Comparison of Calorific Value and Proximate Properties of Coconut Shell Charcoal and Rubber Tires

Abstrak

The energy availability crisis that is a global challenge and the increasing amount of organic and inorganic waste encourage the need for renewable energy development by utilizing the availability of waste. This study aims to compare the thermal characteristics and calorific value of coconut shell waste and waste rubber tires as potential raw materials for renewable energy. In this study using Thermogravimetric Analysis (TGA) method, Derivative Thermogravimetric Analysis (DTG) using thermal analyzer (Simultaneous Thermogravimetric Analyzer) with STA7000 series produced by Hitachi Ltd. (Tokyo, Japan), calorific value test using bomb calorimeter and surface morphology observation using Scanning Electron Microscopy (SEM). Both materials were tested after pyrolysis using microwave pyrolysis technology at 450˚C. The results indicated that coconut shell charcoal had higher water and volatile matter contents of 7.77% and 74.82%, respectively, while rubber tire charcoal only recorded water content of 1.53% and volatile matter of 64.53%. Nonetheless, coconut shell showed better thermal stability, characterized by a Tmax value reaching 325°C. In contrast, tire rubber charcoal showed greater solid residue production and a higher heating value of 6,628 cal/g, which correlated with the high content of carbon, resin and hydrocarbon compounds in the material. Based on analysis using Scanning Electron Microscopy (SEM), coconut shell charcoal showed a finer and more evenly distributed pore structure, while tire rubber charcoal had a denser and more complex surface morphology. Keywords: Coconut shell, Tire rubber, Calorific value, Thermal analysis, Renewable energy