Effects of H3PO4 and KOH in carbonization of lignocellulosic material

Baba Jibril*, Omar Houache, Rashid Al-Maamari, Badir Al-Rashidi

*Corresponding author for this work

Research output: Contribution to journalArticle

38 Citations (Scopus)

Abstract

Samples of lignocellulosic material, stem of date palm (Phoenix dactylifera), were carbonized at different temperatures (400-600 °C) to investigate the effects of their impregnation with aqueous solution of either phosphoric acid (85 wt%) or potassium hydroxide (3 wt%). The products were characterized using BET nitrogen adsorption, helium pycnometry, Scanning Electron Microscopy (SEM) and oil adsorption from oil-water emulsion (oil viscosity, 60 mPa s at 25 °C). True densities of the products generally increased with increase in carbonization temperature. Impregnated samples (acid/base) showed wider differences in densities at 400 (1.978/1.375 g/cm3) than at 600 °C (1.955/2.010 g/cm3). Without impregnation, the sample carbonized at 600 °C showed higher density of 2.190 g/cm3. This sample has impervious surface with BET surface area of 124 m2/g. Acid-impregnated sample carbonized at 500 °C has the highest surface area of 1100 m2/g and most regular pores as evidenced by SEM micrographs. The amounts of oil adsorbed decreased with increase in carbonization temperature. Without impregnation, sample carbonized at 400 °C exhibited equilibrium adsorption of 4 g/g which decreases to about a half for sample carbonized at 600 °C. Impregnation led to different adsorptive capacities. There are respective increase (48 wt%) and decrease (5 wt%) by the acid- or base-impregnated samples carbonized at 600 °C. This suggests higher occurrence of oil adsorption-enhancing surface functional groups such as carbonyl, carboxyl and phenolic in the former sample.

Original languageEnglish
Pages (from-to)151-156
Number of pages6
JournalJournal of Analytical and Applied Pyrolysis
Volume83
Issue number2
DOIs
Publication statusPublished - Nov 2008

Keywords

  • Activated carbon
  • BET surface area
  • Chemical activation
  • Date palm stem
  • Lignocellulose
  • Porosity
  • SEM

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Chemistry(all)

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