Valorization of spent coffee grounds recycling as a potential alternative fuel resource in Turkey: An experimental study

Atabani A., Mercimek S., Arvindnarayan S., Shobana S., Kumar G., Çadir M., ...More

Journal of the Air and Waste Management Association, vol.68, pp.196-214, 2018 (SCI-Expanded) identifier identifier identifier


In this study, recycling of spent coffee ground (SCG) as a potential feedstock for alternative fuels production and compounds of added value in Turkey was assessed. SCG samples were collected from various coffee shops in Kayseri, Turkey. All samples were dried to free them from moisture content. Coffee waste oil was extracted from the dried samples using n-hexane as a solvent. The average oil content was found (≈ 13% w/w). All samples (before and after extraction) were tested for SEM, DSC, TGA, XRD, calorific value, surface analysis and porosity, FT-IR and elemental analysis to assess their potential. Elemental analysis indicated that carbon represents the highest percentage (49.59% and 46.42% respectively), followed by Nitrogen (16.7% and 15.5%), Hydrogen (6.74% and 6.04%) and Sulfur (0.851% and 0.561%). These results indicate that coffee waste can be utilized as compost as it is rich in nitrogen. Properties of the extracted oil were examined, followed by biodiesel production. The quality of biodiesel was compared with ASTM D6751 standards and all the properties complied with standard specifications. The fatty acid compositions were analyzed by Gas chromatography. It is observed that coffee waste methyl ester (CWME) is mainly comprised of palmitic (35.8%) and arachidic (44.6%) acids which are saturated fatty acids. The low degree of unsaturation provides an excellent oxidation stability (10.4 h). CWME has also excellent cetane number, higher heating value and iodine value with poor cold flow properties. The studies also investigated blending of biodiesel with euro diesel and butanol. Following this, a remarkable improvement in cloud and pour points of biodiesel was obtained. Coffee waste after oil extraction is an ideal material for garden fertilizer, feedstock for ethanol, biogas production and as fuel pellets. The outcome of such research work produces valuable insights on the recycling importance of coffee waste in Turkey