Hydroxylethylidene diphosphonic acid with arsenic content <=3ppm and preparation technique thereof

Abstract

The invention discloses an etidronic acid with the content of arsenic less than or equal to 3ppm and a process for preparing the same. The method is to use phosphorus trichloride, acetic acid and ammonium thioacetamide as raw materials and comprises the following steps of: putting one-third of the acetic acid and the ammonium thioacetamide into a reaction kettle, stirring to control the temperature and the pressure, slowly dropping one-third of the phosphorus trichloride and putting one-third of the ammonium thioacetamide into the reaction kettle, stopping stirring and keeping stand; controlling the temperature and the pressure; dropping the remaining phosphorus trichloride into the reaction kettle; then stirring for 1 hour with the rotational speed of 50 to 60 revolutions per minute, raising the temperature slowly and reflowing; controlling the temperature and the pressure while reflowing; hydrolyzing the esters produced after reflowing under the negative pressure; concentrating the materials, filling air, removing impurities, reducing the temperature, putting the remaining phosphorus trichloride into the reaction kettle, sealing the reaction kettle and keeping stand, and then putting the materials into a mixing tank; regulating and filtering the materials so as to obtain an HEDP product. The product has extremely little arsenic with less than or equal to 3ppm, which not only reduces the environmental pollution, but also expands the application fields.

Description

Technical field: [0001] The invention relates to a hydroxyethylene diphosphonic acid with an arsenic content of ≤3ppm and a preparation process thereof, which can be used as a cleaning agent in the electronics industry, an additive for daily chemicals and in the field of medicine. Background technique: [0002] The hydroxyethylene diphosphonic acid involved in the present invention, its English abbreviation is HEDP, and its molecular formula is C 2 h 8 o 7 P 2 . Hydroxyethylene diphosphonate is mainly used in industrial water treatment, it is a high-efficiency water quality stabilizer. It has good chelation, low limit inhibition, lattice distortion and other effects. It can prevent the formation of scaling salts in water, especially the formation of calcium carbonate scale. It also has a corrosion inhibitory effect and can be used as a chelating agent and a corrosion inhibitor. Widely used in large-scale thermal power plants, circulating cooling water in oil refinerie...

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Problems solved by technology

[0003] The arsenic content of hydroxyethylidene diphosphonic acid prepared by the prior art is ≥ 40ppm. In view of the high content of the existing hydroxyethylene diphosphonic acid arsenic, it will pollute the environment on the one hand and limit its application field on the other hand.

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