The sonochemical remediation of phthalate esters : an investigation into products and kinetics

Phthalate esters or phthalates have become ubiquitous water pollutants. They are used as plasticisers in several plastics. Due to them not being bound to the plastic material they leach out over time. Thus phthalate esters have entered the planet’s aquasphere. Phthalates are stable in the environment and also recalcitrant to most standard water processing methods. Due to their being linked to endocrine disruption and cancer they have been classed as a pollutant of concern by the EU and the American EPA. Previous work had shown that ultrasound of frequency between 20 kHz and 500 kHz can be used to remove phthalate esters from aqueous solutions as an advanced oxidation process. These works studied the effects of various parameters on the sonolysis. They however, did not perform a satisfactory analysis of the degradation products of the esters studied. These too may be biologically active and need to be ascertained for ultrasound to be considered for their removal from water in industrial and municipal processing centres. Therefore this work describes the study of additional parameters known to be pertinent to ultrasound science, namely the acoustic power, the type of gas dissolved in the solution and the initial concentration of phthalate on the sonolysis of DBP as a model for the family of phthalate esters. Work was performed using 20 kHz and 515 kHz ultrasound. The performance of these two systems is compared and contrasted throughout. A detailed analysis of the products of the degradation of DBP was then performed using LC-MS based methods. Finally the degradation of other alkyl phthalates was examined as well as the effect of DBP on the quenching of aqueous sonoluminescence. This last topic was performed hoping it would give some insight into the way DBP partitions in the bubble-water interface.EThOS - Electronic Theses Online ServiceGBUnited Kingdo