Some studies on potato common scab disease. Pathological studies

Three streptomyces isolates causing potato common scab disease [i.e., S1, S2 and S3] were successfully isolated and identified from the growing areas at Menia. Pathogenicity tests, either in the laboratory or pots, revealed that potato cultivars Alpha, Diamont and Spunta could be infected by all three S. scabies isolates. The tested isolates caused lesions on the root tips of radish, software, soybean, squash, tomato, turnip and wheat seedlings. Only isolate S2 induced lesion on the root tips of cowpea, Nicotiana glutinosa, and sunflower seedlings. None of the S. scabies isolates infected maize seedlings or storage roots of carrot and sweet potato. However, storage roots of radish were infected by the highly pathogenic isolate S2. S. Scabies isolates produced phytotoxic substances with most produced after five days at 25C

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

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

Thermal and spectroscopic characterization of Pd [II] and Pt [IV] thiobarbiturate complexes

Pd [II] and Pt [IV] thiobarbiturate complexes [Ligaud: 2-thiobarbituric acid; Abbreviation, HTBA] were synthesized as solid phases. Chemical and thermogravimetric analyses, together with IR and electronic absorption spectra of the ligand and the two complexes were carried out. IR vibrational bands support M-S and M-N bondings in the Pd [II] and Pt [IV] ions are tetra-and hexa-coordinated, as deduced from their electronic absorption bands characteristic of square planar and octahedral configurations, respectively. Results of thermogravimetric analysis were in agreement with the general molecular formulae: Pd [TBA]2 and Pt [TBA]4 [HTBA]2 proposed by chemical analysis. The TG and DTG curves of both the Pd [II] complex and the Pt [IV] complex showed three thermal dissociation steps ending with a final step at>790 and >772 omicron, respectively. The thermal stability of the studied compounds was found to have the order: Pt [TBA]4 [HTBA]2> HTBA>pd [TBA]2