Effect of ultrasonic treatment on formation of iron-containing intermetallic compounds in AlSi alloys

Iron is generally regarded as an unavoidable impurity in Al-Si casting alloys.The acicular AI_3Fe andβ-AI_5FeSi(or Al_9Si_2Fe_2) are common iron-containing intermetallic compounds(IMCs) in conventional structure which have a detrimental impact on the mechanical properties.In this paper,ultrasonic field(USF) was applied to modify acicular iron phases in AI-12%Si-2%Fe and AI-2%Fe alloys.The results show that the USF applied to Al-Fe alloys caused the morphological transformation of both primary and eutectic AI_3Fe from acicular to blocky and granular without changes in their composition.In the case of Al-Si-Fe alloys,ultrasonic treatment led to both morphological and compositional conversion of the ternary iron IMCs.When the USF was applied,the acicular β-AI_9Si_2Fe_2 was substituted by star-like α-AI_(12)Si_2Fe_3.The modification rate of both binary and ternary iron IMCs relates to the USF treatment duration.The undercooling induced by the ultrasonic vibration contributes to the nucleation of intermetallics and can explain the transformation effect.

Synthesis of Iron-containing Carbon Microparticles from Deoiled Asphalt and Ferrocene

The deoiled asphalt as the carbon source and the ferrocene as the metal source and the catalyst precursor were chosen to synthesize iron-containing carbon microparticles through co-carbonization at the temperature of about 450℃ for 3 h. The resulting products were treated at 2 000 ℃ for 2 h. All samples were examined by high resolution transmission electron microscopy （HRTEM） and X-ray diffraction （XRD）. The results show that the iron particles in the heat-treated material are completely coated by carbon. In addition to the fully filled carbon microparticles as well as hollow carbon ones, also form carbon fibers with hollow centers. The formation mechanism of the as-prepared products was discussed briefly.

Selective depression action of taurine in flotation separation of specularite and chlorite

Chlorite,as the most representative gangue mineral associated with specularite,of which the separation of these two minerals is difficult.This paper investigated the depression effect of taurine on specularite/chlorite separation via flotation experiments,adsorption tests,contact angle measurements,Zeta potential detection,FT-IR measurements,and XPS analyses.The results of single mineral flotation indicated that chlorite could be depressed selectively by taurine with the recovery of less than 30%,but the floatability of specularite remains high with recovery rate of 81.77%at pH 10.The artificial mixed mineral flotation results confirmed the effectiveness of taurine as a depressant.Surface adsorption,contact angle,and Zeta potential detection revealed taurine primarily adsorbs on the chlorite surface,which hampered the DDA’s subsequent adsorption and results in the chlorite’s poor floatability.The FT-IR spectra and XPS analyses provided further proof that taurine adsorbed on chlorite surface as an electron donor,and part of the electrons transferred from the sulfonic acid group of taurine to metal ions during the adsorption process.In addition,the hydrogen bond between amino-group of taurine and O ions in chlorite surface was also formed in the adsorption process.Finally,optimized adsorption configurations of taurine on chlorite surfaces were proposed.

Influence of moderate pre-oxidation treatment on the physical, chemical and phosphate adsorption properties of iron-containing activated carbon

A novel adsorbent based on iron oxide dispersed over activated carbon （AC） were prepared, and used for phosphate removal from aqueous solutions. The influence of pre-oxidation treatment on the physical, chemical and phosphate adsorption properties of iron-containing AC were determined. Two series of ACs, non-oxidized and oxidized carbon modified by iron （denoted as AC-Fe and AC/O- Fe）, resulted in a maximum impregnated iron of 4.03% and 7.56%, respectively. AC/O-Fe showed 34.0%46.6% higher phosphate removal efficiency than the AC-Fe did. This was first attributed to the moderate pre-oxidation of raw AC by nitric acid, achieved by dosing Fe（II） after a pre-oxidation, to obtain higher iron loading, which is favorable for phosphate adsorption. Additionally, the in-situ formed active site on the surface of carbon, which was derived from the oxidation of Fe（II） by nitric acid dominated the remarkably high efficiency with respect to the removal of phosphate. The activation energy for adsorption was calculated to be 10.53 and 18.88 kJ/mol for AC-Fe and AC/O- Fe, respectively. The results showed that the surface mass transfer and intra-parficle diffusion were simultaneously occurring during the process and contribute to the adsorption mechanism.

Reuse of Ferric Sludge by Ferrous Sulfide in the Fenton Process for Nonylphenol Ethoxylates Wastewater Treatment

In this paper, Fenton process was determined to be an effective technique to treat the refractory Nonylphenol ethoxylates (NPEOs) wastewater. The COD removal efficien-cies above 89% were obtained when the initial COD concentration was 12000mg/L. However, A large number of ferric sludge (SS=8.724g/L) would be produced after the Fenton oxidation of the wastewater and must be disposed appropriately. A novel process for Fenton sludge reused by low-cost ferrous sulfide (FeS) was also investi-gated. Experimental results show that the Fenton sludge could be reduced to produce a certain amount of Fe2+ in the acidic mixed liquor by ferrous sulfide. This mixed liquor from Fenton sludge could be used as the new catalyst in the Fenton process and was also highly effective for the NPEOs wastewater treatment. The residual ferrous sulfide from the mixed liquor could be used for the next batch of the

Reuse of Fenton sludge as an iron source for NiFe_2O_4 synthesis and its application in the Fenton-based process

The potentially hazardous iron-containing sludge from the Fenton process requires proper treatment and disposal, which often results in high treatment cost. In this study, a novel method for the reuse of Fenton sludge as an iron source for the synthesis of nickel ferrite particles （NiFe204） is proposed. Through a co-precipitation method followed by sintering at 800℃, magnetic NiFe204 particles were successfully synthesized, which was confirmed by powder X-ray diffraction （XRD）, scanning electronic microscopy （SEM）, energy dispersive spectroscopy （EDS）, Fourier transform infrared spectroscopy （FT-IR） and Raman spectros- copy. The synthesized NiFe204 could be used as an efficient catalyst in the heterogeneous Fenton process. In phenol degradation with H202 or NiFe204 alone, the phenol removal efficiencies within the reaction time of 330 min were as low as 5.9% ±0.1% and 13.5% ± 0.4%, respectively. However, in the presence of both NiFe204 and H202, phenol removal efficiency as high as 95% ± 3.4% could be achieved, indicating the excellent catalytic performance of NiFe204 in the heterogeneous Fenton process. Notably, a rapid electron exchange between --NiH and --Fem ions in the NiFe204 structure could be beneficial for the Fenton reaction. In addition, the magnetic catalyst was relatively stable, highly active and recoverable, and has potential applications in the Fenton process for organic pollutant removal.

Metabolic utilization of intravenously injected iron from different iron sources in target tissues of broiler chickens

No information is available regarding the utilization of iron (Fe) from different Fe sources at a targettissue level. To detect differences in Fe metabolic utilization among Fe sources, the effect of intravenouslyinjected Fe on growth performance, hematological indices, tissue Fe concentrations and Fe-containingenzyme activities and gene expressions of Fe-containing enzymes or protein in broilers was investigated.On d 22 post-hatching, a total of 432 male chickens were randomly allotted to 1 of 9 treatments ina completely randomized design. Chickens were injected with either a 0.9% (wt/vol) NaCl solution(control) or a 0.9% NaCl solution supplemented with Fe sulphate or 1 of 3 organic Fe sources. The 3organic Fe sources were Fe chelates with weak (Fe-MetW), moderate (Fe-ProtM) or extremely strong (Fe-ProtES) chelation strength. The 2 Fe dosages were calculated according to the Fe absorbabilities of 10%and 20% every 2 d for a duration of 20 d. Iron injection did not affect (P > 0.05) ADFI, ADG or FCR duringeither 1 to 10 d or 11 to 20 d after injections. Hematocrit and Fe concentrations in the liver and kidney ond 10 after Fe injections, and Fe concentrations in the liver or pancreas and ferritin heavy-chain (FTH1)protein expression level in the liver or spleen on d 20 after Fe injections increased (P≤0.05) as injectedFe dosages increased. When the injected Fe level was high at 20% Fe absorbability, the chickens injectedwith Fe-ProtES had lower (P < 0.001) liver or kidney Fe concentrations and spleen FTH1 protein levelsthan those injected with Fe-MetW or Fe-ProtM on d 20 after injections. And they had lower (P < 0.05)liver cytochrome C oxidase mRNA levels on d 20 after injections than those injected with Fe-MetW or Fesulphate. The results from this study indicate that intravenously injected Fe from Fe-ProtES was the least utilizable and functioned in the sensitive target tissue less effectively than Fe from Fe sulfate, Fe-MetW or Fe-ProtM.

Zero-valent iron doped carbons readily developed from sewage sludge for lead removal from aqueous solution

Low-cost but high-efficiency composites of iron-containing porous carbons were prepared using sewage sludge and ferric salts as raw materials. Unlike previous time- and energy-consuming manufacturing procedures, this study shows that pyrolyzing a mixture of sludge and ferric salt can produce suitable composites for lead adsorption. The specific surface area, the total pore volume and the average pore width of the optimal composite were 321 m^2/g, 0.25 cm^3/g, and 3.17 nm, respectively. X-ray diffraction analysis indicated that ferric salt favored the formation of metallic iron, while Fourier transform infrared spectroscopy revealed the formation of hydroxyl and carboxylic groups. The result of batch tests indicated that the adsorption capacity of carbons activated with ferric salt could be as high as 128.9 mg/g, while that of carbons without activation was 79.1 mg/g. The new manufacturing procedure used in this study could save at least 19.5 k J of energy per gram of activated carbon.