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

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 PAH

Investigation Of The Suitability Of Polyphosphoric Acid In Reducing The Degree Of Thermal Aging Of Agabu Natural Bitumen

Bitumen otherwise known as asphalt is a complex mixture of hydrocarbons which are naturally occurring or obtained from crude oil distillation. Bitumen when used as a binder in road pavement deteriorates with time as result of traffic load and contact of the pavement with environmental factors. The degradation of bitumen causes a rapid aging of the asphalt based pavement leading to road problems such as rutting, potholes etc. This deterioration is attributed to oxidative degradation of molecules of bitumen by factors such as heat, moisture and sunlight. This study investigates the viability of using polyphosphoric acid (PPA) to reduce the oxidative degradation effect of heat (at 60oC) on constituents of Agbabu Natural Bitumen (ANB) with a view to making it more durable when used for road pavement. Modification of ANB with PPA was carried out at 160oC using melt blend technique. Thereafter, the PPA modified and neat ANB samples were thermally aged in a hot air oven at 60oC. Fourier Transform Infrared (FTIR) Spectroscopy was used to validate the changes in the structure of ANB and aging indexes of neat and PPA modified samples of ANB calculated. The result showed that aging indexes of PPA modified samples of ANB were lower compared with that of the neat or unmodified samples of ANB. This implies that the rate of aging (at 60oC) of the unmodified ANB was faster than that of PPA modified ANB. Thus, a good potential for reducing thermal aging in ANB was found in PPA

Efficacy of Polyphosphoric Acid in Reducing the Degree of Thermal Aging of Agbabu Natural Bitumen

Bitumen is a complex mixture of hydrocarbons which occurred naturally or obtained from crude oil distillation. The degradation of bitumen causes its rapid aging leading to deterioration of asphalt based pavement readily induced by cracking, rutting, potholes etc. Aging in bitumen is attributed to chemical oxidation of its molecules and exposure to environmental factors, such as heat, moisture and sunlight. This study therefore investigates the viability of using polyphosphoric acid (PPA) to reduce the oxidative degradation effect of heat (60 o C) on constituents of Agbabu natural bitumen (ANB) with a view to making it more durable when used for road pavement. Modification of ANB with PPA was carried out at 150-55 o C using melt blend technique. Thereafter, the PPA modified and neat (unmodified) ANB samples were thermally aged in a hot air oven at 60 o C. Fourier Transform Infrared (FTIR) Spectroscopy was used to evaluate the changes in the structure of ANB and aging indexes of neat and PPA modified samples of ANB were calculated. The neat and PPA modified ANB samples aged as a result of their exposure to temperature at 60 o C. However, the aging indexes of PPA modified samples of ANB were found to be lower compared with that of the neat sample of ANB. This implies that the rate of aging (60 o C) of the neat ANB was faster than that of PPA modified ANB samples. Thus, a good potential for reducing thermal aging in ANB was found in PPA

Proximate Analysis and Polycyclic Aromatic Hydrocarbon Levels in Some Selected Raw Food Stuffs in Aroje and Owode, Nigeria.

Some studies have shown that accumulation of polycyclic aromatic hydrocarbons (PAHs) in soil has the potential of contaminating the food chain. PAHs are complex organic compounds, many of which have been implicated for many health challenges. Information on the levels of PAHs in raw food in Nigeria is very scanty. Thus, an investigation into the levels of PAHs in some raw foods is of great importance from medical and environmental point of view. This study examined some proximate analysis parameters and levels of PAHs in raw cassava, yam, tomatoes, pineapple and maize and levels of PAHs in soil where these raw foods stuffs were collected. The samples were collected from two agrarian towns: Aroje and Owode in Oyo and Osun states, Nigeria. The proximate analysis was carried out according to the methods of Association of Official Agricultural Chemists (AOAC), while PAHs were determined using Gas chromatography-flame ionization detector (GC-FID). The results of proximate analysis for ash, moisture, protein, fat, fibre and carbohydrate ranged from 0.31-1.22%, 13.10-93.48%, 0.41- 9.00%, 0.27- 3.10%, 3.38-73.1% and 1.26-4.10% respectively. The concentration of total PAHs in the food samples are: Cassava (0.19571µg/Kg), Yam (0.15536 µg /kg), Tomatoes (0.02350 µg /kg), Pineapple (0.00753µg/kg) and maize (0.13718µg/kg) for Aroje and Cassava (0.20958µg/kg), Yam (0.16951µg/kg), Tomatoes (0.02408µg/kg), Pineapple (0.00752µg/kg) and Maize (0.13734µg/kg) for Owode. The average concentrations of total PAH in Aroje and Owode soils are 4.33583 and 4.37730 µg/kg respectively. The source diagnostic indices calculated showed that the PAHs in the samples were from pyrolytic source and there exists a correlation between some PAHS and total PAHS in the soil where the foodstuffs were cultivated. Key words: Proximate Analysis, PAHs, Foods, Gas Chromatograph

Characterisation of Agbabu Natural Bitumen and Its Fractions Using Fourier Transform Infrared Spectrometry

Physico-chemical characterization of bitumen is very germane to its applications. There have been many physico-chemical investigations on Agbabu natural bitumen (ANB), but there appears to be some discrepancies in the results of some of the findings. Thus, the need to re-examine some of the physico-chemical parameters of the ANB. Raw sample of ANB was obtained from one of the observatory wells in Agbabu, Ondo State, Nigeria. The sample was dehydrated, purified and asphaltene component precipitated through addition of n-pentane to the sample. The maltene component was fractionated into saturate, aromatics and resin using column chromatographic method. The purified ANB sample and its fractions were each subjected to infrared analysis. In addition, the elemental composition and trace metals in the whole purified ANB were quantified using CHNS-O Analyzer (FlashEA® 1112) and Atomic Absorption Spectrometer (AAS) respectively. Infrared spectral features obtained for the whole bitumen and its fractions bear a good degree of resemblance to the results of earlier workers on the subject with some minor differences. The values obtained for structural indexes from Infrared (IR) spectra showed that all the fractions contained branch and straight chain hydrocarbons. The structural indexes also showed that asphaltenes and resin fractions are strongly polar, both of which contain hetero–atomic compounds. Results of compositional analysis are: C (86.62%), H(10.98%), S (0.92%) N (0.48%), O (0.83%), Maltene (78.34%) aand Asphaltene (21.67%). The concentrations of the trace metals are: Mg (792.00 ppm), Mn (28.40 ppm), Fe (3633.10 ppm), Ca (1082.10 ppm), Zn (17.50 ppm), Cu (17.90 ppm), Cr (153.90 ppm), Pb (93.78 ppm), Ni (103.65 ppm), V (156.53 ppm) and Na (3740.00 ppm). Results of compositional and trace metals analyses of this study are at variance with the earlier results on characterization of ANB in the literatures. The differences in the results might be attributed to variation in the method of sample preparation especially the inclusion of dehydration of the raw ANB in the purification step prior to characterization as introduced in this study. Keywords: Aromatics, Asphaltenes, Agbabu Natural Bitumen, IR, Resins, Saturate

Compositional Changes in Aliphatic and Aromatic Fractions of Agbabu Natural Bitumen under Low Temperature Heating

ABSTRACT The compositions of aliphatic and polycyclic aromatic hydrocarbons in Agbabu natural bitumen (ANB) sample subjected to heating at low temperatures were examined. The raw flow type of ANB was obtained from the observatory well in Agbabu, and subsequently purified. The purified sample was divided and each division heated in an air oven for five hours at a specific temperature. The heated samples were cooled, separated and their aliphatic and polycyclic aromatic hydrocarbons contents were quantified using gas chromatograh coupled with flame ionization detector (GC-FID). The total aliphatic hydrocarbons (TALPH) found in the unheated sample of the bitumen was 484 g/kg, but samples subjected to heating at 50 70, 90,100, 110,120 and 140 o C contained 484, 467 , 462 , 420, 414, 388 and 350 g/Kg respectively. Similarly, the total polycyclic aromatic hydrocarbons (TPAHs) in the control sample was 708 µg/g while samples heated at 50, 70, 90, 100, 110,120, 140 and 160 o C contained 600, 523, 387, 307, 245, 213, 168 and 689 ug/g respectively. Distribution of these hydrocarbon compounds in the unheated sample was at variance with what was found in the heated samples. This implies that exposure of ANB to heating at low temperatures is sufficient enough to qualitatively and quantitatively alter the composition of the aliphatic and polycyclic aromatic hydrocarbons of the bitumen

Efficacy of Polyphosphoric Acid in Reducing the Degree of Thermal Aging of Agbabu Natural Bitumen

Bitumen is a complex mixture of hydrocarbons which occurred naturally or obtained from crude oil distillation. The degradation of bitumen causes its rapid aging leading to deterioration of asphalt based pavement readily induced by cracking, rutting, potholes etc. Aging in bitumen is attributed to chemical oxidation of its molecules and exposure to environmental factors, such as heat, moisture and sunlight. This study therefore investigates the viability of using polyphosphoric acid (PPA) to reduce the oxidative degradation effect of heat (60 o C) on constituents of Agbabu natural bitumen (ANB) with a view to making it more durable when used for road pavement. Modification of ANB with PPA was carried out at 150-55 o C using melt blend technique. Thereafter, the PPA modified and neat (unmodified) ANB samples were thermally aged in a hot air oven at 60 o C. Fourier Transform Infrared (FTIR) Spectroscopy was used to evaluate the changes in the structure of ANB and aging indexes of neat and PPA modified samples of ANB were calculated. The neat and PPA modified ANB samples aged as a result of their exposure to temperature at 60 o C. However, the aging indexes of PPA modified samples of ANB were found to be lower compared with that of the neat sample of ANB. This implies that the rate of aging (60 o C) of the neat ANB was faster than that of PPA modified ANB samples. Thus, a good potential for reducing thermal aging in ANB was found in PPA

Biodegradation of hydrocarbon compounds in Agbabu natural bitumen

The recovery of an environment polluted by petroleum and allied hydrocarbons through bioremediation is being embraced globally as the best technology of removing hydrocarbon pollutants from environment. Infrared spectral changes and gravimetric analysis from the preliminary biodegradability study carried out on Agbabu Natural Bitumen showed the vulnerability of the bitumen to some bacteria: Pseudomonas putrefaciens, Pseudomonas nigrificans, Bacillus licheniformis, Pseudomonas fragi and Achromobacter aerogenes. This study investigates the ability of P. putrefaciens, P. nigrificans, B. licheniformis, P. fragi and A. aerogenes to degrade the aliphatic and polycyclic aromatic hydrocarbon fractions of Agbabu natural bitumen. Samples of the bitumen were separately inoculated with each of the bacteria for 14 days and the hydrocarbon profiles before and after inoculation were quantified using gas chromatography technique. The total aliphatic hydrocarbon compounds (C11 - C29) in the bitumen degraded by P. putrefaciens and P. nigrificans was slightly higher than that in the undegraded bitumen, while the concentration of compounds (C11 - C29) found in samples of the bitumen degraded by B. licheniformis, P. fragi and A. aerogenes was less than what was contained in the undegraded bitumen. Also the even-odd carbon-ratios of the degraded bitumen were higher than unity while these were less than unity in the undegraded bitumen. The polycyclic aromatic hydrocarbons (PAHs) profile in the bitumen degraded samples also differed from that of undegraded bitumen. A substantial reduction in the concentration of some PAHs was found in the bitumen samples following their degradation by the bacteria strains, typically from 55.98 to 30.79%, thus suggesting the possibility of using the bacteria strains for bioremediation process.Keywords: Agbabu, bitumen, bacteria, biodegradability, hydrocarbonsAfrican Journal of Biotechnology, Vol 13(11), 1257-126