Evaluation of apricot (Prunus armeniaca L.) seed kernel as a potential feedstock for the production of liquid bio-fuels and activated carbons

Abstract

Production of liquid bio-fuels (biodiesel and bio-oil) as well as activated carbon from one non-edible feedstock, apricot (Prunus armeniaca L.) seed kernel was the main objective of the present research work. The oil was extracted from apricot seed kernel with a yield of 49.44% w/w of kernels. Potassium hydroxide-catalyzed transesterification of apricot (Prunus armeniaca L.) seed kernel oil with methanol and ethanol was then applied to produce methylic and ethylic, respectively. Properties of the obtained biodiesels were evaluated and found conformed to ASTM D 6751 limits. The apricot de-oiled seed kernel was pyrolyzed in a semi-batch reactor for bio-oil production. The effect of the pyrolysis temperatures (350, 400, 450, 500, 550 and 600°C), pyrolysis time (30, 60, 90, 120 and 150min) and feed particles size (0.25, 0.40, 0.59 and 0.84mm) on the bio-oil yield was investigated. The maximum production of bio-oil (43.66% w/w) was achieved at a pyrolysis temperature of 450°C, 60min pyrolysis time and a feed particles size of 0.25mm. The bio-oil obtained under the optimal conditions was characterized by the elemental analysis, FTIR spectroscopy and column chromatography. The FTIR analysis of the produced bio-fuel indicated that it composes mainly of alkanes, alkenes, ketones, carboxylic acids and amines. Properties of the resulting bio-oil were analyzed in terms of calorific value, density, flash point, pH, acid value, pour point and refractive index. The properties were close to those of petroleum fractions and comparable to those of other bio-oils published in literature. Referring to the experimental results, the obtained bio-oil can be utilized as an important source of alternative fuel and chemicals. The chemical activation method by using sodium hydroxide as the activating agent was utilized to convert the bio-char into activated carbon. The effect of the process parameters including the activation temperatures (400, 500, 600, 700 and 800°C), activation time (30, 60, 90, 120 and 150 min) and feed particles size (20, 30, 40 and 60 mesh size) on the yield, iodine adsorption number and surface area of the obtained activated carbons were investigated. The optimal activated carbon sample was obtained at 600°C activation temperature, 90min activation time and a feed size of 60 mesh. The resulting activated carbon showed good characteristics to be used as adsorbent in water purification as indicated by scanning electron microscope and FTIR spectroscopy.