Co-production of biochar and carbon nanotube from sewage sludge in a two-stage process coupling pyrolysis and catalytic chemical vapor deposition

• Published in: WASTE DISPOSAL & SUSTAINABLE ENERGY
• Main Authors: Ghazali, Mohd Syazwan Mohd; Zaini, Mohd Saufi Md; Arshad, Muhammad; Syed-Hassan, Syed Shatir A.
• Format: Article; Early Access
• Language: English
• Published: SPRINGERNATURE 2024
• Subjects: Science & Technology - Other Topics; Energy & Fuels; Environmental Sciences & Ecology
• Online Access: https://www-webofscience-com.uitm.idm.oclc.org/wos/woscc/full-record/WOS:001191030000001

This study explores the potential of valorizing sewage sludge as a carbon source for the co-production of biochar and carbon nanomaterial via a two-stage thermal-catalytic process. In the first stage, sewage sludge underwent slow pyrolysis, resulting in a biochar yield of 66% (in weight) at 550 degrees C. The resulting pyrolysis vapor was then introduced into a second reactor, where catalytic chemical vapor deposition (CCVD) took place in the presence of a cobalt catalyst, leading to the production of carbon nanotubes (CNTs). It was found that CNTs with an inner diameter of similar to 3.2 nm and an outer diameter of 20-40 nm can be formed in the second stage reactor at temperatures between 650 degrees C and 950 degrees C with a maximum yield of 30% (in weight) under the employed experimental conditions. The obtained CNTs displayed a multiwall structure, exhibited a lack of crystallinity, and demonstrated a high level of disorder. The research findings also indicate that temperature exerts a significant influence on both the yield and properties of the CNTs synthesized.