Cold Plasma Technology and System

ECOTEC's Research Centre has developed a research project concerning "The use of plasma technology in the removal of persistent organic pollutants from sludge and contaminated soil of the chemical and petrochemical industry". The project is co-financed by the European Fund for Regional Development (E.F.R.D.) as part of the National Operational Program (N.O.P.) "Scientific Research, Technological Development, Higher Education" 2000-2006." The project involves the construction of a system, built and assembled in two dedicated rooms located in the pilot park, based on "cold plasma" technology (plasma generated with 13.56 MHz radio frequency). The system is also supplied with a thermal plasma torch.

The system has been developed in collaboration with the CNR Istituto del Plasma of Milan and is one of the largest in Europe. It allows experimentations in the applicability of oxidation processes that removes persistent organic compounds caused by oxygen found in a plasma state. Furthermore, the system allows the testing of the wide possibilities of application of cold plasma on materials: the deposition of nanolayers on specific media.

For experiments on a smaller scale, a small cold plasma pilot system is active, operating with radio frequency of 13.56 MHz and a nominal power of 2 kW. This system has allowed us to perform some preliminary tests on soils contaminated by chemicals and petrochemicals originating from industrial facilities and to obtain experimental data on process and treatment efficiency.

The continuously operating large system consists essentially of three chambers: a loading chamber, a process chamber (cold plasma chamber) and a discharge chamber, isolated from one another through a system of pneumatic valves.

The material that is to be treated is placed inside the loading chamber and dried with a high vacuum pump; after this first phase, the material is transported by a conveyor belt to the second chamber containing the cold plasma reactor. In this chamber, the sample will stop for a period of time necessary for process completion. Thereafter, the sample will be transported to the third chamber (discharge), where the material is cooled and brought to atmospheric pressure.

The chamber was designed to operate in a wide range of temperatures: from about 100 K up to about 473 K. The pressure inside the three chambers can vary from atmospheric pressure to 10-3 mbar.

The power electrode works at 13.56 MHz and has a rated power of 3 kW. The gaseous effluents are released into a cracking chamber and destroyed. They are sent into a plasma reactor that uses a thermal plasma torch ("with non-transfer arc," who operates at a temperature of about 10,000  K).

The process chamber is constructed to operate on various materials using the PECVD technique.

The system is equipped with two mass spectrometers, placed in different areas of the plant that monitor the composition of the effluents at various treatment stages. The composition is measured even after the final treatment with the thermal plasma torch.

The entire system has been designed to be extremely flexible and therefore can be used for various applications. In addition to the various processes related to the categories of "plasma waste treatment", it is possible to test and develop new applications and technology solutions in the field of material property alteration and PECVD in its various applications.