Decomposition and Decoloration of Acid Orange 7 using Sub-critical Water Method

Decomposition and decoloration of 4-(2-Hydroxynaphthylazo) benzenesulfonic acid sodium salt (acid orange 7) was studied as a model for textile wastes using a flow-type sub-critical water system. The experiments were performed in the temperature ranging from 180 to 374 degrees C at pressure range of 10-25 MPa. The main products from decomposition of acid orange 7 were found to be 1,1'-Binaphthalene-2,2'-diol, 2-naphthalenol, phenol, and N-(phenylmethylene)benzenamine. In order to identify the decomposition pathways, the products were also individually treated under a batch type sub-critical water condition. It was found that 2-naphthalenol underwent to further decomposition to 1,1'-Binaphthalene-2,2'-diol during the sub-critical water reaction. Other decomposition products were resulted from decomposition of directly acid orange 7. http://www.iaeng.org/publication/WCECS2009/WCECS2009_pp82-84.pdf