Effectiveness of fresh and used supported noble and non-noble metal based catalysts for industrial organic raffinate oxidation by catalytic wet air oxidation at low operating parameters

Abstract

In the present study, the efficacy of fresh and used noble and non-noble metal based catalysts for degradation of industrial organic raffinate has been studied. The industrial organic raffinate containing refractory and toxic organic compounds was characterized and oxidized by catalytic wet air oxidation (CWAO) at very mild operating conditions and the results were evaluated in terms of chemical oxygen demand (COD) removal (%). The efficacy of catalysts was monitored for determining their potential for long runs by repeating experiments 3 times with same catalyst. The catalysts stability have been checked in terms of their carbonaceous deposition and leaching of active metals in reaction solution. The fresh and used catalysts were characterized and compared by different techniques such as surface area, field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM) and thermo-gravimetric analysis (TGA). The biodegradability in terms of BOD/COD ratio has been calculated for industrial organic raffinate and CWAO effluent obtained after treatment. The results obtained with all catalysts were compared and it was observed that at low operating conditions the non-noble metal ceria promoted manganese catalyst have potential to replace the costly noble metal such as platinum.