Preparation Of Iron-Oxygen Nanocomposites And Study Of Characteristic

Recent development in nanoparticles and nanostrnctural materials hasopened new opportunities for building up functional nanostructures. Nanoscalematerials are of great interests due to their small sizes and large specific surface areas,the nanoparticles exhibit novel properties which differ significantly from those of thebulk materials. The core-shell nanocomposites will become a very important project infurther studies of nanomaterials due to well-controlled and easy-design in structure.In this paper, Preparation of iron-oxygen nanocomposites and their growthmechanism in different conditions are studied and iron-oxygen nanocomposites withdifferent morphology are obtained. Through investigating the adsorption mechanism ofchelating fiber for metal ion, the spindle-shaped composite particles with a stablecore-shell structure were successfully sythsized and the stability and morphology ofthose composites for different time and temperature are studied. The iron-oxygenimbedded polyaniline (PANI) composites are synthesized by emulsion polymerization,and the morphology and thermal stability of those composites are systemically analyzed.Those results provide tried experiments data for iron-oxygen composites in magneticmaterials, optical materials and electrical materials.The monodisperse, spindle-shapedβ-FeOOH nanoparticles are obtained usingFeCl₃ as starting materials. The experimental results reveal that the products are golden,spindle-shapedβ-FeOOH nanoparticles based on XRD and TEM characterization. Theoptimum conditions for preparing those composites are determined. Reaction is carriedout in 0.25 mol/L FeCl₃ solution at 60℃and stirring rate at 120r/min for 24h. Underthe condition, the spindle-shapedβ-FeOOH nanoparticles with a well-distributeddiameter ranging from 190 to 210 nm are obtained. When that spindle-shapedβ-FeOOHnanoparticles grow in the short axis direction, pump-shaped nanoparticles(width:500-700 nm, length: 1200-1400nm) are obtained. The products are characterizedby TEM and the results are that the growth process ofβ-FeOOH nanoparticles isdiscontinuous, and the size does not increase with the reaction time. Crystallineβ-FeOOH nanowires have been synthesized at near-ambient conditions without theapplication of high-temperature heat treatment, high pressure or external electric fields.Theβ-FeOOH nanowires with diameters of 80-100 nm and length of 12um have been fabricated and the results of transmission electron microscopy (TEM) showed that itsgrowth process is continuous.Aim to synthesize chelating fiber with multi-donor atoms via the modification ofthe polyacrylonitrile. Study the adsorption properties of chelating fiber and the effectson the value of equilibrium pH for metal ion. The results revealed the adsorptionisotherm of metal ion on the chelating fiber is of the Freundlich-type equations in therange of metal ion concentrations under investigation. This chelating fiber has goodchemical kinetic property and the adsorption capacities of chelating fiber for metal ionare 2.31m mol/g when the pH is 4.0.The spindle-shapedβ-FeOOH/PANA (PAN-amidhydrazone)/silver compositeparticles with a stable core-shell structurewere successfully fabricated in the mixedsolvent of dimethylformamide (DMF) and methanol using a seed-mediated growthtechnique, where metal silver nanoparticles tethered onβ-FeOOH served as thenucleation sites for the growth of the silver rnanoshell overlayer. The closed silver shellwas finally formed after the seed catalyzed growing process repeated several cycles.The results are characterized by transmission electron microscopy (TEM), UV-visibleabsorption spectroscopy (UV-vis) and powder X-ray diffraction (XRD) showed that thecomposite nanoparticles were spindle shape. The resulting nanoparticles showed goodstability under various conditions.Conductingβ-FeOOH/polyaniline (PANI) composites have been synthesized byseeded emulsion polymerization process using the fine-grade powder (average particlesize of approximately 190-210 nm) ofβ-FeOOH in the polymerization of aniline. Theresults were also well supported by FTIR spectral analysis, UV-spectroscopy,Transmission electron microscope (SEM) and conductivity measurements. Thermalmethod namely TGA and DSC was employed to determine the stability ofβ-FeOOH /PANI nanoparticles for the polymer degradation. The conductivity of nanoparticles wasfound to be of the order of 0.3-0.9 S·cm^-1.