Plasma pyrolysis and gasification of carambola leaves using non-thermal arc plasma

Abstract

Soil pollution (heavy metals and organic matter) is becoming more and more serious, phytoremediation has rapidly become a highly important method to deal with this problem. Therefore, the treatment and disposal of hyperaccumulators have been a topic of concern. In this paper, carambola leaves are selected as feedstock considering that carambola is a potential hyperaccumulator. A series of tests were performed to discuss 6 main influencing factors on total gas yield and metal fixing using a non-thermal arc plasma setup, to investigate the feasibility of plasma treatment of hyperaccumulator and provide a new method to utilize the harvested hyperaccumulator. The maximum total gas yield reached approximately 85% at an airflow rate of 3 L/min, the processing time of 7 min, discharge power of 29.95 W with the addition of water (water: sample = 1:1). A reducing or inert carrier gas or the addition of some specific inorganic additives at optimal conditions were in favor of increasing metal fixing efficiency. However, the effects of these factors usually have two sides, and some factors may have conflicting effects between gas yield and metal fixing, and. It is necessary to optimize these factors for achieving the desired goal. The obtained solid products exhibit the potential to fix metals and act as activated carbon.