This letter is a response to the comment by Professor Ho on our recent article entitled “Acid Green 25 removal from wastewater by organo-bentonite from Pacitan” published in Applied Clay Science 48 (2010) 81–86. Professor Ho raised an... more
This letter is a response to the comment by Professor Ho on our recent article entitled “Acid Green 25 removal from wastewater by organo-bentonite from Pacitan” published in Applied Clay Science 48 (2010) 81–86. Professor Ho raised an issue about citation misleading for the pseudo-first and second order kinetic equations which are widely used to correlate kinetic adsorption data. This letter is intended to clarify the misunderstanding and present the correct citations.
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A potential application of KOH/bentonite as a catalyst for biodiesel production was studied. A series of KOH/bentonite catalysts was prepared by impregnation of bentonite from Pacitan with potassium hydroxide. The ratios between KOH and... more
A potential application of KOH/bentonite as a catalyst for biodiesel production was studied. A series of KOH/bentonite catalysts was prepared by impregnation of bentonite from Pacitan with potassium hydroxide. The ratios between KOH and bentonite were 1:20, 1:10, 1:5, 1:4, 1:3, and 1:2. The characterization of KOH/bentonite and natural bentonite was conducted by nitrogen adsorption and XRD analysis. The effects of various reaction variables on the yield of biodiesel were investigated. The highest yield of biodiesel over KOH/bentonite catalyst was 90.70 ± 2.47%. It was obtained at KOH/bentonite 1:4, reaction time of 3 h, 3% catalyst, methanol to oil ratio of 6, and the reaction temperature at 60 °C.
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The preparation of activated carbon from vacuum pyrolysis char of teak sawdust was studied and the results are presented in this paper. The effects of process variables such as temperature and activation time on the pore structure of... more
The preparation of activated carbon from vacuum pyrolysis char of teak sawdust was studied and the results are presented in this paper. The effects of process variables such as temperature and activation time on the pore structure of activated carbons were studied. The activated carbon prepared from char obtained by vacuum pyrolysis has higher surface area and pore volume than that from atmospheric pyrolysis char. The BET surface area and pore volume of activated carbon prepared from vacuum pyrolysis char were 1150 m2/g and 0.43 cm3/g, respectively.
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Bentonite Pacitan was modified with cetyl trimethylammonium bromide (CTAB) and LAS for bleaching crude palm oil. The organo-bentonites were prepared by normal heating and microwave irradiation. The advantage of using microwave irradiation... more
Bentonite Pacitan was modified with cetyl trimethylammonium bromide (CTAB) and LAS for bleaching crude palm oil. The organo-bentonites were prepared by normal heating and microwave irradiation. The advantage of using microwave irradiation is time efficiency. The bentonites were characterized by FTIR and XRD analysis. LAS modified bentonite was more effective as bleaching agent than CTA-bentonite.
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The capability of surfactant modified-bentonite for adsorption of dyestuff from aqueous solution was investigated. The so-called “organo-bentonite” was obtained by modifying the raw bentonite obtained from Pacitan, Indonesia using cetyl... more
The capability of surfactant modified-bentonite for adsorption of dyestuff from aqueous solution was investigated. The so-called “organo-bentonite” was obtained by modifying the raw bentonite obtained from Pacitan, Indonesia using cetyl trimethylammonium bromide (CTAB) and later employed as adsorbent for Acid Green 25 removal. Isotherm and kinetic experiments were carried out on three different temperatures (30, 40 and 50 °C). Langmuir and Freundlich models were chosen for isotherm equilibria data correlation, of which the former showed better suitability. On kinetic data representation, pseudo-first and second order models were used, with the last model gave better correlation.
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Rice starch is one of the most expensive yet very useful starches due to its unique characteristics. This study aimed to isolate starch from defatted rice bran, an underutilized byproduct of milling and is a relatively inexpensive source... more
Rice starch is one of the most expensive yet very useful starches due to its unique characteristics. This study aimed to isolate starch from defatted rice bran, an underutilized byproduct of milling and is a relatively inexpensive source of rice starch. Starch was extracted from the bran by first soaking it in water. The mixture was then subjected to blending and washing with water, alcohol and alkali solution. About 83% of the rice bran starch was recovered. Characterization of the rice bran starch showed that its gelatinization and retrogradation properties as well as its granule size are similar to those of starch from rice endosperm. Based on the results of this study, defatted rice bran can be a good source of starch that is suitable for applications in food and pharmaceutical industry and other new applications such as a potential material in the biomedical field.
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Rarasaponin that belongs to the natural surfactant was used as modifying agent for preparation of organo-bentonite. This surfactant was extracted from wild plant Sapindus rarak DC. The modifying process was conducted by microwave thermal... more
Rarasaponin that belongs to the natural surfactant was used as modifying agent for preparation of organo-bentonite. This surfactant was extracted from wild plant Sapindus rarak DC. The modifying process was conducted by microwave thermal irradiation. The characterization of bentonite and its modified form was carried out using FTIR, nitrogen sorption and XRD analysis. In order to test the adsorption capability of organo-bentonite, batch adsorption experiments of methylene blue from aqueous solution using this adsorbent were conducted under several operating conditions. The highest adsorption capacity (qm) of organo-bentonite obtained in this study was 256 mg/g while for raw bentonite was 194 mg/g at 60 °C. The adsorption isotherm and kinetic data were modeled using several well known models. Freundlich isotherm model represented the adsorption equilibrium data better than the Langmuir isotherm model. For the kinetic model, the pseudo-second order gave reasonable parameters and could correlate the kinetic data well. New mechanisms of organo-bentonite formation as well as adsorption of methylene blue on the surface of organo-bentonite were also proposed in this paper.► The use of natural surfactant for organo-bentonite preparation. ► Natural chemical as modifying agent. ► New mechanism on the reaction between rarasaponin and silanol group of bentonite.
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ABSTRAK Kulit buah matoa memiliki potensi untuk menggantikan kayu sebagai bahan baku utama pembuatan kertas. Kulit buah matoa mengandung selulosa sehingga dapat diolah menjadi kertas. Dalam penelitian ini, proses pembuatan kertas dari... more
ABSTRAK Kulit buah matoa memiliki potensi untuk menggantikan kayu sebagai bahan baku utama pembuatan kertas. Kulit buah matoa mengandung selulosa sehingga dapat diolah menjadi kertas. Dalam penelitian ini, proses pembuatan kertas dari kulit buah matoa melalui beberapa tahapan yaitu pemasakan, pencucian, pencampuran antara pulp kulit matoa dengan pulp kertas koran bekas, dan pencetakan kertas. Tujuan dari penelitian ini adalah mempelajari pengaruh metode pretreatment (dengan bantuan gelombang mikro dan ultrasonik), rasio volume asam asetat dengan massa kulit matoa, serta waktu paparan gelombang terhadap perolehan α-selulosa dari kulit matoa. Penelitian ini juga mempelajari pengaruh rasio pulp kulit matoa dan pulp koran bekas serta metode pretreatment terhadap karakteristik kertas serat campuran yang dihasilkan seperti daya tembus (bursting strength), kekuatan tarik (tear strength), gramatur (grammage), fleksibilitas/kekakuan (stiffness), dan ketebalan (thickness). Hasil penelitian menunjukkan bahwa pretreatment dengan gelombang mikro dan gelombang ultrasonik dapat meningkatkan perolehan kadar α-selulosa kulit buah matoa dalam kisaran variabel yang dipelajari. Rasio antara kulit buah matoa dan asam asetat 1:15 dan total waktu paparan 10 menit merupakan kondisi terbaik karena mampu memberikan kadar α-selulosa tertinggi yaitu 77,16% untuk gelombang mikro dan 74,86% untuk gelombang ultrasonik. Kertas serat campuran dari pulp kulit matoa hasil pretreatment dengan gelombang mikro memiliki karakteristik yang lebih baik dibandingkan kertas serat campuran dari pulp hasil pretreatment dengan gelombang ultrasonik. Kertas tersebut memiliki karakteristik daya tembus sebesar 1,55 kPa/cm 2 , kekuatan tarik sebesar 706,5 mN, gramatur sebesar 390,95 g/m 2 , fleksibilitas sebesar 85 g/cm, dan ketebalan sebesar 1679,5 mikron. Berdasarkan nilai tiga parameter utama kertas (grammage, tear strength, dan stiffness), pretreatment dengan gelombang mikro dengan rasio pulp kulit buah matoa dan pulp kertas koran 1:1 dapat menghasilkan tipe kertas karton dupleks sesuai SNI 0123:2008. Kata kunci : kulit matoa, microwave, ultrasound, kertas serat campuran I. Pendahuluan Dalam satu dekade terakhir diketahui telah terjadi peningkatan polusi akibat emisi gas CO2. Emisi gas CO2 berasal dari 65% pembakaran bahan bakar fosil, 14% aktivitas pertanian, dan 18% kerusakan hutan. Sesuatu hal yang janggal bahwa hutan yang seharusnya menjadi elemen penting dalam penyerapan gas CO2 justru menjadi salah satu kontributor utama dalam produksi gas CO2. Kerusakan hutan yang terjadi diakibatkan penggundulan hutan secara liar tanpa adanya penanaman kembali. Penggundulan hutan terjadi salah satunya karena tingginya konsumsi kertas dunia, dimana kayu yang merupakan hasil penggundulan hutan merupakan bahan baku utama pembuatan kertas. Berdasarkan data Badan Statistik Kehutanan Indonesia, luas hutan di Indonesia sebesar 99,6 juta hektar atau 52,3% luas wilayah Indonesia [1]. Menurut ilmuwan UGM Prof. Dr. Sudjarwadi, setiap hektar hutan dapat menghasilkan 160 meter kubik kayu, dan setiap industri pulp memerlukan 4,6 meter kubik kayu untuk memproduksi sejumlah 1,2 ton kertas [2]. Sementara itu, hasil riset Kementerian Perindustrian Indonesia, produksi kertas di Indonesia mencapai 13 juta ton pada tahun 2013. Setiap pohon dapat mengikat CO2 di udara sebesar 36 gram CO2 per hari [3]. Dengan asumsi bahwa setiap hektar hutan terdapat 25 pohon, maka setiap hektar hutan dapat mengikat CO2 sebesar 328.500 gram setiap tahunnya. Berdasarkan data-data tersebut didapatkan fakta bahwa dengan produksi kertas sebesar 13 juta ton per tahun dibutuhkan sekitar 300.000 hektar pohon yang sebenarnya dapat mengikat CO2 di udara sebesar 98,55 juta ton. Akibat semakin banyaknya penggunaan kayu untuk pembuatan kertas, maka diperlukan bahan alternatif lain untuk mengatasi masalah ini. Bahan baku terbarukan yang mampu menggantikan peran kayu dalam pembuatan kertas diperlukan, sehingga dapat meminimalisir penebangan hutan dan membantu mengurangi terjadinya efek pemanasan global.