Oxidative decarboxylation of arylacetic acids in water: One-pot transition-metal-free synthesis of aldehydes and ketones

One-pot transition-metal-free synthesis of aromatic aldehydes and ketones via oxidative decarboxylation of arylacetic acids in water is developed. Protocol relies on the direct decarboxylation of sp³-hybridized carbon in water without any over oxidation into carboxylic acids with minimal waste. Reaction mechanism is investigated and application of this protocol is demonstrated on a gram scale.     

Degradation of p-nitrophenol (PNP) in aqueous solution by mFe/Cu-air-PS system

In this study, batch experiments were conducted to investigate the performance of microscale Fe/Cu bimetallic particles-air-persulfate system (mFe/Cu-air-PS) for p-nitrophenol (PNP) treatment in aqueous solution. The results indicate that toxic and refractory PNP in aqueous solution could be decomposed effectively and transformed into lower toxicity intermediates.     

Mechanistic investigations in sono-hybrid (ultrasound/Fe2+/UVC) techniques of persulfate activation for degradation of Azorubine

Persulfate-based oxidation of recalcitrant pollutants has been investigated as an alternative to OH radical based advanced oxidation processes due to distinct merits such as greater stability and non-selective persistent reactivity of ${\text{SO}}_4^{\text{<mglyph src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/rad"></mglyph>}-}$ oxidant species. The present study has attempted to highlight mechanistic features of persulfate-based decolorization of textile dye (Azorubine) using sono-hybrid techniques of activation. Three activation techniques, viz. sonolysis, Fe²⁺ ions and UVC light and combinations thereof, have been examined. UVC is revealed to be the most efficient decolorization technique. The mechanism of sonolysis (i.e. thermal activation of persulfate in the bubble-bulk interfacial region) is revealed to be almost independent of the mechanism of UVC. Fe²⁺ activation is revealed to have an adverse interaction with UVC due to scavenging of sulfate radicals by Fe²⁺ ions. The best hybrid activation technique for persulfate-based degradation and mineralization of Azorubine is UVC + ultrasound. Due to independent mechanisms, degradation and mineralization of the dye obtained with simultaneous application of UVC and ultrasound is nearly equal to the sum of degradation and mineralization obtained using individual techniques.     

Oxidative and photooxidative degradation of poly(acrylic acid)

The oxidative degradation of poly(acrylic acid) (PAA), a water soluble polymer, was studied at various temperatures with different concentrations of persulfates, potassium persulfate (KPS), ammonium persulfate (APS) and sodium persulfate (SPS). The photodegradation of PAA was also examined with APS as oxidizer. The degraded samples were analyzed for the time evolution of molecular weight distribution by gel permeation chromatography. A theoretical model based on the continuous distribution kinetics was developed that accounted for the polymer degradation and the dissociation of persulfate. The rate coefficients for the oxidative and photooxidative degradation of PAA were determined from the parametric fit of the model with experimental data. The rate of degradation increased with increasing amount of persulfate in both oxidative and photooxidative degradation. The rate of degradation also increased with increasing temperature in the case of oxidative degradation.     

测定总氮时影响空白吸光值的因素

针对GB 11894-89测定污水中总氮空白值偏高的情况,分析了碱性过硫酸钾本身以及纯度的影响、消解量、消解温度和时间、去离子水纯度、玻璃器皿的洁净度、碱性过硫酸钾存储时间、环境因素等影响因素,找出了实验出现问题的原因,并进行了校正.     

鲁米诺-过硫酸钠-卡托普利化学发光体系的研究

基于卡托普利对过硫酸钠鲁米诺化学发光体系的强烈抑制作用,建立起一种直接测定卡托普利的流动注射化学发光新方法。该方法灵敏、简单、快速。线性范围为5.0×10-5～1.0×10-3g·L-1,检出限为1.7×10-5g·L-1,相对标准偏差为3.2%。利用该方法对卡托普利片剂含量的测定,结果满意。     

Visible light degradation of ibuprofen using PANI coated WO3@TiO2 photocatalyst

A PANI-coated heterojunction of WO₃@TiO₂ nanocomposite was fabricated in three stages. The performance evaluation of the prepared photocatalyst for the degradation of ibuprofen was performed under visible light. Characterization of the photocatalyst using X-ray diffraction (XRD) analysis showed that the TiO₂ prepared constituted of the anatase phase. Furthermore, results from in situ XRD analysis of WO₃ show that it consisted of monoclinic and orthorhombic crystalline structures. These phases were not affected by the incorporation of PANI as revealed by XRD analysis. Results from Transmission electron microscopy (TEM) examination showed that sphere-like WO₃ and TiO₂ nanorods of different sizes were prepared In addition, fabrication of a heterojunction of WO₃@TiO₂ wrapped in PANI was shown by TEM analysis. Results from photoluminescence studies indicate that coupling TiO₂ with WO₃ enhanced the charge separation and the degradation performance of the nanocomposite. Supporting the heterojunction on PANI enhanced the degradation efficiency as indicated during the performance evaluation process. Diffuse reflectance spectra (DRS) calculations of the PANI/WO₃@TiO₂ catalysts showed that they can be used under visible light. The experimental results of X-ray Photon Spectroscopy (XPS) analysis showed the presence of elements W, C, O, Ti, and N. Solution pH influenced the degradation process and the maximum degradation efficiency was attained at pH 9. The degradation followed the Langmuir-Hinshelwood kinetic model with a Kinetic constant of 3.5 × 10^?2. The rate of degradation increased in the presence of bicarbonate/carbonate ions and persulfate ions.     

Efficient decomposition of sulfamethoxazole in a novel neutral Fered-Fenton like/oxalate system based on effective heterogeneous-homogeneous iron cycle

In this study, efficient sulfamethoxazole (SMX) degradation was demonstrated in a novel neutral Fered-Fenton like/oxalate (electro-Fe²⁺/PDS/Ox, Fered-FL/Ox) system adopting pre-anodized Ti@TiO₂ cathode. Optimization of operational parameters was conducted and the whole reaction mechanism based on the critical solid-liquid interfacial reactions was explored. An efficient neutral heterogeneous-homogenous iron cycle would exist in the Fered-FL/Ox system, depending on the formation of specific COTi bonds through the inner sphere surface complex (ISSC) of Fe(C₂O₄)₃³⁻. It would induce ultrafast electron transfer from the cathode to the Fe^III core, effectively accelerating the neutral Fenton-like reactions and complete mineralization of SMX with relative low dosage of ferrous catalyst and applied voltage. The result of this study is expected to supply a good alternative in treating complex neutral industrial wastewaters     

STUDIES OF THE INITIATION MECHANISM OF VINYL POLYMERIZATION WITH THE SYSTEM PERSULFATE/N-ALKYL SUBSTITUTED ETHYLENEDIAMINE DERIVATIVES

Effects of N-alkyi substituted ethylenediamine derivatives on vinyl polymerization using persulfate as initiator were studied. The apparent kinetic equations and overall activation energies of acrylamide polymerization were determined using the above mentioned system as initiator. The promoting activities of different diamine derivatives on vinyl polymerization are in the order of tertiary diamine>secondary diamine>primary diamine. Diamines having methyl groups as the substituent on their nitrogen atom possess higher promoting activity than that of having larger alkyl groups. The initial free radicals produced through the redox reaction of persuifate and diamines were studied by spin strapping technique and ESR spectroscopy. The results obtained confirm the fact that the initial free radicals of the diamine species can initiate vinyl polymerization and become the amino end group of the resulting polymers.     

Efficient removal of organic pollutant by activation of persulfate with magnetic Co3O4/CoFe2O4 composite

In this study, magnetic spinel Co₃O₄/CoFe₂O₄ composite were synthesized by the mechanical mixing of both powdered pristine samples. Then the catalyst was characterized by TEM, SEM, XRD, BET, XPS and VSM measurement. Next, Co₃O₄/CoFe₂O₄ composite was applied to degrade rhodamine B (RhB) in water by activating persulfate. Results showed that Co₃O₄/CoFe₂O₄ composite exhibited high efficiency for removal of RhB, and 95.59% of it could be degraded in 45 min. Besides, the effects of parameters, such as initial pH, PS dosage, Co₃O₄/CoFe₂O₄ composite dosage, initial concentration of RhB and temperture were studied. Also, the effects of coexisting anions on RhB degradation were observed and explained. Furthermore, we conducted the quenching experiment and found that sulfate radical and hydroxyl radicals were the main active radicals in the degradation process. Finally, recycle experiments proved that Co₃O₄/CoFe₂O₄ had a good stability for RhB degradation. In short, Co₃O₄/CoFe₂O₄ composite is a promising catalyst for wastewater treatment.