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.

Bioplastic has been widely studied in the past decades as a replacement for non-biodegradable and non-environmentally friendly plastic. One of the promising materials to produce bioplastic is cellulose. However, it is rarely used as the main component for bioplastic production. This study reports a facile process to prepare bioplastic using the pure cellulose content of Cladophora sp. algae via the hydrogel method. The effect of epichlorohydrin (ECH) concentrations as the cross-linking agent was investigated toward the biodegradability, thermal, and mechanical properties of the cellulose bioplastic obtained. The results showed that ECH concentrations affected the properties of the cellulose bioplastic produced due to the number of cross-links formed during the process. The cellulose bioplastic possessed relatively high thermal and mechanical properties. The cellulose bioplastic performed excellent biodegradability, as it was degraded by more than 40% within five days. Thus, the cellulose of Cladophora sp. algae has the potential to be developed as the main component for bioplastic application.

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Prekursor serat karbon merupakan bahan baku yang digunakan dalam pembuatan serat karbon dan menghabiskan sekitar 51% dari total biaya produksi serat karbon. Lignin merupakan polimer hayati paling melimpah kedua di bumi dan sangat potensial untuk dimanfaatkan menjadi prekursor serat karbon karena memiliki kandungan karbon yang tinggi mencapai 68%. Pada penelitian ini, dilakukan pembuatan prekursor serat karbon yang berbahan dasar lignin hasil pengolahan limbah black liquor. Lignin diekstraksi dari limbah black liquor dengan menggunakan metode asidifikasi. Lignin yang telah diekstraksi selanjutnya dicampur dengan polivinil alkohol (PVA) dengan variasi konsentrasi sebesar 0%, 10%, 20%, 30%, 40%, 50% (w/w) menggunakan metode wet spinning. Pengujian tarik serat lignin/PVA dilakukan dengan mengacu pada standar ASTM D-3882. Karakterisasi SEM dilakukan untuk mengetahui morfologi serat yang dihasilkan. Karakterisasi TGA dilakukan untuk mengetahui sifat termal dan carbon yield dari serat lignin/PVA. Berdasarkan hasil pengujian yang dilakukan, kekuatan serat lignin tertinggi yang dihasilkan adalah sebesar 633,29 MPa yang diperoleh oleh serat lignin/PVA dengan konsentrasi lignin sebesar 50%. Makin tinggi kandungan lignin akan menghasilkan serat lignin dengan kekuatan tarik dan ketahanan termal yang makin tinggi pula. Berdasarkan hasil pengujian yang telah dilakukan dapat disimpulkan bahwa serat lignin/PVA yang dihasilkan sangat berpotensi untuk dimanfaatkan sebagai prekursor serat karbon.Kata kunci: black liquor, ekstraksi, lignin, prekursor serat karbon, serat lignin