Oxidation of starch and dextrines derivatives to produce a sequestering agent substitute of tripolyphosphate
SummSummary of the work made
In many countries, sodium tripolyphosphate has been banned because responsible of water eutrophication. Therefore, many researches have been made in the world for a possible substitute. Our proposal is to start from starch, depolymerize it with α-amilase and then oxidizing two vicinal hydroxils to carboxylic acids that have shown a great sequestering power and are highly soluble in water. Moreover, by reducing the molecular weigth of the polysaccharides their biodegradability greatly increases.
Work
Sodium tripolyphosphate (STTP) has been used as the main sequestering builder in detergent formulations for many years. In many countries its use has been banned because stimulates eutrophication. Many alternative compounds have been proposed as possible sequestering agents. The problem is that STTP had more than one function in detergent formulation. Therefore, it can be substituted by using more than one compound. However, the sequestering effect is the main one and in this case three properties are fundamental: (1) the efficiency in the sequestering action; (2) the low cost; (3) the biodegradability. At this purpose, we have developed in collaboration with Novamont SpA a new, cheap, efficient and biodegradable sequestering agent obtained from hydrolyzed starch or dextrines opportunely oxidized. In a first step starch or dextrin is hydrolyzed in the presence of α-amilase to reduce the average molecular weight. The obtained product is then oxidized for
introducing carboxylic acid groups in the molecule framework. The vicinal carboxylic groups are responsible for the sequestering properties of the molecules. The obtained sequestering power (275 expressed as mg CaCO3/g) is similar to the one that can be obtained by oxidizing directly starch or dextrines, but these last products are not biodegradable, while, the biodegradability increases by decreasing the molecular weight of the oxidized polyglucosides. The new product has been patented by FERTEC srl [1] and some information about the developed work are reported in [2], while, more general informations about this topic are reported in [3].
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G. Brussani, E. Santacesaria, D. Gelosa;"Agenti sequestranti del calcio a base di carboidrati ossidati e loro impiego come builder per detergenti" (FERTEC Srl) B.I. 67636A/90; EUR. PAT. 91113154.8
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F. Trulli, E. Santacesaria; "New sequestering builders for detergent formulations" Chemistry Today 5,11,(1993)
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E. Santacesaria, F. Trulli, G. F. Brussani, D. Gelosa, M. Di Serio ; "Oxidized glucosidic oligomers: a new class of sequestering agents-preparation and properties” Carbohydrate Polymers 23,35-46 (1994).
