“Confinement effects for nano-electrocatalysts for oxygen reduction reaction”

Oxygen reduction reaction (ORR) is one of the most technologically relevant reactions. It occurs at the interface of the electrocatalyst and electrolyte, where oxygen reacts with protons and electrons to produce water. Because the electrocatalyst is dispersed on a high surface area support, morphological confinement becomes critical, as it dictates proton and oxygen transport. Furthermore, confinement is induced by ionomer, ionic liquids (ILs), or molecular additives, and their impact on electrocatalyst reactivity and transport properties is currently not well understood. We present an overview of electrostatics and mass transport–induced confinement and zoom in into ILs and molecular additives and try to unravel how local confinement induced by them impacts ORR.     

Recent advances in electrochemical water technologies for the treatment of antibiotics: A short review

This short review presents a critical overview of the most recent works published in the literature related to the use of electrochemical advanced oxidation processes (EAOPs) for the treatment of antibiotics present in synthetic and real wastewaters. The first section focuses on novelties within the traditional EAOPs, including electrochemical oxidation and electrochemical Fenton-based processes. The second section is devoted to new electrochemical technologies, including heterogeneous electro-Fenton, electrochemically activated persulfate processes, and combined processes. Future perspectives about these processes are also presented to aid the continuous evolution of research in the area.     

Estimation of the stability of skeletal muscle myoglobin of chilled pork treated with brine activated by low-frequency high-intensity ultrasound

We studied the effect of ultrasonic activation of brine (3%) during salting on the degree of stability of colour parameters of pork with normal (NOR) and abnormal course of autolysis in the CIE Lab colour space. The mechanism of stabilisation of the colour of meat is attributed to donor–acceptor bonds of metmyoglobin (MetMb). The accumulation of excessive number of free electrons in the medium are capable of activating MetMb. This reduces the activity of meat, when the native participants of the metmyoglobin reductase system and their own antioxidant systems of meat are depleted.Based on the additive calculation of deviations (increase / decrease) by the coordinates L*, a*, b* in the CIE Lab system, and the total colour difference (ΔE) in control and experimental samples, recommendations were developed. To optimize the colour characteristics of all types of meat, both on the surface and in the thickness of the meat, the preliminary activation of a 3% brine in a low-frequency submersible ultrasonic unit is recommended. Moreover, preliminary cavitation activation of a 3% is more preferable to stabilise the colour of PSE – meat (pale, soft, exudative (watery),) brine in a flow-through installation.     

Improving efficiency for removal of ammoniacal nitrogen from wastewaters using hydrodynamic cavitation

The present study reports significant improvements in the removal of ammoniacal nitrogen from wastewater which is an important problem for many industries such as dyes and pigment, distilleries and fisheries. Pilot plant studies (capacity, 1 m³/h) on synthetic wastewater using 4-amino phenol as model nitrogen containing organic compound and two real industrial effluents of high ammoniacal nitrogen content were carried out using hydrodynamic cavitation. Two reactor geometries were evaluated for increased efficiency in removal-orifice and vortex diode. Effect of initial concentration (100–500 mg/L), effect of pressure drop (0.5–5 bar) and nature of cavitating device (linear and vortex flow for cavitation) were evaluated along with effect of salt content, effect of hydrogen peroxide addition and aeration. Initial concentration was found to have significant impact on the extent of removal: ~ 5 g/m³ removal for initial concentration of 100 mg/L and up to 12 g/m³ removal at high concentration of 500 mg/L. Interestingly, significant improvement of the order of magnitude (up to 8 times) in removal of ammoniacal nitrogen could be obtained by sparging air or oxygen in hydrodynamic cavitation and a very high removal of above 80% could be achieved. The removal of ammoniacal nitrogen by vortex diode was also found to be effective in the industrial wastewaters and results on two different effluent samples of distillery industry indicated up to 75% removal, though with longer time of treatment compared to that of synthetic wastewater. The developed methodology of hydrodynamic cavitation technology with aeration and vortex diode as a cavitating device was found to be highly effective for improving the efficiency of the conventional cavitation methods and hence can be highly useful in industrial wastewater treatment, specifically for the removal of ammoniacal nitrogen.     

微氧化烧结制备掺杂Y2O3的SiC陶瓷及含镉模拟废水处理

采用了微氧化烧结制备了不同Y₂O₃质量分数（0%、2%、4%、6%）的多孔SiC陶瓷，通过对陶瓷的晶体结构、微观形貌、物理性能和Cd²⁺的去除率测试发现：添加了Y₂O₃的SiC陶瓷出现了较多的第二相Y₂SiO₇、Y₅Si₃C_0.5，随着Y₂O₃的质量分数增加逐渐升高，主相的衍射峰的强度有降低。扫描电子显微镜测试发现，SiC陶瓷的尺寸在2.5 μm，Y₂O₃引入后，SiC陶瓷的晶粒尺寸降低，高温烧结时液相的含量增加，熔体粘度降低，晶粒结合更加紧密，Y₂O₃的引入提高了多孔陶瓷的体积密度，Y₂O₃质量分数为6%SiC的体积密度最大为2.21 g/cm³。热导率随着Y₂O₃质量分数的增加呈现出先升高后降低的趋势。金属Cd²⁺的过滤测试表明：随着Y₂O₃质量分数增加，Cd²⁺的残留质量浓度、膜通量和去除率先降低后升高，当掺杂质量分数为4%时，Cd²⁺残留质量浓度最低为0.042 mg/L，膜通量达到了最大值572 L/（m²·h），去除率最大为99.95%，相比未掺质量分数杂体系的去除率提高了0.14%。随着溶液pH值的逐渐增大，金属Cd²⁺的残留质量浓度逐渐降低、去除率逐渐升高，pH≥9时最终均趋于稳定。综合来看，多孔SiC陶瓷的助烧剂Y₂O₃最佳掺量为4%。     

Preparation of Ag3PO4/CoWO4 S-scheme heterojunction and study on sonocatalytic degradation of tetracycline

In this study, 0.6Ag₃PO₄/CoWO₄ composites were synthesized by hydrothermal method. The prepared materials were systematically characterized by techniques of scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), N₂ adsorption/desorption, and UV–vis diffuse reflectance spectrum (DRS). Furthermore, the sonocatalytic degradation performance of 0.6Ag₃PO₄/CoWO₄ composites towards tetracycline (TC) was investigated under ultrasonic radiation. The results showed that, combined with potassium persulfate (K₂S₂O₈), the 0.6Ag₃PO₄/CoWO₄ composites achieved a high sonocatalytic degradation efficiency of 97.89 % within 10 min, which was much better than bare Ag₃PO₄ or CoWO₄. By measuring the electrochemical properties, it was proposed that the degradation mechanism of 0.6Ag₃PO₄/CoWO₄ is the formation of S-scheme heterojunction, which increases the separation efficiency of electron-hole pairs (e^--h⁺) and generates more electrons and holes, thereby enhancing the degradation activity. The scavenger experiments confirmed that hole (h⁺) was the primary active substance in degrading TC, and free radicals (OH) and superoxide anion radical (O₂^–) were auxiliary active substances. The results indicated that 0.6Ag₃PO₄/CoWO₄ nanocomposites could be used as an efficient and reliable sonocatalyst for wastewater treatment.     

Gutmann's Donor Numbers Correctly Assess the Effect of the Solvent on the Kinetics of SNAr Reactions in Ionic Liquids

We report an experimental study on the effect of solvents on the model S_NAr reaction between 1‐chloro‐2,4‐dinitrobenzene and morpholine in a series of pure ionic liquids (IL). A significant catalytic effect is observed with reference to the same reaction run in water, acetonitrile, and other conventional solvents. The series of IL considered include the anions, NTf₂^?, DCN^?, SCN^?, CF₃SO₃^?, PF₆^?, and FAP^? with the series of cations 1‐butyl‐3‐methyl‐imidazolium ([BMIM]⁺), 1‐ethyl‐3‐methyl‐imidazolium ([EMIM]⁺), 1‐butyl‐2,3‐dimethyl‐imidazolium ([BM₂IM]⁺), and 1‐butyl‐1‐methyl‐pyrrolidinium ([BMPyr]⁺). The observed solvent effects can be attributed to an “anion effect”. The anion effect appears related to the anion size (polarizability) and their hydrogen‐bonding (HB) abilities to the substrate. These results have been confirmed by performing a comparison of the rate constants with Gutmann's donicity numbers (DNs). The good correlation between rate constants and DN emphasizes the major role of charge transfer from the anion to the substrate.     

Prediction of 195Pt NMR chemical shifts of dissolution products of H2[Pt(OH)6] in nitric acid solutions by DFT methods: how important are the counter‐ion effects?

¹⁹⁵Pt NMR chemical shifts of octahedral Pt(IV) complexes with general formula [Pt(NO₃)_n(OH)_{6 ? n}]^2?, [Pt(NO₃)_n(OH₂)_{6 ? n}]^{4 ? n} (n = 1–6), and [Pt(NO₃)_{6 ? n ? m}(OH)_m(OH₂)_n]^{?2 + n ? m} formed by dissolution of platinic acid, H₂[Pt(OH)₆], in aqueous nitric acid solutions are calculated employing density functional theory methods. Particularly, the gauge‐including atomic orbitals (GIAO)‐PBE0/segmented all‐electron relativistically contracted–zeroth‐order regular approximation (SARC–ZORA)(Pt) ∪ 6–31G(d,p)(E)/Polarizable Continuum Model computational protocol performs the best. Excellent second‐order polynomial plots of δ_calcd(¹⁹⁵Pt) versus δ_exptl(¹⁹⁵Pt) chemical shifts and δ_calcd(¹⁹⁵Pt) versus the natural atomic charge Q_Pt are obtained. Despite of neglecting relativistic and spin orbit effects the good agreement of the calculated δ ¹⁹⁵Pt chemical shifts with experimental values is probably because of the fact that the contribution of relativistic and spin orbit effects to computed σ^{iso 195}Pt magnetic shielding of Pt(IV) coordination compounds is effectively cancelled in the computed δ ¹⁹⁵Pt chemical shifts, because the relativistic corrections are expected to be similar in the complexes and the proper reference standard used. To probe the counter‐ion effects on the ¹⁹⁵Pt NMR chemical shifts of the anionic [Pt(NO₃)_n(OH)_{6 ? n}]^2? and cationic [Pt(NO₃)_n(OH₂)_{6 ? n}]^{4 ? n} (n = 0–3) complexes we calculated the ¹⁹⁵Pt NMR chemical shifts of the neutral (PyH)₂[Pt(NO₃)_n(OH)_{6 ? n}] (n = 1–6; PyH = pyridinium cation, C₅H₅NH⁺) and [Pt(NO₃)_n(H₂O)_{6 ? n}](NO₃)_{4 ? n} (n = 0–3) complexes. Counter‐anion effects are very important for the accurate prediction of the ¹⁹⁵Pt NMR chemical shifts of the cationic [Pt(NO₃)_n(OH₂)_{6 ? n}]^{4 ? n} complexes, while counter‐cation effects are less important for the anionic [Pt(NO₃)_n(OH)_{6 ? n}]^2? complexes. The simple computational protocol is easily implemented even by synthetic chemists in platinum coordination chemistry that dispose limited software availability, or locally existing routines and knowhow. Copyright © 2016 John Wiley & Sons, Ltd.     

Single‐Walled Carbon Nanotubes in Highly Viscous Media: A Comparison between the Dispersive Agents [BMIM][BF4], L121, and Triton X‐100

Dispersions of single‐walled carbon nanotubes (SWNTs) have been prepared by using the room‐temperature ionic liquid [BMIM][BF₄] (1‐butyl‐3‐methylimidazolium tetrafluoroborate), the triblock copolymer Pluronic L121 [poly(ethylene oxide)₅‐poly(propylene oxide)₆₈‐poly(ethylene oxide)₅] and the non‐ionic surfactant Triton X‐100 (TX100) in the pure state. The size of the SWNTs aggregates and the dispersion degree in the three viscous systems depend on the sonication time, as highlighted by UV/Vis/NIR spectroscopy and optical microscopy analysis. A nonlinear increase in conductivity can be observed as a function of the SWNTs loading, as suggested by electrochemical impedance spectroscopy. The generation of a three‐dimensional network of SWNTs showing a viscoelastic gel‐like behavior above a critical percolation concentration has been found at 25 °C in all the investigated systems by oscillatory rheology measurements.     

In Situ Synthesis and Characterization of Poly(aryleneethynylene)‐Grafted Reduced Graphene Oxide

Using highly soluble bromo‐functionalized reduced graphene oxide (RGBr) as a key graphene template for surface‐directing Sonogashira–Hagihara polymerization, a novel soluble poly(arylene‐ethynylene)‐grafted reduced graphene oxide, hereafter abbreviated as PAE‐g‐RGO, was prepared in situ. The entirely different electron distribution of LUMO and HOMO of PAE‐g‐RGO suggested the existence of a charge‐transfer (CT) state (PAE^.?–RGO^.+). The negative ΔG_CS value (?2.57 eV) indicates that the occurrence of the charge separation via ¹RGO* in o‐DCB is exothermic and favorable. Upon irradiation with 365 nm light, the light‐induced electron paramagnetic resonance (LEPR) spectrum of PAE‐g‐RGO showed a decrease in the spin‐state density owing to photoinduced intramolecular electron transfer events in this system. A sandwich‐type Al/PAE‐g‐RGO/ITO device showed representative bistable electrical switching behavior. The nonvolatile memory performance was attributed to the CT‐induced conductance changes, which was supported by molecular computation results and conductive atomic force microscopy (C‐AFM) images.