Abstract
Phenol ranks as one of the most common hazardous pollutants present in water and industrial effluents. The object of the work describe herein was to assess the phenol adsorption capacity of fly ash under varying experimental conditions such as adsorbent dosage, pH, varying phenol concentration and contact time. The study showed that, at a phenol concentration of 100 mg/ℓ, the percentage removal of phenol was 95.69% at an optimum dosage of 7 g/ℓ fly ash. The effect of the initial phenol concentration indicated that the percentage phenol removal increased with increasing phenol concentration, being a maximum (98.08%) at a phenol concentration of 700 mg/ℓ. Further increase in phenol concentration (1000 mg/ℓ) resulted in a slight decrease in phenol removal. The adsorption of phenol also varied with the pH and was found to be a maximum at a pH value of 8. Adsorption equilibrium studies indicated that an equilibrium time of 2 h was necessary for the maximum removal of phenol. Isotherm studies showed that the adsorption of phenol onto fly ash was best described by the Langmuir isotherm relative to the Freundlich isotherm. Accordingly, the Langmuir adsorption coefficients, i.e. the maximum adsorption capacity (q0) and the Langmuir adsorption constant (KL) were evaluated and found to be 142.86 mg/g and 0.0199 ℓ/g, respectively. Analysis of the kinetic data indicated that the kinetics of phenol adsorption closely follow the pseudo-second-order model.