Biomass is one of the most significant alternative sources of clean renewable energy, which is generated through the pyrolysis of organic material. Both industry and the environment benefit from this thermochemical conversion of biomass material to renowned biofuel and valuable chemicals through the pyrolysis process that could be used as a substitute for fossil fuels. Pyrolysis is the most fundamental process in the thermal chemical conversion of biomass; hence pyrolysis kinetic analysis is helpful for a thorough investigation of the process mechanisms. Pumpkin seeds are produced as agricultural waste in massive amounts as only a small fraction is used for cultivation, and were selected to be examined and studied using thermal analysis and thermal kinetics as a biomass agriculture waste source, that can produce biochar considered a valuable renewable energy source, as well as a potential adsorbing material.
In this work, pumpkin seeds were first dried and then ground to fine particle size. The waste was then subjected to thermal pyrolysis under a constant inert atmosphere flow rate, at four different heating rates 5, 10, 15, and 20 oC.min-1. The TG-DTG curves indicated a significant weight loss followed by biochar formation. The kinetics of biochar formation was studied using three different iso-conversional methods: the Kissinger-Asahira-Sunoze (KAS), the Flynn-Wall-Ozawa (FWO), and the Friedman method. The values of activation energies obtained by the different methods were comparably ranging from about 104 to 116 kJ.mol-1. Determination of the calorific values of the dry biowaste yielded a value of 16,080 kJ.kg-1.