Judul: Study of Tea Dregs Biopellet with Biodiesel Transesterification Waste as Additive to Improve Quality
Abstrak: The production of packaged tea drinks produces tea dregs which can be used as fuel in the form of biopellets as an environmentally friendly alternative energy. The process of making biodiesel using the transesterification method produces a by-product in the form of a mixture of glycerol, methanol, and a catalyst (KOH). The by-product waste has the potential to be reused, one of which is as an additive in the manufacture of biopellets. This study aims to analyze and characterize tea dregs biopellets with biodiesel waste as an additive to increase the quality value and find out the best formulation for each treatment. Comparison of the formulations used, namely A0 as control (90% tea dregs: 10% adhesive), A1 (85% tea dregs: 5% biodiesel waste: 10% adhesive), A2 (80% tea dregs: 10% biodiesel waste: adhesive 10%), A3 (75% tea dregs: 15% biodiesel waste: 10% adhesive), A4 (70% tea dregs: 20% biodiesel waste: 10% adhesive), and A5 (65% tea dregs: 25% biodiesel waste : adhesive 10%). The parameter value of the quality of the biopellet refers to the SNI 8675:2018 standard. The best formulation was obtained in treatment A2 with a density value of 0.91 g/cm3 , 98.08% resistance, 6.96% moisture content, 73.37% volatile matter content, 6% ash content, with calorific value of 15.05 MJ/kg. The addition of biodiesel waste up to 10% as an additive was proven to be able to improve the quality of tea dregs biopellet., Produksi minuman teh kemasan menghasilkan limbah ampas teh yang dapat dimanfaatkan sebagai bahan bakar berupa biopelet sebagai energi alternatif yang ramah lingkungan. Proses pembuatan biodiesel dengan metode transesterifikasi menghasilkan hasil samping berupa campuran gliserol, metanol, dan katalis (KOH). Limbah hasil samping tersebut memiliki potensi untuk dimanfaatkan kembali, salah satunya sebagai aditif dalam pembuatan biopelet. Penelitian ini bertujuan untuk melakukan analisis dan karakterisasi biopelet ampas teh dengan limbah biodiesel sebagai aditif untuk meningkatkan nilai mutu serta mengetahui formulasi terbaik dari setiap perlakuan. Perbandingan formulasi bahan yang digunakan yaitu A0 sebagai kontrol (ampas teh 90% : perekat 10%), A1 (ampas teh 85% : limbah biodiesel 5% : perekat 10%), A2 (ampas teh 80% : limbah biodiesel 10% : perekat 10%), A3 (ampas teh 75% : limbah biodiesel 15% : perekat 10%), A4 (ampas teh 70% : limbah biodiesel 20% : perekat 10%), dan A5 (ampas teh 65% : limbah biodiesel 25% : perekat 10%). Parameter nilai mutu biopelet mengacu kepada standar SNI 8675:2018. Formulasi terbaik diperoleh pada perlakuan A2 dengan nilai kerapatan 0,91 g/cm3 , ketahanan 98,08%, kadar air 6,96%, kadar zat terbang 73,37%, kadar abu 6%, dengan nilai kalor yaitu 15,05 MJ/kg. Penambahan limbah biodiesel hingga 10% sebagai aditif, terbukti mampu meningkatkan mutu biopelet ampas teh.
Keyword: additive, biodiesel waste, biopellet, tea dregs

Judul: Performance Test of Flat Dies Type Biopellet Machine (Pelletizer) using Tea Brewed Dregs Biomass Material
Abstrak: Limbah ampas seduhan teh yang dihasilkan dari industri pengolahan minuman (beverage) belum dimanfaatkan secara optimal karena sifat limbah biomassa yang tidak seragam ukuran dan bentuknya, serta kandungan energi yang rendah per satuan volume. Salah satu cara yang dilakukan untuk mengatasi masalah ini adalah melakukan densifikasi, agar limbah biomassa ampas teh ini menjadi bahan bakar biopelet yang berkualitas baik. Dalam proses pembuatan produk densifikasi, dikembangkan unit mesin pembuat biopelet (pelletizer). Penelitian ini bertujuan untuk melakukan uji kinerja serta evaluasi mesin biopelet (pelletizer) tipe flat dies untuk mendapatkan frekuensi listrik dan kecepatan putaran roller yang optimal. Pada penelitian ini, dilakukan beberapa taraf frekuensi listrik dari inverter ke motor listrik 3 fasa yaitu 15 Hz, 20 Hz, 25 Hz, 30 Hz, 35 Hz, 40 Hz, 45 Hz, dan 50 Hz yang akan mempengaruhi putaran roller dalam memampatkan biomassa. Hasil pengujian didapatkan kualitas biopelet ampas teh terbaik adalah pada frekuensi listrik 35 Hz, dengan putaran roller 1035,18 rpm. Biopelet yang dihasilkan memiliki karakteristik densitas sebesar 0,77 g/cm3, ketahanan 94,99%, kadar air 50,67%, kadar abu 6,15%, kadar zat terbang 73,89%, kadar karbon terikat 19,96%, serta nilai kalor sebesar 17,93 MJ/kg., The waste of tea dregs from the beverage industry has not been used optimally due to the heterogeneous characteristic of biomass in size, shape, and low energy content per unit volume. One solution is to densify the tea dreg biomass so that it can be used as a high-quality biopellet fuel. A biopellet machine unit (pelletizer) was developed for densified products. This study aims to do the performance tests and evaluate flat dies type bio-pelletizer machines to obtain optimal electrical frequency and roller rotation speed. In this study, several levels of electrical frequency were carried out from the inverter to the 3-phase motor, such as 15 Hz, 20 Hz, 25 Hz, 30 Hz, 35 Hz, 40 Hz, 45 Hz, and 50 Hz, which will affect the rotation of the roller in compressing the biomass. The results showed that the best quality of tea dregs biopellet was 35 Hz, with a roller rotation of 1035.18 rpm. The resulting biopellet had characteristics of density of 0.77 g/cm3, resistance of 94.99%, moisture content of 50.67%, ash content of 6.15%, volatile matter content of 73.89%, bound carbon content of 19.96%, and a calorific value of 17.93 MJ/kg.
Keyword: biomass, biopellet, densification, pelletizer, tea dregs

Judul: Grup dan Homomorfisma Grup pada Rubik Revenge
Abstrak: Rubik cube is a kind of puzzle game. A player must arrange rubik sides, which have been disordered, back to the position where every side has the same colour. This paper does not focus on the settlement solution, but instead on proving the existence of a group homomorphism between rubik movement group and S96 symmetric permutation group in rubik revenge. Firstly, it has been proved that rubik movement set is a group. Then, it also has been proved that the M set, which contains numeric labels of 1 until 96 in cubinos sides, is S96 symmetric permutation group.
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