REMOVAL OF PHENOL FROM WASTEWATER USING LOWCOST ADSORBENTS DEVELOPED FROM RICE HUSK

Organic contaminants from industrial waste streams have been recognised as an
issue of growing concern as they severely affect human health and the environment.
In this research, the development of twenty six (26) low-cost adsorbent materials
from abundant waste rice husk was achieved via chemical treatment, thermal
treatment and activated rice husk (activated carbon). The physiochemical properties
of the developed adsorbent were evaluated. Their adsorption behaviours in batch
system were evaluated for the removal of phenol from aqueous solutions by varying
the initial concentration, pH, required dose, contact time and temperature.
Subsequently, the adsorption behaviour of the best adsorbent in fixed bed column was
further evaluated for phenol, binary system of phenol with benzene and toluene as
well as ternary system of phenol, benzene and toluene. Analysis showed that the
developed adsorbents possessed different physiochemical properties due to the
methods of treatment. It was found that, the surface morphology of rice husk was
progressively changed after treatment. It was also found that, the activated carbons
have the highest surface areas ranged from (117.78 to 586.6 m2 g-1
) followed by
thermally (24.04 to 201.4 m2 g' 1
) and chemically (2.78 to 50.17 m2.g-1
) treated
samples, respectively. Experimental results in batch system show that adsorption
capacity was found to increase with increase in initial concentration, adsorbent dose
and agitation time. The maximum uptake of phenol was found at pH 4. Due to high
surface areas and porosity, at 100 mg.L-1 of synthetic wastewater containing phenol,
the activated adsorbents had shown the highest removal efficiencies ranged from
(86.7 to 98.5 %) followed by thermally (26.9 to 64.9 %) and chemically (22.5 to 48.6
%) treated adsorbents, respectively. Further evaluation of the best activated
adsorbent, D6oo.u, in fixed bed column showed that the adsorption capacity increased
with the increase in the initial concentration and the bed depth. However, it decreased
with the increase in the feed flow rate.