Study of Carbonization and Dielectric behaviour of Teak Wood Leaves

Abstract

In recent years, there has been a lot of research work carried out on how to use natural fibres for value added applications. Advanced countries like USA, Germany, Italy have been producing bio-char from the bio-waste like grass and leaf etc. These bio-char increases the soil potentials, restores the soil quality and plants produces better yield. Here we have taken teak leaves for making bio-char to use it in some value added applications. Teak is a tropical hardwood tree, scientifically called "Tectona" grandis, is a deciduous tree which has large amounts of papery leaves. Teak wood has very good properties like durability, water resistance and so used in a variety of applications. In India teak is found in vast regions and its abundance availability forces the use for a variety of applications. Ripen teak wood leaves fallen from teak trees are collected dried and then powdered through ball milling process. The carbonisation/pyrolysis of the leaves was carried out under inert gas atmosphere at various temperatures i.e. at 400, 600, 800 and 1000°C. The processed samples are characterized /studied through XRD, SEM and FTIR analysis. The amount of fixed carbon in the sample is evaluated by proximate analysis. The amount of moisture content was found to be 10%, the volatile content was found to be 13%, ash content was found to be 6% and the amount of fixed carbon was 71%.
Dielectric analysis of the carburised samples are studied and the factors governing the dielectric strength like dielectric constant, the amount of dielectric loss i.e. tan delta and AC conductivity of the samples have been found out and analysed. Then the sample was chemically treated with NaOH, KMnO4, H2O2, CH3COOH and K2CO3 to evaluate the change/affect on its dielectric behaviour. From FTIR analysis, the carbonate peaks with aromatic compounds and nitrile stretching’s have been found. From the XRD peaks we could observe that whewellite and SiO2, (whewellite is hydrated calcium oxalate) are present: this indicates the presence of lignin and cellulose substances in the sample. From the dielectric analysis it is observed that, dielectric constant and loss decreases with increasing frequency. But it increases with increase in temperature. The effect of chemical treatment on dielectric behavior of the leaf sample is also investigated. The thermal conductivity of the samples was found to be in the range of 0.04125 to 0.04975 KW/m.k.
From this present study, the following conclusions can be made. That:
The teak wood leaves bear a high value of fixed carbon. The carbonisation temperature affects the crystaline/type of unit cells structure (of carbon) which has an impact on the type/valuation of the biochar. Dielectric studies show that, these materials whether chemically treated or pyrolysed, can be used for high frequency electronic applications.