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All Journal CAKRA KIMIA (Indonesian E-Journal of Applied Chemistry) Jurnal Kimia (Journal of Chemistry) Jurnal Sains dan Teknologi Jurnal Penelitian Sains
I. A. Gede Widihati
Department Of Chemistry, University Of Udayana, Jl. Kampus Bukit Jimbaran Bali, Indonesia 80361
Chemical Engineering, Chemistry & Bioengineering Chemistry Computer Science & IT Education Electrical & Electronics Engineering Mathematics Physics

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SINTESIS DAN KARAKTERISASI SIFAT FISIK DAN KIMIA KATALIS BENTONIT-ZnO I. A. G. Widihati; M. Manurung; N. G. A. D. A. Suastuti; N. P. A. J. S. Putri
Jurnal Kimia (Journal of Chemistry) Vol. 16, No.2, Juli 2022
Publisher : Program Studi Kimia, FMIPA, Universitas Udayana (Program of Study in Chemistry, Faculty of Mathematics and Natural Sciences, Udayana University), Bali, Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24843/JCHEM.2022.v16.i02.p13

Abstract

Pemanfaatan lempung bentonit sebagai katalis telah dilaporkan oleh banyak peneliti. Aktivitas katalitik lempung umumnya tidak begitu tinggi. Oleh sebab itu, lempung harus dimodifikasi terlebih dahulu sebelum digunakan. Sintesis dan karakterisasi lempung termodifikasi ZnO (Bentonit-ZnO) telah dilakukan. Penelitian ini bertujuan untuk mengetahui sifat fisik dan kimia dari modifikasi lempung oleh ZnO. Bentonit dipreparasi terlebih dahulu kemudian diinterkalasi dengan ZnO yang diharapkan dapat membentuk pilar. Bentonit-ZnO yang telah tersintesis dikarakterisasi sesuai dengan manfaat Bentonit-ZnO sebagai katalis menggunakan Difraksi Sinar X, SEM-EDS, FTIR, luas permukaan dengan metode adsorpsi Methylene Blue dan situs asam permukaan dengan metode titrasi asam-basa. Hasil karakterisasi menunjukkan bahwa interkalasi ZnO ke dalam bentonit tidak meningkatkan jarak antar lapis, permukaan katalis menjadi lebih homogen serta adanya peningkatan jumlah unsur Zn, munculnya pita-pita serapan pada daerah 3600; 1600 – 1650; 2900-2850 dan 450 cm-1 yang mengidentifikasi karakteristik gugus fungsi dari Bentonit-ZnO, serta luas permukaan dan situs asam berturut-turut sebesar 46,357 m2/g dan 5,887 x 1022 situs/g. Kata kunci: bentonit, katalis, karakterisasi, terpilar, ZnO. ABSTRACT The use of bentonite clay as a catalyst has been reported by many studies. The catalytic activity of clays is generally not very high. Therefore, the clay must be modified before use. Synthesis and characterization of ZnO (Bentonite-ZnO) modified clay was carried out. This study aimed to determine the physical and chemical properties of modified Bentonite with ZnO. Bentonite was dipped first and then intercalated with ZnO which was expected to form pillars. The synthesized Bentonite-ZnO was characterized according to the benefits of Bentonite-ZnO as a catalyst using X-Ray Diffraction, SEM-EDS, FTIR, surface area using Methylene Blue adsorption method, and surface acid sites using an acid-base titration method. The characterization results showed that the intercalation of ZnO into bentonite did not increase the distance between layers, the catalyst became more homogeneous and there was an increase in the number of Zn elements, the appearance of absorption bands in the 3600; 1600 – 1650; 2900-2850 and 450 cm-1 regions which identified the functional group characteristics of Bentonite-ZnO and surface area and acid sites of 46.357 m2/g and 5.887 x 1022 sites/g, respectively. Keywords: bentonite, catalyst, characterization, pillared, ZnO.
PEMANFAATAN ZEOLIT-BENTONIT SEBAGAI ADSORBEN FOSFAT DALAM AIR I. A. G. Widihati; G. S. U. Mahaputra; I. W. Suarsa
Jurnal Kimia (Journal of Chemistry) Vol. 16, No.2, Juli 2022
Publisher : Program Studi Kimia, FMIPA, Universitas Udayana (Program of Study in Chemistry, Faculty of Mathematics and Natural Sciences, Udayana University), Bali, Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24843/JCHEM.2022.v16.i02.p10

Abstract

Salah satu cara yang dilakukan untuk menurunkan kadar fosfat dalam air yaitu dengan cara adsorpsi. Adsorpsi dianggap sebagai metode pengolahan limbah air terbaik karena bahan utamanya yaitu adsorben keberadaannya melimpah dan mudah digunakan. Penelitian ini dilakukan untuk mengetahui kemampuan zeolit yang dikombinasikan dengan bentonit dalam mengadsorpsi fosfat dalam air, menentukan waktu optimum, pola isoterm adsorpsinya serta kapasitas adsorpsi. Kajian yang dilakukan meliputi karakterisasi, dan aplikasinya untuk mengadsorpsi fosfat dengan berbagai variasi waktu kontak dan konsentrasi. Adsorben dikarakterisasi luas permukaan dengan adsorpsi metilen biru dan situs aktif secara titrasi asam-basa. Luas permukaan spesifik masing-masing adsorben nilainya hampir sama, namun yang paling besar adalah kombinasi zeolit : bentonit (1:1) yaitu 45,9637 m2/g. Situs aktif terbesar terdapat pada adsorben kombinasi zeolit : bentonit (1:1) yaitu 1,2842×1024 situs/g adsorben. Semua adsorben kombinasi zeolit : bentonit memiliki waktu kontak optimum yang sama yaitu 24 jam. Adsorben yang terdiri dari zeolite saja atau zeolit : bentonit (5:0) mengikuti pola isoterm adsorpsi Langmuir, sedangkan zeolit : bentonit (1:1) mengikuti pola isoterm Freundlich. Adsorben zeolit : bentonit (5:0), (1:1), dan (0:5) memiliki kapasitas adsorpsi yang optimum pada konsentrasi 100 ppm dengan persen teradsorpsi berturut-turut 96,66; 97,67; dan 97,02 %, sehingga dapat dilihat bahwa adsorben zeolit : bentonit (1:1) merupakan adsorben yang paling banyak menyerap fosfat. Kata Kunci: adsorpsi, bentonit, fosfat, zeolit. ABSTRACT One way to reduce phosphate levels in water is by adsorption. Adsorption is considered as the best wastewater treatment method because the main material, namely adsorbent, is abundant and easy to use. This research was conducted to determine the ability of zeolite combined with bentonite to adsorb phosphate in water, the optimum time, the pattern of adsorption isotherms and the adsorption capacity. The studies included the characterization of the adsorbent as well as its application to adsorb phosphate with various contact times and concentrations. The surface area of the adsorbents was characterized by the methylene blue adsorption method and the active site by acid-base titration. The specific surface area of ??each adsorbent had almost the same value, but the largest was the combination of zeolite: bentonite (1:1) which was 45.9637 m2/g. The largest active site of the adsorbent was the combination of zeolite: bentonite (1:1) adsorbent, which is 1.2842×1024 sites/g adsorbent. All the zeolite : bentonite combination adsorbents had the same optimum contact time of 24 hours. The zeolite: bentonite (5:0) followed the Langmuir adsorption isotherm pattern, while the zeolite : bentonite (1:1) followed the Freundlich isotherm pattern. Zeolite : bentonite (5:0), (1:1), and (0:5) had the optimum adsorption capacity at the concentration of 100 ppm with the percentage of phosphate adsorbed of 96.66; 97.67; 97.02%, respectively, so it showed that the zeolite : bentonite (1:1) adsorbed the most phosphate. Keywords: adsorption, bentonite, phosphate, zeolite.
Synthesis and Characterization of SRF Fertilizer using a Mixture of Urea and Bentonite Clays K. R. Pangestu; P. Suarya; I. A. G. Widihati
Jurnal Kimia (Journal of Chemistry) Vol. 17, No.1, Januari 2023
Publisher : Program Studi Kimia, FMIPA, Universitas Udayana (Program of Study in Chemistry, Faculty of Mathematics and Natural Sciences, Udayana University), Bali, Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24843/JCHEM.2023.v17.i01.p01

Abstract

Penggunaan pupuk nitrogen secara berlebihan mengakibatkan pencemaran lingkungan serta merusak kondisi tanah. Penelitian ini bertujuan untuk membuat pupuk slow release fertilizer (SRF) mengunakan formula campuran lempung bentonit dengan urea. Sintesis pupuk SRF mengunakan metode pencampuran padat-cair dengan mengelusikan senyawa urea ke dalam 20 g lempung bentonit dengan variasi massa urea sebesar 10, 20, 30, 40, dan 50 g. Karakterisasi terhadap hasil sintesis pupuk SRF dilakukan dengan FTIR dan metode Kjeldahl. Spektra FTIR menunjukkan adanya vibrasi dari gugus fungsi N-H, C=O, dan C-N yang menjadi penyusun pupuk urea pada bilangan gelombang 3506.59, 1691.57, dan 1176.58. Kadar nitrogen yang terkandung dalam pupuk SRF di analisis dengan metode Kjeldhal dan didapatkan kadar nitrogen tertinggi sebesar 13.35 g/100g, dengan komposisi lempung bentonit 20 g dan 50 g pupuk urea. Kata kunci: lempung bentonit, slow release fertilizer, urea. ABSTRACT Excessive use of nitrogen fertilizers causes environmental pollution and damages soil conditions. This research aimed to synthesis a slow release fertilizer (SRF) using a mixture of bentonite clay with urea. The synthesis of SRF using the solid –liquid method was carried out by eluting the urea fertilizer in the 20 g of bentonite clay with various masses of urea of 10, 20, 30, 40, and 50 g. The characterization of the SRF was done by FTIR and Kjeldhal methods. The FTIR spectra showed the presence of vibration of N-H, C=O, and C-N functional groups, which indicated the urea constituents, at the wave number of 3506.59, 1691.57, and 1176.58 cm-1. The nitrogen content in the SRF analyzed by the Kjeldhal method resulted in the highest value of 13.35 g/100g prepared with a composition of 20 g of bentonite clay and 50 g of urea fertilizer. Keywords: bentonite clay, slow release fertilizer, urea.
SPESIASI DAN BIOAVAILABILITAS Pb DAN Cu DALAM TANAH PERTANIAN ORGANIK SERTA KANDUNGAN LOGAM TOTALNYA DALAM SAYUR PAKCOY (BRASSICA RAPA L.) Sari, A. A. D. P.; Widihati, I. A. G.; Bawa, I G. A. G.
Jurnal Kimia (Journal of Chemistry) Vol. 17, No.2, Juli 2023
Publisher : Program Studi Kimia, FMIPA, Universitas Udayana (Program of Study in Chemistry, Faculty of Mathematics and Natural Sciences, Udayana University), Bali, Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24843/JCHEM.2023.v17.i02.p14

Abstract

Denpasar sebagai salah satu pusat kota penghasil sayur organik di Bali dan juga sebagai daerah destinasi pariwisata, memiliki tingkat pencemaran yang relatif tinggi. Penelitian ini bertujuan untuk mengetahui spesiasi dan bioavailabilitas logam Pb dan Cu pada tanah dan edible part sayur pakcoy yang ditanam di Kota Denpasar. Metode untuk menentukan bioavailabilitasnya menggunakan ekstraksi bertahap dan pengukuran konsentrasi logam Pb dan Cu menggunakan Instrumen AAS (Atomic Absorption Spectrophotometer). Spesiasi logam Pb dominan bersifat berpotensi bioavailable dengan persentase sebelum penanaman dan saat panen sebesar 90,46% dan 79,30%. Sementara itu, spesiasi logam Cu pada tanah dominan bersifat non bioavailable dengan persentase sebelum penanaman dan saat panen sebesar 55,98% dan 48,85%. Kandungan Pb dan Cu total.dalam tanah sebelum penanaman diperoleh sebesar 45,1504 mg/kg dan 84,9271 mg/kg namun, saat panen logam Pb mengalami kenaikan sebesar 99,84% dan logam Cu mengalami penurunan sebesar 12,50% dari kondisi awal. Pada bagian edible part sayur pakcoy kandungan Pb dan Cu sebesar 7,7164 mg/kg dan 20,6295 mg/kg. Berdasarkan Badan Pengawas Obat dan Makanan, sayur pakcoy pada semua lahan dalam penelitian ini tergolong tercemar logam Pb dan Cu karena melebihi ambang batas yang telah ditentukan. Kata Kunci: bioavailabilitas, logam total, pakcoy, Pb dan Cu, pertanian organik. ABSTRACT Denpasar as one of the city centers in Bali, which produces organic vegetables and is also a tourism destination, has a relatively high level of pollution. The goal of this research was to determine the speciation and bioavailability of Pb and Cu metals in soil and edible parts of Bok choy vegetables grown in Denpasar City. The method used to determine the bioavailability was sequential extraction and the Pb and Cu metal concentrations using the AAS (Atomic Absorption Spectrophotometer) instrument. The speciation of Pb was dominantly potentially bioavailable with the percentage before planting and at harvest of 90.46% and 79.30%, respectively. Meanwhile, the speciation of Cu on the soil was dominantly non-bioavailable with the percentage before planting and at harvest of 55.98% and 48.85%, respectively. The total Pb and Cu contents in the soil before planting were 45,1504 mg/kg and 84.9271 mg/kg, but when harvested, the Pb content increased by 99.84% and the Cu content decreased by 12.50% from the initial conditions. In the edible part of the Bok choy vegetable, the Pb and Cu contents were 7.7164 mg/kg and 20.6295 mg/kg. Based on the Food and Drug Supervisory Agency, Bok choy vegetables in all lands in this study were classified as contaminated with Pb and Cu metals because they exceeded the specified threshold. Keywords: bioavailability, Bok choy, organic agriculture, total metal, Pb and Cu
EFEKTIVITAS INHIBITOR KOROSI DARI EKSTRAK DAUN JERUK LEMON (Citrus limon L.) PADA BAJA ST-37 DALAM MEDIA NaCl DAN HCl Cahyanti, N. N. A. T.; Asih, I. A. R. A.; Widihati, I. A. G.
Jurnal Kimia (Journal of Chemistry) Vol. 18, No.2, Juli 2024
Publisher : Program Studi Kimia, FMIPA, Universitas Udayana (Program of Study in Chemistry, Faculty of Mathematics and Natural Sciences, Udayana University), Bali, Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar

Abstract

ABSTRAK Korosi merupakan fenomena alam yang dapat merusak material logam seperti baja St-37 dan juga menyebabkan degradasi struktur serta penurunan kinerja material logam. Beberapa penelitian telah dilakukan untuk mengembangkan inhibitor korosi sebagai solusi yang efektif. Salah satu bahan alam yang digunakan sebagai inhibitor korosi adalah ekstrak daun lemon, yaitu senyawa kimia yang ditambahkan ke lingkungan korosif untuk menghambat atau mencegah reaksi oksidasi logam. Penelitian ini bertujuan untuk mengetahui laju korosi baja St-37 dalam media korosif NaCl dan HCl serta efisiensi inhibisi penggunaan inhibitor ekstrak daun lemon dengan berbagai konsentrasi untuk mencegah korosi. Daun lemon diekstraksi menggunakan metode maserasi, kemudian ekstrak tersebut diuji kandungan metabolit sekundernya. Laju korosi ditentukan menggunakan metode kehilangan berat. Hasil uji fitokimia menunjukkan bahwa ekstrak daun lemon positif mengandung alkaloid, fenol, flavonoid, tanin, dan tanin terkondensasi. Laju korosi terendah baja St-37 pada media korosif NaCl dan HCl masing-masing sebesar 0,1685 dan 0,0658 mmpy (millimetre per year), dan efisiensi inhibibisi tertinggi untuk melindungi media korosif masing-masing sebesar 96,6963 dan 40,3065%, dicapai pada konsentrasi inhibitor 500 ppm. Pengurangan laju korosi dan efisiensi penghambatan oleh ekstrak daun lemon pada baja S-37 dalam media korosif HCl lebih baik daripada dalam media NaCl. Kata kunci: Efisiensi inhibisi, Inhibitor, Korosi, Laju korosi, Lemon ABSTRACT Corrosion is a natural phenomenon that can damage metal materials such as St-37 steel and also causes structural degradation and decreased performance of metal materials. Several studies have been conducted to develop corrosion inhibitors as an effective solution. One of the natural products used as a corrosion inhibitor is lemon leaf extract, a chemical compound added to corrosive environments to inhibit or prevent metal oxidation reactions. This study aimed to determine the corrosion rate of St-37 steel in NaCl and HCl corrosive media and the inhibition efficiency of using lemon leaf extract inhibitors with varying concentrations to prevent corrosion. Lemon leaves were extracted using the maceration method, and then the extract was tested for secondary metabolite content. The corrosion rate was determined using the weight loss method. The results of the phytochemical test showed that lemon leaf extract positively contained alkaloids, phenols, flavonoids, tannins, and condensed tannins. The lowest corrosion rate of the St-37 steel in the NaCl and HCl corrosive media of 0.1685 and 0.0658 mmpy (millimeter per year), respectively, and the highest efficiency of the inhibitor to protect corrosive media of 96.6963 and 40.3065%, respectively, were achieved at the inhibitor concentration of 500 ppm. The corrosion rate reduction and the inhibition efficiency by lemon leaf extract on the S-37 steel in HCl corrosive media was better than in NaCl media. Keywords: Corrosion, Corrosion rate, Inhibition efficiency, Inhibitor, Lemon
Co-Authors Asih, I. A. R. A. Cahyanti, N. N. A. T. Emmy Sahara G. S. U. Mahaputra I G. A. A. Ratih Megasari I G. A. K. S. P. Dewi I Gede Darma Putra I Gusti Agung Gede Bawa I Made Siaka I Nengah Wirajana I Putu Eka Suwita Hegara I Wayan Suarsa I Wayan Suirta I. A. R. Astiti Asih I. Apriliyanto Ida Bagus Putra Mahardika Ika Juliana Iryanti Eka Suprihatin James Sibarani Juniari, Tjokorda Istri Trisna K. R. Pangestu Luh De Dwi Jayanthi M A Yohanita Nirmalasari Manuntun Manurung N. P. A. H. Saraswati N. P. A. J. S. Putri Nanik Wijayanti Ni G. A. M. Dwi Adhi Suastuti Ni Made Puspawati Ni Putu Diantariani Ni Wayan Sekarini Novita Rambu Atandawu Oka Ratnayani P. Suarya Sari, A. A. D. P. Tri Rahayu Widia Purwaningrum Yuky Astary Hermanto Yuliana Farhatun Nikmah Yunita Angelina