Publication: Experimental investigation of microalgae pyrolysis : kinetics, thermodynamics, and product characterization
Abstract
Mikroalg pirolizinin deneysel yöntemle incelemesi : kinetik, termodinamik ve ürün karakterizasyonu Fosil yakıtların tükenmesi ve artan çevresel problemler, sürdürülebilir enerji kaynaklarının arayışını hızlandırmıştır. Özellikle Chlorella vulgaris gibi mikroalgler; hızlı büyüme, yüksek fotosentetik verim ve zengin biyokimyasal bileşimleriyle biyoyakıt üretimi için umut verici biyokütle kaynaklarıdır. Bu tez çalışması kapsamında, C. vulgaris’in piroliz süreci detaylı olarak incelenmiş, termal bozunma davranışı, kinetik parametreleri ve sürdürülebilir enerji ürünleri olan biyochar ile biyoyakıt üretim potansiyeli değerlendirilmiştir. Termogravimetrik analiz sonuçları, aktif piroliz işleminin 200–500 °C aralığında gerçekleştiğini ve bu sıcaklık aralığında önemli miktarda uçucu bileşiklerin açığa çıktığını göstermiştir. Analiz sonuçları, elde edilen biyocharın belirgin şekilde artmış karbon içeriğine (%80,8), geniş yüzey alanına (161,3 m²/ g) ve yüksek ısıl değere (31,6 MJ/ kg) sahip olduğunu göstermiştir. Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose, Starink ve Tang gibi model-free yöntemlerle kullanılarak yapılan hesaplamalar sonucunda ortalama aktivasyon enerjisi 140 kJ/ mol olarak hesaplanmıştır. Termodinamik değerlendirmeler, sürecin endotermik ve kendiliğinden gerçekleşmeyen bir yapıda olduğunu göstermiştir. TGA-FTIR-MS analizi sonucunda başlıca gaz ürünler CO2, H2O ve CH4 olarak belirlenmiştir. Box–Behnken deney tasarımı optimizasyonu sonucunda, biyoyakıt verimini artırmada en etkili parametrenin ısıtma hızı olduğu tespit edilmiş ve optimum koşullar altında sıvı ürün verimi %32,08 olarak elde edilmiştir.
Experimental investigation of microalgae pyrolysis : kinetics, thermodynamics, and product characterization The search for renewable energy sources is growing as fossil fuels run out and environmental problems become more prominent. Microalgae, especially Chlorella vulgaris, are great sources of biomass for making biofuels because they grow quickly, photosynthesize better, and have complex metabolic systems. This thesis performed an extensive analysis of the pyrolysis process of C. vulgaris, evaluating its thermal degradation properties, kinetic parameters, and the potential of biochar and bio-oil as sustainable energy sources. Thermogravimetric analysis indicates that active pyrolysis occurs between 200 and 500 °C, during which several volatile compounds are released. The investigation revealed that the biochar contains a significant carbon content (80.8%), an extensive surface area (161.3 m²/ g), and an elevated calorific value (31.6 MJ/ kg). The average activation energy was determined to be 140 kJ/ mol using model-free techniques, specifically the Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose, Starink, and Tang methods. Thermodynamic assessments demonstrated that the process was endothermic and non-spontaneous. Gaseous products such as CO2, H2O, and CH4 were identified via TGA-FTIR-MS. Process optimization using the Box–Behnken design identified heating rate as the most influential factor for maximizing bio-oil yield, achieving a maximum yield of 32.08 wt% under optimal conditions. In conclusion, the present study suggested that C. vulgaris appeared to be a promising renewable biomass for biofuel production using pyrolysis technology.
Experimental investigation of microalgae pyrolysis : kinetics, thermodynamics, and product characterization The search for renewable energy sources is growing as fossil fuels run out and environmental problems become more prominent. Microalgae, especially Chlorella vulgaris, are great sources of biomass for making biofuels because they grow quickly, photosynthesize better, and have complex metabolic systems. This thesis performed an extensive analysis of the pyrolysis process of C. vulgaris, evaluating its thermal degradation properties, kinetic parameters, and the potential of biochar and bio-oil as sustainable energy sources. Thermogravimetric analysis indicates that active pyrolysis occurs between 200 and 500 °C, during which several volatile compounds are released. The investigation revealed that the biochar contains a significant carbon content (80.8%), an extensive surface area (161.3 m²/ g), and an elevated calorific value (31.6 MJ/ kg). The average activation energy was determined to be 140 kJ/ mol using model-free techniques, specifically the Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose, Starink, and Tang methods. Thermodynamic assessments demonstrated that the process was endothermic and non-spontaneous. Gaseous products such as CO2, H2O, and CH4 were identified via TGA-FTIR-MS. Process optimization using the Box–Behnken design identified heating rate as the most influential factor for maximizing bio-oil yield, achieving a maximum yield of 32.08 wt% under optimal conditions. In conclusion, the present study suggested that C. vulgaris appeared to be a promising renewable biomass for biofuel production using pyrolysis technology.