Judul: Depolimerisasi Lignin dari Limbah Jerami Padi (Oryza sativa) Menggunakan Katalis Ni/GQDs
Abstrak: Lignin yang diisolasi dari limbah jerami padi didepolimerisasi menjadi monomernya untuk meningkatkan reaktivitasnya. Proses depolimerisasi lignin dibantu oleh katalis berbasis nikel untuk menghasilkan monomer yang mengandung situs aktif. Logam berbasis nikel memiliki aktivitas katalitik yang baik, terutama dengan adanya material penyangga yang dapat mencegah agregasi dan meningkatkan aktivitas katalitik logam. Aktivitas katalitik nikel dengan Graphene Quantum Dots (GQDs) sebagai penyangga belum pernah dilaporkan sebelumnya. Peningkatan aktivitas katalitik nikel oleh GQD disebabkan karena sifat donor dan akseptor elektron yang baik serta luas permukaan yang besar. Penelitian ini bertujuan untuk menghitung rendemen lignin yang diisolasi dari limbah jerami padi dan mengidentifikasi monomer hasil reaksi depolimerisasi. Lignin diisolasi dari limbah dengan metode organosolv, yang kemudian direaksikan dengan katalis yang disintesis dalam autoclave reactor. Penyangga disintesis menggunakan metode Hummer yang dimodifikasi. Penelitian ini menghasilkan lignin dengan rendemen 15%. GQD hasil sintesis memiliki pendaran berwarna hijau kebiruan pada panjang gelombang 366 nm, yang stabil dalam bentuk koloid tanpa agregasi. Katalis yang disintesis memiliki sifat kemagnetan yang baik, sehingga pemisahan katalis dari lignin yang tidak terkonversi dapat dilakukan secara efisien dengan menggunakan magnet. Katalis memiliki aktivitas yang baik dalam menghasilkan unit-unit penyusun lignin, seperti siringil (S), guaiasil (G), p-hidroksifenil (H), dan alkil benzena (AB), dan dimer (D) dengan % yield yang relatif sama setelah digunakan berulang kali., Lignin isolated from rice straw waste was depolymerized into its monomer to increase its reactivity. The lignin depolymerization process is assisted by a nickel-based catalyst to produce monomers containing an active site. Nickel-based metals have good catalytic activity, especially with the presence of supporting material that can prevent aggregation and increase the catalytic activity of metals. The catalytic activity of nickel with Graphene Quantum Dots (GQDs) as a supporting material has never been reported. The increased in catalytic activity of nickel by GQDs is due to its good donor and electron acceptor properties and a large surface area. This study aims to calculate the yield of lignin isolated from rice straw waste and to identify monomers resulting from depolymerization reactions. Lignin was isolated from the waste by the organosolv method, which then reacted with the synthesized catalyst in an autoclave reactor. The supporting material was synthesized using the modified Hummer method. This study produced lignin with a yield of 15%. The synthesized GQDs have a bluish-green luminescence at a wavelength of 366 nm, which is stable in a colloidal form without aggregation. The synthesized catalyst has good magnetic properties, so separating the catalyst from unconverted lignin can be efficiently done using magnets. Catalysts have good activity in producing lignin constituent units, such as syringyl (S), guaiacyl (G), p-hydroxyphenyl (H), and alkyl benzene (AB), and dimers (D) with relatively the same % yield after repeated use.
Keyword: catalyst, depolymerization, Ni/GQDs, organosolv lignin, rice straw

Judul: Utilization of Lignin from Black Liquor of Waste Paper Industry as Antimicrobial in Food Packaging
Abstrak: Lignin merupakan polimer kimia alami yang belum dimanfaatkan dengan baik dan berpotensi sebagai agen antimikroba karena mengandung senyawa fenolik. Tujuan penelitian ini memanfaatkan lignin dari lindi hitam sebagai agen antimikroba yang diaplikaskan pada biofilm untuk kemasan pangan. Lignin diperoleh dari proses isolasi lindi hitam menggunakan asam encer melalui enam kali pencucian. Lignin hasil isolasi dilakukan pengujian karakteristik fisik, seperti kadar air, kadar abu, kadar kemurnian lignin, FTIR, DSC, TGA, dan aktivitas antimikroba. Biofilm lignin diuji karakteristik fisik, mekanik, dan aktivitas antimikroba. Hasil penelitian menunjukkan rendemen isolat lignin 34,45%. Kadar air lignin sebesar 10,28%, dan kadar abu sekitar 1.06%, dengan kadar kemurnian lignin 103,49%. Degradasi termal lignin terjadi pada suhu 340 oC, dan Tg 2 terjadi pada suhu 166 oC. Karakteristik gugus fungsi lignin yaitu terdapat senyawa fenolik-siringil, guaiasil, dan eter. Aktivitas antimikroba lignin yang terbaik yaitu pada konsentrasi 0.1 g/mL dengan pelarut ethanol-air dan 0.4 g/mL dengan DMSO. Biofilm lignin rheomix pada konsentrasi 2% secara keseluruhan memiliki karakteristik fisik dan mekanik, serta dapat menghambat pertumbuhan bakteri uji yang lebih baik dibanding metode pelarutan., Lignin is a natural chemical polymer that has not been utilized properly and has the potential as an antimicrobial agent because it contains phenolic compounds. The purpose of this study was to utilize lignin from black liquor as an antimicrobial agent which was applied to biofilms for food packaging. Lignin was obtained from the black liquor isolation process using dilute acid through six washings. The isolated lignin was tested for physical characteristics, such as moisture content, ash content, lignin purity, FTIR, DSC, TGA, and antimicrobial activity. Lignin biofilms were tested for physical, mechanical, and antimicrobial activity characteristics. The results showed that the lignin isolate yield was 34.45%. The lignin water content is 10.28%, and the ash content is about 1.06%, with a lignin purity level of 103.49%. Thermal degradation of lignin occurs at a temperature of 340 oC, and Tg 2 occurs at a temperature of 166 oC. The characteristics of the lignin functional group are phenolic-syringyl, guaiacil, and ether compounds. The best antimicrobial activity of lignin was at a concentration of 0.1 g/mL with ethanol-water and 0.4 g/mL with DMSO. The rheomix lignin biofilm at a concentration of 2% overall has physical and mechanical characteristics, and can inhibit the growth of test bacteria better than the dissolving method.Lignin is a natural chemical polymer that has not been utilized properly and has the potential as an antimicrobial agent because it contains phenolic compounds. The purpose of this study was to utilize lignin from black liquor as an antimicrobial agent which was applied to biofilms for food packaging. Lignin was obtained from the black liquor isolation process using dilute acid through six washings. The isolated lignin was tested for physical characteristics, such as moisture content, ash content, lignin purity, FTIR, DSC, TGA, and antimicrobial activity. Lignin biofilms were tested for physical, mechanical, and antimicrobial activity characteristics. The results showed that the lignin isolate yield was 34.45%. The lignin water content is 10.28%, and the ash content is about 1.06%, with a lignin purity level of 103.49%. Thermal degradation of lignin
Keyword: antimicrobial, biofilm, black liquor, lignin, starch

Judul: Posisi Filogenetik Kura-Kura Carettochelys Insculpta  (Reptillia: Testudinata)
Abstrak: Carettochelys insculpta is an endemic freshwater turtle of southern Papua and northern Australia. Phylogenetic position of this turtle is remain unresolved until now. Most of the research conducted show close relationships of C. insculpta and members of Trionychidae family. However, some of the research show distance between C. insculpta and members of Trionychidae family. This research is conducted to analyze phylogenetic relationship between C. insculpta and other members of Testudinata using 12S rRNA, 16S rRNA, and both gene as markers. DNA samples were obtained from three different organisms of C. insculpta. Two species used as outgroups were Alligator mississippiensis and Iguana iguana. Phylogenetic analysis was carried out using Neighbor-Joining method with Felsenstein 1981 (F81) modeltest. A polytomy tree of Testudinata was produced by using 12S rRNA gene. However, analysis using 16S rRNA and both genes as markers confirmed that C. insculpta was located between the Chelonidae and the Trionychidae family.
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