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All Journal JURNAL KIMIA SAINS DAN APLIKASI Jurnal Riset Kimia Indonesian Journal of Chemistry Jurnal Pendidikan dan Konseling Jurnal Kimia Unand
Rahmayeni
Universitas Andalas
Biochemistry, Genetics & Molecular Biology Chemical Engineering, Chemistry & Bioengineering Chemistry Education Energy Engineering Languange, Linguistic, Communication & Media Materials Science & Nanotechnology Mathematics Other

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SINTESIS, KARAKTERISASI, DAN UJI AKTIFITAS FOTOKATALITIK NANOPARTIKEL MAGNETIK TiO2-CoFe2O4 -, Rahmayeni,; Septiani, Upita; Arief, Syukri; Hamdi, Hayatul
Jurnal Riset Kimia Vol 4, No 2 (2011): March
Publisher : Universitas Andalas

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25077/jrk.v4i2.134

Abstract

 ABSTRACT Magnetic nanoparticles of TiO2−CoFe2O4 were prepared using metal nitric and tiatniumisopropoxide as starting materials by coprecipitation and hydrolysis method. XRD, SEM, EDX and VSM were used to characterize the structure, morphology, composition and magnetic property of the particles, respectively. XRD pattern show the diffraction peaks of TiO2 anatase at 2θ = 25.3° and CoFe2O4 at 2θ = 35.5° in TiO2−CoFe2O4 particles. SEM image show the regular morphology and size distribution of particles. From VSM analysis indicate that the particles have paramagnetic properties. Photocatalytic activities of particles were applied for degradation of rhodamin B  and the results showed that CoFe2O4 doped into TiO2 can increase the activities of particles in visible light until 82 %. Key words : nanopartikel magnetik, TiO2−CoFe2O4, fotokatalis    
SYNTHESIS OF MAGNETIC NANOPARTICLES OF TiO2-NiFe2O4: CHARACTERIZATION AND PHOTOCATALYTIC ACTIVITY ON DEGRADATION OF RHODAMINE B Rahmayeni Rahmayeni; Syukri Arief; Yeni Stiadi; Rianda Rizal; Zulhadjri Zulhadjri
Indonesian Journal of Chemistry Vol 12, No 3 (2012)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (418.312 KB) | DOI: 10.22146/ijc.21335

Abstract

Magnetic nanoparticles of TiO2-(x)NiFe2O4 with x = 0.01, 0.1, and 0.3have been synthesized by mixture of titanium isopropoxide (TIP) and nitric metal as precursors. The particles were characterized by XRD, SEM-EDX, and VSM. XRD pattern show the peaks at 2q = 25.3°, 38.4° and 47.9° which are referred as anatase phase of TiO2. Meanwhile NiFe2O4 phase was observed clearly for x = 0.3. The present of NiFe2O4 can prevent the transformation of TiO2 from anatase to rutile when the calcination temperature increased. Microstructure analyses by SEM show the homogeneous form and size of particles. The magnetic properties analysis by VSM indicates that TiO2-NiFe2O4 is paramagnetic behavior. TiO2 doped NiFe2O4 has higher photocatalytic activity than TiO2 synthesized for degradation of Rhodamine B in aqueous solution under solar light irradiation.
Hubungan Kelembagaan Antara Kecamatan dan Kelurahan Berdasarkan Peraturan Pemerintah No. 17 Tahun 2018 (studi kasus di kecamatan Pauh) Sri Rahmayeni; Asrinaldi Asrinaldi; Tengku Rika Valentina
Jurnal Pendidikan dan Konseling (JPDK) Vol. 5 No. 2 (2023): Jurnal Pendidikan dan Konseling
Publisher : Universitas Pahlawan Tuanku Tambusai

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31004/jpdk.v5i2.13066

Abstract

Hubungan kelembagaan kecamatan dengan kelurahan saling mempengaruhi kelurahan sebagai perangkat daerah pada saat ini menjadi perangkat kecamatan. Dalam Peraturan Pemerintah Nomor 17 Tahun 2018, menyebutkan bahwa kecamatan adalah sebuah perangkat daerah kabupaten/kota sekaligus penyelenggara pemerintah umum sehingga, konsekuensinya lurah tidak lagi bertanggung jawab kepada Bupati/Walikota tetapi langsung kepada kecamatan. Artinya, lurah menjadi salah satu unsur yang berada di tingkat kecamatan dan lurah bertanggung jawab kepada camat. Kondisi ini mengakibatkan hubungan kerja camat dan lurah, yang selama ini bersifat koordinasi menjadi atasan dan bawahan. Namun, belum terwujudnya tugas pemerintahan daerah yang efektif dan optimal, di perlukannya upaya penguatan kelembagaan antara kecamatan dan kelurahan untuk bekerjasama untuk menjadi kelembagaan yang mengembang. Penelitian ini bertujuan untuk mendeskripsikan dan menganalisis model Kelembagaan Antara Kecamatan dengan Kelurahan. Penelitian ini menggunakan metode kualitatif dengan tipe deskriptif. Teknik pengumpulan data dalam penelitian ini menggunakan teknik wawancara, pengamatan, dan pendalaman dokumen-dokumen.. Dalam pemilihan informan penelitian, peneliti menggunakan teknik purposive sampling. Hasil penelitian menunjukkan bahwa dalam hal hubungan kelembagaan antara kecamataan dengan kelurahan berdasarkan Peraturan Pemerintah No.17 tahun 2018 tentang kecamatan saling mempengaruhi. Kelurahan yang semula sebagai perangkat daerah pada saat ini menjadi perangkat kecamatan. Kemudian, hal lainnya yang peneliti temukan ialah perubahan anggaran kelurahan dari yang semula dari kabupaten/ kota menjadi bersumber dari kecamatan, ini yang menyebabkan kelurahan kewalahan dalam masalah anggaran.
A New Combination Method of N-doped TiO2 Nanoparticles Synthesis for Heavy Metal Ions Cr(VI) Photoreduction Applications Diana Vanda Wellia; M. Rafli Habibillah; Atika Syafawi; Rizka Rahmadini; Rahmayeni Rahmayeni; Nurul Pratiwi
Jurnal Kimia Sains dan Aplikasi Vol 26, No 2 (2023): Volume 26 Issue 2 Year 2023
Publisher : Chemistry Department, Faculty of Sciences and Mathematics, Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/jksa.26.2.70-78

Abstract

Through a combination of biosynthetic and hydrothermal methods, N-doped TiO2 photocatalyst has been successfully synthesized using various concentrations of ammonia as a nitrogen source, namely 10% w/w (NTO10), 20% w/w (NTO20), 35% w/w (NTO35), and 50% w/w (NTO50). The synthesis of TiO2 was conducted using Aloe vera (L) Burm F. rind extract as a natural capping agent via the biosynthetic method, followed by a nitrogen doping process via the hydrothermal method. The X-ray Diffraction (XRD) analysis revealed that all phases were anatase. According to the results of the UV-Vis Diffuse Reflectance Spectroscopy (UV-Vis DRS) analysis using the Tauc-Plot method, all N-doped TiO2 samples showed a decrease in the energy gap compared to the TO sample. This indicates that the doping of TiO2 using nitrogen has been successfully doped into TiO2. The photocatalytic activity of N-doped TiO2 was evaluated for the photoreduction of the Cr(VI) model pollutant using a 24-watt LED lamp as a visible light source for 120 minutes. The results indicate that the NTO35 is the best-prepared N-doped TiO2, which showed a reduced rate for the Cr (VI) model pollutant of 50.88%, or two times greater than that of undoped TiO2.
Structure, Morphology, Optical, Magnetic and Dielectric Properties of Ni1-xCdxFe2O4 Material Synthesized by Autocombustion Method Libra, Poppi Darmila; Syukri, Syukri; Stiadi, Yeni; Rahmayeni
Jurnal Riset Kimia Vol. 16 No. 2 (2025): September
Publisher : Universitas Andalas

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25077/jrk.v16i2.855

Abstract

Materials with nanoscale dimensions have recently attracted attention due to their outstanding electrical, magnetic, and dielectric capabilities. Electromagnetic materials, known as spinel ferrite MFe2O4 (M = divalent ion), are essential in advanced technology. Cadmium-substituted ferrite spinel with composition Ni1-xCdxFe2O4 (x = 0, 0.1, 0.15, and 0.2) was synthesized by the autocombustion method using citric acid as a fuel agent. X-Ray Diffraction (XRD) confirms that the spinel structure is present in the prepared nanocrystalline ferrites. Fourier Transformed Infrared Spectroscopy (FTIR) spectra showed intensive absorption bands in the 400-600 cm-¹ range corresponding to tetrahedral and octahedral sites. The absorption spectrum of FTIR shifts towards lower wave numbers as the Cd2+ ion concentration increases. Cd2+ ions doping is important for crystal growth, as evidenced by Scanning Electron Microscopy (SEM) images. The band gap energy values of Ni1-xCdxFe2O4 samples are 1.53 eV, 1.46 eV, 1 43eV, 1.42 eV for x=0-0.2, which indicates the samples absorb in visible light. Analysis of magnetic properties with Vibrating Sample Magnetometer (VSM) shows a small hysteresis loop, so Ni1-xCdxFe2O4 is a soft magnetic material. The dielectric constant increases as the Cd2+ ion concentration increases. The characterization outcomes recommend that the compounds can be used for several applications such as memory, and energy storage devices.
Perlindungan Baja Ringan Dalam Medium Asam Klorida Menggunakan Ekstrak Daun Sungkai (Peronema canescens Jack) Stiadi, Yeni; Emriadi; Rahmayeni; Yolanda, Putri; Della Rosalynna S.
Jurnal Kimia Unand Vol. 13 No. 1 (2024): May 2024
Publisher : Departemen Kimia Universitas Andalas

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25077/jku.13.1.22-30.2024

Abstract

Corrosion inhibition of mild steel in 1 M hydrochloric acid (HCl) by leaves extract of sungkai (Peronema canescens Jack) was studied by weight loss method, Fourier Transform Infra-Red (FTIR), spectroscopy UV-Vis, and optical microscopy. The corrosion rate of mild steel increase with the increase of temperature and decrease with the increase of concentration from leaves extract of sungkai in medium. The weight loss method shows that the inhibition efficiency increased with concentration and increases with temperature increase. The highest inhibition efficiency was 90.70% with the addition of 10 g/L extracts at 60ºC. The adsorption of the inhibitor on the surface of mild steel follows the Langmuir adsorption isotherm because it forms a monolayer. Analysis of FTIR and UV-vis spectroscopy showed an interaction between leaves extract of sungkai and mild steel surface. Optical microscopy analysis revealed differences in the surface of mild steel immersed in 1 M HCl medium with and without the addition of extract.  
Sintesis Lapis Empat Fasa Aurivillius Ca1-xBaxBi3,5La0,5Ti4O15 Dengan Metode Lelehan Garam Zulhadjri; Silpa , Riga Oktry; Rahmayeni; Pratiwi, Nurul
Jurnal Kimia Unand Vol. 13 No. 1 (2024): May 2024
Publisher : Departemen Kimia Universitas Andalas

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25077/jku.13.1.7-13.2024

Abstract

The four-layer Aurivillius phase Ca1-xBaxBi3.5La0.5Ti4O15 (x = 0.2, 0.4, 0.6, 0.8, and 1) has been synthesized by molten salt method. The effect of varying x on the structure, morphology, and dielectric properties was studied. X-ray diffraction (XRD) and Le Bail refinement revealed that the compounds with the composition x = 0, 0.2, and 0.4 were single-phase product with orthorhombic A21am structure, whereas for higher x value (composition of Ba doped), a Ba2TiO4 impurity is found in products. Changes in unit cell volume were investigated, and the size increased with larger x. The substitution of larger Ba2+ ions resulted in a shorter Ti-O bond, shifting vibration mode to higher wave number that showed in FTIR spectra. SEM images show anisotropic plate-like grain with distributed particle sizes at 1.9 – 3.1μm. The dielectric constant values decrease with increasing x, otherwise the dielectric loss values increase for x = 0 and 0.2, however decrease for x = 0.4. The resulting Aurivillius compound has potential for applications in ferroelectric and piezoelectric devices.
Co-Authors Asrinaldi Asrinaldi Atika Syafawi Della Rosalynna S. Della Rosalynna S. Emriadi Emriadi - Hamdi, Hayatul Libra, Poppi Darmila M. Rafli Habibillah Nurul Pratiwi Nurul Pratiwi Nurul Pratiwi Putri Yolanda Rianda Rizal Riga Oktry Silpa Rizka Rahmadini Silpa , Riga Oktry Syukri Arief Syukri Syukri Tengku Rika Valentina Upita Septiani Wellia, Diana Vanda Yeni Stiadi YOLANDA, PUTRI Zulhadjri Zulhadjri Zulhadjri