Sol-gel synthesis of nanosized titanium phosphates

Alpha-titanium phosphate was prepared by three methods: Solid-solid reaction, Direct precipitation and Sol-gel methods. The produced samples were dried and characterized by using X-ray diffraction, IR spectra, thermal analysis and scanning electron microscopy. For the samples prepared by solid-solid reaction, a residual of unreacted materials was observed which disappeared by increasing the sintering temperature. The other two methods give a crystalline single phase of alpha-TiP. By increasing the refluxing time, the crystallinity of the samples improved. The IR results show the main absorption bands which characterized the phosphate compounds. Also, the IR patterns indicate that the TiP is coordinated as Ti-O-P-O-Ti and not TiO2 which coordinated as Ti-O-Ti. The thermal analysis indicates that the alpha-TiP underwent dehydration and it converted to alpha-TiP2O7 at high temperature. The characterization of the different samples indicates that the products depend on the method of preparation and on the controlled preparation

Studies on the dissolution of phosphate ore in mineral acids

The dissolution of Abou-Tartor phosphate ore in sulphuric acid, phosphoric-sulphuric acid mixture and hydrochloric acid was studied. The effects of time, temperature, acid/ore ratio and shaking were investigated. The results indicated that the dissolution of the ore in sulphuric acid was rather difficult; but the dissolution in H3PO4- H2SO4 mixture [76.1: 54.5 g] gave good result from 100 g of the ore at an acid/ore ratio of 1.4 after 30 min, at 70 degree and a shaking rate of 100-200 rhm. The optimum condition of the dissolution in HCl/ore ratio of 27: 1 was 80 min, at 25 degree and a rate of shaking of 120 rhm. The obtained results showed that the dissolution of Abou- Tartor phosphate ore in HCl is more preferable than other mineral. acids

Preparation and characterization of some phosphate salts from crude phosphoric acid

Monosodium phosphate, MSP, di - sodium phosphate, DSP, and trisodium phosphate, TSP, samples were prepared both from partially purified and solvent extracted phosphoric acid fractions. Chemical analysis and preliminary tests showed that the degree of purity of the prepared samples from the solvent extracted acid were in good agreement with the standard samples. TGA confirmed the above findings. The x-ray diffraction patterns and IR- spectra showed that the prepared MSP [b,c], DSP [c] and TSP [c]possessed the same crystalline structures and specific IR absorption bands as the standard sample [S]. Preparations from partially purified phosphoric acid using step filtration and back-acidification, indicated that the orthophosphates obtained had satisfactory purity, but it was slightly less than those of samples produced from solvent extracted acid

Study of the preparation and characterization of copper ferrite including ferritization of copper scraps

Samples of copper ferrite, CuFe2O4, were prepared using both dry and wet processes, either from powders of iron oxide or from interaction of copper and iron sulfates, or co-precipitation of copper and iron hydroxides from homogeneous sulphate solutions at different pH values. Also, a sample of copper ferrite was prepared in optimum conditions from copper scraps. The effects of temperature and time of ferritization were studied. The prepared samples were investigated by X-ray diffraction analysis, differential thermal analysis, DTA, and scanning electron microscopy, SEM. Optimum conditions were found to depend on the input materials, the pH values, time and temperature

optimum conditions for dissolution of phosphate ore in hydrochloric acid

The optimum conditions to prepare pure phosphoric acid by dissolution of Sebaiya phosphate ore in hydrochloric acid were studied. The phosphate ore was ground and submitted to complete chemical and sieve analyses. The percentages of P[2]O[5] and Fe were determined spectrophotometrically and the fluoride content was determined by means of an ion selective electrode. The factors affecting the dissolution of the ore in hydrochloric acid including percent P[2]O[5] particle size of the phosphate grains, period of acidulation, acid concentration, temperature and acid-to-rock ratio were investigated. The results showed that the optimum conditions for the preparation of phosphoric acid are P[2]O[5] - 26.3, F- = 3.18, Fe = 0.962 and SiO[2] = 12.84 for chemical composition of the phosphate ore, particle size = 125-250 micro m, period of acidulation = 30 min, acid concn. = 6N, temperature = 25 degree and HC1: ore ratio = 30.86:1. The obtained results were discussed and compared with the literature data. It is concluded that the variation of the optimum conditions may be affected by the chemical composition and the particle size of the phosphate ore, besides the other factor

Extraction and stripping of phosphoric acid from dissoluble phosphate or in hydrochloric acid

H3PO4, CaCl2, and some chlorides of impurities, derived from the phosphate ore, e.g. Al, Fe,... are formed when phosphate ore is dissolved in hydrochloric acid. Both iso-butanol and n-butanol are used to extract H3PO4 from the digestion medium, and H3PO4 is then stripped by water from the organic layer. Optimum conditions of extraction and stripping are studied. A stepwise process to improve the extraction and recovery is also applied. The chemical analysis of the stripped H3PO4 points out that the iron content is reduced to 0.79% and 0.13% and the fluoride content reduced to 3.8%, 4.2% of the original values of iso-butanol and n-butanol, respectively. The results are discussed in comparison with the literature data. They indicated that, the efficiency of extraction and stripping depends on the nature of the solvent, the ratio of the organic to the aqueous layers and the number of steps followed in the process

Purification of wet-process phosphoric acid by solvent extraction

The purification of wet-process phosphoric acid [WPA] by di-isopropyl ether [DIPE] was studied. The partition coefficient, K, of WPA between water and DIPE at different temperatures was determined. The average value amounted to 4.7 X 10-2 at 25, decreasing as the temperature increased from 25 to 55. The extraction of WPA is apparently more favorable around room temperature. It was also found that the extraction of phosphoric acid in the organic layer increased the greater solvent/acid weight ratio. The batch-wise extraction and stripping of phosphoric acid from 200 ml crude acid yielded 39 g of pure phosphoric acid, 154.7 g of pure Na2HPO4, 7H2O and 215.2 g of pure Na3PO4, 8H2O beside 75 g of a precipitated cake during the chemical treatment of the raffinate

Some of the dielectric properties of irradiated cotton fibers

The effect of gamma-radiation on the dielectric constant, epsilon ['], and the dielectric loss, epsilon [']for cotton fibres is studied. The dielectric measurements are carried out over the frequency band 0.2 to 10 Me./Sec. and at several temperatures between -10 to 85 degree. The results indicate that both epsilon['] and epsilon["] increase with increasing gamma-doses.. This increase is attributed to the degradation of cellulose chain by gamma radiation. A dielectric loss peak is observed at high temperature and specify gamma-doses of irradiation which is attributed to the formation of carbonyl groups by oxidation

photodegradation of grafted cellulose

The effect of the ultraviolet light on the cellulose chain bas been frequently studied proving that the photodegradation of the cellulose chain involves oxidation of the alcoholic groups of carboxylic groups. In certain cases contradictory results have been obtained, especially with respect to the role of the medium and the mechanism of the degradation. On the other hand, the study of the effect of grafting on the photodegradation of cellulose is much less frequently studied. In and recent study, it has been found that grafting increases the thermal stability decreases the amount of the absorbed water and decreases the dielectric constant. The aim in the given presentation is to introduce an undertaken study of grafting on photodegradation of cellulose, where the dielectric constant is applied as an index for photodegradation