Fabrication of carbon-slag composite via a pyrolytic platform and its environmental application for arsenic removal as a case study

Taewoo LEE, Jeong-Ik OH, Haakrho YI, Yiu Fai TSANG, Eilhann E. KWON

Research output: Contribution to journalArticle

Abstract

For the valorization of biomass and steel slag, co-pyrolysis of rice straw and steel slag was carried out as a case study. To achieve the more sustainable pyrolytic platform, carbon dioxide (CO₂) was employed as reactive medium. Therefore, this study laid great emphasis on chasing the mechanistic roles of CO₂ in the thermolysis of the mixture (rice straw + steel slag) at the fundamental level. This study experimentally validated that CO₂ reacted with thermally induced hydrocarbon species from rice straw via the gas phase reactions. Such reactions resulted in CO formation at temperatures ≥ 480 ˚C, of which the reaction kinetics was catalytically accelerated when steel slag was co-pyrolyzed with rice straw. Note that steel slag contained the significant amount of metals and alkaline compounds. However, co-pyrolysis of rice straw and acid-washed slag revealed that the enhanced reaction kinetics resulting in CO formation at temperatures ≥ 480 ˚C was imparted from alkaline compounds such as CaCO₃. Also, this study showed that CO₂ effectively suppressed dehydrogenation during the thermolysis of rice straw. Such mechanistic roles of CO₂ played a pivotal role to shift carbon distribution from pyrolytic oil to pyrolytic gas. The different thermal degradation routes triggered by CO₂ led to the morphologic change to carbon-slag composite. In detail, the surface area of carbon-slag composite was enlarged in the CO₂ atmosphere. To impart the desirable functionality, the surplus amount of CO formed from CO₂ was re-used to transform iron oxides in the composite into zero-valent iron (Fe⁰). Porosity and zero-valent iron in carbon-slag composite increased the As(V) sorptive capability, of which the removal efficiency reached up to 99.3 % at pH 6.9. Copyright © 2019 Elsevier B.V. All rights reserved.
LanguageEnglish
JournalChemical Engineering Journal
Early online dateJan 2019
DOIs
Publication statusE-pub ahead of print - Jan 2019

Fingerprint

Arsenic
slag
Slags
arsenic
Carbon
Straw
Fabrication
Steel
straw
carbon
Composite materials
rice
steel
Carbon Monoxide
Thermolysis
Pyrolysis
reaction kinetics
Reaction kinetics
pyrolysis
Iron

Citation

Lee, T., Oh, J. I., Yi, H., Tsang, Y. F., & Kwon, E. E. (2019). Fabrication of carbon-slag composite via a pyrolytic platform and its environmental application for arsenic removal as a case study. Chemical Engineering Journal. Advance online publication. doi: 10.1016/j.cej.2019.01.022

Keywords

  • Waste-to-Energy
  • Biomass
  • Steel slag
  • Pyrolysis
  • Carbon dioxide
  • As removal