Abstract
Batch adsorption of COD and NH3-N from palm oil mill effluent onto natural adsorbents from activated coconut shells carbon (ACSC), activated cow bones powder (ACBP) and zeolite has been investigated under hydrophobic and hydrophilic conditions. The study also investigates the suitability of the natural adsorbents for the preparation of composite. The result of the investigation revealed that reduction of COD and NH3-N was optimum under hydrophobic condition at ratio (15:25) volumetric dosage of ACSC:ACBP, respectively. This was achieved at 79.8% reduction of COD and 48.2% removal of NH3-N. Similarly, under hydrophilic condition, the reduction of COD and NH3-N was optimum at 35 cm(3) at 45.2% reduction of COD and 65.4% removal of NH3-N. Further optimization study under hydrophobic-hydrophilic conditions revealed that the optimum reduction of pollutants was observed at 25:15 cm(3) volumetric dosage which was equivalent to 78.2% reduction of COD and 68.5% removal of NH3-N. The composite was prepared at 80:20 adsorbent:binder ratio which was the optimum ratio achieved for the reduction of the investigated parameters under batch study. Equilibrium data fitted better to the Langmuir isotherm for both reductions of COD and NH3-N which indicates that homogeneous adsorption occurred on a monolayer surface. The result of the kinetic uptake reveals that kinetic data fitted better to the pseudo-second order model which suggested that adsorption was by chemisorption. The intraparticle diffusion model indicates that adsorption was not only affected by rate controlling step but also influenced by adsorption along the boundaries.