This study aims to study the conformation, the hydrogen bond network, and the stabilities of all the possible intermolecular interactions in phosphorylated nata de coco membrane with water

Vitamin C or ascorbic acid is needed by the human body but it is already damaged by the rise in temperature due to be oxidized to L-dehydroascorbic acid. This research aims to determine the kinetics of oxidation of ascorbic acid due to an increase if temperature (40-80 °C) and to design an ascorbic acid oxidation reaction laboratory module to be applied in the senior high school reaction kinetics curriculum. The determination of the kinetics of the oxidation of ascorbic acid applies the integral and half-change time methods, while the concentration of the remained ascorbic acid in sixty minute intervals is determined by iodimetric titration method. Decomposition of ascorbic acid was measured at 40, 50, 60, 70 and 80 °C. The results of this research indicate that at 40, 50, 60, 70 and 80 °C the kinetics of the oxidation of ascorbic acid is a first-order reaction with rate constants of 4.55 x 10-4, 5.85 x 10-4, 8.4 x 10-4, 1.1 x 10-3 and 1.015 x 10-3 min-1, respectively. Pre-exponential factor or the frequency of collisions is a factor which is a measure of the collision rate. The activation energy and the pre-exponential factor for the oxidation of ascorbic acid were found to be 20.73 kJ.mol-1 and 1.372 min-1. The procedure used in this study was modified into a laboratory module will be applied in the teaching of reaction kinetics at the senior high school level.

Banana peel is a biomass waste that has the potential to be used as charcoal briquettes. Banana peels contain lignocellulose, including 58.5% lignin, 41.8% cellulose and 38.1% hemicellulose, which are the main ingredients that must be present in the raw material for charcoal briquettes. This study aims to identify the characteristics of charcoal briquettes produced based on the Indonesian National Standard (SNI). The adhesive used is sago flour with a concentration of 5%, 10%, and 15% in 100 g of charcoal briquette raw material. The results obtained were the best adhesive concentration used, namely 5%. By testing, it obtained several characteristics that meet the SNI, including a density of 0.5957 g/cm3 , a compressive strength of 4.8920 kg/cm2 , and a calorific value of 10,815.9437 cal/g. At the same time, the characteristics that did not meet SNI were water content of 8.465%, ash content of 27.850%, volatile matter content of 46.967% and bound carbon content of 25.183%.

This study aims to determine the physical and chemical characteristics of the edible film of jackfruit seed starch (Artocarpus heterophyllus) added with antioxidant rosella flower extract (Hibiscus sabdariffa). The type of plasticizer used is glycerol. The best treatment in this study was the jackfruit seed edible film with the addition of rosella flower extract 3% (v/v) with the results obtained respectively for a thickness of 0.09 mm, tensile strength 0.003332 N/mm2, elongation percentage 126.36%, elasticity 0.002637 Kgf/mm2, pH 6.122, water absorption 61.67%, solubility 40%, water vapor transmission speed 0.6714 gram/hour m2, FTIR test results show that the process of making edible film in this research is the mixing process Physics, the shelf life of edible film at room temperature is 6 days and at cold temperatures is 8 days, and has antioxidant activity with an IC50 value 219.948 ppm. The addition of rosella flower extract enhances another benefit of edible film which functions as a food protector from the oxidation process (antioxidant).

This research aims to calculate energetics parameters, hydrogen bonding, characteristics local hydration, and proton transfer in phosphorylated nata de coco (NDCF) membrane using ab initio method. The minimum energy structure of NDCF membranes and the addition of n water molecules (n = 1-10) Calculation of the rotational energy at the center of C-O indicates that the pyranose ring structure, with a maximum barrier energies of~12.5 J/mol, is much more flexible than the aromatic backbones of sulfonated poly(phenylene) sulfone (sPSO2) and the polytetrafluoroethylene (PTFE) backbones in perfluorosulfonic acid ionomers (PFSA). These energy calculations provide the basis that the flexibility of the pyranose ring and the hydrogen bonding between water molecules and phosphonate groups influence the transfer of protons in the membrane of NDCF. Keywords: proton transfer; ab initio; nata de coco ABSTRAK Penelitian ini bertujuan untuk menghitung parameter energetika, ikatan hidrogen, karakteristik hidrasi lokal, dan transfer proton pada membran nata de coco terfosfosfatasi menggunakan metode ab initio. Struktur energi minimum untuk nata de coco terfosfatasi dan penambahan n molekul air (n = 1-10) yang ditentukan dengan metode B3LYP/6-311G(d) menunjukkan bahwa untuk disosiasi proton minimal dibutuhkan empat molekul air. Proton yang terdisosiasi distabilkan dengan terbentuknya ion-ion hidronium, Zundel dan Eigen. Perhitungan energi interaksi dengan n molekul air menunjukkan perubahan energi (∆E), dan perubahan entalpi (∆H) yang semakin negatif. Hal ini