Presence Of nano-Fe3O4 Research Articles

Effect of nano and micro iron oxide particles on the workability, strength and absorption rate of cement mortar containing fly ash

Due to the negative environmental impact of cement production, partial replacement of cement with by-products and wastes has been drawn much attention. However, the reduction in binder fraction can affect the fresh and mechanical properties of cement-based materials. In this study, the effects of nano and micro Fe3O4 on the fresh and mechanical properties of plain mortar as well as mortar modified with fly ash were investigated. The preliminary study shows that the optimum dosage of Fe3O4 particle in mortar is 5% nano Fe3O4 (NF). Further study was conducted with 5% NF where cement was replaced by up to 30% fly ash. The results showed that the partial replacement of binder with fly ash at 10% decreases the compressive strength from 18.8 MPa to 15.4 MPa at 28 days, and the least compressive strength was achieved in the presence of 30% fly ash (10.3 MPa). Despite an insignificant change in splitting tensile strength in the presence of 10% fly ash (2.27 MPa), further increase in fly ash content considerably decreased the splitting tensile strength. Although the increasing dosage of fly ash decreased the strength of mortar, the presence of NF could counteract these effects and improve the strength development.

Development of a Novel Magnetic Brake Shoe for Mine Hoists Based on Nano-Fe3O4 and Nd-Fe-B Additive.

The brake is an important safety protection device for mine hoists, in which the performance of the brake shoe affects directly the safe operation of the hoist system. In order to solve problems such as high wear rate and unstable friction coefficient of brake shoe under high temperature, this paper indicated that adding magnetic powder to the composite material of traditional mine hoist's brake shoe will be a creative and effective approach to improve its properties. Based on relevant China patents of the authors, several new formulas of brake shoe material were designed in the presence of Nano-Fe3O4 and Nd-Fe-B, and the methods of both preparation and performance testing of the magnetic brake shoes were introduced. The experiment of formula design was carried out by uniform prescription design, and the friction coefficient and wear rate of each kind of brake shoes made through different formulas were measured. Furthermore, the formula was optimized by application of fuzzy comprehensive evaluation method and analytic hierarchy process. Compared with ordinary formulas, the optimized formula is higher totally and changes more steadily as well. Its wear rate is far lower than the national standard. Namely, its comprehensive properties are better. Few relevant patents to the topic have been reviewed and cited. This paper proved that it is practically valuable and feasible to improve the properties of hoist brake shoes by adding magnetic powder to its composite material.

NanoFe3O4 accelerates anoxic biodegradation of 3, 5, 6-trichloro-2-pyridinol

3, 5, 6-trichloro-2-pyridinol (TCP) is a widespread organic pollutant with persistent, mobile and high antimicrobial effects. Here, nanoFe3O4 was firstly introduced into the anoxic biodegradation of TCP. It was found that nanoFe3O4 significantly accelerated TCP biodegradation. The removal rate of TCP (100 mg L−1) increased from 83.03% to 98.74% within 12 h in the presence of nanoFe3O4, and the addition of nanoFe3O4 also promoted the accumulation of CO2. Reductive dechlorination mechanism was involved in anoxic biodegradation of TCP. Molecular approaches further revealed that nanoFe3O4 distinctly induced the shifts of bacterial community. The dominant genus Ochrobactrum was converted to genus Delftia in nanoFe3O4 treatment, and the relative abundance of Delftia increased from 10.26% to 44.62%. Meanwhile, the total relative abundance of bacteria related to TCP dechlorination and degradation significantly increased in the presence of nanoFe3O4. These results indicated that nanoFe3O4 induced the enrichment of TCP-degrading bacteria to promote the anoxic biodegradation of TCP.

Stimulation of Smithella-dominating propionate oxidation in a sediment enrichment by magnetite and carbon nanotubes.

Recent studies have shown that application of conductive materials including magnetite and carbon nanotubes (CNTs) can promote the methanogenic decomposition of short-chain fatty acids and even more complex organic matter in anaerobic digesters and natural habitats. The linkage to microbial identity and the mechanisms, however, remain poorly understood. Here, we evaluate the effects of nanoscale magnetite (nanoFe3 O4 ) and multiwalled CNTs on the syntrophic oxidation of propionate in an enrichment obtained from lake sediment. The microbial populations were composed mainly of Smithella, Syntrophomonas, Methanosaeta, Methanosarcina and Methanoregula. In addition to acetate, butyrate was transiently accumulated indicating that propionate was oxidized by Smithella via the dismutation pathway and part of the leaked butyrate was oxidized by Syntrophomonas. Propionate oxidation and CH4 production were significantly accelerated in the presence of nanoFe3 O4 and CNTs. While propionate oxidation was suppressed upon H2 application and suspended completely upon formate application in the control, this suppressive effect was substantially compromised in the presence of nanoFe3 O4 and CNTs. The tests on hydrogenotrophic methanogenesis of a pure culture methanogen and of the enrichment culture without propionate showed negative effect by both materials. The positive effect of nanoFe3 O4 disappeared when it was insulated by surface-coating with silica. Observations made with fluorescence in situ hybridization and scanning electron microscope indicated the extensive formation of microbial cell-conductive material mixture aggregates. Our results suggest that direct interspecies electron transfer is likely activated by the conductive materials and operates in concert with H2 /formate-dependent electron transfer for syntrophic propionate oxidation in the sediment enrichment.

The catalytic effect of nano-Fe3O4 on RhB decolorization by CGDE process

A magnetic quasi-circular nano-Fe3O4 was synthesized by coprecipitation and used for the decolorization of rhodamine B (RhB) in contact glow discharge electrolysis (CGDE). The results indicated that nano-Fe3O4 significantly enhanced the decolorization of RhB. The decolorization efficiency reached 94.0% and 33.6% of RhB was mineralized in only 20min when the dosage of nano-Fe3O4 was 1g L−1. The effects of initial pH, temperature, RhB concentration and nano-Fe3O4 dosage on the decolorization efficiency and the catalytic mechanism were also studied. It has been demonstrated that H2O2 produced in CGDE underwent decomposition in the presence of nano-Fe3O4. Nano-Fe3O4 appears to be an excellent catalyst in the degradation of RhB solution by the CGDE process.

Power Ultrasound, Microwaves, and Nanomagnetite Organocatalyst: A Comparison Protocol in Anti-selective Aldol and Mannich Reaction

ABSTRACTAn efficient, rapid, and energy-efficient approach to asymmetric Mannich reaction was developed using different conditions such as ultrasonic and microwave irradiations in the presence of nano-Fe3O4–L-proline as nanomagnetic organocatalyst. This work has been successful in achieving the comparison trend under different conditions. Good yields of the desired products were obtained by ultrasound-assisted reaction utilizing of Fe3O4–L-proline NPs. The major advantages of this protocol are accessible conditions, easy work up, shorter reaction time, anti-selectivity, and higher yields in comparison with other methods.

Enhanced reductive debromination and subsequent oxidative ring-opening of decabromodiphenyl ether by integrated catalyst of nZVI supported on magnetic Fe3O4 nanoparticles

The magnetic Fe0@Fe3O4 nanocomposite was prepared and used to achieve the reductive/subsequent oxidative ring-opening of decabromodiphenyl ether (BDE209) in this work. The characterization results indicated that the structure of the composite consisted of small nanoscale zero-valent iron (nZVI) particles surrounding the surface of Fe3O4 nanoparticle (NP). A 100% removal efficiency and 80% degradation efficiency of BDE209 was reached by the composite accompanied with ultrasound(called NP/US system) for 36h, which is higher than that obtained with conventional nZVI particles. Furthermore, the enhanced debromination and ring-opening of BDE209 was realized by a Fenton-like degradation process lasting for 12h after the addition of H2O2 to the NP/US reaction at 36h. Based on the degradation products identified, a two-stage reduction/oxidation degradation mechanism was proposed. During the first stage, which was reductive debromination, the major reductive activity of nZVI was efficiently enhanced in the presence of nano Fe3O4, which served as a catalyst to improve the stability of the nZVI nanoparticles and accelerate electron transfer, enhancing the degradation efficiency of BDE209. During the second stage, the oxidative ring-opening, the debromination products of BDE209 were proved to be attacked by abundant hydroxyl radicals generated both in the solution and on the surface of the Fe0@Fe3O4 nanoparticles. Thus, this work provides an efficient method to achieve the complete ring-opening of PBDEs using iron-based nanomaterials.

Stability and enzyme activity of lysozyme in the presence of Fe3O4 nanoparticles

The goal of this work was investigation the effect of adsorption the Fe3O4 as magnetic nanoparticle on lysozyme activity and thermal stability. The turbidimetric assay (activity) of lysozyme was followed by the decreased optical density of a turbid cell suspension (about 0.3 mg/cm3 Micrococcus lysodeikticus) photometrically at 450 nm. In this study, the effect of nano-Fe3O4 on lysozyme activity was investigated by UV–Vis spectrophotometry at pH = 7.25 at 35 °C using sodium phosphate buffer. Measurements were carried out using 6 × 10−8 M (0.1 mg/cm3) concentration of lysozyme and a range of nano-Fe3O4 concentrations between 0 and 0.06 mg/cm3. It was found that by increasing nano-Fe3O4, the rate of M. lysodeikticus lyses (lysozyme activity) increases. The thermal stability of lysozyme was investigated in the presence of nano-Fe3O4 over the temperature range of 293–363 K in sodium phosphate buffer and pH = 7.25. Results indicated that by increasing nano-Fe3O4, the thermal stability of lysozyme increases.

Direct interspecies electron transfer accelerates syntrophic oxidation of butyrate in paddy soil enrichments.

Syntrophic interaction occurs during anaerobic fermentation of organic substances forming methane as the final product. H2 and formate are known to serve as the electron carriers in this process. Recently, it has been shown that direct interspecies electron transfer (DIET) occurs for syntrophic CH4 production from ethanol and acetate. Here, we constructed paddy soil enrichments to determine the involvement of DIET in syntrophic butyrate oxidation and CH4 production. The results showed that CH4 production was significantly accelerated in the presence of nanoFe3 O4 in all continuous transfers. This acceleration increased with the increase of nanoFe3 O4 concentration but was dismissed when Fe3 O4 was coated with silica that insulated the mineral from electrical conduction. NanoFe3 O4 particles were found closely attached to the cell surfaces of different morphology, thus bridging cell connections. Molecular approaches, including DNA-based stable isotope probing, revealed that the bacterial Syntrophomonadaceae and Geobacteraceae, and the archaeal Methanosarcinaceae, Methanocellales and Methanobacteriales, were involved in the syntrophic butyrate oxidation and CH4 production. Among them, the growth of Geobacteraceae strictly relied on the presence of nanoFe3 O4 and its electrical conductivity in particular. Other organisms, except Methanobacteriales, were present in enrichments regardless of nanoFe3 O4 amendment. Collectively, our study demonstrated that the nanoFe3 O4 -facilitated DIET occurred in syntrophic CH4 production from butyrate, and Geobacter species played the key role in this process in the paddy soil enrichments.

Synthesis of new 3-Cyanocoumarins with C-6 azo function using ultrasound and grinding techniques in the presence of nano Fe3O4

Synthesis of new 3-Cyanocoumarins with C-6 azo function using ultrasound and grinding techniques in the presence of nano Fe3O4

Preparation and property characterization of PAA/Fe3O4 nanocomposite

PAA/Fe3O4 nanocomposites were prepared by mixing nano-Fe3O4 and polyacrylic acid (PAA) ethanol solution and then evaporating the solvent. The materials were characterized by transmission electron microscope (TEM), Fourier transform infrared spectroscope (FTIR), thermogravimetry analysis (TGA), dynamic ultra-micro hardness tester (DUMHT) and superconducting quantum interference device (SQUID) magnetometer. Results showed that PAA coordinated with nano-Fe3O4 to form a cross-linking structure. The presence of nano-Fe3O4 enhanced the thermal stability of the nanocomposite. The elasticity and hardness of the nanocomposite increased, and the indentation depth reduced with the increase of Fe3O4 content in the composites. The nanocomposites showed superparamagnetic properties at 300 K.