Methanol extracts of onion peel waste (Allium cepa) were applied as natural sensitizer in Dye-Sensitized Solar Cell (DSSC) fabrication. This research investigated the dye characteristics of onion peel extract and its power conversion efficiency. Onion peel extraction was carried out using unacidified methanol extract (UME) and acidified methanol extract (AME). Dye absorption was characterized by UV-Vis Spectrophotometer at a wavelength of 200-800 nm and FT-IR at a wave number of 4000-500 cm-1. The power conversion efficiency of the fabricated DSSC was determined by calculating the voltage and current generated by the multimeter. The red onion peel extracts, both acidified and unacidified methanol, had maximum absorption at UV-Visible range (457, 659 and 662 nm). Onion peel extract has several functional groups such as –OH, C=O, C-O-C, C=C, and C-H aromatics- showing specific absorption corresponding to the anthocyanin structure. A solar energy conversion efficiency of η= 0.0413% was obtained from UME extract with a short circuit current of up to Jsc=0.6031 mAcm-2 and a fill factor of 0.2764.

The demand for biodiesel in the renewable energy sector continues to grow yearly. However, the majority of biodiesel sources currently still compete with the food sector. Feun Kase seeds contain high oil and do not compete with food, so they have prospects as a new source of biodiesel. This study aimed to find the optimal conditions for synthesizing biodiesel from Feun Kase seed oil, carried out through transesterification with four reaction variables: catalyst variation, time, temperature, and the molar ratio of oil/methanol. This study was equipped with parameter test data according to SNI (Indonesian National Standard) 7182:2015, also equipped with characterization using FTIR (Fourier Transform Infrared) and GCMS (Gas Chromatography Mass Spectroscopy). The highest biodiesel yield of 84.09% was obtained using optimum conditions of 1% NaOH catalyst, oil/methanol molar ratio of 1:6 at 70°C for 90 minutes of reaction. The test results of biodiesel parameters are density (851 kg/m3), smoke point (6°C), kinematic viscosity (5.35 cSt); acid number (1.08 mg KOH/gr), saponification number (159.32 mg KOH/gr), iodine number (78.62 g I2/100 g sample), flash point (165°C), and cetane number (62.86). FTIR analysis proved the presence of methyl esters with typical absorption at 1743 cm-1, 1195.87 cm-1, and 1436.97 cm-1. GCMS characterization showed that Feun Kase biodiesel was dominated by methyl oleate (53.45%), methyl palmitate (27.05%), methyl stearate (10.96%), and methyl linoleate (6.29%).

<p>Fabrikasi DSSC dengan menggunakan sensitizer zat warna sintetik yang mahal dan susah diperoleh dapat diatasi dengan memanfaatkan zat warna alami dari limbah biomassa kulit bawang merah. Penelitian tentang ekstraksi antosianin dari limbah kulit bawang merah <em>(Allium cepa)</em> dan pemanfaatannya sebagai zat pemeka (<em>sensitizer</em>) pada <em>Dye Sensitized Solar Cell</em> (DSSC) telah dilakukan dengan tujuan untuk mengetahui karakteristik warna ekstrak antosianin dalam limbah kulit bawang merah dan potensinya sebagai zat pemeka dalam DSSC. Antosianin dalam limbah kulit bawang merah diekstraksi dengan menggunakan pelarut etanol 95% dengan penambahan asam (ET) dan etanol tanpa penambahan asam (ETT). Ekstrak kulit bawang merah dikarakterisasi serapan warna dan gugus fungsinya dengan Spektrofotometer UV-Vis pada panjang gelombang 200 nm – 800 nm dan <em>Fourier Transform Infrared</em> (FTIR) pada bilangan gelombang 4000 cm^-1 – 500 cm^-1. Selanjutnya DSSC difabrikasi dan efisiensi DSSC ditentukan melalui perhitungan tegangan dan kuat arus yang terukur oleh multimeter. Hasil karakterisasi warna menunjukkan bahwa ekstrak kulit bawang merah baik dengan pelarut etanol terasamkan dan tidak terasamkan memiliki serapan maksimum pada panjang gelombang UV dengan serapan utama pada panjang gelombang 221, 251, 291 dan 366 nm. Spektrum FTIR ekstrak kulit bawang menunjukkan serapan khas gugus fungsi pada molekul antosianin pada rentang bilangan gelombang 3418 cm^-1– 3375 cm^-1 untuk gugus –OH, 2842 cm^-1 – 2959 cm^-1 untuk C–H alifatik, 1635 cm^-1 – 1668 dan 714 cm^-1 masing-masing untuk C=C dan C–H aromatic, 1040 cm^-1– 1091 cm^-1 untuk C–O–C dan 1198 cm^-1– 1122 cm^-1 untuk C–O alkohol. Hasil pengujian efisiensi sel menunjukkan bahwa sel DSSC yang difabrikasi menggunakan ekstrak etanol TT memiliki nilai efisiensi yang lebih tinggi yaitu sebesar 0,0491%.</p><p><strong>The Application of Anthocyanins Extracts from Red Onion Peel  Waste (<em>Allium cepa</em>) as a Sensitizer in Dye-Sensitized Solar Cell (DSSC).</strong> DSSC fabrication using synthetic dye sensitizers which are expensive and difficult to obtain can be overcome by utilizing natural dyes from onion peel. Anthocyanin extraction from red onion peel (<em>Allium cepa</em>) and its use as a sensitizer in dye-sensitized solar cells (DSSC) has been investigated. The purpose of this study was to determine the color characteristics of anthocyanin extract in onion peel waste and its potential as a sensitizer. Anthocyanin in onion peel waste was extracted using 95% ethanol as a solvent with acid (ET) and ethanol without acid (ETT). The color absorption and functional groups of onion peel extract were characterized using UV-Vis spectrophotometer at 200 nm – 800 nm wavelength and Fourier Transform Infrared (FTIR) at wavenumber of 4000 cm^-1 – 500 cm^-1. Furthermore, DSSC was fabricated, and an efficiency value was achieved by calculating the voltage and current measured by the multimeter. Onion peel extract has maximum absorption in acidified and unacidified ethanol at UV wavelengths, with the main absorption at 221, 251, 291, and 366 nm. The FTIR spectrum of onion peel extract shows typical absorption of functional groups in anthocyanin at wavenumbers of 3418 cm^-1 – 3375 cm^-1 for the –OH group, 2842 cm^-1– 2959 cm^-1 for aliphatic CH, 1635 cm^-1–1668 cm^-1, and 714 cm^-1 for C=C and C–H aromatics, respectively. The absorption band at 1040 cm^-1– 1091 cm^-1 and 1198 cm^-1 – 1122 cm^-1 correspond to C–O–C and C–O alcohol. DSSC cells fabricated using unacidified ethanol extract have the highest efficiency of 0.0491%.</p>

Spectrophotometric determination of boron in food products by ester borate distillation into curcumin was studied. The sensitivity and selectivity of curcumin method were overcome by generating ester borate at proper temperature, time and pH. Boron was separated as triethyl borate by distillation in a vessel using ethanol solvent and reacted with curcumin. Distillation system reached optimum condition at temperature of 75oC and pH 5-6. Boron-curcumin complex was measured at 555 nm after 10 minutes of reaction. Separation of boron by distillation method complied with validation parameters. The standard curve was linier at concentration range of 1.2-4.8 ppm (R2=0.9995) and had molar extinction value (?) 4.7 x 105 L mol-1 cm-1 for high sensitivity level which is higher than the previous study. Percent recovery was found to be 96.09-104.92 %. Boron content in meatball and tofu products was in the range of 1.406-3.589 and 0.010-1.085 mg/kg. Ester borate distillation into curcumin has been successfully applied to the determination of boron in food products because of its high selectivity and sensitivity.

A simple analyte separation through an in-situ volatilization system in a polytetrafluoroethylene (PTFE) container was carried out for boric acid analysis in a food product by spectrophotometry. Separation was conducted in two teflon containers divided into the reagents compartment (outer vessel) and sample compartment (inner vessel). System optimization was done by varying the curcumin content and ethanol: water ratio. The optimum condition of the volatilization system was achieved at a curcumin concentration of 0.1% and ethanol: water ratio of 3:1. LOD and LOQ measurements, respectively, gave a value of 0.0413 mg/L and 0.1088 mg/L. The established method was used to determine boric acid content in sausage products by UV-Vis Spectrophotometry at 555 nm. The boric acid concentration in food samples was found to be 0.913-3.518 mg/kg. The separating method through in-situ volatilization systems in a polytetrafluoroethylene (PTFE) container can be used for boric acid analysis in food samples.