Electronegative Functional Groups Research Articles

Performance and Mechanism of the Modified Group Regulated the MIL-101(Fe) Type Fenton-like Catalysts.

In order to avoid the disadvantages of the Fenton process in wastewater treatment and reduce the cost of wastewater treatment, a series of MIL-101(Fe)-X (X = -OH, -NH2, -NO2, -H) solid Fenton catalysts were successfully prepared. The performance of these Fenton-like catalysts was studied with the Fenton experiment as a reference and methylene blue (MB) as an organic pollutant. The effects of the H2O2 concentration, catalyst dosage, and reaction pH on catalytic performance were systematically studied. The research had shown that the optimal concentration of H2O2 for catalytic reactions was 0.10 mmol/L and the pH was 3. At this point, their catalytic degradation MB performance was superior to the Fenton reaction and photocatalytic reaction. When the H2O2 participated in the reaction, the performance of MIL-101(Fe)-X (X = -OH, -NH2, -NO2, -H) in catalyzing the degradation of MB followed the rule of -OH > -NH2 > -NO2 > -H. This was due to the synergistic effect of Fenton-like catalysis and photocatalytic degradation in the catalytic degradation of MB. In addition, the electron paramagnetic resonance and electrospray ionization mass spectrometry showed that the hydroxyl radical (·OH) generated during the catalytic process first underwent a redox reaction with the highly electronegative functional groups in the MB molecule, and finally oxidized it to CO2 and H2O. This study successfully prepared commercially applicable Fenton-like catalysts and explored their optimal reaction conditions. This provides a technical reference for wastewater treatment.

Weak Electrostatic Force on K+ in Gel Polymer Electrolyte Realizes High Ion Transference Number for Quasi Solid-State Potassium Ion Batteries.

Quasi-solid-state potassium-ion batteries (SSPIBs) are of great potential for commercial use due to the abundant reserves and cost-effectiveness of resources, as well as high safety. Gel polymer electrolytes (GPEs) with high ionic conductivity and fast interfacial charge transport are necessary for SSPIBs. Here, the weak electrostatic force between K+ and electronegative functional groups in the ethoxylated trimethylolpropane triacrylate (ETPTA) polymer chains, which can promote fast migration of free K+, is revealed. To further enhance the interfacial reaction kinetics, a multilayered GPE by in situ growth of poly(vinylidenefluoride-co-hexafluoropropylene) (PVDF-HFP) on ETPTA (PVDF-HFP|ETPTA|PVDF-HFP) is constructed to improve the interface contact and provide sufficient K+ concentration in PVDF-HFP. A high ion transference number (0.92) and a superior ionic conductivity (5.15 × 10-3 S cm-1) are achieved. Consequently, the SSPIBs with both intercalation-type (PB) and conversion-type (PTCDA) cathodes show the best battery performance among all reported SSPIBs of the same cathode. These findings demonstrate that potassium-ion batteries have the potential to surpass Li/Na ion batteries in solid-state systems.

Adsorption performance of the functional COFs for removal of bisphenol A: Molecular dynamic simulations

The inherent structural features of the covalent organic frameworks (COFs) play a crucial role in determining their adsorption performances for bisphenol A (BPA). The computational methods were advantageous in unraveling intrinsic molecular properties about their performances. Herein, some COFs with different functional groups (–COOH, –NH2, –NO2 and –CF3) were designed to demonstrate the efficacy of the functional COFs for adsorbed BPA in gas phase and aqueous solution. The density functional theory (DFT) and Grand Canonical Monte Carlo (GCMC) methods were used to analyze the interaction energy between COFs and BPA, structure properties, and adsorption performances etc.. The results indicated that the addition of strong electronegative functional groups in COFs increased these COFs’ isosteric heat of adsorption (Qst) (TpBD-(COOH)2 > TpBD-(CF3)2 > TpBD-(NH2)2 > TpBD-(NO2)2 > TpBD) for gas phase BPA, but their introduction also reduced the pore size of COFs (TpBD > TpBD-(COOH)2 > TpBD-(NH2)2 > TpBD-(CF3)2 > TpBD-(NO2)2). However, these functional COFs demonstrated the stronger the adsorption capacity for gas phase BPA (At 298 K and 1 bar, the BPA uptake of TpBD-(COOH)2, TpBD-(NH2)2, TpBD, TpBD-(NO2)2 and TpBD-(CF3)2 was 242.52, 232.43, 219.31, 206.64 and 197.73 mg/g, respectively.). The amount of BPA adsorbed by functional COFs was the result of the synergistic effect of the electronegativity of functional groups and the pore size. Molecular dynamic (MD) simulation performed the same phenomenon for BPA in aqueous solution. In addition, the higher temperature will decrease the adsorption amount of BPA by COF, but increase its desorption ability.

Hydrogen bond recombination regulated by strongly electronegative functional groups in demulsifiers for efficient separation of oil–water emulsions

Tight oil extraction and offshore oil spills generate large amounts of oil–water emulsions, causing serious soil and marine pollution. In such oil–water emulsions, the resin molecules are bound by π–π stacking and bind to interfacial water molecules via hydrogen bonds, which impede the aggregation between water droplets and thereby the separation of the emulsion. In this study, strongly electronegative oxygen atoms (in ethylene oxide, propylene oxide, esters, and hydroxyl groups) were introduced through poly(propylene glycol)-block-polyether and esterification with acrylic acid to attract negative charges in order to form electron-rich regions and enhance interfacial hydrogen bond recombination. The potential distribution in the demulsifier molecules and their space occupancy were regulated by the polymerization reaction to destroy the π–π stacking interaction between resin molecules. The results show that the binding energies (binding free energy and hydrogen bonding energy) of oxygen-containing demulsifier molecules with water molecules were higher than those of resin molecules with water molecules, resulting in the fission of the hydrogen bonds between resin and water molecules. The introduction of demulsifier molecules that occupied large interfacial space reduced the binding energy between resin molecules from −2176.06 to −110.00 kJ·mol−1. Noteworthy, the binding energy between demulsifier molecules and resin molecules was −1076.36 kJ·mol−1 lower than that between resin molecules (−110.00 kJ·mol−1), indicating the adsorption of the surrounding interfacial resin molecules by the demulsifier molecules and destruction of the π–π stacking between them, thus favoring the collapse of the interfacial structure of the oil–water emulsion and achieving its separation. This study provides important theoretical support for the treatment of oil-contaminated soil and offshore oil spill pollution.

Amidated Pectic Polysaccharides (Pectin) as Methane Hydrate Inhibitor at Constant Cooling and Isobaric Condition.

This study aims to address the environmental impact of using common commercial hydrate inhibitors such as Methanol (MeOH) in extremely cold oil and gas environments. As a greener alternative, Pectic Polysaccharides (pectin) can act as a kinetic hydrate inhibitor (KHI) to delay hydrate formation. We evaluated the performance of amidated pectin (AMP), a type of pectin with higher electronegative functional groups, using a high-pressure micro-differential scanning calorimeter (HP µ-DSC) under isobaric conditions with constant cooling. We compared AMP to low-methoxylated pectin (LMP) and high-methoxylated pectin (HMP) and found that AMP was the best KHI among the tested pectin types. At a concentration of 1.0 wt.%, the AMP Relative Inhibitor Performance (RIP) was 0.10, and at 0.1 wt.%, it had an RIP of 0.07, which were the only positive RIPs obtained amongst the tested KHIs. The results suggest that AMP can be a sustainable KHI option in extremely cold environments where the KHI effectiveness typically declines.

High-Efficiency CsPbI2Br Perovskite Solar Cells with over 83% Fill Factor by Synergistic Effects of a Multifunctional Additive.

All-inorganic CsPbI2Br with outstanding thermal stability and excellent photoelectric properties is considered as a promising candidate for photovoltaic applications. However, the efficiency of CsPbI2Br perovskite solar cells (PSCs) is still much lower than that of their organic-inorganic hybrid counterparts or CsPbI3-based devices. Herein, we obtained an optimized CsPbI2Br PSC (0.09 cm2) with a champion efficiency of 17.38% and a record fill factor of 83.6% by introducing potassium anthraquinone-1,8-disulfonate (DAD) in the precursor solution. The synergistic effect between the electronegative functional groups and K+ ions in the DAD structure can not only effectively regulate the crystallization growth process to improve the crystalline quality and stability of photo-active CsPbI2Br but also optimize the energy level alignment and passivate the defects to improve the carrier transport properties. The efficiency of the corresponding large-area device (5 cm × 5 cm with an active area of 19.25 cm2) reached 13.20%. Moreover, the optimized CsPbI2Br PSC exhibited negligible hysteresis and enhanced long-term storage stability as well as thermal stability. Our method produces more stable photo-active CsPbI2Br with excellent photoelectric properties for industrial applications or perovskite/silicon tandem cells.

Effects of Light Energy with Different Densities on Denitrification: Metabolic Intermediates, Electron Behavior, Enzyme Activities, and Sludge Settleability

Light energy, as one of the most influencing parameters in microalgal–bacterial consortium (MBC) systems, can regulate activities and metabolisms of microalgae and bacteria consortia. However, its effects on denitrifying bacterial remain unclear. Herein, variations of denitrification, microbial (denitrifiers’) metabolism, sludge surface characteristics, and settleability were systematically investigated with five light energy density conditions. Results showed that light energy decreased the denitrification rate with obvious accumulation of denitrifying intermediates (NO2– and N2O). This could be associated with the inhibition of light energy on electron behavior, evidenced from reduced nicotinamide adenine dinucleotide (by 67.0–71.3%), lowered electron transport system activity (by 66.7%), decreased denitrifying enzyme activities (e.g., NAR, NIR, and NOS), and downregulated gene expressions. Moreover, light energy worsened sludge settleability by regulating sludge extracellular polymeric substance (EPS) types, compositions, and surface characteristics. Specifically, light energy stimulated the soluble and lightly bounded EPS, as well as the hydrophilic and electronegative functional groups in EPS. These findings advance our understandings on denitrifiers activities and their electronic behavior responses to short-term light energy. Ultimately, this may promote the development of MBC as a sustainable approach for wastewater treatment.

Modulating the Schottky barriers of metal-2D perovskite junctions through molecular engineering of spacer ligands.

The crucial role of spacer ligands in affecting the contact properties of metal-2D perovskite junctions, which can severely affect device performance, is revealed in this work. We studied the contact properties of Ag, Au, and Pt with 2D perovskites that possess ligands with different sizes and functional groups. It is found that the interface binding energy, Schottky barrier height (SBH), and tunneling property depend strongly on the ligand size and functional group type. Small-size ligands can induce effective interface coupling and result in perturbed perovskite electronic properties and a high tunneling probability. In addition, high work-function metals and more electronegative functional groups can induce more severe band shifts at the interface. The features of diverse ligands ensure a widely tunable SBH ranging from 0-1.07 eV. This study provides guidance for developing more effective 2D perovskite-based electric nanodevices by tuning the contact properties through molecular engineering of spacer ligands.

Theoretical study of electronic and optical properties of functionalized Indigo and Alizarin as potential organic semi-conductors for solar cells applications

The optical and electronic properties of two conjugated organic molecules, Indigo and Alizarin, as potential organic solar cells were studied theoretically. The electronic properties, reorganization energy (λh and λe), adiabatic Ionization potential (IA), adiabatic Electron affinity (EA),HOMO, LUMO and Energy gap (Eg) were calculated using DFT. The optical properties as the maximum absorption (λmax) along with oscillator strengths (f) at the excited states in vacuum and solvent were also calculated using TD-DFT. The molecules were functionalized by electronegative functional groups to understand the effect of functionalization on the optical and electronic properties. It was found that the functionalization of Indigo and Alizarin has resulted in overall conversion of the materials to better n-type molecules. The Eg for both molecules has been generally reduced upon the introduction of electronegative functional groups. This indicates the possibility of tuning organic molecules optical and electronic properties by introducing functional groups. Also, both studied molecules along with their functionalized molecules show properties that fall among organic semiconductors and thereby, can be potentially used in solar cells.

Research on the wetting mechanism of coal dust by different surfactants: combination of experimental characterization and molecular dynamics simulation.

Surfactants can reduce the surface tension of water and improve the efficiency of spray dust reduction, but the synergistic mechanism of composite surfactant solutions wetting coal dust remains unclear. In this study, sodium dodecyl sulfonate (SDDS)/sodium dodecylbenzene sulfonate (SDBS) solution and SDDS/primary alcohol ethoxylate (AEO-9) solution were prepared to wet three types of coal with different deterioration degrees. The surface tension, contact angle, and functional group composition were measured. The results show that SDDS/AEO-9 solution had lower surface tension and critical micelle concentration than SDDS/SDBS solution at the same mixing ratio. When the ratio of SDDS: SDBS was 2:1, it had the best wetting effect on coal dust. It is found that for SDDS/SDBS solutions, aliphatic hydrocarbons and surface tension have a positive correlation with the contact angle, and hydroxyl groups have a negative correlation with the contact angle. For SDDS/AEO-9 solution, only the surface tension and contact angle show a significant linear relationship. The main factors that affect the wetting change with the combination of surfactants. AEO-9 has an electrostatic shielding effect on SDDS, while SDBS increases the electrostatic repulsion between SDDS solution and electronegative functional groups of coal. The synergism among these surfactants plays an important role in the process of wetting coal.

Corrosion Inhibition of Mild Steel in Hydrochloric Acid Environments Containing Sonneratia caseolaris Leaf Extract

Sonneratia caseolaris leaf extract was characterized for its mitigation of the electrochemical corrosion of steel in naturally aerated hydrochloric acid environments by electrochemical methods and surface analysis. The presence of S. caseolaris leaf extract (SCLE) in the hydrochloric acid medium ameliorated the corrosion resistance of steel via the adsorption of SCLE species to form a barrier layer. The improved inhibition effectiveness was demonstrated to be independent of the SCLE concentration and the corrosive environment. The highest inhibition performance of approximately 98% was reached for steel in a 1 M HCl medium containing 2500 ppm SCLE. The performance significantly decreased with a decrease in the HCl concentration from 1.00 to 0.01 M with the same SCLE concentration. In addition, severe corrosion occurred on the uninhibited steel surface but was significantly reduced on the inhibited steel surface. The analyzed results also indicated the existence of electronegative functional groups in SCLE, which could promote the adsorption process for the self-formation of the barrier layer on the steel surface. The work reported herein suggested a powerful strategy to mitigate electrochemical corrosion by adding an effective new inhibitor to achieve a green inhibitor system.

Removal of cyanobacteria using novel pre-pressurized coagulation: The effect of cellular properties and algogenic organic matter characteristics

• Pre-pressurized coagulation reduces coagulant dosage for M. flos-aquae removal. • Changes in cell properties/AOM characteristics after pre-pressurization is studied. • Pre-pressurization ruptures mucilaginous sheath and raises coagulation efficiency. • Exposure to more electronegative functional groups promotes the cell-CPAM binding. Pressurization pretreatment is reported as a novel pretreatment method for the coagulation removal of Microcystis sp . from eutrophicated water, as less coagulant is required than without pressurization. However, how cellular properties and algogenic organic matter (AOM) characteristics change with pressurization pretreatment and thus reduce the coagulant dose are still not understood. Using Microcystis flos-aquae in Lake Taihu, this study analyzed the changes in cellular morphology, size distribution, and charge density, as well as the changes in concentration and composition of cell-based protonated functional groups. Coagulation experiments using different combinations of cells and AOM with/without pressurization pretreatment showed that the changes in cell surface properties played a bigger role in coagulation enhancement than AOM. The enhancement of the coagulation efficiency of M. flos-aquae with pressurization pretreatment is related to the rupture of the mucilaginous sheath and subsequent exposure of cells with more active functional groups, the content of phosphodiester, carboxyl and phosphoryl functional groups on the surface of M. flos-aquae cells increased by 55%, 29% and 203%, respectively. Thus increasing the binding sites between M. flos-aquae cells and cationic polyacrylamide (CPAM). As a result, with pressurization pretreatment, the dose of CPAM was reduced from 5 mg L −1 to 0.8 mg L −1 for the same removal efficiency of 90%. These results may help us understand the mechanism by which pressurization treatment impacts M. flos-aquae coagulation and thus provide a new perspective for the low-cost and sustainable removal of cyanobacterial blooms.

Study on the effect of imidazolium ionic liquid as a modulator of corrosion inhibition of anionic surfactant sodium dodecyl sulfate (SDS) on mild steel in sodium chloride solution

Present paper reports investigation done on two organic compounds to test them as corrosion inhibitors for mild steel exposed to neutral NaCl solution. Organic compounds capable of corrosion inhibition must form a protective film over the metal surface. This is usually possible since many of these organic compounds possess strong interaction properties with metal and get adsorbed over its surface. These organic compounds contain electronegative functional groups and atoms like S, N, P, and O, which form center for establishment of adsorption process. Accordingly, SDS and DMImCl were chosen as organic compounds to test as corrosion inhibitors. Electrochemical polarization tests, performed in this study, reveal decrease in corrosion rate of mild steel in NaCl solution by 14.3 to 6.08 mpy (mils per year) corresponding to increased inhibition efficiency of 57.3% on addition of up to 200 ppm SDS. On mixing 200 ppm of DMImCl in NaCl + SDS solution, the inhibition efficiency enhances to 85.1%. Similar outcome is also noticed from Electrochemical impedance and weight loss test results. Analysis of results obtained through FTIR, SEM/EDAX indicate adsorption of SDS/DMImCl mixture on the mild steel surface.Tensiometry tests, on ionic solution, reveal decrease in surface tension on addition of inhibitors with consequently increased surface activity and hydrophobic interaction between chains of the two inhibitors. Calculation done on the adsorption process indicates it to be ‘Langmuir adsorption isotherm’. This inference suggests that binding sites on steel surface are identical and homogeneously distributed. This layer is covered with a monolayer of adsorbed molecules i.e. DMImCl and SDS which is responsible for corrosion inhibition.

Removal of malachite green and mixed dyes from aqueous and textile effluents using acclimatized and sonicated microalgal (Oscillatoria sp.) biosorbents and process optimization using the response surface methodology

Synthetic dyes are toxic and their release into the environment harms the ecosystem. Phycoremediation of synthetic dyes with acclimatized and native species has advantages over other methods. In this study, textile effluent-acclimatized microalgae species of Oscillatoria were grown in Bold’s Basal Medium (BBM), dried, powdered using sonication, and optimized the removal malachite green (MG), using the response surface methodology (RSM). The effects of algal biosorbent concentration (AC), pH, and contact time (CT) were studied with 1 g L−1 MG in an aqueous solution, and the interaction model exerted significance (p < 0.001). The removal of MG was higher at alkaline pH (90% at pH 8.5) than at acidic pH (70% at pH 4). Under the optimized conditions of 1.2 g L−1 AC, 8.5 pH, and 30 min CT, the MG removal was documented at 90.8% with the biosorption capacity of 757 mg g−1. Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) analysis revealed the occurrence of different electronegative functional groups, aromatic vibrations, and the crystalline nature of the biosorbent. The algal sorbent exhibited a good performance of 80.9% for the removal of the crude color in real textile effluents. This microalgal sorbent is an attractive option for promoting large-scale applications.

A novel approach to prepare highly oxidized graphene oxide: structural and electrochemical investigations

This research presents two new modified Hummers' methods which include the pre-oxidation of graphite powder by mixtures of H3BO3/H2SO4 and H3BO3/H2SO4/CrO3. Compared to the traditional Hummers’ method, these significant improvements substantially enhanced the number of oxygen functionalities onto graphene oxide (GO) layers. The GO samples were characterized by X-ray photoelectron spectroscopy (XPS), Boehm titration, Raman spectroscopy, X-ray diffraction (XRD), dynamic light scattering (DLS), and zeta potential analysis. Boehm titration results showed that GO layers contain oxygen functionalities such as phenolic, ketone, lactone, carboxyl, and epoxy. Quantitative XPS analysis reveals that GO obtained using a pre-oxidation step with H2SO4/H3BO3/CrO3 mixture has a higher oxidation degree (C/O = 1.03). Moreover, this sample possessed a greater number of electronegative functional groups, resulting in the decrease of the zeta potential (-43.3 mV). Raman analysis revealed a slightly higher structural disorder in GO layers during the increase in oxidation levels. Further, reduced GO (rGO) obtained from new synthesized GO were tested as label-free H2O2 sensors electrodes. The electrochemical investigations showed that the samples were prospective on H2O2 sensing. Our results suggest that the properties of rGO can be tuned by varying the oxidation degree of GO, which may stimulate new developments in rGO-based sensors.

Optimization of chromium(VI) removal by indigenous microalga (Chlamydomonas sp.)-based biosorbent using response surface methodology.

Phycoremediation of heavy metals has garnered considerable recent research interest. In this study, an indigenous microalga (Chlamydomonas sp.)-based biosorbent was employed for biosorption of Cr(VI) dissolved solids (Cr(VI)-DS), optimized using response surface methodology (RSM). The effects of microalga concentration, pH, and contact time were studied with 250mgCr(VI)-DSL-1 . The biosorption of Cr(VI)-DS was higher at acidic pH (94.17% at pH 4) than at alkaline conditions (68.53% at pH 10). The interaction of pH and microalga concentration exerted significant (p<0.05) influence on the biosorption. Under the optimized parameters of 1.5gmicroalgaL-1 , pH 4, and contact time of 30min, a predicted biosorption of 91.31% and biosorption capacity of 152mgCr(VI)-DSg-1 biomass were documented. FTIR analysis attested the electronegative surface functional groups of the microalgae biomass, bracketed together with its high biosorption potency. The study evinced the potential of the indigenous microalga for remediation of hexavalent chromium. PRACTITIONER POINTS: Indigenous Ethiopian microalga (Chlamydomonas sp.) exhibited 94% Cr(VI) abatement with biosorption capacity of 152mgCr(VI)g-1 . FTIR analysis of the biosorbent divulged the presence of electronegative functional groups (amino, carboxyl, hydroxyl, and carbonyl groups). Higher biosorption of Cr(VI)-DS under acidic pH (94.17% at pH 4) than alkaline pH (68.53% at pH 10). Significant (p<0.05) interaction effect of pH and biomass concentration on the biosorption, evinced in RSM optimization 91% Cr(VI) removal achieved under optimal conditions of 1.5gbiosorbentL-1 , 30min of contact time, and pH 4.

Tuning Surface Electronic Structure of Two‐Dimensional Cobalt‐Based Hydroxide Nanosheets for Highly Efficient Water Oxidation

AbstractHighly exposing active sites and well tuning their electronic configuration are great challenges toward highly efficient oxygen evolution reaction (OER) catalysts. Herein, we demonstrate an in situ surface modification strategy for α and β‐Co(OH)2 nanosheets to boost their OER activities via a simple substitution of their surface hydroxyl functional groups by carboxylate or acetic anhydridate ones, respectively. This in situ surface modification can increase the areal densities of active sites and reduce the OER energy barriers while maintaining initial structure and morphology. Experimental results show that the modified catalysts can present much larger electrochemical active surface area (ECSA) and lower OER onset overpotential in comparison with the fresh ones. In case of carboxylate‐modified α‐Co(OH)2 nanosheets, the onset overpotential has decreased from 266 to 233 mV and the required overpotential at 10 mA cm−2 has decreased from 309 to 288 mV on glassy carbon electrode. Density of states (DOS) calculations reveal an optimized adsorption energy of reaction intermediates. Remarkably, tuning surface electronic structure of catalyst by appropriately choosing highly electronegative functional groups can be considered as an efficient approach to enhance its OER activity.

Simultaneous Adsorption of Multi-lanthanides from Aqueous Silica Sand Solution Using Pectin–Activated Carbon Composite

Extraction of pectin (Pec) from banana (Musa paradisiaca L.) peels, the agricultural waste of banana fruit treated in acidic condition, and its fabrication into pectin–activated carbon (Pec–AC) composite by impregnation method were investigated. This Pec–AC composite was applied as an adsorbent to simultaneously remove multi-lanthanides, namely yttrium (Y), lanthanum (La), cerium (Ce), neodymium (Nd), and samarium (Sm), which were released from an acidic silica sand aqueous solution. Various fractions of Pec in Pec–AC composite and the effects of different parameters on the adsorption capacity of the multi-lanthanides were also evaluated. At the optimum condition, the adsorption capacity of the lanthanides was 84.4, 77.7, 67.5, 57.5, and 53.7% for Y, Nd, Sm, Ce, and La, with respect to their content in the silica sand. The Qmax value was estimated to be 21.80, 27.78, 18.22, 21.09, and 24.91 mg g−1 for La3+, Y3+, Nd3+, Sm3+, and Ce3+, respectively. Fourier-transform infrared analysis suggests that the lanthanides are bound to the electronegative functional groups on the active sites of the Pec–AC composite. The simultaneous adsorption of the lanthanides on Pec–AC composite is governed by the pseudo-second-order kinetics, and the adsorption process of the lanthanides can be described by Temkin isotherm model. Overall results suggest in this study that the Pec–AC composite is an efficient potential adsorbent to simultaneously absorb multi-lanthanides from leachate of silica sand as the primary step of isolation of lanthanides.

Synthesis and Evaluation of Anionic Schiff Bases As Pitting Corrosion Inhibitor for Stainless Steel 304 in NaCl Solution

The high corrosion resistance of austenitic stainless steel (SS) arises from the formation of a thin, adherent and protective passive film that forms instantaneously on the surface. Unfortunately, in the presence of aggressive ions like chloride anion, the corrosion resistance of passivated stainless steel is limited by local breakdown and pit nucleation [1]. An efficient and economical method to decrease the metal dissolution in aggressive media is the use of corrosion inhibitors. A large number of organic molecules containing electronegative functional groups, such as π-electron systems or heteroatoms have been proposed for the inhibition of general metallic corrosion, although the use of organic compounds as pitting corrosion inhibitors in neutral solutions is still rather limited. On the other hand, inorganic-based compounds such as chromates and nitrates are also used as pitting corrosion inhibitors for SS in aggressive media; however the application of these inorganics, especially chromates and phosphates, is not recommended because of their biological toxicity. More recently, Schiff bases have been described as cost effective inhibitors due to their robust and convenient synthesis from inexpensive precursors. They are organic compounds containing the imine (-C=N-) functional group in their structure. Schiff base derivatives with additional heteroatoms, such as N and O, and aryl groups have been used as corrosion inhibitors [2,3], but their application as pitting corrosion inhibitors has not been described. In the present study, three new anionic Schiff bases were synthesized through by reacting para-amino benzoic acid with several aromatic aldehydes containing different functional groups in their para- site. They were designed to improve water solubility, to enhance coordination with Fe atoms by including N and O heteroatoms, two benzene rings and the imine group in their chemical structure, and to be large enough to create heavy hydrophobic complex with Fe+3. The inhibitor efficiency of these compounds as pitting corrosion inhibitor for 304 SS in neutral 0.1 M NaCl was examined using potentiodynamic polarization measurements, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) . Polarization data show the shift of the pitting potential to more positive values with increasing inhibitor concentration. Surface analysis shows chromium enrichment at the metal surface under anodic polarization in the passive region of the metal when the inhibitor compound is present in the test solution, whereas no effect occurs under open circuit conditions. XPS data show that the inhibitor molecules do not adsorb on the clean metal, but on the passive layer instead. [1] G.T. Burstein, C. Liu, R.M. Souto, S.P. Vines, Corros. Eng. Sci. Technol. 39 (2004) 25. [2] M.A. Hegazy, Corros. Sci. 51 (2009) 2610. [3] R. Sadeghi Erami, M. Amirnasr, K. Raeissi, M.M. Momeni, S. Meghdadi, J. Iran. Chem. Soc. 12 (2015) 2185.

Investigating the Structure of an Active Material–Carbon Interface in the Monoclinic Li3V2(PO4)3/C Composite Cathode

A widely adopted strategy to enhance the electronic conductivity of lithium transition metal phosphates is to form a phosphate/C composite by introducing reagents (carbon sources) that can transform to carbon during calcination. In the present work, a systematic study combining X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, solid-state nuclear magnetic resonance, and electrochemical measurements was conducted to investigate how the electrostatic interaction between the functional groups (carboxyl, hydroxyl, etc.) of a carbon source and the building units of Li3V2(PO4)3 (Li+, VO2+, PO43–, etc.) in the original precursor affects the structure of a Li3V2(PO4)3–carbon interface in the final composite. It was demonstrated that the types and concentrations of electronegative functional groups in a carbon source play an important role in controlling not only the morphology of the product but also the composition, crystallinity and microstructure of the Li3V2(PO...