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All Journal Reaktor IPTEK Journal of Proceedings Series IPTEK The Journal for Technology and Science BERKALA SAINSTEK Bulletin of Chemical Reaction Engineering & Catalysis Jurnal Rekayasa Kimia & Lingkungan Bulletin of Chemical Reaction Engineering & Catalysis
Widiyastuti Widiyastuti
Institut Teknologi Sepuluh Nopember
Agriculture, Biological Sciences & Forestry Biochemistry, Genetics & Molecular Biology Chemical Engineering, Chemistry & Bioengineering Chemistry Computer Science & IT Control & Systems Engineering Energy Industrial & Manufacturing Engineering Materials Science & Nanotechnology Mathematics Physics

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Controlled Morphology of Silica Particle by Spray Drying Method Albar, Abdurrahman Anis; Widiyastuti, Widiyastuti; Setyawan, Heru
IPTEK Journal of Proceedings Series No 6 (2020): 6th International Seminar on Science and Technology 2020 (ISST 2020) - IN-PRESS
Publisher : Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j23546026.y2020i6.11118

Abstract

The controlled morphology of mesoporous silica particle with colloidal silica as precursor solution was investigated using spray drying method. The colloidal silica solution was made from sodium silicate (waterglass) using sol-gel method. The operating condition of spray dring such as precursor solution volumetric rate and hot air flowrate was varied to study the effect of the silica particle’s morphology. Two-fluid nozzle was used as atomizer with volumetric rate ranged from 1.6 mL/min to 5 mL/min, and hot air heated from tubular furnace with flowrate ranged from 210 L/min to 414 L/min, both resulting doughnut-like shape with more doughnut fraction with increased volumetric rate. With the increase of volumetric rate from 1.6 mL/min to 5 mL/min, the surface area and total pore volume are tend to decrease (168.234 to 131.001 m2/g and 0.1652 to 0.1251 cc/g respectively). Meanwhile, for increasing hot air flowrate from 210 L/min to 414 L/min, the surface area are tend to increase (135.353 to 168.234 m2/g) but total pore volume tend to decrease (0.1921 to 0.1652 cc/g).
High-Stability Foam of Silica Nanofluid to Overcome Liquid Loading in Enhancing Natural Gas Production Ajiz, Hendrix Abdul; Mawarani, Lizda Johar; Widiyastuti, Widiyastuti; Setyawan, Heru
IPTEK The Journal for Technology and Science Vol 32, No 1 (2021)
Publisher : IPTEK, LPPM, Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j20882033.v32i1.7092

Abstract

One of the promising solutions to overcome the liquid loading problem in natural gas production is using a foaming agent. The extreme condition in the gas well causes the foam used tends to break up. Therefore, it is required to enhance the foam stability by adding a stabilizer agent. This research aims to investigate the effect of silica nanoparticles as a surfactant stabilizer to obtain a high-stability foam using silica nanofluid. Silica nanofluid was synthesized from sodium silicate solution by the solgel method. Then, the colloidal silica was added to the surfactant solution without a coupling agent. The effects of aging time and silica concentration were investigated. The results show that the surface tension tends to increase with the increase of aging time and silica concentration but decrease in foam stability which is indicated by a decrease in the foam half-life time. The best foam stability is obtained in silica nanofluids with an aging time of 6 hours and a silica concentration of 30 ppm, which shows a foam half-life of 42 hours and can improve foam stability with several parameters representing the conditions of the gas well
Corrosion Characteristics of Carbon Steel upon Exposure to Biodiesel Synthesized from Used Frying Oil Adhi Setiawan; Nora Amelia Novitrie; Agung Nugroho; W Widiyastuti
Reaktor Volume 17 No. 4 Desember 2017
Publisher : Dept. of Chemical Engineering, Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1037.72 KB) | DOI: 10.14710/reaktor.17.4.177-184

Abstract

The use of biodiesel leads to corrosion of automotive material, which can potentially shorten engine lifetime. The study aims to investigate the effect of temperature and contact time on the corrosion characteristics of carbon steel upon exposure to biodiesel synthesized from used frying oil. The corrosion rate of carbon steel was analyzed based on weight loss measurement according to the standard of ASTM G31 as affected by temperature and contact time. The immersion temperatures used in this study were 30oC, 40oC, and 70o, respectively. The contact times studied were 30 days, 40 days, and 50 days respectively. The results show that the increase of temperature and contact time of biodiesel on carbon steel surface speeds up the corrosion rate. Maximum corrosion rate (0.083 mmy) was observed on the carbon steel contacted to biodiesel at 70oC for 50 days. The SEM results showed an irregular shape of the corroded carbon steel surface. XRD / FTIR analysis of carbon steel samples show the presence of peaks, detected as Fe2O3, FeO(OH) and Fe2O2CO3, as the corrosion products. Keywords: biodiesel; carbon steel; corrosion; FAME; used frying oil
KINETIKA REAKSI SINTHESIS BIOMATERIAL HIDROXYAPATITE DENGAN JENIS PREKURSOR NITRAT DAN ASETAT Adhi Setiawan; W Widiyastuti; Sugeng Winardi; Agung Nugroho
Reaktor Volume 15, No.2, OKTOBER 2014
Publisher : Dept. of Chemical Engineering, Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (950.596 KB) | DOI: 10.14710/reaktor.15.2.104-110

Abstract

Hidroxyapatite (HAp) merupakan salah satu biomaterial yang banyak diaplikasikan dalam dunia medis untuk membuat implant jaringan tubuh terutama tulang dan gigi sehingga kemurnian produk HAp memegang peranan yang cukup penting. Agar diperoleh HAp dengan kemurnian tinggi, kinetika reaksi pembentukan HAp harus diketahui secara jelas. Metode yang digunakan untuk memperoleh kinetika reaksi HAp adalah dengan analisis TG-DTA  yang dilakukan pada dua jenis prekursor HAp yaitu asetat dan nitrat. Metode TG-DTA tersebut dilakukan dengan memanaskan prekursor HAp dengan variasi laju pemanasan 10, 15, 17, dan 20 oC/menit. Hasil analisis TG-DTA menunjukkan bahwa reaksi dekomposisi prekursor asetat dan nitrat membentuk HAp masing-masing terjadi pada suhu 659 oC dan 560 oC. Hasil fitting parameter kinetika menunjukkan bahwa energi aktivasi pembentukan HAp pada prekursor asetat sebesar 161,56 kJ/mol  dengan model kinetika Normal Grain Growth sedangkan pada prekursor nitrat sebesar 374 kJ/mol dengan model kinetika Johnson-Mehl-Avrami. Kata kunci: Biomaterial, hidroxypapatite, Dekomposisi, Energi Aktivasi ABSTRACT KINETIC STUDY OF THE BIOMATERIAS HIDOXYAPATITE SINTHESIS WITH PRECURSOR NITRATE AND  ACETATE. Hidroxyapatite (HAp) is one of the biomaterials widely applied in the medical world to make implant tissues of the body, especially bones and teeth so that the purity of the HAp plays a fairly important. In order to obtain high purity HAp, reaction kinetics should be known clearly. TG-DTA  is method used to obtain the reaction kinetics of HAp.TG-DTA analyzes were conducted on precursors acetate and nitrate. TG-DTA method is carried out by heating HAp precursor with variation heating rate 10, 15, 17, and 20° C/min respectively. The results of TG-DTA  showed decomposition precursor acetate and nitrate formed HAp occurs on temperature 659° C and 560° C respectively. The results of the fitting kinetic showed activation energy of  the HAp formation on acetate precursors about 161.56 kJ/mol with Normal Grain Growth kinetic model whereas the nitrate precursor about 374 kJ/mol with Johnson-Mehl-Avrami  kinetic model.
SINTESIS BIOMATERIAL HYDROXYAPATITE DENGAN PROSES FLAME SPRAY PYROLYSIS DISERTAI PENAMBAHAN ADITIF ORGANIK Adhi Setiawan; W Widiyastuti; Sugeng Winardi; Agung Nugroho
Reaktor Volume 16 No.4 Desember 2016
Publisher : Dept. of Chemical Engineering, Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (847.85 KB) | DOI: 10.14710/reaktor.16.4.189-198

Abstract

SYNTHESIS OF HYDROXYAPATITE BIOMATERIALS BY FLAME SPRAY PYROLYSIS PROCESS WITH ADDITION OF ORGANIC ADDITIVES. Hydroxyapatite is  biomaterial which is widely used for biomedical aplication such as implant because  biocompatible, bioactivity, and strong affinity to biopolymers. Therefore parameters of morphology and crystallinity becomes an important parameter to be controlled. The addition of the organic additive on HAp precursor with ethylene glycol, polyethylene glycol 400, and urea is the alternative to improve the size, morphology, and crystallinity of HAp particles. The equipment for flame spray pyrolysis process includes ultrasonic nebulizer, flame reactor, and eletrostatic precipitator. The amount of organic additives used in experiment is  30%, 50%, and 100% by mass of the precursor. The result of SEM and XRD showed HAp synthesized by the addition of additive material has a smaller size than without using the additive and crystallinity is better than no additive. In addition HAp synthesized by the addition of 30% PEG additive have smallest average particle size about 114 nm, crystalite size about 16,6 nm and spherical morphology with a low agglomeration. Keywords: Hidroxyapatite, organic additives, flame spray pyrolysis, morfology  Abstrak Hydroxyapatite merupakan biomaterial yang seringkali diaplikasikan dalam biomedis sebagai bahan implant karena sifatnya yang biocompatible, bioactivity, dan memiliki afinitas yang kuat terhadap biopolimer. Oleh karena itu parameter morfologi serta kristalinitas partikel menjadi parameter penting untuk dikontrol. Penambahan aditif organik pada prekursor HAp dengan etilen glikol, polietilen glikol 400, serta urea merupakan alternativ agar memperbaiki ukuran, morfologi, serta meningkatkan kristalinitas partikel HAp. Peralatan utama flame spray pyrolysis meliputi ultrasonic nebulizer, reaktor flame, dan eletrostatik precipitator. Jumlah aditif organik yang digunakan pada eksperimen antara lain 30%, 50%, dan 100% massa prekursor. Hasil SEM dan XRD menunjukkan bahwa HAp yang disintesis dengan penambahan bahan aditif memiliki ukuran lebih kecil daripada tanpa menggunakan aditif dan tingkat kristalinitasnya lebih baik dibandingkan tanpa aditif. Selain itu HAp yang disintesis dengan penambahan aditif PEG sebanyak 30% memiliki ukuran rata-rata partikel yang terkecil yaitu sebesar 114 nm dengan ukuran kristal mencapai 16,6 nm serta memiliki morfologi bulat dengan tingkat aglomerasi yang rendah.
Peningkatan Stabilitas Busa dengan Nanofluida Silika Untuk Meningkatkan Produksi Gas Alam Hendrix Abdul Ajiz; Lizda Johar Mawarani; Widiyastuti Widiyastuti; Heru Setyawan
BERKALA SAINSTEK Vol 8 No 1 (2020)
Publisher : Universitas Jember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.19184/bst.v8i1.15401

Abstract

Pemanfaatan gas alam sebagai sumber energi alternatif masih belum optimal karena masalah beban cairan pada sumur gas, surfaktan merupakan solusi yang menjanjikan untuk mengatasi masalah tersebut, namun dengan kondisi sumur gas yang ekstrem diperlukan stabilizer untuk meningkatkan stabilitasnya. Penelitian ini mempelajari pengaruh pencampuran surfaktan dan stabilizer berupa silika (SiO2) nanopartikel yang disintesa dari sodium silikat (Na2SiO3) untuk mendapatkan kondisi optimum nanofluida SiO2 terhadap waktu paruh busa yang menunjukkan kestabilannya. Silika nanopartikel disintesa dengan metode sol-gel dan dipertahankan dalam fase koloid stabil yang kemudian didispersikan ke dalam larutan surfaktan tanpa perlu penambahan bahan penyambung. Nanofluida SiO2 kemudian dimatangkan dengan variasi waktu dan konsentrasi silika. Dari hasil yang diperoleh menunjukkan bahwa peningkatan waktu pematangan dan konsentrasi silika memengaruhi nilai tegangan permukaan yang berakibat menurunkan waktu paruh busa. Penurunan kestabilan busa terjadi karena peristiwa adsorbsi fisik molekul surfaktan oleh silika nanopartikel yang ditunjukkan oleh nilai tegangan permukaan, karena silika yang bersifat hidrofilik akan membentuk ikatan fisik dengan surfaktan, semakin meningkatnya waktu pematangan dan konsentrasi silika yang didispersikan kedalam larutan akan meningkatkan adsorbsi molekul surfaktan pada permukaan silika dan menyebabkan terjadinya peningkatan nilai tegangan permukaan nanofluida. Stabilitas busa terbaik diperoleh pada sampel dengan waktu pematangan selama 6 jam dan konsentrasi silika 0,001% menghasilkan waktu paruh selama 1170 menit yang jika dibandingkan dengan surfaktan tanpa penambahan silika nanopartikel hanya memeroleh waktu paruh selama 90 menit, sehingga penggunaan silika nanopartikel sebagai stabilizer memberikan efek yang signifikan terhadap kestabilan busa.
Synthesis of PVA/SiO2 Nanofibers by Electrospinning Method for Supercapacitor Separators Muhamad Nirwan; Heru Setyawan; Widiyastuti Widiyastuti
IPTEK Journal of Proceedings Series No 6 (2020): 6th International Seminar on Science and Technology 2020 (ISST 2020)
Publisher : Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j23546026.y2020i6.11119

Abstract

In this research, polyvinyl alcohol (PVA)/silica nanofibers have been synthesized using electrospinning technique. Solutions of sodium silicate (Na2SiO3) in water and PVA flakes were blended and then processed by electrospinning method to obtain PVA/silica nanofibers. The effect of silica concentration on the resulting morphology and diameter of as-spun nanofibers were investigated by using scanning electron microscopy (SEM). The electrolyte uptake and retention of the as-spun nanofibers were measured. The silica concentration has an effect on the resulting nanofibers, where an increase in silica concentration resulted in a decrease on the diameter of the fibers. The manufactured nanofibers have an average diameter of 200-300 nm. The electrolyte uptake and retention values are also affected by the concentration of the silica in the electrospun solution, with the electrolyte uptake and retention values decreasing with the increase in silica concentration. The best values obtained are 151% for electrolyte uptake and 60% for electrolyte retention, which shows potential for PVA/silica nanofibers as an alternative material for supercapacitor separators.
The Effect of Furnace Temperature and Precursor Concentration Ratio to The Characteristics of Nanocomposite ZnO-Silica Iva Maula; Widiyastuti Widiyastuti; Tantular Nurtono; Fadlilatul Taufany; Siti Machmudah; Sugeng Winardi
IPTEK Journal of Proceedings Series Vol 1, No 1 (2014): International Seminar on Applied Technology, Science, and Arts (APTECS) 2013
Publisher : Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j23546026.y2014i1.323

Abstract

Zinc Oxide is a semiconductor with relatively non-toxic, cheap and abundant properties which can be applied to LEDs. ZnO colloids are unstable due to further chemical reactions and coagulation so the addition of silica is needed to inhibit the growth of ZnO. ZnO was synthesized using sol-gel method by hydrolyze zinc acetate dihydrate in ethanol solution. Silica colloids was prepared by dissolving waterglass in distilled water at a temperature of 60 °C then passed into cation resin that has been activated using 2N HCl for ion exchange with Na+ to H+. In this study, the spray drying method was used to produce ZnO-silica nanocomposite. Morphological characterization of particles formed was analyzed using Scanning Electrostatic Microscope (SEM) (Zeiss Evo MA LS, Cambridge, England). X-Ray Diffraction (XRD) (Cu-Kα 1.54 A0, 40 kV, 30 mA, X’pert Pro, PAN alytical, Netherlands) and Fourier Transform Infrared (FTIR) (Therniscientific Nicolet iS10, US) were used to analyze the crystallinity and group functionalization, respectively. The results show that more particles are formed on 10% concentration volume of ZnO colloids rather than 5%.
Synthesis of Composite Graphene/ Fe3O4 by Electrophoretic Deposition Using Pulse Direct Current Ervina Rumpakwakra; Hariyati Purwaningsih; Widiyastuti Widiyastuti; Heru Setyawan
IPTEK Journal of Proceedings Series No 6 (2020): 6th International Seminar on Science and Technology 2020 (ISST 2020)
Publisher : Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j23546026.y2020i6.11101

Abstract

Composites Graphene/Fe3O4 have been successfully synthesized by the electrophoretic deposition method using pulse direct current (PDC) on a nickel foam substrate. In this study, we synthesized graphene and Fe3O4 separately before the two materials were composited. We synthesize graphene from coconut shell charcoal and synthesize Fe3O4 from pure iron. Graphene and Fe3O4 which have been formed, are dissolved with demineralized water as a dispersing medium so that a solution of 1.5 mg / mL is obtained which is then compiled layer by layer on the surface of the substrate with variations in deposition time of 10 to 30 minutes at room temperature. This aims to determine the effect of deposition time on the formation of graphene/Fe3O4 composites. The results showed that the use of PDC was able to precipitate graphene/Fe3O4 composites on the surface of the substrate. The use of longer deposition time, results in more graphene/Fe3O4 composites which adhere to the substrate surface. This result is also supported by XRD testing which shows the longer the deposition time, the diffraction peaks appear sharper.
Graphitization of Coconut Shell Charcoal for Sulfonated Mesoporous Carbon Catalyst Preparation and Its Catalytic Behavior in Esterification Reaction Fahmi Fahmi; Widiyastuti Widiyastuti; Heru Setyawan
Bulletin of Chemical Reaction Engineering & Catalysis 2020: BCREC Volume 15 Issue 2 Year 2020 (August 2020)
Publisher : Department of Chemical Engineering - Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.9767/bcrec.15.2.7745.538-544

Abstract

Here, we reported the utilization of coconut shell charcoal used for solid acid catalysts and its performance in the esterification reaction of acetic acid and methanol. The graphitization of coconut shell charcoal was carried out by the calcination and KOH activation at the temperature of 400 °C for an hour and continued at the temperature of 800 °C for an hour under nitrogen flow resulted in graphitic carbon. The effect of the addition of KOH activation was observed by varied the weight ratio of coconut shell charcoal as raw material (RM) and KOH. The selected weight ratio of RM:KOH was 1:1, 1:2, and 1:4. The resulted graphitic carbon was sulfonated by heating with the sulfuric acid to obtain a solid acid catalyst. The sulfonic time was evaluated for 5 and 10 hours. The generated particles were characterized to examine the morphology, the crystallinity, the specific surface area, the chemical bonding, and the ionic capacity using Scanning Electron Microscopy (SEM), X-Ray diffraction (XRD), nitrogen gas absorption-desorption, Fourier Transform Infrared Spectroscopy (FTIR), and titration method, respectively. The best condition for graphitization of raw material is the use of RM:KOH = 1:4, resulting in the highest surface area reaching 1259.67 m2/g and the most dominant of the sulfonic group of −SO3 bond. Furthermore, increasing the sulfonating time from 5 to 10 hours led to the increase of the yield of esterification reaction from 85% to 96.57% for graphite synthesized using RM:KOH = 1:4. Copyright © 2020 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 
Co-Authors Abdul Halim Adhi Setiawan Agung Nugroho Agung Nugroho Ajiz, Hendrix Abdul Albar, Abdurrahman Anis Delyana Ratnasari Ervina Rumpakwakra Fadlilatul Taufany Fahmi Fahmi Hariyati Purwaningsih Hendrix Abdul Ajiz Heru Setyawan Iva Maula Mawarani, Lizda Johar Muhamad Nirwan Ni Made Intan Putri Suari Nora Amelia Novitrie Sahara Tulaini Siti Machmudah Tantular Nurtono Winardi, Sugeng