Advanced Study on Uptake of Zn, Pb, Cu and Fe Ions from Spent and Unspent Engine Oil Using Termite Soil

Removal of Zn, Pb, Cu and Fe ions from unspent and spent engine oil was studied using Termite soil. Improper disposal of spent engine oil leads to a buildup of essential inorganic nutrients such as phosphorus, calcium, and magnesium, and trace amounts of lead, zinc, iron, copper and cobalt. These elements if in excess accumulate in plant tissues. Process parameters such as contact time and adsorbent dosage were varied. Values from contact time were used for predicting kinetics equation of their uptake. At optimum time of 40 minutes, percentage adsorption was of the order Fe>Zn>Cu>Pb for both spent and unspent engine oil. Kinetics equation such as Elovich, Intra-particle, Pseudo-first order and Pseudo-second order were tested. Results obtained shows that their sequestering pattern fit into the pseudo-second order kinetics. Initial reaction rates, h (mg/g.min) and ? (mg. g-1min-1) for all metal ions obtained from Pseudo-second order and Elovich kinetic models followed the trends Zn>Fe>Cu>Pb and Zn>Fe>Pb>Cu respectively in spent engine oil while for unspent engine oil, the trend was Fe>Zn>Cu>Pb for h (mg/g.min) and Zn>Fe>Pb>Cu for ? (mg. g-1min-1). Electrostatic attraction existing on the surface of the adsorbent assisted in the high initial reaction of Zn and Fe ions, implying good affinity of the ions for the adsorbent. Desorption constant ? (g/mg) was of the trend Cu>Pb>Fe>Zn and Cu>Pb>Zn>Fe for spent and unspent engine oils respectively. Intra-particle diffusion constant kid (mgg-1 min-1/2) followed a similar pattern, revealing strong binding between Zn and termite soil than any of the metal ion. Several kinetics models were tested but pseudo-second order kinetics was the best for predicting the kinetics for uptake of the studied metal ions. This pilot research has been able to suggest a kinetic process for uptake of the studied ions from spent and unspent engine oil.