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Abstract
V. SUMMARY AND CONCLUSION
V.1. Summary
It is well known that seventeen elements are essential for plant growth .Eight of them are required in such small quantities, so that they are called micronutrients. These elements namely are: iron, manganese, cobalt, copper, zinc, boron, molybdenum and chlorine. In addition there also claims which stated that nickel is considered as an essential element.
The dominant forms of micronutrients that occur in the soil are determined largely by the pH and soil aeration. The cations of these elements may be present in either simple cations or hydroxyl-metal cations.The simple cations tend to be dominant under highly acid conditions. On the other hand the more complex hydroxy metal cations [e.g. Fe (OH)2+ ; Zn (OH)+; Cu (OH)2+] form as the soil pH is increased.
In that respect it can be said that the solubility of iron .manganese, zinc, copper, cobalt, and nickel decreases by increasing the pH due to the formation of their corresponding sparingly soluble hydroxides.
The annual demands of using the micronutrient fertilizers in Egypt was found to be increased after construction of the high dam as a result of the remarkable increase in pH value of the soil in several parts in the country. This problem can be solved by the production of some metal-organic complexes which show a remarkable stability in neutral and faintly alkaline solutions such as complexes of EDTA and DTPA for using as micronutrient fertilizers.
Chapter II in the thesis is concerned with the experimental work and techniques used in characterization of complexes. It is concerned with the sources of chemicals used as the starting materials for the preparation of different complexes as well as the reagents used in the analysis of complexes Descriptions of the purification of glassware, EDTA acid, DTPA acid, were mentioned in details. The methods of preparation and purification of complexes of Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) with EDTA , as well as complexes of Fe(III), Ni(II), Cu(II) and Zn(II) with DTPA are mentioned in details. The techniques used in the investigation of complexes mentioned before namely are: thermal analysis, electronic absorption and infrared spectra, mass spectra and electron spin resonance.
In chapter III, the structural formulae of the six EDTA complexes were suggested in the light of the results obtained from different techniques; mentioned before in chapter II
In chapter IV, the structural formulae of the four DTPA complexes were suggested based on the results obtained from different techniques mentioned before.
Chapter V includes English and Arabic summaries of the thesis together with conclusions.
V.2. Conclusion
The complexes of micronutrient elements (Mn, Fe, Co, Ni, Cu, Zn) with EDTA and DTPA ligands can be prepared on an economical basis since, the yield of production of complexes varied between 85 and 90 %.
The complexes showed a remarkable stability at normal temperatures which enable the user to store them for a long time.
The chemical and thermal analysis as well as spectroscopic techniques clarified that the complexes can be prepared in a very pure state.