GREEN SINTESIS OKSIDA GRAFENA TEREDUKSI DARI ARANG TEMPURUNG KELAPA DAN KAYU DENGAN MENGGUNAKAN REDUKTOR RAMAH LINGKUNGAN ASAM L-ASKORBAT
Abstract
Material oksida grafena tereduksi (rGO) dilaporkan mempunyai beberapa sifat menarik dan salah satu metode sintesisnya adalah metode kimia yang dapat menggunakan prekursor bahan alam yaitu arang. Dalam penelitian ini, dilakukan sintesis rGO dari bahan arang tempurung kelapa dan arang kayu dengan menggunakan metode Hummer termodifikasi dengan menggunakan osidator kuat KMnO4, campuran H2SO4/H3PO4 (9:1) dan asam L-askorbat sebagai reduktor. Hasil sintesis dikarakterisasi dengan menggunakan spektroskopi Raman dan infra merah, sedangkan sifat fisis yang diukur adalah konduktivitas listriknya. Spektra Raman prekursor arang tempurung kelapa, arang kayu dan produk rGO menunjukkan puncak khas dari pita D (modus vibrasi yang berkaitan dengan defek pada struktur grafitik) pada bilangan gelombang ~1340 cm-1 dan G (modus vibrasi berkaitan dengan struktur normal grafit) pada bilangan gelombang ~1590 cm-1. Spektra Raman produk rGO mempunyai kesesuaian dengan pola spektra Raman yang telah dilaporkan oleh peneliti lain yang menindikasikan bahwa rGO sudah terbentuk. Nilai rasio intensitas vibrasi Raman pita D dan pita G (ID/IG) produk rGO dari (a) arang tempurung kelapa sebesar 2,471dan (b) arang kayu sebesar 2,001. Rasio ID/IG yang diperoleh menunjukkan bahwa struktur produk rGO mempunyai defek yang besar yang disebabkan karena kandungan pengotor (senyawa karbon berstrukur grafitik) masih banyak. Spektrum IR arang tempurung kelapa, arang kayu, produk rGO menunjukkan puncak IR pada bilangan gelombang ~1060 (modus vibrasi C-O), ~1502 (modus vibrasi C=C), ~1702 (modus vibrasi C=O), dan ~3244 (modus vibrasi O-H) cm-1. Modus vibrasi IR yang teridentifikasi merupakan gugus fungsi dari produk rGO. Hasil pengukuran konduktivitas listrik menunjukkan bahwa nilai konduktivitas listrik dari rGO arang tempurung kelapa, dan rGO arang kayu masing-masing adalah 2,148x10-7 dan 1,806x10-5 S/cm. Nilai konduktivitas yang diperoleh masih rendah yang dimungkinkan karena sampel yang diperoleh masih banyak mengandung pengotor.
Kata kunci: arang tempurung kelapa, arang kayu, rGO, asam L-askorbat.
ABSTRACT
Reduced graphene oxide (rGO) material is reported to have several interesting properties and one of the synthesis methods is a chemical method that can use natural material precursors, i.e. charcoal. In this study, the synthesis of rGO from coconut shell charcoal and sengon (Albizia chinensis) wood charcoal via the modified Hummer method using the strong oxidizing agent KMnO4, a mixture of H2SO4/H3PO4 (9:1) and L-ascorbic acid as a reducing agent. The results of the synthesis were characterized using Raman and infrared spectroscopy, while one of the physical properties measured was the electrical conductivity. The Raman spectra of coconut shell charcoal, wood charcoal, and rGO products showed the D band (The vibration mode corresponds to defects in the graphic structure) at wavenumber ~1340 cm-1) and the G band (The vibrational mode corresponds to the normal structure of graphite) at wavenumber ~1590 cm-1, and the type of Raman spectra of rGO products was in agreement with the Raman spectrum pattern that previously reported by other researchers. The ratio of the Raman vibration intensity of the D band and G band (ID/IG) of rGO products from (a) coconut shell charcoal was 2.471, and (b) wood charcoal was 2.001. The ratio ID/IG rGO product obtained showed that the structure of the rGO product had a large defect due to impurities (carbon material with graphitic structure) compounds). The IR spectrum of coconut shell charcoal, wood charcoal, and rGO products showed IR peaks at wavenumbers ~1060 (C-O vibrations), ~1502 (C=C vibrations), ~1702 (C=O vibrations), and ~3244 (O-H vibrations) cm-1. The identified IR vibration mode was the functional group of the rGO product. The results of the electrical conductivity measurement showed that the electrical conductivity of coconut shell charcoal rGO and wood charcoal rGO was 2.148x10-7 S/cm, and 1.806x10-5 S/cm, respectively. The conductivity value obtained was still low which was possible because the sample product still contained many impurities.
Keywords: acid L-ascorbate, coconut shell charcoal, rGO, wood charcoal
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