Development Status of Disodium Octaborate Tetrahydrate    

Disodium octaborate tetrahydrate (DOT) is an important fine boride. In recent years, it has developed rapidly against a relatively buoyant market and received industry-wide attention. At present, the product is mainly used as a boric fertilizer in agriculture, and its applications are yet to be expanded.

1. Production status   

Prior to 2003, almost all DOT appearing in Chinese market were imported from countries like the United States, Italy, Argentina, Chile, Peru and India, while the selling price of the imported agricultural grade DOT reached a record high of RMB58 000/t. In 2003, Anhui General Station of Soil & Fertilizer and Anhui Fertilizer Corporation co-developed a DOT production process and for the first time realized industrial production in China with a capacity of 1 000 t/a. Both the product's purity and dissolution performance were much the same as those imported. The process also won an invention patent in May 2007. In 2006, Baoding Jinyang Biological Fertilizer Plant, a company located in Hebei province, developed high-quality  hybrid of borates successfully with a 20.5% of boron content and a production capacity of 3 000 t/a. In addition, Zhenjiang Chemical Agent Factory in Jiangsu province, Yantai Star Technology of Agriculture Co., Ltd. and Yingkou Pengda Fine Chemicals Co., Ltd. in Shandong province have all built DOT production plants with a production capacity of 2 000 t/a, 1 500 t/a and 600 t/a respectively. In 2008, China's total DOT capacity was about 9 000 t/a, and the production processes adopted are almost invariably hybrid of borax and boric acid. Domestic DOT projects under construction include: a 1 000 t/a production line of Shandong Qingdao Huaren Chemical Co., Ltd., a 1 000 t/a production line of Qinghai Jihua Jiangyuan Group Co., Ltd., a 1 500 t/a production line of Xinjiang Kunpeng Chemical Co., ltd., and so on. It's estimated that, the overall domestic capacity will reach 13 000 t/a before 2011.

2. Applications     

    * Agriculture   
In China, ninety eight percent of DOT is used in boric fertilizer to correct boron's deficiency to improve crop yield and at the same time, prevent the occurrence of crop pests and diseases. The product's water solution is neutral, and can be mixed with almost all pesticides. Besides, it can also be used as a herbicide.

    * Other industries   
DOT has a wide application in industries like the daily chemical industry, paints, cultural relic protection, as well as medical and health care.
    Treating timbers with DOT can prevent the erosion of wood components by wood-rotting fungi, and also timber damage caused by long-horned beetles and powder-pest beetles.
    As an environmentally friendly preservative, DOT has good antibacterial performance, and is not toxic or an irritant. It is compatible with most coatings without changing the color of the final products it protected. These advantages make it especially useful in wall painting, cultural relic protection and medicines.
    DOT features moderate water content and a high boron trioxide content of 67% (43% higher than boron trihydroxide), so it has excellent transportation and storage performance and enjoys more advantages over DOT when applied in the high borosilicate glass industry. In recent years, China's high borosilicate glass industry relies too much on foreign countries for raw materials, and some of its production lines are facing shutdown threat due to an inadequate supply of boron trihydroxide. Therefore, to substitute DOT for boron trihydroxide will greatly alleviate the problem. From this point of view, the application prospect of DOT in industry will be even broader than in agriculture. As a result, to continue to explore new application areas of DOT will exert a profound influence on the product's development.