Liquid phase selective oxidation of veratryl alcohol to veratraldehyde using pure and Mg-doped copper chromite catalysts.

Mg-doped copper chromite (CuCr2O4) nanocomposites were synthesised through conventional technique. The pure and doped CuCr2-xMgx O4 (x = 0.00-0.1, 0.2 and 0.3%) nanocomposites were characterized in terms of their morphology, crystal structure, surface area and catalytic performance. The chemical composition of CuCr2-xMgx O4 was confirmed via FT-IR. The formation of pure and doped catalysts was validated by XRD results. TEM/SEM confirmed the formation of CuCr2-xMgxO4 nanoparticles. Mg-doped samples possess a high specific surface area compared to pure CuCr2O4. Thus, the effects of temperature, solvent, time, oxidant and the amount of catalyst on the oxidation of veratryl alcohol were reported. Furthermore, detailed mechanisms of the catalytic oxidation of veratryl alcohol as well as the reusability and stability of the nanomaterial were investigated. The resulting composites were shown to be effective heterogeneous catalysts for the oxidation of veratryl alcohol.

Correlation between the particle size, structural and photoluminescence spectra of nano NiCr2O4 and La doped NiCr2O4 materials.

Nano NiCr2O4 undoped and La doped NiCr2O4 nanorods array were successfully prepared by solution based conventional method[sbcm]. The synthesized samples were characterized by the diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) spectroscopy for finding optical properties. Further, the samples structure confirmed by Fourier transforms infrared (FTIR), and X-ray diffraction (XRD)techniques. High-resolution transmission electron microscopy (HRTEM) analysis revealed the attachment of NiCr2O4 nanorods on surface of nanoparticles. From the results, it was found that the reaction time, band gap energy, and particle size strongly influenced by changing the concentration of La in NiCr2O4. This work is notable for its examination of the impact of the precursor on the optical and structural characteristics of samples of La-doped and undoped NiCr2O4. This was the first time the investigation had been done. The average particle size of the La-doped and undoped NiCr2O4 samples is between 16 and 24 nm.

Enhancement of the structure, solar cells and vibrational studies of undoped CuCr2O4 and La-doped CuCr2O4 semiconductor compounds.

In the present paper, we report the successful synthesis of spinel-type of CuCr2O4 and La doped CuCr2O4 semiconductor nanoparticles by a microwave method. Starting with the precursor complex, this technique includes the creation of homogenous solid intermediates, which reduces atomic diffusion pathways during the microwave process. CuCr2O4 and La doped CuCr2O4 were characterized by the following analytical methods for instance X-ray diffraction (XRD), transmission electron microscopy (TEM), Ultraviolet-visible (UV-Vis) spectroscopy and Fourier transform infrared spectroscopy (FTIR). The results demonstrated that modifying the precursor had a significant impact on the size, solar cell size, as well as reaction period of synthesizing CuCr2O4 and La doped CuCr2O4. The impacts of precursors on the morphological and structural characteristics of CuCr2O4 and La doped CuCr2O4 were examined for the first time in this publication.

Activated Graphite Supported Tunable Au-Pd Bimetallic Nanoparticle Composite Electrode for Methanol Oxidation.

Methanol (CH3OH) is a favorable fuel for direct methanol fuel cells (DMFCs) in compact devices. This work, we present a facile and simple approach to make divergent molar ratios uniform gold (Au) and palladium (Pd) nanoparticles (NPs) decoration on an activated graphite (AGR) electrode. The binary combination of these AGR/Au-Pd catalysts composition is controlled by modifying the molar ratio of the Au and Pd precursors. The AGR/Au-Pd composite was characterized by suitable microscopy and spectroscopy characterization technique. Electrochemical studies of the prepared material were also conducted by chronoamperometry (CA) and cyclic voltammetry (CV) methods. The AGR/Au-Pd composite nanoparticles were successfully prepared and decorated on an activated screen-printed carbon electrode (ASPCE) surface. The ASPCE/AGR/Au-Pd electrode has great potential and stability for DMFCs. The prepared modified electrode was compared by a Pt/C electrode, and its efficiency was better than those of previously reported modified electrodes. Additionally, the electrocatalytic reaction of methanol oxidation is a surface controlled process on the electrode surface.

Combustion and emission analysis of hydrogenated waste polypropylene pyrolysis oil blended with diesel.

Petroleum-based plastic pyrolysis oil contains unsaturated compounds, and the presence of these compounds makes the produced fuel unsuitable for combustion in diesel engines. Hydrogenation of pyrolysis oil is performed to convert unsaturated compounds to saturated compounds. Past studies have shown that hydrogenation of petroleum-based plastic pyrolysis oil is viable; however, its combustion and emissions analysis in diesel engines has not yet been reported. In this study, we investigated the combustion, performance, and emissions of hydrogenated polypropylene pyrolysis oil (HPPO) blended with diesel. Polypropylene (PP) was converted to pyrolysis oil using ZSM-5 as the catalyst. The hydrogenation of polypropylene pyrolysis oil (PPO) was conducted at pressure of 70 bar, and the reaction temperature was maintained at 350 °C. Ni metal impregnated on the ZSM-5 base support was used as the catalyst of choice. The produced HPPO possessed physicochemical properties that match the EN590 standards(European diesel fuel standards). Gas chromatography-mass spectrometry (GC-MS) studies of PPO and HPPO showed the effectiveness of hydrogenation for the complete conversion of alkenes to alkanes, and hydrocracking resulted in cracking higher carbon number alkanes to lower values. HPPO was blended with diesel in ratios of 10 wt.%, 20 wt.%, 30 wt.%, and 40 wt.%. The diesel engine performance results for the blended fuel showed combustion, performance, and emissions on par with pure diesel fuel for blending ratios up to 20 wt.%. As is known, plastic solid waste (PSW) materials pose serious hazards to the environment. Our HPPO physicochemical properties matched the EN590 standards for diesel fuel. The combustion of HPPO in diesel engines can provide an option for environmentally cleaner disposal of PSW.

Recent advances in the synthesis and applications of mordenite zeolite - review.

Among the many industrially important zeolites, mordenite is found to be interesting because of its unique and exceptional physical and chemical properties. Mordenite (high silica zeolite) is generally prepared by the hydrothermal method using TEA+ cations. TEA+ cations are the best templating agent, though they can create a number of issues, for instance, generating poison and high manufacturing cost, wastewater contamination, and environmental pollution. Hence, it is necessary to find a mordenite synthesis method without using an organic template or low-cost template. In this review, a number of unique sources were used in the preparation of mordenite zeolite, for instance, silica sources (rice husk ash, silica gel, silica fumes), alumina sources (metakaolin, faujasite zeolite) and sources containing both silica and alumina (waste coal fly ash). These synthesis approaches are also based on the absence of a template or low-cost mixed organic templates (for instance, glycerol (GL), ethylene glycol (EG), and polyethylene glycol 200 (PEG)) or pyrrolidine-based mesoporogen (N-cetyl-N-methylpyrrolidinium) modifying the mordenite framework which can create unique properties. The framework properties and optical properties (indium-exchanged mordenite zeolite) have been discussed. Mordenite is generally used in alkylation, dewaxing, reforming, hydrocracking, catalysis, separation, and purification reactions because of its large pore size, strong acidity, and high thermal and chemical stability, although the applications are not limited for mordenite zeolite. Recently, several applications such as electrochemical detection, isomerization, carbonylation, hydrodeoxygenation, adsorption, biomass conversion, biological applications (antibacterial activity), photocatalysis, fuel cells and polymerization reactions using mordenite zeolite were explored which have been described in detail in this review.

Reduced Graphene Oxide/Multiwalled Carbon Nanotube Composite Decorated with Fe3O4 Magnetic Nanoparticles for Electrochemical Determination of Hydrazine in Environmental Water.

In the present work, a reduced graphene oxide and multiwalled carbon nanotube (RGO/MWCNTFe3O4) composite decorated with Fe3O4 magnetic nanoparticles was prepared as an electrochemical sensor. The surface morphology of the prepared composite was identified by scanning electron microscopy and X-ray diffraction. The electrochemical properties of the GCE/RGO/MWCNT-Fe3O4 electrode were investigated by electrochemical impedance spectroscopy, cyclic voltammetry and amperometry. The GCE/RGO/MWCNT-Fe3O4 electrode exhibited higher electrocatalytic performance towards the oxidation of hydrazine. In the optimal conditions, the GCE/RGO/MWCNT-Fe3O4 electrode showed a wide linear range (0.15-220 µM), low limit of detection (LOD) (0.75 µM), and high sensitivity (2.868 µA µM-1 cm-2). The prepared GCE/RGO/MWCNT-Fe3O4 electrode also had excellent repeatability, selectivity, and reproducibility. The practical application of the electrode was confirmed with various spiked water samples and demonstrated acceptable recovery.

Facile synthesis of core-shell nanocomposites Au catalysts towards abatement of environmental pollutant Rhodamine B.

Magnetically recoverable Au nanoparticles immobilized/stabilized on core-shell nanocomposites are synthesized by the combination of suspension polymerization as well as surface initiator atom transfer radical polymerization (SI-ATRP) methods. The magnetic core-shell supported Au nanocatalysts are namely Fe3O4-PAC-AuNPs, Fe3O4-PVBC-g-PAC-AuNPs, Fe3O4-HEA-AuNPs, and Fe3O4-PVBC-g-HEA-AuNPs. Among all the catalysts, Fe3O4-PVBC-g-PAC-Au NPs exhibited an excellent activity in the reduction of Rhodamine B with an apparent rate constant of 10.77 × 10-3 s-1 and TOF value of 47.62 × 10-3 s-1 under pseudo-first order reaction condition. Further, Fe3O4-PVBC-g-PAC-Au NPs has an outstanding activity and recyclability without applying any external magnetic field. This new approach provides an exciting potential way in the preparation of recyclable metal nano-catalysts with high catalytic activity.

Environmentally friendly synthesis of CeO2 nanoparticles for the catalytic oxidation of benzyl alcohol to benzaldehyde and selective detection of nitrite.

Cerium oxide nanoparticles (CeO2 NPs) are favorable in nanotechnology based on some remarkable properties. In this study, the crystalline CeO2 NPs are successfully prepared by an efficient microwave combustion (MCM) and conventional route sol-gel (CRSGM) methods. The structural morphology of the as-prepared CeO2 NPs was investigated by various spectroscopic and analytical techniques. Moreover, the XRD pattern confirmed the formation of CeO2 NPs as a face centered cubic structure. The magnetometer studies indicated the low saturation magnetization (23.96 emu/g) of CeO2 NPs for weak paramagnetic and high saturation magnetization (32.13 emu/g) of CeO2 NPs for super paramagnetic. After that, the oxidation effect of benzyl alcohol was investigated which reveals good conversion and selectivity. Besides, the CeO2 NPs modified glassy carbon electrode (GCE) used for the detection of nitrite with linear concentration range (0.02-1200 µM), low limit of detection (0.21 µM) and higher sensitivity (1.7238 µAµM-1 cm-2). However, the CeO2 NPs modified electrode has the fast response, high sensitivity and good selectivity. In addition, the fabricated electrode is applied for the determination of nitrite in various water samples. Eventually, the CeO2 NPs can be regarded as an effective way to enhance the catalytic activity towards the benzyl alcohol and nitrite.

Green reduction of reduced graphene oxide with nickel tetraphenyl porphyrin nanocomposite modified electrode for enhanced electrochemical determination of environmentally pollutant nitrobenzene.

Nitrobenzene (NB) is widely used in the manufacturing of different types of products and other aromatic chemicals. Moreover, it is highly toxic and environmental pollutant compound. Therefore, the detection of nitro aromatic compounds (NACs) has gained more attention in the field of sensor. This article describes the green reduction utilized to preparation of green reduced graphene oxide/nickel tetraphenyl porphyrin (GRGO/Ni-TPP) nanocomposite modified electrode for the determination of nitrobenzene (NB). The GRGO was prepared by environmentally friendly method and using caffeic acid (CA) as a reducing agent. Moreover, the GRGO/Ni-TPP nanocomposite was prepared via the π-π stacking interaction between the RGO and Ni-TPP. In addition, the prepared material was confirmed by the UV-Visible spectroscopy (UV), nuclear magnetic resonance spectroscopy (NMR) and Fourier transform infrared spectroscopy (FTIR). The structural morphology and elemental composition of the prepared nanocomposite was confirmed by the scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX). Besides, the electrochemical studies of the prepared nanocomposite was characterized by the CV and DPV technique. The DPV studies displayed the linearity response of the proposed sensor about 0.5-878µM with the sensitivity of 1.277µAµM-1cm-2 and the limit of detection (LOD) is 0.14µM. Furthermore, the GRGO/Ni-TPP nanocomposite modified electrode shows good selectivity towards the detection of NB. In addition, the real sample analysis exhibited appreciable recovery towards the determination of NB using various types of water samples.

Electrocatalytic oxidation of dopamine based on non-covalent functionalization of manganese tetraphenylporphyrin/reduced graphene oxide nanocomposite.

In the present work, a reduced graphene oxide (RGO) supported manganese tetraphenylporphyrin (Mn-TPP) nanocomposite was electrochemically synthesized and used for the highly selective and sensitive detection of dopamine (DA). The nuclear magnetic resonance, scanning electron microscopy and elemental analysis were confirmed the successful formation of RGO/Mn-TPP nanocomposite. The prepared RGO/Mn-TPP nanocomposite modified electrode exhibited an enhanced electrochemical response to DA with less oxidation potential and enhanced response current. The electrochemical studies revealed that the oxidation of the DA at the composite electrode is a surface controlled process. The cyclic voltammetry, differential pulse voltammetry and amperometry methods were enable to detect DA. The working linear range of the electrode was observed from 0.3 to 188.8 µM, limit of detection was 8 nM and the sensitivity was 2.606 µA µM(-1) cm(-2). Here, the positively charged DA and negatively charged porphyrin modified RGO can accelerate the electrocatalysis of DA via electrostatic attraction, while the negatively charged ascorbic acid (AA) repulsed by the negatively charged electrode surface which supported for good selectivity. The good recovery results obtained for the determination of DA present in DA injection samples and human pathological sample further revealed the good practicality of RGO/Mn-TPP nanocomposite film modified electrode.