Reflux Process Research Articles

SINTESIS DAN IDENTIFIKASI STRUKTUR SENYAWA 3-(3,5-DINITROBENZOIL)-1-FENILTIOUREA SEBAGAI KANDIDAT ANTIKANKER

Thiourea derivatives are known to be potential anticancer agents. 3-(3,5-dinitrobenzoyl)-1-phenylthiourea as a thiourea derivatives has been synthesized through acylation between 3,5-dinitrobenzoyl chloride and 1-phenylthiourea in tetrahydrofuran with triethylamine ascatalyst through reflux process with stirring for 6 hours. The percentage of yield was13,86%. The purity of the product was shown by the single spot on the TLC and narrowrange of melting point. The structure identification results with UV spectrophotometry, IRspectroscopy and 1HNMR spectroscopy showed that the structure of the product wasappropriate to the prediction.

Designed Formation of Hybrid Nanobox Composed of Carbon Sheathed CoSe2 Anchored on Nitrogen-Doped Carbon Skeleton as Ultrastable Anode for Sodium-Ion Batteries.

Research on sodium-ion batteries (SIBs) has recently been revitalized due to the unique features of much lower costs and comparable energy/power density to lithium-ion batteries (LIBs), which holds great potential for grid-level energy storage systems. Transition metal dichalcogenides (TMDCs) are considered as promising anode candidates for SIBs with high theoretical capacity, while their intrinsic low electrical conductivity and large volume expansion upon Na+ intercalation raise the challenging issues of poor cycle stability and inferior rate performance. Herein, the designed formation of hybrid nanoboxes composed of carbon-protected CoSe2 nanoparticles anchored on nitrogen-doped carbon hollow skeletons (denoted as CoSe2 @C∩NC) via a template-assisted refluxing process followed by conventional selenization treatment is reported, which exhibits tremendously enhanced electrochemical performance when applied as the anode for SIBs. Specifically, it can deliver a high reversible specific capacity of 324 mAh g-1 at current density of 0.1 A g-1 after 200 cycles and exhibit outstanding high rate cycling stability at the rate of 5 A g-1 over 2000 cycles. This work provides a rational strategy for the design of advanced hybrid nanostructures as anode candidates for SIBs, which could push forward the development of high energy and low cost energy storage devices.

Study of Fabrication and Improvement of Mechanical Properties of Mg-based Inorganic Fiber using Reflux Process and Silica Coating

Whisker-type magnesium hydroxide sulfate hydrate (5Mg(OH)2·MgSO4·3H2O, abbreviated 513 MHSH), is used in filler and flame-retardant composites based on its hydrate phase and its ability to undergo endothermic dehydration in fire conditions, respectively. In general, the length of whiskers is determined according to various synthetic conditions in a hydrothermal reaction with high temperature (~180oC). In this work, high-quality 513 MHSH whiskers are synthesized by controlling the concentration of the raw material in ambient conditions without high pressure. Particularly, the concentration of the starting material is closely related to the length, width, and purity of MHSH. In addition, a ceramic-coating system is adopted to enhance the mechanical properties and thermal stability of the MHSH whiskers. The physical properties of the silica-coated MHSH are characterized by an abrasion test, thermogravimetric analysis, and transmission electron microscopy.

Aqueous synthesis of the CdTe NCs and influence of size on photovoltaic performance of the CdS/CdTe co-sensitized solar cells

In this work CdTe NCs with different sizes were synthesized through a hot-injection chemical precipitation method. Then they were applied as the co-sensitizers in the photoelectrode of the CdTe and CdS sensitized solar cells. The photoelectrodes were composed of a nanocrystalline TiO2 layer formed of hydrothermally grown TiO2 NCs with dominant size of 25 nm. This layer was sensitized with CdS and CdTe NCs via the successive ionic layer adsorption and reaction (SILAR) and drop casting methods. The average size of utilized CdTe NCs was altered in the range of 2.7–3.4 nm in the experiments. Polysulfide electrolyte and CuS counter electrodes were also applied in conventional structure of these QDSCs. Different photoanodes were fabricated with various sizes of the as prepared CdTe NCs. Then the effect of corresponding bandgap energies and band edge positions on the photovoltaic performance of the CdS/CdTe sensitized solar cells was investigated. According to the results, a maximum efficiency of 3.8% was achieved for the QDSC with CdTe NCs prepared at 5h of refluxing process (3.2 nm). This efficiency was increased about 72% compared to the reference cell which was sensitized with just CdS NCs. The optimization was also addressed based on the energy band diagram of the composing components of the fabricated QDSCs.

Palladium enriched tungsten oxide thin films: an efficient gas sensor for hazardous gases

Palladium enriched tungsten trioxide thin films were prepared by spraying solution of ammonium tungstate as a precursor on glass substrates using spray pyrolysis deposition technique. Palladium chloride as a precursor for palladium was introduced in the precursor solution during refluxing process before deposition. The catalyst Pd with different concentrations was introduced on series of WO3 films. X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy were applied to analyze structure and morphology of the deposited thin films. The effect of Pd enrichment on the microstructure, electrical and gas sensing properties of the as-synthesized WO3 thin films was studied. Variation in the electrical conductivity of pure and Pd supplemented WO3 films was measured in air and in the presence of hazardous gases such as NO2, SO2 and NH3. The addition of 3 w/o Pd in WO3 raised the gas response of the film to 1.1 towards NO2 at lowest operating temperature of 100 °C. The film shows adequate response towards SO2 (0.32) and NH3 (0.27) at 200 °C and 225 °C, respectively. The response and recovery time ranged in 0.5–1.25 s and 1–6.7 s respectively even for high gas concentrations upto 750 ppm.

Electrochemical Detection of Chloride Ions by Copper (II) Complex with Mixed Ligand of Oxindole Derivative and Dithiocarbamates Moiety

The present work describes the synthesis of a new copper (II) complex with bidentate ligands based on oxindole (indolin-2-one) derivatives, namely: 1H,1′H,1″H-[2,3′:2′,3″-terbenzo[b]pyrrol]-2″(3″H)-one (L1) and [sodium diethyldithiocarbamate (DTC)] (L2) as a second bidentate ligand. The ligand L1 was prepared by the cyclization reaction of oxindole (2-indolone) with phosphorus oxychloride. A mixed-ligand was synthesized using L1 and L2 ligands with copper (Cu (II)) via a simple reflux process. The synthesized mixed Cu (II) complex [C53H44CuN7O4S2 and [Cu(L1)2(L2)]2H2O] exhibited superior solubility in organic solvents like dichloromethane, chloroform, ethanol, methanol, DMF and DMSO. The optical characterizations revealed that the synthesized Cu (II) complex displayed a broad band (2Eg→2T2g) with the absorption at ~420 nm, suggesting a distorted octahedral geometry due to the strong Jahn-Teller distortion of the Cu2+ ion. The elemental analysis confirmed the existence of Cu, C, S, N, and other elements in the synthesized mixed Cu (II) complex. The physicochemical studies of the organic ligand and Cu(II) complex were investigated by TG analysis, NMR, FTIR, SEM, EDX, electronic spectra and cyclic voltammetry measurements. The detection of chloride ions with the prepared mixed Cu(II) complex was studied by cyclic voltammetry measurements at different scan rates.

N-doped 3D porous carbon-graphene/polyaniline hybrid and N-doped porous carbon coated gC3N4 nanosheets for excellent energy density asymmetric supercapacitors

Nitrogen doped hierarchically porous 3D porous carbon-graphene/polyaniline (3D PC-g/PANi) hybrid nanocomposites are prepared by a simple in-situ polymerization process. 3D PC is synthesized using bio-waste Bombax malabaricum seeds as the carbon precursor and the interconnected 3D PC-g are prepared by a simple refluxing and activation process with a large specific surface area of 2418 m2 g−1. The specific capacitance (Cp) of 3D PC-g and 3D PC-g/PANi electrodes are 610 and 1198 F g−1 in 1 M H2SO4, respectively at a very high current density of 2 A g−1. Also, a symmetric supercapacitor (SSC) exhibits a high energy density (Ed) of 61 Wh kg−1 and 117 Wh kg−1in 1 M H2SO4 and 0.5 M Na2SO4 electrolytes, respectively. It still persist a high power density (Pd) of 15 kW kg−1 and 20 kW kg−1 with an Ed of 49.1 Wh kg−1 and 84.4 Wh kg−1 at a very high current density of 30 A g−1. Further, an asymmetric supercapacitor (ASC) based on 3D PC-g/PANi as positive and hierarchical porous N-doped porous carbon covered gC3N4 nanosheets (N-P(gCN)-700) as a negative electrode is successfully fabricated, which exhibit a high Ed of 97.5 Wh kg−1 in 0.5 M Na2SO4. The presented results are higher than most of earlier reported PANi based composite carbon electrode materials. Further, the assembled SSC and ASC devices exhibit 94% and 91% capacitance retention even after 10,000 cycles. Furthermore two ASC connected in series can power up red LED for 30 min after charging for 60 s.

Phase-pure Na3V2(PO4)2F3 embedded in carbon matrix through a facile polyol synthesis as a potential cathode for high performance sodium-ion batteries

In this study, a pseudo-layered Na super-ionic conductor of Na3V2(PO4)2F3 (NVPF)/C cathode for sodium-ion batteries is prepared successfully using a facile polyol refluxing process without any impurity phases. The X-ray diffraction and Rietveld refinement results confirm that NVPF possesses tetragonal NASICON-type lattice with a space group of P42/mnm. In this preparative method, polyol is utilized as a solvent as well as a carbon source. The presence of nanosized NVPF particles in the carbon network is confirmed by field-emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM). The existence of carbon is analyzed by Raman scattering and elemental analysis. When applied as a Na-storage material in a potential window of 2.0–4.3 V, the electrode exhibits two flat voltage plateaus at 3.7 and 4.2 V with an electrochemically active V3+/V4+ redox couple. In addition, Na3V2(PO4)2F3/C composite achieved a retention capacity of ~ 88% even after 1,500 cycles at 15 C. Moreover, at high current densities of 30 and 50 C, Na3V2(PO4)2F3/C cathode retains the specific discharge capacities of 108.4 and 105.9 mAh·g–1, respectively, revealing the structural stability of the material prepared through a facile polyol refluxing method.

Ni-Al layered double hydroxide with regulated interlayer spacing as electrode for aqueous asymmetric supercapacitor

Using sodium oleate as surfactant and intercalating agent, a regulated Ni-Al layered double hydroxide (NA-LDH-OA) nanosheets with a high interlayer space were prepared by two-phase method combined with a short reflux process and mild solvothermal reaction. In the process of electrochemical reaction, the electron transport is accelerated by the higher base spacing of the NA-LDH-OA ultrathin nanosheets. The as-prepared material exhibited a high specific capacity (1.040 C cm−2 at a current density of 1.68 mA cm−2) and good cycling performance (capacity retention of 88.25% after 2000 cycles) in a three-electrode system. Moreover, an aqueous asymmetric supercapacitor (ASC) was assembled using the synthesized NA-LDH-OA nanosheets as the positive electrode and activated carbon (AC) as the negative electrode. The aqueous ASC device (NA-LDH-OA-2//AC) achieved a high energy density of 40.26 Wh kg−1 at a power density of 943 W kg−1, and a good cycling performance of 94.5% retention after 5000 cycles. These results demonstrated that the NA-LDH-OA nanosheets possess the potential for upcoming energy storage devices.

The graphene/lanthanum oxide nanocomposites as electrode materials of supercapacitors

In this paper, the nanocomposites of reduced graphene oxide/lanthanum oxide are prepared by a simple reflux process. The reduced graphene oxide with a large specific surface area is successfully decorated with lanthanum oxide. The reduced graphene oxide/lanthanum oxide composites are fabricated as the electrode material in a supercapacitor device which displays a high specific capacitance of 156.25 F/g at a current density of 0.1 A/g and excellent cycle stability. The material keeps 78% of its initial charge-discharge efficiency after 500 cycles. The excellent electrochemical performance of composite material may be attributed to the deposited lanthanum oxide nanoparticle on the surface of reduced graphene oxide, which increase the effective conductive area of reduced graphene oxide and the contact area between electrolyte and graphene. The graphene-lanthanum oxide composites can significantly improve the stability and electrical performance of supercapacitors and has great potential in chemical sensors, microelectronics, energy storage and conversion applications.

ZnO incorporated antimicrobial LDPE: Effect of PVA-Neem Functionalization

Abstract Antimicrobial low-density polyethylene composites were prepared by blending functionalized ZnO with LDPE using melt blending method. The functionalized ZnO was prepared by grafting the polyvinyl alcohol (PVA) followed by addition of Neem extraction through reflux process. The stability of these particles was studied by comparing FTIR, DLS and Zeta potential analysis. The result showed the PVA-Neem functionalization has successfully stabilized the particle thus improve the dispersion of ZnO in polymer matrix. LDPE/PVA-Neem functionalized ZnO exhibited strong antibacterial activity (99%) against E-Coli followed by LDPE/ZnO (39 %) and bare LDPE (0%). The 60% improvement of PVA-Neem functionalization was presumably attribute to homogeneous distribution of particle in the bulk of the film, improved hydrophilicity and polarity that allowed water absorption to activate the photocatalytic proses as well as enhance diffusion rate of Zn ion and ROS release.

Homogeneous cobalt and iron oxide hollow nanocages derived from ZIF-67 etched by Fe species for enhanced water oxidation

To develop highly efficient non-noble-metal electrocatalysts for oxygen evolution reaction is still a great challenge. Herein, cobalt and iron oxide with hollow structure has been fabricated using ZIF-67 as template, via reflux process followed by calcination. The simultaneous structural and electronic modulation are achieved due to the homogenous Fe incorporation. The Co sites in higher oxidation states and Fe sites with higher electron density can enhance the adsorption of H2O molecules and OOH species, and thus promote the water oxidation. The unique hollow structure also facilitates the mass transfer at the interface of electrolyte and active atoms. The optimal cobalt and iron oxide hollow nanocages exhibit superior OER performance, delivering an ultralow overpotential of 274 mV at 10 mA cm−2 and a very small Tafel slope of 31 mV dec−1 in alkaline media, which outperform the state-of-the-art RuO2. This work provides an efficient approach to design and explore non-precious electrocatalysts for electrochemical energy conversion and storage.

Oxidative acid treatment of carbon nanotubes

This study investigated the oxidative acid treatment of multi-walled carbon nanotubes (MWCNT). Experiments were conducted by refluxing MWCNT with HNO3 and H2SO4/HNO3 (3:1 v/v) at two different molar concentrations. Treated MWCNT were characterized for their weight loss, surface chemistry, surface morphology, structural integrity, thermal stability and dispersion stability using a precision scale, X-ray Photoelectron Spectroscopy (XPS), Transmission Electron Microscopy (TEM), Thermogravimetric Analysis (TGA), and visual observation. The results showed that treatment with 15 M HNO3 introduced the highest atomic % of oxygen-containing chemical moieties to MWCNT surface with less sample weight loss. The TEM micrographs showed that during treatment with 15 M HNO3, MWCNT fragmented into smaller nanotubes of an average length of 900 nm. MWCNT experienced the most severe structural degradation after treatment with 15 M H2SO4/HNO3, where the nanotubes were completely dissolved during the refluxing process. Carboxyl and carbonyl groups were identified as the predominant functional groups present on treated MWCNT surfaces. TGA study revealed the preservation of graphitic MWCNT structure, increased water sorption capacity, and newly formed functional groups after the treatments. Dispersion of MWCNT was improved after all treatments. However, 10 M HNO3-treated sample showed the weakest stability. According to the experimental results, MWCNT treatment with 15 M HNO3, yielded a formation of 5.2 at% surface oxygen with only 6.8% sample weight loss. The extent of surface oxidation in the case of 10 M H2SO4/HNO3 treatment was 3.2 at% and the weight loss was about 17%.

Synthesis of Metal–Organic Framework Materials by Reflux: A Faster and Greener Pathway to Achieve Super-Hydrophobicity and Photocatalytic Application

In this contribution, reflux was demonstrated to be a faster and greener pathway in the synthesis of heterometallic metal–organic frameworks (MOFs) [Li2Sn2(BDC)3(H2O)2]n (LiSn; H2BDC = 1,4-benzenedicarboxylic acid). By means of this method, LiSn solid materials with various particle sizes and surface morphologies were achieved by simply changing the lithium sources (LiOH, 1, and LiNO3, 2). During the reflux process, the precursors were prone to grow from polyhedral LiSn materials, of which the LiOH was preferable to produce uniformly dispersed LiSn-1 nanoparticles with smaller sizes. These as-prepared LiSn materials possess good thermal stability proven by maintaining their structural crystallinity up to 250 °C. UV–vis diffuse reflectance spectroscopy suggested band gap energies (Eg) of 3.14 and 2.96 eV for LiSn-1 and LiSn-2, respectively, indicating the potential photocatalytic ability of these materials. Visible-light-driven degradation of methyl orange, methylene blue, and rhodamine B showing a higher photocatalytic performance in the presence of LiSn revealed high photocatalytic activity based on a first order kinetic study. Moreover, the LiSn-coated films resulted in the generation of hydrophobic substrate surfaces due to their specific hierarchy hills-and-valley type surface terrain with lotus leaf effects. Of special notice is the LiSn-1-coated stainless steel mesh and 200-mesh filter cloth showing magnificent oil–water separation property. This study discovered a family of bifunctional LiSn materials with both photocatalytic activity and super-hydrophobicity, showing great promise in water purification applications.

Layered BiOBr/Ti3C2 MXene composite with improved visible-light photocatalytic activity

Layered BiOBr/Ti3C2 (BTC) composites were synthesized by first preparing Ti3C2 nanosheets through the liquid etching of Ti3AlC2 powder and then hybridizing with BiOBr via a facile reflux process. The morphology, crystal structure, light-harvesting capacity, chemical nature of atoms and visible-light photocatalytic degradation activity were systematically studied and discussed. It was found that the introduction of Ti3C2 nanosheets improved UV–Vis light absorption region of BiOBr. A contact interface was formed between BiOBr nanoplate and Ti3C2 nanosheet due to the similar layered structures, which could accelerate the efficient separation and transfer of photoinduced electrons and holes. Thus, the obtained BTC composites showed the higher visible-light photocatalytic activity for the degradation of RhB than pure BiOBr. The generated active species were determined by the active species capture experiment and ESR spectra, showing that ·O2− and ·OH played a crucial role in the photocatalytic degradation of RhB. The corresponding photocatalytic mechanism was proposed. This work may provide a new insight into the construction of earth-abundant MXene-based photocatalysts with high performance and low cost.

Electrochemical Detection of Nitrite in Food Based on Poly (3,4-ethylenedioxythiophene) Doped with Fe3O4 Nanoparticles Loaded Carboxylated Nanocrystalline Cellulose

Carboxylated nanocrystalline cellulose (CNCC) was prepared by oxidation degradation of microcrystalline cellulose (MCC) using ammonium peroxydisulfate and modified with Fe3O4 nanoparticles to form Fe3O4-CNCC nanocomposite via simple refluxing process. The Fe3O4-CNCC nanocomposite doped poly(3,4-ethylenedioxythiophene) (PEDOT) was successfully decorated on the glassy carbon electrode (GCE) by electrochemical deposition. The PEDOT/Fe3O4-CNCC modified GCE with enlarged real electrochemical surface area was used to determine nitrite with high selectivity, sensitivity and outstanding reproducibility. Using amperometric current-time (i-t) curve, the proposed sensor provided a wider linear range (0.5-2500 ∆M) and a lower detection limit (0.1 ∆M) towards nitrite compared with the method of differential pulse voltammetry (DPV). This analytical method gave good selectivity in the practical measurement of nitrite in pickles.

Photocatalytic degradation of azo dye using core@shell nano-TiO2 particles to reduce toxicity.

Clean and safe water is fundamental for human and environmental health. Traditional remediation of textile dye-polluted water with chemical, physical, and biological processes has many disadvantages. Due to this, nano-engineered materials are drawing more attention to this area. However, the widespread use of nano-particles for this purpose may lead to photocatalytic degradation of xenobiotics, while increasing the risk of nano-particle-induced ecotoxicity. Therefore, we comparatively evaluated the toxicity of novel synthesized core@shell TiO2 and SiO2 nano-particles to embryonic stages of Danio rerio and Xenopus laevis. The ability of photocatalytic destruction of the synthesized nano-particles was tested using toxic azo dye, disperse red 65, and the effects of reducing the toxicity were evaluated. The reflux process was used to synthesize catalysts in the study. The samples were characterized by scanning electron microscopy, X-ray fluorescence spectroscopy, X-ray diffractometry, BET surface area, and UV-vis-diffuse reflectance spectra. It was determined that the synthesized nano-particles had no significant toxic effect on D. rerio and X. laevis embryos. On the other hand, photocatalytic degradation of the dye significantly reduced lethal effects on embryonic stages of the organisms. Therefore, we suggest that specific nano-particles may be useful for water remediation to prevent human health and environmental impact. However, further risk assessment should be conducted for the ecotoxicological risks of nano-particles spilled in aquatic environments and the relationship of photocatalytic interaction with nano-particles and xenobiotics.

Synthesis of Graphene Functionalized Melamine and its Application for Supercapacitor Electrode

In this work, we describe the development of graphene as energy storage materials that are supercapacitors. Melamine is successfully used as a Nitrogen source for graphene doping by simple reflux process. The influence of reducing agent ratio is also investigated to study the degree of reducing of graphene functionalized melamine on capacitive behavior. At reducing agent/graphene ratio of 1:1, the nitrogen functional graphene can deliver the highest specific capacitance of 333.38 F/g at 10mV/sec, which is much higher than that obtained from bare graphene. The increasing of reducing agent ratio higher than 1 tends to decrease the capacitive values of graphene functionalized melamine confirming the efficiency of doped Nitrogen content on graphene. This N-doped graphene feature can be viewed as the potentially ideal candidate materials for supercapacitor application.

Applying the hydrodistillation process to Pentadiplandra brazzeana Baill. root: a chemical assessment

A chemical study of the volatile components obtained by applying the hydrodistillation and reflux processes to Pentadiplandra brazzeana roots was performed by GC-FID and GC-MS. The hydrodistillation process showed a total yield of 0.97% with 0.11% of essential oil and 0.86% of volatile compounds from the aqueous reaction medium; in the reflux process, the volatile extract yield was 1.03%. Benzylic-type isothiocyanates were the major degradation products of glucosinolates in the essential oil (95.0%); the CH2Cl2 extracts obtained from the aqueous solutions were characterised by alcohols and amines in both processes. This study has shown that during hydrodistillation, only 10% of the glucosinolate degradation products are recovered in the essential oil whereas 90% remain in the aqueous medium, being converted into alcohols and amines. The relative percentages of the different chemical classes recovered in our experimental conditions are discussed in relation with the glucosinolate composition in the raw material.

Preparation of broadband antireflective coatings with ultra-low refractive index layer by sol-gel method

In this paper, a novel long-time refluxing process has been applied for ultra-low refractive index antireflective coatings preparation. Coating with refractive index of 1.12 was obtained. Double layer antireflective coatings with refractive index of 1.12 for the top layer and that of 1.30–1.40 for the bottom layer have been fabricated on soda-lime glasses. By adjusting the preparation parameters, the numerical difference between peak and valley transmittance value gradually reduced, i.e. the broadband antireflective coatings were prepared. The light transmittance of double layer antireflective coatings achieved to 99.04%, while the average transmittance attained to 95.49% in 300–1200 nm wavelength.