Production of high yield and high-quality carbon nanotubes from biomass wastes under microwave irradiation-Mechanism and properties

abstract

This study explores to optimize the synthesis of multi-walled carbon nanotubes (MWCNTs) from the carbonaceous low-cost resources (biochar and graphite) as the precursors under controlled microwave irradiation (MI) via a sustainable route and cost-effective route. Biochar used in this study was produced from the pyrolysis of pinewood that was characterized by high carbon content (similar to 72 %). Ferrocene was the catalyst to facilitate nucleation and growth of carbon nanotubes (CNTs) by providing catalytic sites for decomposing hydrocarbon precursors and subsequent formation of CNTs. While biochar alone as a precursor resulted in incomplete conversion of carbon atoms to CNTs, a mixture of biochar and graphite significantly improved the yield and quality of the final products. To enhance the properties of MWCNTs, variables such as microwave power, reaction time, operating temperature, and headspace capacity of the reactor were studied and optimized. Additionally, Response Surface Methodology (RSM) and Central Composite Design (CCD) were implemented to optimize specific surface area (SSA) and yield of the produced MWCNTs. Optimal conditions were determined at 9.70 min, the output power of 300 W, 80 degrees C, and a headspace of 10 %. Detailed characterization of the produced MWCNTs under optimum conditions revealed successful production of MWCNTs with diameters ranging from 12 nm to 46 nm with a wall thickness ranging from 2 nm and 6 nm. The materials developed represent a relatively high specific surface area of 229 m(2)/g. The study discussed the mechanisms involved in catalytic synthesis of MWCNTs from the carbonaceous resources.

keywords

CHEMICAL-VAPOR-DEPOSITION; ASSISTED SYNTHESIS; BIOCHAR; GROWTH; FUNCTIONALIZATION; OCTADECYLAMINE; NANOPARTICLES; COMPOSITES; DIOXIDE; ROUTE

subject category

Science & Technology - Other Topics; Energy & Fuels; Materials Science

authors

Nemati, B; Kamali, M; Aminabhavi, TM; Dewil, R; Ferreira, P; Silva, MRF; Costa, MEV; Capela, I

Groups

G2 - Photonic, Electronic and Magnetic Materials

Projects

Collaboratory for Emerging Technologies, CoLab (EMERGING TECHNOLOGIES)

CICECO - Aveiro Institute of Materials (UIDB/50011/2020)

CICECO - Aveiro Institute of Materials (UIDP/50011/2020)

Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)

acknowledgements

The authors acknowledge Portuguese Foundation for Science and Technology (FCT) for financial support under the doctoral scholarship No. 2020.05304.BD for the first author. It is also acknowledged financial support of the FCT - Fundacao para a Ciencia e a Tecnologia I.P., under the project/grant UID/50006 + LA/P/0094/2020 (DOI 10.54499/LA/P/0094/2020) . Thanks are also due to the financial support of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 (DOI 10.54499/UIDB/50011/2020) , UIDP/50011/2020 (DOI 10.544 99/UIDP/50011/2020) & LA/P/0006/2020 (DOI 10.54499/LA/P/0006/2020) , financed by national funds through the FCT/MCTES (PIDDAC) . Thanks, are also due to the financial support from the PDM program, KU Leuven.