Abstract
Lignin isolated from black liquor waste was studied in this research to be utilized as binderless, all-lignin briquette, with a calorific value in the range of 5670–5876 kcal/kg. Isolation of lignin from black liquor was conducted using the acid precipitation method. Sulfuric acid, citric acid, and acetic acid were used to maintain the pH level, which varied from 5 to 2 for the precipitation process. The influence of these isolation conditions on the characteristic of lignin and the properties of the resulted briquette was evaluated through the Klasson method, proximate analysis, ultimate analysis, Fourier Transform Infrared (FTIR), adiabatic bomb calorimeter, density measurement, and Drop Shatter Index (DSI) testing. The finding showed that the lignin isolated using citric acid maintained to pH 3 resulted in briquette with 72% fixed carbon content, excellent 99.7% DSI, and a calorific value equivalent to coal-based briquette.
Highlights
Inevitable depletion of non-renewable and limited fossil fuel in the future, such as petroleum, coal, natural gas, etc., is an issue, since 80% of world’s energy generation was still dependent on the utilization of these fossil fuels [1,2,3]
Lignin could be obtained through extraction from plants or the more readily available black liquor
Lignin, which is usually used as the binder, should be capable of being compacted into an all-lignin, binderless briquette
Summary
Inevitable depletion of non-renewable and limited fossil fuel in the future, such as petroleum, coal, natural gas, etc., is an issue, since 80% of world’s energy generation was still dependent on the utilization of these fossil fuels [1,2,3]. This is because the addition of inorganic substances tends to increase the ash content and burn out temperature, and reduces the calorific value of the resulted briquette [1,26] Despite their flexibility, binder-based briquettes have some disadvantages such as non-uniform combustion properties and decrease in compacting properties at high temperatures, as the influence of different thermal behavior between the binder and fuel material [19,20]. Lignin, which is usually used as the binder, should be capable of being compacted into an all-lignin, binderless briquette This capability was possible since it has both significant properties as fuel and the ability to bind with each other through a hydrogen bond, which is contributed from the hydroxy group (-OH) in lignin.
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