TREATMENT OF PYRIDINE . BEARING WASTE WATER

Abstract

Pyridine (C5H5N) and 3-picoline (C6H7N) are the parent of a series of compounds that are important in medicinal, agricultural and industrial chemicals and are used for synthesis of vitamins and drugs, etc. They are highly toxic, odorous compounds and demands additional precautions to prevent the escape of vapours as they are detectable and disagreeable at very low concentrations. Pyridine manufacturing plants are plagued with the problem of intense odour of pyridine and their derivatives escaping from either the waste water or handling and storage sections. Picotines are important derivatives of pyridine which are also present in the pyridine bearing waste water. So it is necessary to reduce their concentrations to safe values. Majority of organic chemicals are either non-biodegradable or require tertiary treatment for safe disposal to environment. Various tertiary treatment methods include adsorption, membrane separation process, ultra filtration, reverse osmosis, etc. Adsorption has been found to be efficient for the removal of most organic compounds in waste water at lower concentrations. Activated carbon is commonly used adsorbent, however, due to its high cost and loss in regeneration, various low cost adsorbents have been investigated during recent years. The aim of the present research is to explore the possibility of utilizing bagasse fly ash and carbon slurry for the removal of pyridine and 3-picoline. Proximate analysis, chemical analysis, particle size analysis, surface area determination, XRD and SEM studies vere conducted for the characterization of adsorbents. The adsorbing capacity of both adsorbents have been compared with activated carbon. Batch studies were conducted to see the effect of contact time, adsorbent dose, initial concentration and pH on the removal of iii pyridine and 3-picoline. Equilibrium data were fitted in Langmuir, Freundlich and Redlich Peterson isotherms. Removal to the extent of 60 percent and 90 percent was achieved for pyridine anc: 3-picoline using bagasse fly ash and carbon slurry as adsorbents respectively. Hence both bagasse fly ash and carbon slurry have good adsorptive capacity. for pyridine and 3-picoline. For activated carbon, 100 percent removal was obtained. Adsorptive capacities were found to be in the order : activated carbon > carbon slurry > bagasse fly ash. Kinetics of removal has been also presented. Adsorption was found to follow first order kinetics. Weber and Morris plot has also been used for intra-particle diffusion. Two stage batch adsorption (using bagasse fly ash and carbon slurry) was conducted. For BFA-pyridine system, 85 percent removal and for CS-pyridine system, 100 percent removal was obtained. Column studies were also conducted for the removal of pyricline,.using bagasse fly ash as adsorbent. BAST model was used to analyse the column data.