Biosorption of nickel (II) ion from synthetic wastewater on watermelon rind activated carbon using reponse surface methodology (RSM) optimization approach

The introduction of lethal heavy metals into the environment from industrial wastes is a major problem that needs immediate attention. In the present study the adsorption efficiency of nickel ions from a synthetic wastewater using watermelon rind activated carbon as a biosorbent is reported. Four basic process variables – initial Ni2+ concentration (5 – 100mg/l); pH (2 – 7); contact time (20 – 720 minutes) and adsorbent dosage (5 – 25g/l) were used for the investigation. Response surface (Box Behnken design expert 7.0®) methodology based on a design of experiment (DOE) that produced 29 batch experimental runs was used. The amount of Ni2+ adsorbed was optimized numerically to determine the optimum conditions for the adsorption process. The results of the study show that initial Ni2+ concentration of 100 mg/l; pH value of 6.69; 5g adsorbent dosage and 365.89 minutes contact time were the optimum process conditions for the removal of 18.43mg/g of Ni2+ representing 97% of the maximum predicted adsorption rate. It can be concluded therefore, that water melon rind activated carbon has high adsorption capacity and can be used effectively as adsorbent for the removal of nickel from nickel polluted waste and surface water.Keywords: Adsorption, nickel ion, optimization, response surface methodology, water melon rin