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“…Residual asphalts obtained from 25 samples of Nigerian light, medium, and heavy crude oils were chemically treated by air-oxidation and sulfurization (Oyekunle and Onyehanere, 1990, 1991a, 1991bOyekunle and Adesanya, 2000;Oyekunle and Onwa, 2000;Oyekunle et al, 2004). The chemical treatment brought about changes in chemical composition, manifold increases in asphaltene content, and more than a 20% rise in softening point.…”
Section: Previous Studies On Asphaltsmentioning
“…Oyekunle and others [5, [46][47][48][49][50][51][52][53][54][55][56][57][58][59] have carried out various studies on the physical characteristics and chemical composition of asphalts. Investigation of the residual asphalts produced from twenty-three Nigerian crude oil samples revealed that these asphalts have low asphaltene contents (1.52 -6.0 wt.%) with softening points varying between 25-66.5°C (R & B) and penetration values of 26-300 (0.1 mm) and above at 25°C [46,48,58].…”
Section: Previous Studies On Asphaltsmentioning
“…Craig (1980) obtained asphalt yields of 22-wt% and 27-wt% from Adibawa and Agbada crudes respectively. Oyekunle and others (Oyekunle, 1982;Oyekunle and Adesanya, 2000a;Oyekunle and Onwa, 2000b;Onyehasere, 1990, 1991) have carried out some basic studies on residual asphalts including catalytic treatments and kinetic studies. Oyekunle and others (Oyekunle, 1982;Oyekunle and Adesanya, 2000a;Oyekunle and Onwa, 2000b;Onyehasere, 1990, 1991) have carried out some basic studies on residual asphalts including catalytic treatments and kinetic studies.…”
Section: Previous Studies On Nigerian Crude Oils For Asphalt Productionmentioning
“…To meet these requirements, special grades are manufactured by treating the straight run residual asphalt by various means. Some of the methods used include the conventional air-blowing, which is used extensively to alter the chemical composition and improve its rheological properties via oxidation (Gun, 1973;Hobson and Pohl, 1973;Oyekunle and Adesanya, 2000;Oyekunle and Omatsone, 2004). Correspondingly, the controlled addition of elemental sulphur to residual asphalts also resulted in chemical 252 L. O.…”
Section: Introductionmentioning
“…The API gravities of the mainstream Nigerian crudes range from 25.5 for Bonny Medium to 39.8 for Brass (Coker, 1982). Some preliminary studies have been carried out (Egbuna, 1977;Obiaga et al, 1982;Oyekunle and Adesanya, 2000;Oyekunle and Onwa, 2000;Oyekunle and Onyehanere, 1991). The low sulfur content of Nigerian crude oils is very desirable, as high sulfur crudes require special processes for sulfur removal.…”
Section: Introductionmentioning