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  • A systematic study of the degradation of dimethyl phthalate using a high-frequency ultrasonic process.

A systematic study of the degradation of dimethyl phthalate using a high-frequency ultrasonic process.

Ultrasonics sonochemistry (2012-12-05)
L J Xu, W Chu, Nigel Graham
ABSTRACT

A comprehensive study of the sonochemical degradation of dimethyl phthalate (DMP) was carried out using high-frequency ultrasonic processes. The effects of various operating parameters were investigated, including ultrasonic frequency, power density, initial DMP concentration, solution pH and the presence of hydrogen peroxide. In general, a frequency of 400kHz was the optimum for achieving the highest DMP degradation rate. The degradation rate was directly proportional to the power density and inversely related to the initial DMP concentration. It was interesting to find that faster removal rate was observed under weakly acidic condition, while hydrolysis effect dominated in extreme-basic condition. The addition of hydrogen peroxide can increase the radical generation to some extent. Furthermore, both hydroxylation of the aromatic ring and oxidation of the aliphatic chain appear to be the major mechanism of DMP degradation by sonolysis based on LC/ESI-MS analysis. Among the principle reaction intermediates identified, tri- and tetra-hydroxylated derivatives of DMP, as well as hydroxylated monomethyl phthalates and hydroxylated phthalic acid were reported for the first time in this study. Reaction pathways for DMP sonolysis are proposed based on the detected intermediates.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Dimethyl phthalate, ≥99%
Supelco
Dimethyl phthalate, PESTANAL®, analytical standard
Sigma-Aldrich
Dimethyl phthalate, ≥99%
Supelco
Density Standard 1191 kg/m3, H&D Fitzgerald Ltd. Quality