) and dendrite growth, as well as formation of ion blocking interfaces are some of the crucial issues preventing the commercialization of batteries depending on the implementation of Li/Na/K/Mg/Ca metal anodes.[1,2] In the first part of my talk, I will focus on the chemistry of formed interfaces, including growth and ion transport control. Second part of my talk deals with bulk liquid, polymer and hybrid electrolyte molecular structure approaches for circumventing dendrite formation.Understanding of the SEI growth on alkali and alkaline earth metals in contact with liquid electrolytes under open circuit potential conditions important for shelf aging is still in its infancy. I will show that the SEI formed on Li in contact with glyme-based electrolyte grows via reaction-controlled mechanism that is rapidly substituted by the diffusion-controlled one.[3] The ionic transport and stability of the complex composite SEI material under current is highly dependent on the salt chemistry, with detrimental effects of LixSy and positive effects of the Li3N constituents. Most recent ion transport and morphological studies show that the initial SEI formed in contact with liquid electrolytes on Li, Na and Mg is nanoporous.[4,5] Based on the electrochemical impedance spectroscopy measurements in symmetric cells and related equivalent circuit models, I will discuss potential growth mechanism via SEI densification. Finally, I will present a possibility of using gas/solid synthesis for preparation of sulfide-based artificial SEIs for both liquid-based and solid-state batteries.[6]Dendrite formation on alkali and alkaline earth metal anodes is closely related to the ion concentration gradients formed near the electrodes in contact with the electrolytes. I will discuss the method to circumvent this problem by using electrolytes with high cationic transference number. In soft matter electrolytes this is possible when (i) interfacial effect enables preferential anionic adsorption in liquid/solid electrolytes,[7] (ii) the size and steric effects control the association and mobility of the anion in the liquid electrolytes,[8] (iii) ion transport proceeds through percolating amorphous clusters in polymer-in-salt electrolytes. [9]

Remediation of Soils Contaminated by Fluoride Using a Fermentation Product of Seaweed (Eucheuma cottonii)

This study investigated the efficacy of fermented seaweed (Eucheuma cottonii) on the remediation of fluoride-contaminated soil. The soil was amended with either 1.25, 3.0, or 5.0% (w/w) fermented seaweed (FSW), parallel with the controls (0%). The amendment improved the physicochemical properties of the soil particularly pH regulated from strong alkaline (9.3) to neutral (7.0) which is essential for germination, crop growth, and yield. The amount of water soluble-fluoride (Ws-F) dropped from 81.7 ± 3.1 mg/kg to 42.7 ± 2.4, 33.7 ± 1.2, 19.6 ± 0.9, and 12 ± 1.3 mg/kg following 0, 1.25, 3, and 5% amendment dosage, respectively. Most of the Ws-F was converted into exchangeable fluoride (Ex-F) and to fluoride-bound to iron and manganese (Fe/Mn-F). Furthermore, the amendment also enhanced microbial mass and diversity in the soil. The FSW contains organic acids which participate in ionic bonding with the multivalent cations in the soil. The formed compound participates in ion exchange with clay or with anionic adsorption to positively charged clay sites at the edges. This interaction is further essential for enhancing the fluoride holding capacity of the soil. The use of seaweed reduced the bioavailability of fluoride in the agricultural soils and had positive effects on promoting soil fertility. However, further studies to observe its effects on crop performance is of significance.

Unique Tunability to Conducting Polymer Enabled by Ionic Liquid Doping and its Application in Nitrite Sensing

Ionic liquids, owning multiple combinations of cations and anions, provide unique tunability for conducting polymer, which can provide distinctive properties tailored to different applications of these conducting polymer/ionic liquid composites. Herein, five different ionic liquids were utilized to dope poly (3, 4-ethylenedioxythiophene), PEDOT, affording five different PEDOT/ionic liquid composites, which were evaluated for their electrochemical sensing performance towards environmental pollutant nitrite. Among them, ionic liquid N,N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium bis(trifluoromethanesulfonyl)imide ([Deme][NTf2]) was unique in tuning PEDOT’s charge properties. No π-π intermolecular interactions were formed between bulky ammonium and PEDOT’s planar thiophene ring, thus cation [Deme] and anion [NTf2] tended to compete for doping into PEDOT matrix. The bulky cation N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium would remain more on PEDOT outside, affording more positive charge. The accumulated more positive charge on [Deme][NTf2]-doped PEDOT’s surface was beneficial to attract more adsorption of nitrite anion, contributing to its improved electrochemical sensing performance. [Deme][NTf2]-doped PEDOT was characterized by various techniques and served as excellent electrode modifier to enable nitrite determination, achieving a broad linear range of 0.05 to 10 mM and a high sensitivity of 642.38 μA mM−1 cm−2. Ionic liquid [Deme][NTf2] demonstrated its unique tuning capabilities to afford conducting polymer/ionic liquid composite, aiming for promising electrochemical sensing application.

A comprehensive review of anionic azodyes adsorption on surface-functionalised silicas.

Surface -functionalised silica networks are advanced adsorbents. They have been given much attention for treating wastewater using the adsorption technique due to the silanol reactivity, resulting in strong binding affinities towards many pollutants. This review discusses the removal of anionic azo dyes utilising various functional groups such as amines, surfactants, polymers, macrocyclic, and other chelating groups functionalised on silica's surface. This review also reveals the steadily increasing interest in surface-functionalised silicas as adsorbents, emphasising the scholarly advancements in this field as a platform for future research. For that, adsorption capacities with different experimental conditions have been compared. The possible adsorption mechanisms, rate-limiting step, and factors affecting the anionic azo dye adsorption process have been comprehensively discussed. This review discloses that adsorbent characteristics such as porosity and functional groups, besides structural properties of an anionic azo dye, significantly affect adsorption. The adsorption process followed the Langmuir isotherm and pseudo-second-order models, with a predominantly spontaneous and endothermic nature. Multiple interactions, including electrostatic interaction, π-π interactions, and hydrogen bonding, are observed between dyes and functionalised silicas, indicating the adsorption process's complexity. Regeneration and cost-economic analysis are also presented to provide a roadmap for sustainable improvements. Chemical and biological regeneration techniques restore > 80% of the spent functionalised silicas. There is a significant opportunity to improve their efficiencies and regenerability, resulting in surface-functionalised silicas being used commercially instead of only in the laboratory. Finally, future research has been proposed by identifying current research gaps, particularly concerning the application of functionalised silicas in wastewater treatment.

Simulation of Adsorption Process of l-Tryptophan on Mixed-Mode Resin HD-1 with Combined Physical Adsorption and Ion Exchange.

The mass-transfer process of l-tryptophan (l-Trp) in the hydrophobic interaction/ion-exchange mixed-mode resin HD-1 particles and fixed bed was studied experimentally and theoretically. The adsorption kinetics of l-Trp in single-component and multicomponent adsorption systems was investigated under different pH conditions. The co-adsorption of sodium ions (Na+) and l-Trp anions was found to be negligible. A modified liquid-film linear driving force model considering the physical adsorption of l-Trp zwitterions and anions as well as ion exchange of l-Trp cations was proposed. The dissociation equilibria of l-Trp molecules and functional groups on the resin were introduced in the model. The model could well fit the kinetic adsorption curves of l-Trp at different pH values. The presence of Na+ and the impurity amino acid l-glutamic acid (l-Glu) did not significantly affect the mass-transfer rate of l-Trp. The dynamic adsorption processes of l-Trp under different pH and concentration conditions were studied. A modified transport-dispersive model considering axial diffusion, liquid-film mass transfer, and a combined physical adsorption and ion-exchange equilibrium was established, which could predict the adsorption breakthrough curves of l-Trp well. During the dynamic adsorption process, the pH of mobile phase in the fixed bed changed with changing the l-Trp concentration in the mobile phase. l-Trp was well separated from Na+ and l-Glu with the purity of l-Trp higher than 99%, the recovery rate higher than 95%, and a concentration of 4.69 × 10–3 mol/L. The elution chromatographic peaks of l-Trp, l-Glu, and Na+ and the pH of the outlet solution were predicted satisfactorily.

Synergy between Ionic Capacity and Intrinsic Porosity in Imidazolium-Based Cationic Organic Polymers and Its Effect on Anionic Dye Adsorption

Synergy between Ionic Capacity and Intrinsic Porosity in Imidazolium-Based Cationic Organic Polymers and Its Effect on Anionic Dye Adsorption