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In this research, two magnetic nano catalysts of zirconium and palladium, Fe3O4-(3-propyl) trimethoxysilane—natural asphalt sulfonic acid @metal, (metal = Pd and Zr) are synthesized by immobilizing palladium and zirconium nanoparticles on the functionalized natural asphalt sulfonate and, then, characterized using diverse microscopic and spectroscopic techniques. These catalysts are applied as recoverable, efficient and new heterogeneous catalysts for the synthesis of symmetrical and unsymmetrical aryl/alkyl disulfides by coupling the thiols without using any oxidizing agent. Moreover, the results and behavior of the two catalysts are comparable in some cases. The Fe3O4-PTMS-NAS@M, (M = Pd and Zr), nanocatalysts exhibited efficient magnetization as 38 and 39 emu/g, and are easily separated from the reaction mixture using an external magnet and reused for several runs while maintaining their catalytic activity. [ABSTRACT FROM AUTHOR]

Enzyme-inhibited electrochemical sensor is a promising strategy for detecting organophosphorus pesticides (OPs). However, the poor stability of enzymes and the high oxidation potential of thiocholine signal probe limit their potential applications. To address this issue, an indirect strategy was proposed for highly sensitive and reliable detection of chlorpyrifos by integrating homogeneous reaction and heterogeneous catalysis. In the homogeneous reaction, Hg2+ with low oxidation potential was employed as signal probe for chlorpyrifos detection since its electroactivity can be inhibited by thiocholine, which was the hydrolysate of acetylthiocholine catalyzed by acetylcholinesterase. Additionally, Co,N-doped hollow porous carbon nanocage@carbon nanotubes (Co,N-HPNC@CNT) derived from ZIF-8@ZIF-67 was utilized as high-performance electrode material to amplify the stripping voltammetry signal of Hg2+. Thanks to their synergistic effect, the sensor exhibited outstanding sensing performance, excellent stability and good anti-interference ability. This strategy paves the way for the development of high-performance OP sensors and their application in food safety. • A novel turn-on indirect electrochemical chlorpyrifos sensor was proposed; • Integration of homogeneous reaction and heterogeneous catalytic signal amplification; • Hg2+ with low oxidation potential and high peak current was used as signal probe; • Hollow Co,N-HPNC@CNT was employed to catalyze signal amplification of Hg2+; • The sensor showed excellent performance in pesticide detection in real samples. [ABSTRACT FROM AUTHOR]

Efficient nanocatalyst with incredible performance is highly demanding in a heterogeneous catalysis system. Herein, we report the facile fabrication of uniform and highly stable Cerium Oxide nanoparticles (CeO2 NPs), through chemical precipitation method using sodium hydroxide as reducing agent. The synthesized material is characterized through highly sophisticated techniques including UV-Visible, FT-IR, SEM, AFM, XRD, and Zeta Sizer- Potential to check the particle formation, surface morphology, topography, crystalline nature, size, and surface potential. The heterogeneous catalytic performance of CeO2 NPs has been accomplished for the reduction of 2-nitroaniline from the aqueous media. The CeO2 nanocatalyst displayed excellent reusability, while the reduction in several repetitive catalytic cycles against 2-nitroaniline under optimized conditions. The CeO2 nanocatalyst shows 99.12% efficiency within 60s reaction time under a greener source of microwave radiation. [ABSTRACT FROM AUTHOR]

In this work, we have developed a simple and very effective experimental strategy for the reaction of Knoevenagel via the condensation of aromatic aldehydes substituted with active methylene compounds in the presence of hybrid nanocomposites xMCl2-yNaPO3 (MCl2 = 2,2′-dibenzimidazolyl butane dichlorhydrates), under ecological conditions. The Phosphate-Benzimidazole hybrid nanocomposite as heterogeneous catalysts has demonstrated a high catalytic activity for the Knoevenagel condensation in ethanol as an ecological solvent. It has several advantages such as light reaction conditions, a simple and ecological working procedure. Meanwhile, xMCl2-yNaPO3 can be recovered by simple filtration and this catalytic system having an interesting lifetime (five cycles) with no decrease in activity.

This study investigates the degradation and mineralization of BTEX by heterogeneous electro-Fenton process using GO/MWCNT/Fe3O4 as a catalyst and MWCNT-Ce/WO3/GF as an electrode. The nanoscale MWCNT-Ce/WO3 composite catalyst was distributed more evenly on GF surface to form a catalyst layer with higher oxygen reduction reaction performance. After optimization of pH and time variables, the Box–Behnken experimental design (BBD) and response surface methodology (RSM) were used to design and optimize the performance of proposed system and energy consumption. Analysis of variance (ANOVA) revealed that the quadratic model was adequately fitted to the experimental data with R2 (0.98) and adj-R2 (0.97). The significance levels of linear and interaction effects of the reaction parameters on process efficiency were obtained. Then, the optimization of the working conditions for the design of a sustainable treatment system with optimum efficiency was carried out using a response surface methodology. The experiment carried out in the calculated optimal conditions for the electro-Fenton degradation process (current intensity 300 mA, catalyst dosage of 0.6 g, initial BTEX concentration of 100 ppm, and electrode distance of 1 cm) showed a BTEX removal of 73.2% and energy consumption of 12.3 (kWh/m3) close to the theoretical value predicted by the model 73. 2% and 11.8 (kWh/m3), respectively. Furthermore, the reusability test of GO/MWCNT/Fe3O4 nanocomposite after several cycles confirmed the high catalytic activities of adsorbent. Comparing the proposed system with conventional GF electrode and Fe2+ catalyst showed that modification of cathode and catalyst led to increasing COD removal efficiency by around 36.6 and 31.6%, respectively. The findings of present study revealed that the proposed heterogeneous electro-Fenton process can be utilized as pre-treatment technology to improve the biodegradability and reduce the organic load of wastewater by combine oxidation and coagulation. [ABSTRACT FROM AUTHOR]

Highlights • Heterogeneous electro-Fenton process without external aeration was applied into AMX degradation. • Response surface methodology was used for analyzing and optimization of the experimental factors. • Under optimum conditions, the maximum removal efficiency was obtained to be 98.2%. • Reusability tests showed that nano-Fe 3 O 4 after several cycles has a high catalytic activities of adsorbent. Abstract The process of amoxicillin (AMX) degradation was investigated by heterogeneous electro-Fenton without external aeration. Graphite felt was modified by means of carbon black and polytetrafluoroethylene (PTFE) to increase the production of hydrogen peroxide and nano- Fe 3 O 4 was also synthesized by chemical co-precipitation method. After optimization of pH and time variables, Box-Behnken design was applied for analyzing and optimization of the experimental factors such as applied current, amoxicillin concentrations, catalyst load and the distance between electrodes. The characteristics of nano-particles with cubic spherical structure and an average diameter of about 20–30 nm were determined via XRD and FESEM techniques. Modification of cathode led to increasing yield of H 2 O 2 by around 5.2 times. Analysis of variance (ANOVA) revealed that the quadratic model was adequately fitted to the experimental data with R2 (0.9884) and adj-R2 (0.9769). Under optimum conditions, the maximum removal efficiency was obtained to be 98.2%. Furthermore, the reusability test of nano-Fe 3 O 4 after several cycles confirmed the high catalytic activities of adsorbent. The findings of present study revealed that heterogeneous electro-Fenton process without external aeration was a proper method for degradation of AMX from aqueous solutions. [ABSTRACT FROM AUTHOR]

Six metalloporphyrin-based porous coordination polymers, Mn(TCP)-Mn ( CP1), Fe(TCP)-Fe ( CP2), Co(TCP)-Co ( CP3), Ni(TCP)-Ni ( CP4), Cu(TCP)-Cu ( CP5) and Zn(TCP)-Zn ( CP6), (TCP = 5,10,15,20-tetra(4-(phenoxy-4-yl)butanoic acid)porphyrin tetravalent anion) were prepared and characterized. CP1, CP2, CP3, CP4 and CP6 are amorphous aggregation supported by SEM, TEM and powder XRD. CP5 is a small particles aggregation with lower crystallinity. These coordination polymers exhibit effective dye scavenging and catalytic activities toward the oxidation of alkylbenzene to ketones, and can be reused by filtration with slight decreasing of catalytic activities. Graphical Abstract: [ABSTRACT FROM AUTHOR]

[Display omitted] • Synergistic effect of Fe 3 O 4 /C can improve the activity and recyclability of catalyst. • Mo 72 V 30 @Fe 3 O 4 /C displays the high activity of 99.4 % conversion and 100 % selectivity. • Polymetallic centers of Mo 72 V 30 @Fe 3 O 4 /C synergistically promote the catalytic reaction. It is a great challenge to develop recyclable polyoxometalate (POM) based catalysts with high efficiency and selectivity in oxidation of 5-hydroxymethylfurfural (HMF). In this paper, MIL-88A(Fe) derived Fe 3 O 4 /C is designed as an efficient carrier to entrap Keplerate-type POM and form Mo 72 V 30 @Fe 3 O 4 /C composite catalyst. Due to the confined and synergistic effect of Fe 3 O 4 /C framework, as compared to other reported catalysts, Mo 72 V 30 @Fe 3 O 4 /C exhibits the highest catalytic activity and selectivity in aerobic oxidation of HMF with a 99.4 % conversion and a 100 % selectivity to 2,5-diformylfuran (DFF). The Mo 72 V 30 @Fe 3 O 4 /C catalyst still shows a high activity even after ten cycles. A possible synergistic catalytic mechanism is proposed that Mo 72 V 30 @Fe 3 O 4 /C oxidizes HMF to DFF through a proton coupled electron transfer (PCET) process indicating the polymetallic center in Mo 72 V 30 @Fe 3 O 4 /C synergistically promotes this reaction. This work not only provides a giant POM based catalyst in biomass conversion, but also highlights a polymetallic active center concept for the design of biomass oxidation catalyst. [ABSTRACT FROM AUTHOR]

Six Mn(porphyrin)-based porous coordination polymers, Mn(FCPp)-Mn ( CP1, FCPp=5-(pentafluorophenyl)-10,15,20-tri(4-carboxyphenyl)porphyrin dianion), Mn(FCPp)-Co ( CP2), Mn(FCPp)-Ni ( CP3), Mn(FCPp)-Mn ( CP4, FCPp=5,15-bis(pentafluorophenyl)-10,20-bis(4-carboxyphenyl)porphyrin dianion), Mn(FCPp)-Co ( CP5), and Mn(FCPp)-Ni ( CP6), were prepared and characterized. The precursors were identified by UV-Vis, GC-MS, infrared spectra and elemental analysis in the procedures of Mn(porphyrin)-based polymers synthesis. CP1, CP4, CP3 and CP6 are amorphous aggregation supported by SEM, TEM and powder XRD. CP2 and CP5 are rod-like microcrystalline particles supported by powder XRD and SAED. These polymers exhibit high catalytic activities and selectivities toward the oxidation of ethylbenzene to acetophenone in quantitative over 70 % yields, and can be reused by filtration with only slight decreasing of catalytic activities. Graphical Abstract: [ABSTRACT FROM AUTHOR]

This research investigated the efficiency of nanosized ZnO in the catalytic ozonation of 4-chloro-2-nitrophenol and determined the effect of pH on heterogeneous catalytic ozonation. Use of ozone with ZnO catalyst leads to conversion of 98.7% of 4-chloro-2-nitrophenol during 5 min. In addition, it was found that in ZnO catalytic ozonation, the degradation efficiency of 4-chloro-2-nitrophenol was higher at low pH conditions (pH 3.0) than high pH (pH 7–9). This result was not in accordance with ozonation alone, following which higher pH had positive effect on the degradation of 4-chloro-2-nitrophenol. During the catalytic ozonation of 4-chloro-2-nitrophenol, an increase of nitrate ions in water sample solution was observed. At pH = 3, the concentration of nitrate formed during nano-ZnO catalytic ozonation was 7.08 mg L −1 and the amount of total organic carbon was 54.9% after 30 min. [ABSTRACT FROM AUTHOR]

Peroxymonosulfate (PMS)-based advanced oxidation process are widely used in the degradation of organic pollutants. The degradation of the electron-rich azo dye Acid Orange 7 (AO7) through a PMS/CuO heterogeneous system in borate and phosphate buffer were systematically investigated. The CuO was characterized via X-ray diffraction, scanning electron microscopy, fourier-transform infrared spectra, X-ray photoelectron spectroscopy and energy dispersive spectroscopy (SEM-EDS) techniques. The difference of AO7 degradation by PMS/CuO system in borate and phosphate buffer varied with the buffer concentration, PMS concentration, CuO dosage and pH. AO7 degradation fitted well with the pseudo-first order kinetics in these two buffer solutions, the reaction rate constant (k obs) of AO7 degradation in phosphate buffer increased with the increase of phosphate concentration firstly and then reached the maximum value of 0.0123 min−1 at 0.2 M, but it decreased obviously with the increase of borate concentration. It was found that the k obs in two buffers increased linearly with the increase of PMS concentration, and increased with the increase of CuO dosage in borate, while the reaction in phosphate buffer was slightly affected by CuO dosage. Additionally, the k obs increased from 0.0057 min−1 to 0.0487 min−1 with the increase of pH value in phosphate, but decreased gradually with the increase of pH value from 7.0 to 8.5 in borate due to the deprotonation of PMS. Fewer reactive species were produced in phosphate including SO 4 •–, •OH and 1O 2. The conversion between Cu(Ⅱ) and Cu(Ⅰ) was a crucial process for the activation of PMS by CuO in borate, which was hindered in phosphate. This study will provide a reference for the application of different types of buffers in heterogeneous catalysis of PMS. [Display omitted] • The k values in borate buffer (0.08 M) was 7 times higher than that in phosphate buffer at pH = 7.5. • More reactive species were produced by PMS/CuO system in borate. • Conversion between Cu(Ⅱ) and Cu(Ⅰ) was proved to play a crucial role in PMS/CuO system. • More attention should be paid to the use of borate buffer in the studies of PMS-based AOPs. [ABSTRACT FROM AUTHOR]

In this work, we have developed a simple and very effective experimental strategy for the reaction of Knoevenagel via the condensation of aromatic aldehydes substituted with active methylene compounds in the presence of hybrid nanocomposites xMCl 2 -yNaPO 3 (MCl 2 = 2,2'-dibenzimidazolyl butane dichlorhydrates), under ecological conditions. The Phosphate-Benzimidazole hybrid nanocomposite as heterogeneous catalysts has demonstrated a high catalytic activity for the Knoevenagel condensation in ethanol as an ecological solvent. It has several advantages such as light reaction conditions, a simple and ecological working procedure. Meanwhile, xMCl 2 -yNaPO 3 can be recovered by simple filtration and this catalytic system having an interesting lifetime (five cycles) with no decrease in activity., (© 2020 Published by Elsevier Ltd.)

The wide application of traditional Fenton reactions was firmly restricted by the requirement for harsh acid conditions, as well as the inevitable generation of iron slurry. The FeOCl nanosheets, prepared by the chemical vapor transformation method, were used to degrade RhB via activation of H 2 O 2 . The FeOCl was characterized by a field emission scanning electron microscope (FE-SEM) and X-Ray Diffractometer (XRD), the results showed that FeOCl exhibited a fine crystal structure and nanosheet-like morphology, which was favorable for exposure of active sites. The results of degradation experiments showed that the RhB was totally removed within 15 min under the conditions of[H 2 O 2 ]=1.67 mmol·L -1 and[FeOCl]=200 mg·L -1 . The initial pH plays a negative role in RhB degradation, and the initial pH increased from 3 to 7 as the RhB removal efficiency decreased from 100% to 84%. Typically, when the initial pH was 9, the RhB degradation sharply decreased to 57.6%. Compared with traditional Fenton reactions, the FeOCl/H 2 O 2 system widened the pH range, which resulted in superior organics removal even under a mild-acidic to medium pH condition. The quenching experiments demonstrated that the·OH was the major reactive oxygen species. Additionally, Electron Paramagnetic Resonance (EPR) results showed that intense DMPO-HO·signals were detected in the FeOCl/H 2 O 2 system, which further demonstrated the important role of·OH in RhB degradation.