Influence Of Reaction Parameters Research Articles

Influence of reaction parameters on the fate of nitrogen during the supercritical water gasification of dewatered sewage sludge

This study investigated the effects of different parameters on the fate of nitrogen (N) in products after supercritical water gasification (SCWG) of dewatered sewage sludge (DSS). N distribution and morphology were most affected by temperature, followed by reaction time and heating rate, while reaction pressure had little effect on them. In terms of specific performance, higher temperature, longer reaction time, and slower heating rate were beneficial to the increase of NH4+-N content in the liquid phase. Compared with raw sludge, after SCWG, the solid phase contained more inorganic-N and less protein-N, a certain proportion of quaternary-N and nitrile-N. The proportion of N-containing compounds in the biocrude phase was between 0.26%–20.34%, suggesting the importance of more research on N in the biocrude phase. The recovery rate of N in all samples was between 64.34%–93.82%. The major proportion of N (42.27%–60.91%) was transformed into the liquid phase, while the remaining entered the solid phase (10.54%–21.45%) and the biocrude phase (6.18%–15.78%). These findings are helpful to better understand the principle of N distribution in products of DSS after SCWG and provide some new ideas for reducing N-containing by-product formation in the future.

Process optimization for the rapid conversion of calcite into hydroxyapatite microspheres for chromatographic applications

Microsphere hydroxyapatite (HAp) is widely used in various biomedical and chromatographic applications. The work described in this manuscript focuses on a dissolution precipitation method for production of HAp microspheres. This method overcomes certain drawbacks of conventional preparation methods used for HAp preparation, which produce polydisperse particles and are time-consuming and expensive. In the present work, the calcium carbonate (calcite) particles were directly and rapidly converted into HAp microspheres using an inexpensive dissolution precipitation method. The effects of the reaction temperature, time, and mechanical stirring rates were studied, and the reaction parameters were optimized. As confirmed by the XRD studies, the higher reaction temperature and time promote complete HAp conversion, while calcite residues were observed for lower temperatures and times. SEM images show the influence of reaction parameters on the surface microstructure of the microspheres produced. It was observed that the HAp microspheres undergo disintegration at a higher stirring rate. The reaction parameters optimized in this work were ideal for preparing HAp microspheres. The resultant HAp particles were utilized as matrices for chromatographic separation of protein mixtures.

Heterogeneous activation of peroxymonosulfate by SBA-15 supported Co-based bimetallic catalysts for unsymmetrical dimethylhydrazine degradation in water

A set of SBA-15 supported Co-based bimetallic catalysts was prepared by the incipient wetness impregnation method and then used to activate peroxymonosulfate (PMS) to eliminate unsymmetrical dimethylhydrazine (UDMH). The physicochemical properties of catalysts were studied by serious of techniques. The reusability of the catalyst and the influence of reaction parameters were investigated. The results showed that AgCo/SBA-15 exhibited the best degradation efficiency. The good conductivity of Ag nanoparticles, strong UDMH adsorption ability, moderate Co ions leaching concentration, and the synergistic effect between Co and Ag were responsible for the excellent catalytic activity. Complete UDMH (100 mg/L) degradation and 75.2 % mineralization could be achieved at the reaction times of 15 and 180 min, respectively. The quenching experiments and EPR analysis indicated 1O2 played a dominant role in UDMH degradation. Furthermore, the possible degradation pathways were proposed according to the GC–MS intermediates and DFT calculation. This study provides new insights into heterogeneous activation of PMS and offers an efficient method for wastewater treatment.

Vital Role of Synthesis Temperature in Co–Cu Layered Hydroxides and Their Fenton-like Activity for RhB Degradation

Cu and Co have shown superior catalytic performance to other transitional elements, and layered double hydroxides (LDHs) have presented advantages over other heterogeneous Fenton catalysts. However, there have been few studies about Co–Cu LDHs as catalysts for organic degradation via the Fenton reaction. Here, we prepared a series of Co–Cu LDH catalysts by a co-precipitation method under different synthesis temperatures and set Rhodamine B (RhB) as the target compound. The structure-performance relationship and the influence of reaction parameters were explored. A study of the Fenton-like reaction was conducted over Co–Cu layered hydroxide catalysts, and the variation of synthesis temperature greatly influenced their Fenton-like catalytic performance. The Co–Cut=65°C catalyst with the strongest LDH structure showed the highest RhB removal efficiency (99.3% within 30 min). The change of synthesis temperature induced bulk-phase transformation, structural distortion, and metal–oxygen (M–O) modification. An appropriate temperature improved LDH formation with defect sites and lengthened M–O bonds. Co–Cu LDH catalysts with a higher concentration of defect sites promoted surface hydroxide formation for H2O2 adsorption. These oxygen vacancies (Ovs) promoted electron transfer and H2O2 dissociation. Thus, the Co–Cu LDH catalyst is an attractive alternative organic pollutants treatment.

Catalytic activity of CuI/CuII cyanide based phenanthroline-bicarbonate system for enhancing aerobic oxidation of 2,6-di-tert-butylphenol

The metal organic framework {[Cu2(CN)3(phen)3]5H2O} MOF1- bicarbonate system was investigated as an efficient catalyst for aerobic oxidation of 2, 6-di-tert-butylphenol (2,6- DTBP). The catalytic system showed very efficient catalytic behavior for the oxidation of selective coupling of 2,6- DTBP to 3,3′,5,5′-tetra-tert-butyl-4,4′-diphenoquinone (DPQ) in excellent yield. The influence of reaction parameters on the selective oxidation of 2, 6-DTBP to DPQ had been investigated. Photoluminescence probing technology of Disodium salt of terephthalic acid as well as scavenging experiments revealed the creation of the hydroxyl radicals as the main active oxidation radicals produced by the MOF1/O2/basic bicarbonate system. The oxidation reaction mechanism was also discussed. The recycled catalytic system retained its activity for eight successive runs.

Au decorated Pd nanowires for methane oxidation to liquid C1 products

The direct methane (CH4) oxidation to high value-added C1 chemicals is a great promising strategy to explore the CH4 resource utilization. However, the low activity and selectivity of catalytic performance remains a great conundrum due to the difficulty to activate the CH bond and the unmanageable over oxidation. Herein, PdxAuy nanowires (NWs) with various Pd/Au atomic ratios are presented as ideal models to explore the atomic-level effect of PdAu atoms for the direct CH4 oxidation. The influence of reaction parameters are systematically investigated, and Pd9Au1 NWs display a maximum yield of 2890.3 μmol g−1 h−1 with 99% selectivity for the liquid C1 oxygenated products. This enhanced performance is attributed to the combination of one-dimensional structure and the synergistic effect from the suitable portion of Au on Pd sites, which regulates bond strength between adsorbed radicals (•OH, •OOH, •CH3) and PdAu atoms, confirmed by the density function theory calculations.

Molybdenum and zirconium oxides supported on KIT-6 silica: A recyclable composite catalyst for one–pot biodiesel production from simulated low-quality oils

The development of feasible ecofriendly processes for biodiesel production is highly desirable to meet the requirement of green chemistry and sustainable development. To reach this goal, the molybdenum and zirconium oxides were incorporated into commercial available KIT-6, mesoporous silica nanoparticle, by a solvothermal method, to form MoO3/ZrO2/KIT-6 catalyst. The targeted solid composite catalysts were structurally characterized using XRD, TEM, SEM, XPS, EDS, TG, and nitrogen porosimetry measurement. The characterization results showed that the ordered porous structure of the support was well persevered with high surface area, and the molybdenum and zirconium oxides could be highly dispersed on the mesoporous support. The acidic nature of the solid catalyst was evaluated in detail by means of NH3-TPD and infrared spectra of adsorbed pyridine techniques. It was indicated that the acidities of the solid catalysts, with both Brønsted and Lewis acid sites, could greatly affected their catalytic activity. This catalyst displayed high activities to the transesterification of triglycerides and esterification of free fatty acids (FFAs) simultaneously owing to the synergistic effect of Brønsted and Lewis acid sites, thus achieving one-pot heterogeneous production of biodiesel as the low-quality oil was used as feedstocks. The influence of reaction parameters and the catalyst reusability were also investigated, and the best oil conversion of 92.7% was obtained under the optimized reaction conditions. The targeted catalyst exhibited a better FFAs and water tolerant for the reaction, advantageously with no noticeable decline in the catalytic performance even after five reaction cycles.

Boosting the activation of Peroxymonosulfate and the degradation of metronidazole over FeCo2O4 quantum dots anchored on β-FeOOH Nanosheets: Inspired from octahedral Co(II) with missing angle

Peroxymonosulfate (PMS) activation by bimetallic Co/Fe oxides, especially spinel FeCo2O4, is a promising way in decontaminating organic pollutants in wastewaters. However, it suffers from low efficiency and the intrinsic catalytic mechanisms are still poorly understood. Therefore, we applied lattice VOs (oxygen vacancies) adjustment strategy to construct a octahedral Co(II)–enriched FeCo2O4 quantum dots anchored on β-FeOOH nanosheets composite (Co(II)-FCQDs/FNS) for boosting PMS activation during the degradation of Metronidazole (MNZ), and pure FeCo2O4 quantum dots (FCQDs) was studied as a comparison. As a result, in PMS/Co(II)-FCQDs/FNS system, 5–30 mg·L−1 MNZ could be completely degraded within 5 min with the usage of 0.05 g·L−1 catalyst, and the degradation efficiency of 100 mg·L−1 MNZ reached 99.92% within 40 min with the PMS utilization of 62.90% at the same condition, whose degradation rate constant was 6.45 times than that of the FCQDs/PMS system. The electron paramagnetic resonance (EPR) and quenching experiments indicated that PMS /Co(II)-FCQDs/FNS system was a pure radical-based (sulfate radicals (SO4•−), hydroxyl radicals (•OH) and superoxide radical (O2•−) oxidation process. Density functional theory (DFT) calculation revealed that the generation of octahedral Co(II) derived from oxygen vacancies, improved the charge transfer in the spinel lattice while providing a new electron transfer channel from lattice Co(II)/Fe(II) to the surface of FeCo2O4. Simultaneously, strengthened the surface adsorption of HSO5− and increased the number of unpaired electrons, thus boosting the PMS activation performance. In addition, the influence of reaction parameters and water matrix were investigated. Finally, the degradation pathway of MNZ was proposed and the toxicity of intermediates was also assessed. This work is expected to facilitate the design and application of PMS/Co(II)-FCQDs/FNS system for decontaminating organic pollutants from wastewater.

Effects of pH and Potential in Kolbe Electrolysis of Acetate on Platinum

Over many decades, reliable pathways have been invented for heating and power, as well as facilitating the complex chemical transformations in standard industrial chemical plants that enable the goods around us. Unfortunately, essentially all these processes are higher greenhouse gas (GHG)-emitting, which has led to global climate change, which is a looming threat for our world. Therefore, there is a need to find alternative processes that are able to reduce, or possibly eliminate GHG emissions.Biofuels have been, and continue to be, researched as promising alternative fuels. However, the high carboxylic acids content of the resulting bio-oil is troublesome and requires further upgrading [1]. One possible process that is able to selectively upgrade these carboxylic acids are electrochemical reactors. Electrochemical upgrading of carboxylic acids proceeds through the Kolbe reaction. In this reaction, a pair of carboxylic acids decarboxylate to two radicals which can dimerize and form alkanes (Equation 1).2 RCOOH → R–R + 2 CO2 + 2 H+ + 2 e- (Equation 1)In bio-oil upgrading studies, Kolbe electrolysis of acetic acid is typically used as a model reaction. A large number of studies on Kolbe electrolysis have published, many that focus on gaining fundamental insight in the influence of reaction parameters, like potential, pH and reactor configuration on the product yield and selectivity of the reaction [2-4]. From these studies, it is known that the Kolbe reaction proceeds through a methyl-radical pathway. Interestingly, such observations also make this reaction a potential proxy reaction for methane activation, another reaction that has received increased interest in recent years [5-7]. However, despite the previous work in this area, the work has largely been descriptive and contradictory.Therefore, this work aims to provide experimental data and optimize the methyl-radical pathway by changing pH and potential to promote selectivity of ethane, the primary Kolbe product. To do that, several studies have been performed using dilute solutions of acetate on polycrystalline platinum. Two three-electrode electrochemical cells, one batch and one flow configuration, were used for this study. The cells were equipped with a platinum foil working electrode, a platinum counter electrode and an Ag/AgCl reference electrode. The formed gas products were analyzed using in situ GC-MS. Offline liquid analysis was performed using NMR. In addition, an attempt was made to study the surface reactions on a platinum electrode under various potentials using ATR-FTIR experiments.The potential window used in this work was 2.8 V to 3.5 V vs RHE. In this range, an array of products was observed in both the gas phase (e.g., methanol, ethanol, ethylene, methane, ethane, carbon dioxide, carbon monoxide, hydrogen) and the liquid phase (e.g., methanol). It was observed that under the applied potentials high faradaic efficiencies (~90-96%) to ethane can be obtained and that this is increased with more positive potentials. Furthermore, it was observed the faradaic efficiency was maximized at pH values approaching the pKa of acetic acid. Electrolyte solutions with a bulk pH of 8 and 12 showed decreased faradaic efficiencies towards the formation of ethane over time. This occurs because the formation of bicarbonate (produced by dissolved CO2 in the electrolyte) hinders the dimerization reaction.Positively, the results of this study demonstrated high selectivity and yield of ethane from acetate on platinum for high potentials and slightly acidic acetate solutions. This finding is promising because ethane derived from the electrolysis of bio-oils can lead to the development of green chemicals – which reduces our dependence on petroleum.

Mechanistic Investigations on the Catalytic Transfer Hydrogenation of Lignin-Derived Monomers over Ru Catalysts: Theoretical and Kinetic Studies

The hydrodeoxygenation (HDO) reaction of oxygenated compounds such as lignin-derived phenolics is well studied using molecular H2 as a hydrogen source, yet the use of high pressures discourages its use on an industrial scale. As an alternative, the catalytic transfer hydrogenation (CTH) pathway provides in situ hydrogenation species, which reduces the need for the high-pressure infrastructure required when molecular hydrogen is used. Nevertheless, this strategy is scantly studied, and in lieu with this, herein we report the kinetic and mechanistic investigations of the CTH strategy for the HDO of guaiacol, phenol, anisole veratrole, and eugenol to their respective products. For potential commercialization purposes, low loading of metal, milder reaction conditions, and high selectivity toward desired products with a high H/C ratio were considered while designing catalysts (0.5 wt % Ru on SiO2–Al2O3, SiO2, Al2O3-acidic, Al2O3-basic, and Al2O3-neutral) for these reactions. As high as 74% cyclohexanol yield from guaiacol was achieved at 225 °C in the presence of isopropyl alcohol (IPA) as the hydrogen source and over the Ru/Al2O3-acidic catalyst reduced at 150 °C. A detailed kinetic study is carried out to understand the interaction of the substrate and intermediates with the catalyst and the influence of reaction parameters on the product formation. It was observed that the cis-isomer of 2-methoxycyclohexanol rapidly undergoes further conversion than the trans-isomer. The experimental observations are substantiated through density functional theory (DFT) studies on Ru(0001) and guaiacol molecule complexes. DFT studies indicate that the adsorption of the cis-isomer is more exothermic as compared to that of the trans counterpart, and the underlying electronic factors are elucidated using charge density difference and density of states plots.

A comprehensive review on catalytic O-alkylation of phenol and hydroquinone

ABSTRACT The alkylation process involves two competitive paths of O- and C-alkylation and achieving better selectivity for desired products is a very challenging problem. The development of new process for synthesis of O-methylated products of phenol and dihydric phenols is a subject of high industrial and academic interest. Alkyl phenyl ethers, especially anisole and 4-methoxyphenol, have captivated significant interest due to their increasing applications in pharmaceutical industries. The main emphasis of the present review is to explore the recent development in two catalytic O-alkylation processes. The first process is O-methylation of phenol into anisole and another is selective mono O-methylation of hydroquinone into 4-methoxyphenol. The present article covers O-alkylation methods with methanol and dimethyl carbonate as alkylating agent over various acidic and basic catalytic systems. The catalyst systems analyzed involves Bronsted and Lewis acidic and basic ionic liquids, conventional acids, metal oxides, solid acid and basic catalysts, hydrotalcites, various zeolites and heteropolyacids. The mechanistic behavior of alkylation reactions in presence of different catalytic system is reviewed critically which is important to design new and/or modified catalyst in order to maximize the yield of desired product. Additionally, an influence of reaction parameters, role of catalyst and their active sites on product distribution is described. The review paper gives useful insight for researchers in the field of catalysis and reaction engineering of alkylation reactions. Understandings of the reaction pathways will help in developing reliable kinetic models necessary for process scale-up to industrial scale reactor system.

Visible light excited graphitic carbon nitride for efficient degradation of thiamethoxam: Removal efficiency, factors effect and reaction mechanism study

In this decade, photocatalytic degradation of organic contaminants has attracted great attentions. In this study, we used graphic carbon nitride (g-C3N4) nanosheets as the photocatalyst for the degradation of thiamethoxam (THM). The properties of g-C3N4 nanosheets have been fully characterized by the analysis techniques. The experiments results shown that under the optimum condition, 91.3% of THM degradation efficiency can be reached in the presence of g-C3N4 nanosheets within 60 min under visible light irradiation. Take the realistic application into consideration and to fully investigate the reaction process, the influence of reaction parameters, including the dosage of g-C3N4 nanosheets, initial THM concentration, and initial solution pH value, co-existence ions, humic acid (HA) and fulvic acid (FA) have been systematically studied and discussed. Results demonstrated that weak acidity and neutral condition is benefit for THM decomposition, and Ca2+ and Mg2+ present enhanced inhibition effect than Na+ for THM removal. Meanwhile, PO43- and CO32- show strong inhibition effect, but HA and FA performed weak inhibitory effect. The trapping experiments and electron spin resonance (ESR) measurement demonstrated that superoxide radical (•O2-), hydroxyl radical (•OH) and holes (h+) are all generated during the reaction process. There are all participated in the THM decomposition process and •O2- plays the major role on it. The results obtained in this study indicated that metal free g-C3N4 present great photocatalytic activity and stability for THM removal and owns great potential in the application of actual agricultural environment.

Carboxymethyl Jackfruit Seed Starch: synthesis, characterization, and influence of reaction parameters

Carboxymethyl jackfruit seed starch (CMS) was synthesized under different reaction conditions. The influence of sodium hydroxide concentration, monochloroacetic acid (MCA) concentration, IPA-water ratio, solvent-starch ratio, reaction time, and temperature were evaluated for degree of substitution (DS). Results have shown that the optimal DS of 0.68 was obtained at 50 °C, 90 minutes in solvent-starch ratio and isopropanol-water were 8:1 and 10:0. The ratio of sodium hydroxide and monochloroacetate acid moles to anhydroglucose unit (AGU) moles for the optimal DS were 1 and 1. Scanning electron microscope (SEM) of CMS particles showed the starch grain structure remains the same but the surface appeared many alveolar holes and no longer smooth as MS. Fourier transform infrared spectra (FTIR) of CMS and MS confirmed that carboxymethylation takes place on native starch molecules when the absorption band appears at a wavenumber of 1643 cm−1 corresponding to the vibrations of featured functional C=O group in CMS structure.

Bioinspired manganese complex for room-temperature oxidation of primary amines to imines by t-butyl hydroperoxide

A sustainable method is developed for the selective and additive-free synthesis of imines from primary amines with TBHP catalyzed by bioinspired manganese complex (MnCl2(TPA)) at room temperature. Use of 0.2 mol % MnCl2(TPA) was efficient enough for this transformation by offering excellent conversions up to 98.2% along with 93.4% product yield within 1 h. The influence of reaction parameters (catalyst dosage, solvent, reaction temperature, time, etc.) on the catalytic performance was also investigated in detail. Building on these results, the selected MnCl2(TPA) was further employed to transform various primary amines into corresponding imines and exhibited good compatibility even for the challenging aliphatic amine. The high efficiency, combining with a large substrate scope and ambient reaction conditions, makes the developed bioinspired Mn complex/TBHP system a promising pathway to produce imines. This work also paves a way to the expansion of non-heme metal catalysts as efficient platforms for various oxidation reactions.

Efficient Imine Formation by Oxidative Coupling at Low Temperature Catalyzed by High-Surface-Area Mesoporous CeO2 with Exceptional Redox Property.

High-surface-area mesoporous CeO2 (hsmCeO2 ) was prepared by a facile organic-template-induced homogeneous precipitation process and showed excellent catalytic activity in imine synthesis in the absence of base from primary alcohols and amines in air atmosphere at low temperature. For comparison, ordinary CeO2 and hsmCeO2 after different thermal treatments were also investigated. XRD, N2 physisorption, UV-Raman, H2 temperature-programmed reduction, O2 temperature-programmed desorption, EPR spectroscopy, and X-ray photoelectron spectroscopy were used to unravel the structural and redox properties. The hsmCeO2 calcined at 400 °C shows the highest specific surface area (158 m2 g-1 ), the highest fraction of surface coordinatively unsaturated Ce3+ ions (18.2 %), and the highest concentration of reactive oxygen vacancies (2.4×1015 spins g-1 ). In the model reaction of oxidative coupling of benzyl alcohol and aniline, such an exceptional redox property of the hsmCeO2 catalyst can boost benzylideneaniline formation (2.75 and 5.55 mmol h-1 based on >99 % yield at 60 and 80 °C, respectively) in air with no base additives. It can also work effectively at a temperature of 30 °C and in gram-scale synthesis. These are among the best results for all benchmark ceria catalysts in the literature. Moreover, the hsmCeO2 catalyst shows a wide scope towards primary alcohols and amines with good to excellent yield of imines. The influence of reaction parameters, the reusability of the catalyst, and the reaction mechanism were investigated.

A Review of Catalytic Upgrading of Biodiesel Waste Glycerol to Valuable Products

Glycerol is an organic polyol compound, and is an important raw material with extensive applications in daily/petrochemical and pharmaceutical industry. Glycerol is typically obtained by propylene chlorination, while the method used is complicated process and requires high energy consumption. Interestingly, glycerol is recognized as a major by-product of biodiesel production. Approximately 100 kg of glycerol is yielded for 1 tonne of biodiesel production. With the rapid development of the biodiesel industry, glycerol production capacity has been a serious surplus. This review introduces the selective conversion of glycerol into a variety of value-added chemicals such as propylene glycol, propanol, glyceraldehyde, and dihydroxyacetone via selective hydrogenation and oxidation, as well as hydrocarbons and ethers via pyrolysis, gasification and etherification, respectively. The efficiency of different types of catalysts and the influence of reaction parameters on the valorisation of glycerol have been elucidated. Emphasis is also laid on the study of catalytic mechanisms and pathways for some specific reactions.

Influence of Reaction Parameters on the Gelation of Silanised Linseed Oil.

The subject of this work was to characterize the catalytic course of the linseed oil silylation reaction with vinyltrimethoxysilane (VTMOS), carried out under elevated pressure and temperature conditions, and an explanation of the reasons for rapid gelation of the reaction product. To explain and describe the process, analytical methods were used, i.e., 1H and 13C NMR (nuclear magnetic resonance), GC-FID (gas chromatography coupled with flame ionisation detection), and GPC (gel permeation chromatography). Reaction products were monitored after 3, 6 and 12 h. The molar mass of the VTMOS-modified oil in only 3 h was comparable with the molar mass of the product obtained by conventional polymerisation. An increase in the reaction time resulted in further transformations resulting from the hydrolysis and condensation reactions taking place. In contrast to reactivity of soybean oil, the silanisation of linseed oil occurred much faster and without the need for cross-linking catalysts. The reason for the high reactivity of linseed oil to VTMOS and rapid gelation of the resulting product was primarily the amount of double bonds present in linseed oil and their high availability, in particular the double bond in the acid linolenic acid located at the C16 carbon.

Fabrication and catalytic performance of meso-ZSM-5 zeolite encapsulated ferric oxide nanoparticles for phenol hydroxylation

An encapsulation-structured Fe2O3@meso-ZSM-5 (Fe@MZ5) was fabricated by confining Fe2O3 nanoparticles (ca. 4 nm) within the ordered mesopores of hierarchical ZSM-5 zeolite (meso-ZSM-5), with ferric oleate and amphiphilic organosilane as the iron source and meso-porogen, respectively. For comparison, catalysts with Fe2O3 (ca. 12 nm) encapsulated in intra-crystal holes of meso-ZSM-5 and with MCM-41 or ZSM-5 phase as the shell were also prepared via sequential desilication and recrystallization at different pH values and temperatures. Catalytic phenol hydroxylation performance of the as-prepared catalysts using H2O2 as oxidant was compared. Among the encapsulation-structured catalysts, Fe@MZ5 showed the highest phenol conversion and hydroquinone selectivity, which were enhanced by two times compared to the Fe-oxide impregnated ZSM-5 (Fe/Z5). Moreover, the Fe-leaching amount of Fe@MZ5 was only 3% of that for Fe/Z5. The influence of reaction parameters, reusability, and · OH scavenging ability of the catalysts were also investigated. Based on the above results, the structure-performance relationship of these new catalysts was preliminarily described.

Magnetic hydroxyapatite nanocomposites: The advances from synthesis to biomedical applications

Nanoscale materials continue to amaze researchers due to their fascinating versatile properties. One such inspiring development in nanomaterials is the design of the nanocomposite materials for multifunctional purposes from energy storage to biomedical applications. Magnetic hydroxyapatite [MHAp] nanoparticles have achieved considerable attention during the last two decades and possess exceptional prospects in the field of nanomedicine with improved multi-therapeutic approaches. The progress from controlled fabrication to advanced applications of MHAp nanocomposites is still in its infancy and few efforts have been devoted to this cause. The hybrid structure of MHAp is anticipated to be an auspicious platform for biomedical applications particularly in cancer theranostics because of good stability and biocompatibility. In this review, recent exciting features in the development of MHAp nanocomposite and promising applications in controlled drug/gene delivery and magnetic hyperthermia treatment, tissue engineering and bone regeneration, antimicrobial activity, heavy metals and toxic dyes removal, fire retardant behaviour, biosensors and the development of contrast agents for magnetic resonance imaging are highlighted and explained in detail. In addition, this study provides a comprehensive assessment of the synthesis of MHAp nanocomposites by various preparation methods, the influence of reaction parameters on the morphology and structure-property relationships based on recent studies. Finally, novel perceptions are examined regarding the ability of MHAp nanoparticles to improve hybrid nanocarriers with homogeneous structure to enhance multifunctional biomedical applications.

Study on catalytic efficiency of platinum and silver nanoparticles confined in nanosized channels of a 3-D mesostructured silica

A scalable route to encapsulate homogeneously fine Pt and Ag nanoparticles (NPs) inside amine-functionalized KIT-6 mesochannels via two different reduction routes as heterogeneous mesoporous catalysts is demonstrated. The active amine groups functionalized KIT-6 mesochannels act as anchor sites to immobilize the homogeneous Pt and Ag NPs catalysts with small-sized NPs of approximately 6.0 and 3.0 nm, respectively. The catalysts were fully characterized, and the surface areas were relatively decreased after deposition of the metals NPs. Even after metal NPs deposition, the mesochannels are readily accessible for enhancing their catalytic activity. The meso-KIT-6-Pt catalyst synthesized with ascorbic acid (AA) reduction route shows a higher catalytic efficiency for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with a reaction rate almost 2 times higher than that of the meso-KIT-6-Ag synthesized using formaldehyde. The as-prepared mesoporous catalysts exhibit a good reusability, with a high catalytic efficiency for at least 5 successive cycles without an obvious loss in their catalytic activity. The influences of reaction parameters, such as catalyst dose, reaction temperarture and nature of solvent on the catalytic performance of the mesoporous catalysts are of the main study.