English abstract
Disposal of spent catalyst which is produced as a waste material from the cracking of petroleum refineries is becoming a major concern to Sohar refinery due to stringent environmental regulations in the recent years. Methods for recycling and beneficial reuse of the raw spent catalyst in different applications should be investigated. In this research the potential use of spent catalyst as adsorbent for copper, chromium, cadmium and lead from water was studied. Batch experiments to evaluate equilibrium and kinetic properties of the spent catalyst were performed for the four heavy metals.
The results revealed that the spent catalyst has good removal efficiency. The average removal efficiencies for copper, chromium, cadmium and lead are 63%, 62%, 34% and 93%, respectively.
However, it has relatively low adsorption capacity and has a fluctuated adsorption performance. The maximum adsorption uptake capacity for copper, cadmium, chromium and lead are 3.8 mg/g, 1.9 mg/g, 3.5 mg/g and 4.9 mg/g, respectively. The average values of the adsorption uptake capacity as revealed from the kinetic experiments for Cu, Cd, Cr and Pb are 3.2 mg/g, 1.7 mg/g, 3.1 mg/g and 4.6 mg/g, respectively. Adsorption of Cu, Cd, Cr and Pb on Sohar spent catalyst was found to be well fitted to Langmuir isotherm.
Also, it was observed that Pseudo second order model is well fitted to data representing the variation of the adsorption capacity with respect to shaking time for all studied heavy metals. Therefore, Sohar spent catalyst could be a good adsorbent for the above metals but it should be subjected to further studies.
