Investigating the Effect of α-Fe2O3 Oxides on the BaFe2O4 Pyrosynthesis Temperature - The Digital Processing of TG and DTA Curves

In the research activities on the barium monoferrite pyrosynthesis, an important place is occupied by TG and DTA analysis. The effects of different hematite (α-Fe2O3) granulations on the BaFe2O4 pyrosynthesis temperature were followed. Four types of commercial hematite powders were used, the difference between them being the fineness of the powder granules and the purity. Only one type of commercial barium carbonate (BaCO3) powder was also used as a barium additive in the BaFe2O4 pyrosynthesis. Each of the 4 types of α-Fe2O3 with BaCO3 were subjected to the homogenization process in a planetary mill for a more intimate mixing of the powders in order to obtain error-free results regarding the pyrosynthesis reaction. To determine BaFe2O4 pyrosynthesis temperature, a derivatograph device was used. All the data obtained with this thermal device were digitally processed in order to extract the two TG and DTA curves. The protective atmosphere in the furnace was nitrogen. BaFe2O4 pyrosynthesis temperatures recorded different values for the four mixtures, depending on the particle size of the α-Fe2O3 powders, protective atmosphere from furnace and the mixing conditions. The effects of Fe2O3 oxides on the BaFe2O4 pyrosynthesis temperature is observed when are used very fine hematite powders in mixtures, obtaining a reduction of pyrosynthesis temperature up to 16% compared to the mixture where the size of the hematite is coarser.

Microstructure of CuO Assisted Activated Carbon Adsorbent from Rubber Wood Sawdust Produced by Mechanochemical Processing

A series of single carbon source and metal oxide assisted carbon source were prepared by mechanochemical process followed by carbothermal reduction which obtained via the reaction between activated carbon (AC) from rubber wood sawdust (Havea brasiliensis) and CuO precussor. Microstructure of the single AC and CuO assisted AC (CuO-AC) has been studied using Field Emission Scanning Electron Microscopy (FESEM). The products were further characterized using X-ray diffraction (XRD) and thermal analysis (TG and DTA). A significant difference of the microstructure between AC and CuO-AC samples were observed in FESEM micrograph. The micrograph of single AC in indicates porous structure with numerous pores present due to dehydration of volatile matters. Milling process and reduction of CuO by AC has contributed to the increasing formation of porous structure with nanopore size ranging from 100-200 nm. TG and DTA results revealed that single AC and CuO-AC have a significant difference in thermal decomposition and stability. Doping of CuO to AC has affected the exothermic and endothermic reaction of the samples. These were further being clarified by X-ray diffraction where phase analysis is studied. It was found that the addition of CuO to AC brought a significant increase in the degree of crystallinity which is accompanied by mechanochemical process followed by carbothermal reduction to produce Cu. Incomplete reduction also cause the formation of Cu2O. Production of CuO-AC were successfully characterized and revealed the potential enhancement for waste treatment.

The challenge of methods of thermal analysis in solid state and materials chemistry

Thermogravimetry (TG) and differential thermal analysis (DTA) are traditional, but still useful, experimental techniques for obtaining information in the realms of materials and solid state chemistry. This paper presents two case studies (many more could be cited) to illustrate the strengths (and limitations) of these techniques: (1) Iron doping of clinoptilolite (the most common zeolite): the typical parameters of both components appear clearly in the TG and DTA curves. The decrease of the Tmax value of the structurally-typical DTA effect of FeOOH by approximately 100°C is attributed to the weakening of chemical bonds in FeOOH due to the incorporation of the doping component into the structure of this zeolite. (2) Macrodefect-free (MDF) materials: the results of both TG and DTA unambiguously locate the typical temperature range of the decomposition of the P{4}–O–Al/Fe{6} cross-links within the interval of 200–300°C. The presence of cross-links is shown by the DTA data while the TG data can be used to measure the degree of cross-linking, which is valuable information when studying both raw mixes and the final materials for a variety of MDF materials.

Influence of Hydrocycloning Pressure on the Purification of Bentonite

The bentonite clays are rich in accessory minerals, the presence of these minerals, depending on the application can impact the value of an industrial warehouse, reducing its value and compromising its quality and industrial applications. Thus, the need to go through clay beneficiation processes to meet market specifications in order to use more than one hundred industrial applications. The objective of this work is to study the influence of pressure in the process of purification of hydrocycloning betonites clays: Superior Grey, Green Superior and Inferior Green District Cubati-PB performed to optimize the process of organophilization . The characterization of natural clays betonites was taken and purified at pressures of 1.5-2bar and 3-3.5bar through techniques: AG, XRD, EDX, TG and DTA. The results showed that the purification process is more efficient pressure 3-3.5bar.