The potential of biochar as sorptive media for removal of hazardous benzene in air

Azmatullah Khan, Jan E. Szulejko, Pallabi Samaddar, Ki Hyun Kim, Botao Liu, Hubdar Ali Maitlo, Xiao Yang, Yong Sik Ok

Research output: Contribution to journalArticlepeer-review

94 Citations (Scopus)


Airborne benzene is hazardous even at sub-ppm levels. Therefore, an effective strategy is required for its removal, such as the use of a sorbent with large adsorption capacity or high breakthrough volume. To meet the goal, the performance for the removal of benzene was assessed by loading benzene at 5 Pa inlet partial pressure against seven types of biowaste-derived biochar: (1) paper mill sludge, (2) conventional biochar with magnetic properties, (3) biochar composites with carbon nanotubes (CNTs), (4) gasification biochar from mixed feedstock, (5) gasification biochar from a single feedstock, (6) modified gasification biochar, and (7) activated carbon (AC) as a reference. The 298 K maximum adsorption capacities (mg g−1), when measured at a benzene inlet pressure of 5 Pa (or 50 ppm in ultrapure nitrogen) and flow rate of 50 mL atm min−1, varied widely for different biochars, from 0.35 (MS: Swine manure + plastic mulch film waste) to 144 mg g−1 (XC-1: biochar from mixed feedstock); their 10% breakthrough volumes (BTV) were in the range of 0.22–492 L g−1, respectively. The experimental data (capacity vs. benzene outlet partial pressure) could be fitted to either two or three linearized Langmuir isotherms with distinctive sorption mechanisms ((1) a retrograde region (Type III isotherm: 0 to ∼0.2 Pa), (2) an intermediate pressure region (0.2 and 2.0 Pa), and (3) a higher pressure region (>2 Pa)) which was also confirmed similarly by Freundlich, Dubinin–Radushkevich, and Elovich fitting. About 65% of the maximum capacity was achieved in the retrograde region. The strongest biochar sorbent, XC-1, showed similar performance as activated carbon to prove its feasibility toward air quality management (AQM) applications.

Original languageEnglish
Pages (from-to)1576-1585
Number of pages10
JournalChemical Engineering Journal
Publication statusPublished - 2019 Apr 1

Bibliographical note

Publisher Copyright:
© 2018 Elsevier B.V.


  • Activated carbon
  • Adsorption
  • Benzene
  • Biochar
  • Retrograde isotherm

ASJC Scopus subject areas

  • General Chemistry
  • Environmental Chemistry
  • General Chemical Engineering
  • Industrial and Manufacturing Engineering


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