Microwave-induced combustion: Thermal and morphological aspects for understanding the mechanism of ignition process for analytical applications.

In the present work, for the first time a systematic study was performed using an infrared camera and scanning electron microscopy (SEM) coupled to energy dispersive X-ray spectrometry (EDS) to evaluate the mechanisms involved in microwave-induced combustion method, which has been extensively used for sample preparation. Cellulose and glass fiber discs, wetted with the igniter solution (6molL NHNO), were evaluated under microwave field in a monomode system. The temperature of the discs surface was recorded during microwave irradiation and the effect of NHNO concentration and irradiation time on cellulose oxidation was evaluated.

Intensification of ultrasonic-assisted crude oil demulsification based on acoustic field distribution data.

Water removal is an essential step during crude oil production due to several problems such as increased transportation costs and high corrosion rate due to dissolved salts. Indirect low frequency ultrasonic energy (US), using baths, has been recently proposed as an effective alternative for crude oil demulsification. However, the reactor position during sonication and its influence on the demulsification efficiency for crude oil has not been evaluated.

Determination of elemental impurities in poly(vinyl chloride) by inductively coupled plasma optical emission spectrometry.

In this work, a method for poly(vinyl chloride) (PVC) analysis by inductively coupled plasma optical emission spectrometry (ICP-OES) was developed. Samples were digested by microwave-induced combustion (MIC) and thirteen elements (Ba, Cd, Co, Cu, Fe, Mg, Mn, Mo, Ni, Pb, Sr, V and Zn) were determined by ICP-OES. Operational conditions of MIC were investigated allowing quantitative determination of all the analytes and suitable results were achieved using a 3 mol L(-1) HNO3 solution.