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Journal : Elkawnie

Green Synthesis of Reduced Graphene Oxide Using Lime Juice Reductor From Citrus aurantifolia Said Ali Akbar; Fitriya Nanda; Nispi Mawaddah; Mima Yuriati
Elkawnie: Journal of Islamic Science and Technology Vol 5, No 2 (2019)
Publisher : Universitas Islam Negeri Ar-Raniry Banda Aceh

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22373/ekw.v5i2.4948

Abstract

In this study, the reduced graphene oxide (rGO) synthesized by using lime juice as an environmentally friendly reducing agent and inexpensive cost. The synthesis was carried out by oxidizing graphite with the Hummer method to form graphene oxide (GO) was formed, then the GO was reduced by using lime as the natural reducing agent. X-ray analysis shown a vital diffraction pattern for graphite at 2θ = 26.4°, for graphene oxide appears around 2θ = 10° and 43o, and rGO at 2θ = 23.8°. Furthermore, the infrared spectrum of the three samples showed the peak of the hydroxyl group at 3412 cm-1, which appeared on graphene oxide, but was not observed in rGO. The vibrational mode of carbonyl (C=O) at 1723 cm-1 was also observed with high intensity on graphene oxide. This information showed that GO has a large number of oxygen-containing groups. Then, in the dissolution test shown that the GO was more soluble in polar solvents such as water than ethanol.
Evaluation of Antioxidant Activity On Plum Fruit (Prunus domestica L.) Skin Extract Applied For Natural Acid-Base Indicator Said Ali Akbar
Elkawnie: Journal of Islamic Science and Technology Vol 5, No 1 (2019)
Publisher : Universitas Islam Negeri Ar-Raniry Banda Aceh

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22373/ekw.v5i1.4516

Abstract

Plum peel was extracted through the maceration method with 100 mL ethanol. This process obtained 5% (50 µg/µL) skin extract. The UV-Vis spectrum of the extract displayed the major absorption peak at λmax = 526 nm in acid media, this assigned by the electronic transition from flavylium which as characteristic of anthocyanin compounds. The of anthocyanins stability on temperature effect showed the absorbance decreases with the heating time, while the level of pigment color loss, or the percentage of color loss, gradually increases. The pigment was maintained at 100oC for 100 min with the loss rate reaches 58.5%. Therefore, The loss of anthocyanin color in the plum peel is relatively stable at lower temperatures. Then, The plum peels extract shown the red color at pH 1-3, almost colorless at pH 4-7, and violet color at pH 12. Finally, plum peels extract was potentially used as the acid-base indicator.
The UV-Vis Study On Anthocyanin Pigments Activities Extracted From Gayo Arabika Coffee Husks Hasby Hasby; Nurhafidhah Nurhafidhah; Said Ali Akbar
Elkawnie: Journal of Islamic Science and Technology Vol 5, No 2 (2019)
Publisher : Universitas Islam Negeri Ar-Raniry Banda Aceh

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22373/ekw.v5i2.5232

Abstract

The anthocyanin activity of Gayo Arabica coffee husk in variations in acid solution, temperature, and pH has been assessed through UV-Vis studies. It is important to optimize these factors to increase the long-term stability of anthocyanins for use in various fields. Gayo Arabica coffee husks was extracted through maceration method with methanol. This process obtained a coffee husks extract of 1.176 mg/μL. The UV-Vis spectrum of the extract displayed the major absorption peak at λmax= 529 nm in hydrochloric acid (HCl), this assigned by the electronic transition from flavylium as the particular characteristic of anthocyanin compounds. The anthocyanin from the extract was stable at temperatures of 35oC and 50oC, to have a major absorption peak at λmax= 529 nm. Therefore, it could probably be said that the lower the temperature, the higher the absorbance value of anthocyanin. Then, husks extract was getting red at pH 1 and 3; almost colorless at pH 5, 8 and 10; and yellow at pH 12. The more acidic conditions causes more anthocyanin pigments to be observed in the form of flavylium or oxonium cations color. Finally, Gayo Arabica coffee husks extract can absorb both ultraviolet (UV) and visible light (visible).