Influence of variables on the synthesis of CoFe_(2)O_(4)pigment by the complex polymerization method

Synthetic inorganic pigments are most widely used in ceramic applications due to their excellent chemical and thermal stability and their lower toxicity to both human and environment as well.In the present work,black ceramic pigment CoFe_(2)O_(4)has been synthesized by the complex polymerization method(CPM)with good chemical homogeneity.In order to study the influence of variables on the process of obtaining pigment through CPM,2^((5-2))fractional factorial design with resolution III was used.The variables studied in the mathematical modeling were:citric acid/metal concentration,pre-calcination time,calcination temperature,calcination time,and calcination rate.Powder pigments were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),and UV-visible(UV-Vis)spectroscopy.Based on the results,the formation of cobalt ferrite phase(CoFe_(2)O_(4))with spinel structure was verified.The color of pigments obtained showed dark shades,from black to gray.The model adjusted to the conditions proposed in this study due to the determination coefficient of 99.9%and variance(R²)showed that all factors are significant at the confidence level of 95%.

In situ polymerization preparation and characterization of Li_4Ti_5O_(12)-polyaniline anode material

Li4Ti5O12 powders were prepared by so-gel method using tetrabutyl titanate,lithium acetate and absolute alcohol as starting materials.Li4Ti5O12-polyaniline(Li4Ti5O12-PAn)composite was prepared by in situ polymerization method using aniline, ammonium persulfate and hydrochloricarried as starting materials.Li4Ti5O12-PAn composite was characterized by X-ray diffractometry(XRD),infrared spectrum(IR)combined with electrochemical tests.The results show that the electrical conductivity is enhanced obviously due to the introduction of PAn to Li4Ti5O12.Li4Ti5O12-PAn composite exhibits better high-rate capability and cyclability than Li4Ti5O12.The composite can deliver a specific capacity of 191.3 and 148.9 mA·h/g,only 0.13%and 0.61%of the capacity is lose after being discharged 80 times at 0.1C and 2.0C,respectively.

Effect of Main Material Ratio on Properties of SiC-Al_2O_3 Porous Ceramics via Polymeric Replication Method

In order to fabricate porous ceramics with good properties and proper production cost,SiC-Al2 O3 porous ceramics were prepared at 1 450 ℃ for 2 h from the powders of commercial silicon carbide and white fused corundum via a polymeric replication method. Effects of the mass ratio of SiC powder to white fused corundum powder（ 1 ∶ 3,1 ∶ 1 and 3 ∶ 1） on the appearance,phase composition,sintering properties and thermal shock resistance were investigated. The research results indicate that the as-prepared Si C-Al2 O3 porous ceramics have uniform pores,and their linear shrinkage ratio,apparent porosity and bulk density reach 4. 70%,67. 17%and 0. 83 g·cm-3,respectively. The thermal shock cycles from 1 400 ℃ to room temperature reach 23 including 15 cycles in air cooling condition and then 8 cycles in water cooling condition. Their main phases areα-Al2 O3 and Al6 Si2 O13 as well as a small amount of SiC and free SiO2. The as-prepared porous ceramic with the ratio of m（ SiC） ∶ m（ Al2 O3） = 1∶ 1 possesses prior comprehensive properties.

A NOVEL POLYMER ENZYME LINKED IMMUNOASSAY METHOD AND ITS APPLICATIONS

During the course of study, we found that both poly (N-isopropylacrylamide ) (PNIP) and PNIP-Ab (enzyme-labelled antibody)could be adhere tightly to a cellulose acetale-nitrate membrane, and that the retention of PNIP-Ab on the membrane increased over 30-fold when compared with the unconjugated Ab.Thus we used this characteristic to develop a novel immunoassay method-polymer enzyme linked immunoassay method: homogeneous antigen-antibody reaction and heterogeneous separation process. When applied for detection of human serum HBsAg, this immunoassay system can detect as little as 1 ng/ml of human serum HBsAg.

Use of Perovskite-Type Lanthanum Nickelate Synthesized by the Polymeric Precursor Method in the Steam Reforming Reaction of Methane

In the current work, LaNiO3 perovskite was synthesized using the polymeric precursor method. The materials were thermally treated at 300°C for 2 hours, subsequently supported on alumina or zirconia and finally calcined at 800°C for 4 hours. The resulting samples were characterized by X-ray diffraction, thermogravimetry, BET surface area and thermo-programmed reduction. Steam reforming reactions were carried out at 750°C and 6 bar during 4 hours using a pilot reactor under a H2O:CH4 ratio of 2.5. The mass of catalysts was about 5.7 g. X-ray diffraction patterns confirmed the formation of the perovskite structure in all samples prepared. The results also showed that lanthanum nickelate was more efficient when supported on alumina than zirconia. Finally, it was observed that the methane conversion was approximately 94% and the selectivity to hydrogen was about 70%. In all cases low selectivity to CO and CO2 was verified.

Morphological and Electrochemical Characterization of Ti/MxTiySnzO2 (M = Ir or Ru) Electrodes Prepared by the Polymeric Precursor Method

This paper describes the effect of the composition of the oxide films on the properties of electrodes Ti/MxTiySnzO2 (M = Ir or Ru) prepared by the polymeric precursor method. XRD studies showed that the anodes are formed by solid solutions. The electrodes containing IrO2 exhibit lower activity for the oxygen evolution reaction. The doping of the electrode surface with SnO2 improves the catalytic properties of the anodes. However, it should be held in appropriate compositions, because the change in the atomic ratio of this element shows a marked effect on the stability of the oxides. Electrode Ti/Ir0.2Ti0.3Sn0.5O2 has lower lifetime, i.e. 6 hours. The 20% decrease in the stoichiometric amount of SnO2 increases the time to a value above 70 hours, as observed for Ti/Ir0.3Ti0.4Sn0.3O2. Electrode Ti/Ru0.3Ti0.4Sn0.3O2 shows lifetime of 11 hours;therefore IrO2 is more stable than RuO2 under the conditions investigated. These results suggest that electrode Ti/Ir0.3Ti0.4Sn0.3O2 is promising for different applications, such as water electrolysis, capacitors and organic electrosynthesis.

Effects of Surface Modifi cation on the Properties of Microcapsules for Self-healing

Poly（urea-formaldehyde）（UF） microcapsules with epoxy resin E-51 as core material used as self-healing materials were prepared by interfacial polymerization method. The surface of UF microcapsules was modifi ed by γ-（2,3-epoxypropoxy） propytrimethoxysilane（KH-560）. The interfacial interactions between UF microcapsules and KH-560 were studied by Fourier transform infrared spectroscopy（FTIR） and X-ray photoelectron spectrometric analysis（XPS） of microcapsules. The surface topography of microcapsules was characterized by scanning electron microscopy（SEM）. The thermal stability and mechanical properties were evaluated. FTIR and XPS results showed that there were physical and chemical combinations between the silicon coupling agent and the microcapsules surface. The thermal stability and mechanical property analysis showed that the addition of KH-560 could greatly improve the thermal stability, tensile property and elastic property. SEM results indicated that the addition of KH-560 could improve the bonding between the surface of microcapsules and resin matrix and improve the ability of self-healing.

Synthesis and characterization of yttrium-aluminum-iron and yttrium-cerium-iron citric complexes

Fe-, Y-Fe-Al- and Y-Ce-Fe- citrates were synthesized in ethylene glycol （EG） medium under conditions similar to those used in the polymerized complex method. Their elemental composition, IR,^ 13C and ^1H NMR, X-ray photoelectron and Mossbauer spectra were studied, and formulae describing their composition were proposed. The complexes contained EG bonded as adduct and ester with citric acid ligand and did not contain ligands with deprotonated alcoholic groups. The complexes consisted of agglomerated spheres, 0.7-3 μm in diameter. The local composition of the products was established by energy dispersive X-ray microanalysis. The comparison of the number of the ligands, their average electrical charge and the esterification degree of mono-, di- and trimetallic complexes proved the mixed-metal nature of the species studied. The thermal decomposition of the complexes was studied and a general scheme of the processes taking place was proposed. Highly crystalline, phase homogeneous YaFe4AlO12 was produced after heating the respective complex at 1000 ℃. Ce-doped yttrium-iron garnet, similarly prepared, contained traces of CeO2.

Synthesis of the superfine high-entropy zirconate nanopowders by polymerized complex method

The high-purity and superfine high-entropy zirconate nanopowders,namely(Y_(0.25)La_(0.25)Sm_(0.25)Eu_(0.25))_(2)Zr_(2)O_(7)nanopowders,without agglomeration,were successfully synthesized via polymerized complex method at low temperatures for the first time.The results showed that the crystallinity degree,lattice strain,and particle size of the as-synthesized powders were gradually enhanced with the increase of the synthesis temperature from 800 to 1300℃.The as-synthesized powders involved fluorite phase in the range of 800-1200℃while they underwent the phase evolution from fluorite to pyrochlore at 1300℃.It is worth mentioning that the as-synthesized powders at 900℃are of the highest quality among all the as-synthesized powders,which is due to the fact that they not only possess the particle size of 11 nm without agglomeration,but also show high purity and good compositional uniformity.

The influence of monomer concentration on the optical properties of electrochemically synthesized polypyrrole thin films

Polypyrrole （PPy） thin films were deposited on stainless steel and ITO coated glass substrate at a constant deposition potential of 0.8 V versus saturated calomel electrode （SCE） by using the electrochemical polymerization method. The PPy thin films were deposited at room temperature at various monomer concentrations ranging from 0.1 M to 0.3 M pyrrole. The structural and optical properties of the polypyrrole thin films were investigated using an X-ray diffractometer （XRD）, FTIR spectroscopy, scanning electron microscopy （SEM）, and ultravioletvisible （UV-vis） spectroscopy. The XRD results show that polypyrrole thin films have a semi crystalline structure. Higher monomer concentration results in a slight increase of crystallinity. The polypyrrole thin films deposited at higher monomer concentration exhibit high visible absorbance. The refractive indexes of the polypyrrole thin films are found to be in the range of 1 to 1.3 and vary with monomer concentration as well as wavelength. The extinction coefficient decreases slightly with monomer concentration. The electrochemically synthesized polypyrrole thin film shows optical band gap energy of 2.14 eV.

Effect of different starting materials on the synthesis of Ba_(0.8)Ca_(0.2)TiO_(3)

Literature has reported the synthesis of barium calcium titanates by various synthesis methods such as solid state reaction,co-precipitation and polymer precursors.These compounds are usually obtained using calcium carbonate(CaCO_(3)),barium carbonate(BaCO3)and titanium oxide as starting materials.This study investigated the effect of different starting reagents on the synthesis of Ba_(0.8)Ca_(0.2)TiO_(3)(BCT)by complex polymerization method(CPM).Two sets of starting precursors were used:titanium citrate,CaCO_(3)and BaCO3,and titanium citrate and Ba1-xCaxCO3 solid solution precursor.Samples were crystallized at a temperature range from 400℃to 700℃for different time.The obtained powders were characterized by X-ray diffraction(XRD),thermogravimetry(TG)and differential thermal analysis(DTA),and Raman and infrared spectroscopy.The infrared spectroscopy indicated that the chelation processes of Ba,Ca,Ti and CA ions are very similar.The results showed that the use of CaCO_(3)and BaCO3 or Ba1-xCaxCO3 solid solution as precursors does not affect the final properties of BCT powders obtained by CPM.

Critical review of EPS production, synthesis and composition for sludge flocculation

Extracellular polymeric substances（EPS） produced by microorganisms represent biological macromolecules with unfathomable potentials and they are required to be explored further for their potential application as a bioflocculant in various wastewater sludge treatment. Although several studies already exist on biosynthetic pathways of different classical biopolymers like alginate and xanthan, no dedicated studies are available for EPS in sludge. This review highlights the EPS composition, functionality, and biodegradability for its potential use as a carbon source for production of other metabolites. Furthermore, the effect of various extraction methods（physical and chemical） on compositional, structural, physical and functional properties of microbial EPS has been addressed. The vital knowledge of the effect of extraction method on various important attributes of EPS can help to choose the suitable extraction method depending upon the intended use of EPS. The possible use of different molecular biological techniques for enhanced production of desired EPS was summarized.