REMOVAL OF NITROGEN CONTAINING ORGANIC COMPOUNDS USING CATALYTIC WET AIR OXIDATION

Abstract

Wastewater treatment and re-use of industrial process water is a critical issue for the suitable development of human activities. The need for effective water recycling has reinforced the research on tailored low cost pollution abatement since the existing solutions are no longer universal. The nitrogen-containing organic waste produced in industries is usually characterized by high concentration and high temperature, and is not treatable by biological methods directly. In particular, the Catalytic Wet Air Oxidation (CWAO) process is one of the most promising technologies for the remediation of moderately concentrated and toxic pollutants with the use of a stable and active catalyst. The experimental runs were conducted in a stainless steel high pressure reactor. In this study, a hydrophobic Cu-Co/C (Copper 5% wt.-Cobalt 5%wt. supported on carbon) catalyst (heterogeneous) and CuSO4 (homogeneous catalyst) were first used in a batch reactor to remove nitrogen containing organic compound from wastewater. For this purpose, the catalytic activity and stability of copper and cobalt based catalyst supported by activated carbon was tested for the catalytic wet air oxidation of the target compound, pyridine at mild conditions of temperature and pressure. Copper and cobalt, are relatively inexpensive catalytic material and have shown stability to yield higher conversion efficiencies. Kinetic modelling of the results is also undertaken using the classical gradient based method. Detailed kinetic analysis of CWAO is shown. It was found that higher temperature and higher oxygen partial pressure enhanced the removal of pyridine. In our study the initial pH of the sample was optimised which was 4 for both the catalyst. Apart from that the catalyst concentration also plays important role in getting higher conversion efficiencies. Both the catalysts were studied at various reaction conditions and found that CuSO4 is more active as compared to Cu-Co/C. The highest reactivity of 75.1 was observed using 5mg/i concentration of CuSO4 catalyst at 160 °C, 9 bar total pressure after 2 hour reaction time. The kinetics of the reaction shows a first order reaction with respect to substrate concentration.