Evaluation of Different Grades of Granular Activated Carbon Adsorbents for Scavenging Priority Pollutants from Wastewater

Abstract

Increasing environmental awareness and concern have expanded the role of powdered activated carbon (PAC) and granular activated carbon (GAC) adsorbents in scavenging the soluble, chemically stable and biologically non-degradable pollutants from industrial and domestic wastewater. In the present investigation adsorbents prepared from bituminous coal, namely, Filtrasorb-100 (F-100),
Filtrasorb-200 (F-200), Filtrasorb-300 (F-300), Filtrasorb-400 (F-
400) and coconut shell based carbons LCK and RRL were evaluated
for their efficiency and performance in scavenging pollutants from
water. Aqueous solution of m-nitrophenol was used as adsorbate.
These GAC samples were subjected to Proximate and Ultimate
Analysis, Pore Size Distribution (PSD), Scanning Electron Microscopy
(SEM) and Fourier Transform Infrared Spectroscopy (FTIR).
Results show that the source material used for preparation of GAC
has significant effect on its pore structure, surface texture, resistance
to fragmentation and adsorption capacity. Bituminous coal based
carbons show high ash content, a rough surface having lot of cracks
and irregular protrusions, high pore volume and a widely dispersed
pore structure. In contrast, the coconut shell based GAC samples
have low ash content, low pore volume and exhibit uniformly dispersed
finer pores, which are well connected by solid mass. FTIR
spectra show the presence of various carbon-oxygen complexes on
the granular activated carbon surface, which makes the surface
slightly polar. The effect of physico-chemical parameters associated
with the adsorbent on the adsorption equilibrium and adsorbate
removal rate was also studied. Adsorption equilibrium and kinetic
experiments were carried out in a batch reactor. The obtained results
showed that bituminous coal based carbons have higher adsorption
capacity for phenols as compared to the coconut shell based carbons.