Development and application of methods for the separation of polyhydroxy compounds

Part I. The complexing of molybdate or tungstate ion with polyhydroxy compounds has been studied with a view to utilizing the complexes for the separation of polyhydroxy compounds. The separation of a large number of polyhydroxy compounds by methods such as anion exchange chromatography, paper chromatography, cellulose column chromatography and thin-layer chromatography, has been described. It has been shown that complex forming polyols possessing four adjacent hydroxyl groups can be separated on molybdate or tungstate forms of anion-exchange resin from the polyols which either do not form a complex or complex due to the presence of 1,2,3-cis,cis triol system. The reason for the non-sorption of the polyols of the latter type on the molybdate or tungstate form of resin has been dicussed.The chromatography on paper partially impregnated with tungstate has divided the polyols into non-complexing polyols, complex forming polyols possessing three adjacent hydroxyl groups and those possessing four adjacent hydroxyl group. The technique of chromatography on paper wholly impregnated with tungstate has, in addition to the separation of a wide variety of substances, further afforded a means of studying the structure of the compounds. Structures for the polyol-tungstate complexes have been suggested and their correlation with the migration rates (on wholly impregnated paper) has been discussed. The mode of complex formation of D-galactose has been studied and the conformation suitable for the formation of D-galactose-tungstate comlex has been proposed. Part II. The preparation of phenylboronates of someacyclic pentitols has been described and the position of hydroxyl group not involved in the ester formation located. Detailed structures of several phenylboronates have been investigated. It has been shown that ribitol and xylitol form 1,3:2,4-bisphenylboronates and 1-deoxy-L-galactitol forms 3,5:4,6-bisphenylboronate. The formation of phenylboronates has been compared with the reaction of aldehydes and ketones with polyols.<p

INTERCEPTOR DRAINS ALONG IRRIGATION CANALS

Interceptor Drains were installed along three Canals of Fordwah Eastern Sadiqia (South) irrigation and Drainage Project. Ground watertable behaviour was observed before and after the installation of intercepror drains. Seepage rate of the canals was measured through ponding test method. The lithology of the area along the trial sites didn’t allow the interceptor drains to receive the expected design discharge. Measured seepage from the canals was much lower than originally envisaged at the time of design of interceptor drains. The measured discharge of interceptor drains was 31%, 47% and 82% of the design discharge at Malik Branch, Hakra Branch and 3-R Khatan Distributary respectively. The quality of the drained water was not too bad for reuse for irrigation after mixing with canal water. The interceptor drains could not significantly reduce the need of field drainage. Based on the results of trials conducted by IWASRI, main interceptor drain component of 280 km was dropped from the project. In this way, the results of the study have helped save unnecessary expenditure of approximately US $ 20 million (over Rs. 1000 million) allocated for installing interceptor drains in FESS Project. Moreover an additional amount of Rs. 25 million to be incurred annually for operation and maintenance has also been saved. Interceptor drains cannot be recommended as recharge reducing technology in flat areas without proper investigations and testing