Polycyclic Aromatic Hydrocarbons in Smokes of Two Biomasses Used For Domestic Cooking In Nigeria

Abstract

Domestic cooking of foods is predominantly carried out in Nigeria through the burning of different types of biomass. Smoke resulting from such burning in most cases is been inhaled by people in the immediate environment where the cooking exercise is taking place. Where incomplete combustion occurs, the smoke may carry some products of incomplete combustion; prominent among these are polycyclic aromatic hydrocarbons (PAHs). Some of these PAHs have been implicated for various health challenges such as cancer. Incomplete combustion of fuels is known to generate PAHs. Smokes from some biomasses have also been established to contain some PAHs.This group of organic compounds is of global environmental concern. The composition and concentration of PAHs in the smokes of two biomasses used in domestic cooking in Nigeria were determined. For this purpose, a pyrolytic unit was fabricated and used for the pyrolysis of Wood Charcoal (WC) and Palm Kernel Shell (PKS). Gases resulting from their pyrolysis were collected and analyzed using Gas Chromatography (GC). The results of GC analysis showed that the composition and concentration of PAHs in gas obtained from the pyrolysis of WC were; Acenaphthene (0.218µg/cm³), Fluorene (0.573 µg/cm³), Phenanthrene (13.305 µg/cm³), Anthracene (0.552 µg/cm³), Fluoranthene (9.069 µg/cm³), Pyrene (8.677 µg/cm³), Benzo(a)anthracene (0.660 µg/cm³), Chrysene (0.660 µg/cm³), Benzo(b)Fluorene (0.593 µg/cm³) and Benzo(k)fluoranthene (0.853 µg/cm³). While the composition  and concentration of PAHs in gas obtained from the pyrolysis of PKS were; Acenaphthene (0.208 µg/cm³), Fluorene (0.567 µg/cm³), Phenanthrene (14.190 µg/cm³), Anthracene (0.527 µg/cm³), Fluoranthene (11.808 µg/cm³), Pyrene (9.794 µg/cm³), Benzo(a)anthracene (0.448 µg/cm³), Chrysene (0.415 µg/cm³), Benzo(b)Fluoranthene (0.346 µg/cm³) and Benzo(k)fluoranthene (0.215 µg/cm³). Source diagnostic ratios calculated for the PAHs found in the pyrolytic gases of the biomasses showed that these PAHs were of pyrogenic origin, thus confirming that they were generated from the pyrolysis of WC and PKS

Key words: Biomass, pyrolysis, GC, Smoke and PAHs