“Experimental and kinetics of vanadium recovery from spent catalyst using caustic soda

A Theoretical  and experimental investigation was conducted to study recovery of vanadium from spent catalyst via leaching process using sodium hydroxide to investigate the effect of process variables on vanadium recovery and study kinetic of recovered  was investigated by determining the controlling step.The effect of process variables (temperature, particle size,molarity of sodium hydroxide and leaching time) on the percentages of vanadium recovery were investigated and it was found that the percentage of vanadium recovery increased with:
• Increasing the temperature up to 100 ℃ ,
• Increasing sodium hydroxide molarities in the rang ( 2 to 4M),
• Increasing leaching time,
• Decreasing particle size from (200 to 100 µm).A complete vanadium recovery was achieved at the following conditions:
• Temperature (100˚C), particle size (100 µm),molarity of NaOH (4 molar), and time (5 hours).A second order polynomial mathematical correlation was employed in the range of independent variables temp. X
(60˚C - 100˚C), X particle size (100 µm - 200 µm), time X up to 5 hr and molarity X  between (2M and 4M) with correction factor of 0.9890 .The kinetic study shows that the Chemical reaction is the
controlling step due to the highest resistance among the other steps (Fluid film and Ash layer).