Decomposition and decoloration of synthetic dyes using hot/liquid (subcritical) water.

We have studied the decomposition and decoloration of 4-(2-Hydroxynaphthylazo) benzenesulfonic acid sodium salt (AO7, acid dye) as a model for textile wastes by using a flow-type subcritical water system. The operating temperature was ranged from 180 to 374 degrees C at 10-25 MPa at a wide range of residence time. The pressure (up to 25 MPa) did not affect the decomposition reactions.

Conversion of Japanese red pine wood (Pinus densiflora) into valuable chemicals under subcritical water conditions.

A comparative study on the decomposition of Japanese red pine wood under subcritical water conditions in the presence and absence of phosphate buffer was investigated in a batch-type reaction vessel. Since cellulose makes up more than 40-45% of the components found in most wood species, a series of experiments were also carried out using pure cellulose as a model for woody biomass. Several parameters such as temperature and residence time, as well as pH effects, were investigated in detail.

Electrodecomposition in subcritical water using o-xylene as a model for benzene, toluene, ethylbenzene, and xylene pollutants.

The possibility of the combination of electrolysis and subcritical water as a novel electrolyte was investigated. A stainless steel reactor was used as an undivided electrochemical cell containing platinum as the anode and a stainless steel reactor as the cathode. At first, the effect of temperature on the electrolysis current as the main parameter was studied in a cell containing only pure water and a supporting electrolyte.

Dehydration of fructose to 5-hydroxymethylfurfural in sub-critical water over heterogeneous zirconium phosphate catalysts.

Dehydration of fructose to 5-hydroxymethylfurfural in a batch-type process with sub-critical water (sub-CW) was performed in the presence of different laboratory-made zirconium phosphate solid acids at 240 degrees C. A direct relation was found between increasing the crystallinity and decreasing the surface area of solid acids. However, irrespective of the different surface areas, similar catalytic behaviors were observed.