Hariyati Purwaningsih
Sepuluh Nopember Institute of Technology
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Featured researches published by Hariyati Purwaningsih.
Frontiers of Chemical Engineering in China | 2014
Diah Susanti; A. A. Gede Pradnyana Diputra; Lucky Tananta; Hariyati Purwaningsih; George Endri Kusuma; Chenhao Wang; Shaoju Shih; Ying-Sheng Huang
Carbon monoxide is a poisonous and hazardous gas and sensitive sensor devices are needed to prevent humans from being poisoned by this gas. A CO gas sensor has been prepared from WO3 synthesized by a sol-gel method. The sensor chip was prepared by a spin-coating technique which deposited a thin film of WO3 on an alumina substrate. The chip samples were then calcined at 300, 400, 500 or 600 °C for 1 h. The sensitivities of the different sensor chips for CO gas were determined by comparing the changes in electrical resistance in the absence and presence of 50 ppm of CO gas at 200 °C. The WO3 calcined at 500 °C had the highest sensitivity. The sensitivity of this sensor was also measured at CO concentrations of 100 ppm and 200 ppm and at operating temperatures of 30 and 100 °C. Thermogravimetric analysis of the WO3 calcined at 500 °C indicated that this sample had the highest gas adsorption capacity. This preliminary research has shown that WO3 can serve as a CO gas sensor and that is should be further explored and developed.
Frontiers of Chemical Engineering in China | 2012
Diah Susanti; N. Stefanus Haryo; Hasnan Nisfu; Eko Prasetio Nugroho; Hariyati Purwaningsih; George Endri Kusuma; Shaoju Shih
Tungsten (VI) oxide (WO3) nanomaterials were synthesized by a sol-gel method using WCl6 and C2H5OH as precursors followed by calcination or hydrothermal treatment. X-Ray diffraction (XRD), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM) equipped with energy dispersive X-ray spectroscopy (EDX) were used to characterize the structure and morphology of the materials. There were significant differences between the WO3 materials that were calcinated and those that were subjected to a hydrothermal process. The XRD results revealed that calcination temperatures of 300°C and 400°C gave hexagonal structures and temperatures of 500°C and 600°C gave monoclinic structures. The SEM images showed that an increase in calcination temperature led to a decrease in the WO3 powder particle size. The TEM analysis showed that several nanoparticles agglomerated to form bigger clusters. The hydrothermal process produced hexagonal structures for holding times of 12, 16, and 20 h and monoclinic structures for a holding time of 24 h. The SEM results showed transparent rectangular particles which according to the TEM results originated from the aggregation of several nanotubes.
5TH NANOSCIENCE AND NANOTECHNOLOGY SYMPOSIUM (NNS2013) | 2014
Diah Susanti; Agung Seras Perdana; Hariyati Purwaningsih; Lukman Noerochim; George Endri Kusuma
CO gas sensor chips have been successfully prepared from WO3 nanomaterial synthesized using sol-gel method followed by hydrothermal process at various temperatures of 160 °C, 180 °C and 200 °C for 12 hours. The sensor preparation is necessary to prevent human from being poisoned by CO gas. The sample hydrothermally processed at 160 °C showed the most sensitive response to CO gas because it had the highest active surface area of 58.5 m2g−1 based on BET analysis. The sensitivity of the sensor material to CO gas increased with the increasing of CO gas concentrations of 10, 100, 250 and 500 ppm and operating temperatures of 30 °C, 50 °C and 100 °C. In this experiment, the morphology and structure of materials before and after CO gas exposure were analyzed and compared using XRD and SEM instruments. The research results highlighted the potential of WO3 material as a CO gas sensor, comparable with other semiconductor materials such as ZnO, TiO2 and SnO2.
Frontiers of Materials Science | 2013
Diah Susanti; Rizky Narendra Dwi Wibawa; Lucky Tananta; Hariyati Purwaningsih; Rindang Fajarin; George Endri Kusuma
Electrochemical capacitor (EC) is a promising energy storage device which can be hybridized with other energy conversion or energy storage devices. One type of ECs is pseudocapacitor made of metal oxides. WO3 is an inexpensive semiconductor metal oxide which has many applications. However the application of WO3 as an EC material was rarely reported. Therefore in this research EC was prepared from WO3 nanomaterial synthesized by a sol-gel process. The WO3 gel was spin-coated on graphite substrates and calcined at various temperatures of 300°C, 400°C, 500°C and 600°C for 1 h. Cyclic voltammetry (CV) measurements were used to observe the capacitive property of the WO3 samples. SEM, XRD, FTIR and Brunauer-Emmett-Teller (BET) analyses were used to characterize the material structures. WO3 calcined at 400°C was proved to have the highest capacitance of 233.63 F·g−1 (1869 mF·cm−2) at a scan rate of 2 mV·s−1 in 1 mol/L H2SO4 between potentials −0.4 and 0.4 V vs. SCE. Moreover it also showed the most symmetric CV curves as the indication of a good EC. Hence WO3 calcined at 400°C is a potential candidate for EC material of pseudocapacitor type.
INTERNATIONAL CONFERENCE ON ENGINEERING, SCIENCE AND NANOTECHNOLOGY 2016 (ICESNANO 2016) | 2017
Juliana Anggono; Suwandi Sugondo; Sanjaya Sewucipto; Hariyati Purwaningsih; Steven Henrico
Sugarcane fibers have been studied as reinforcement fibers to develop biocomposites of sugarcane fibers-polypropylene (PP). In this study, two different alkaline solutions were used to modify the sugarcane bagasse fibers, i.e. 10% v/v NaOH and 14% v/v Ca(OH)2 solution for 4 hours. Sugarcane fibers filled to polypropylene (PP) matrix was 3 cm, 5 cm and as their original length. They were added in the various weight percentage ratios between sugarcane fibers to PP of 20/80, 25/75, and 30/70. Fourier-Transform Infrared (FTIR) spectroscopy was used to study the chemical structure of bagasse fibers after treatment. Composite strength was measured by tensile test which was performedin accordance with ASTM D638-03. The fracture surface of tensile tested composite specimens contained fibers from both treatment was evaluated using Scanning Electron Microscope (SEM). Results from the tensile test show that performing NaOH treatment for 4 hours could increase the tensile strength of the composites to 24.92 MPa when ...
Applied Mechanics and Materials | 2015
Juliana Anggono; Suwandi Sugondo; Steven Henrico; Hariyati Purwaningsih
Milling sugarcanes to produce sugar generates by-product called bagasse. Due to the large availability and low cost, the potential of obtaining renewable and biodegradable fibers from bagasse had been explored. To produce fibers from these bagasse, the bagasse was treated in alkali solution using 14 % v/v calcium hydroxide, Ca (OH)2 at high temperature (60-70°C) for 4 hours. After treatment and washed to remove dissolved substances, the fibers were cut into 3 and 5 cm length. Some fibers were prepared in their original length. These fibers were mixed with polypropylene (PP) matrix in weight % ratios of bagasse fibers/PP 20/80, 25/75, and 30/70 and hotpressed to make composite samples. Composites produced were characterised with tensile test to evaluate their tensile properties. Scanning electron microscopy (SEM) was performed on the fiber surface as well as on the fracture area of the tensile tested samples. Tensile strength of the composite shows an increase with the increase of the fiber length and weight % ratios of bagasse fibers/PP up to 25/75 and decreases when bagasse fibers were added to 30 wt.%. The highest strength of 11,30 MPa was obtained when 5 cm fibers were used in a weight % ratio of bagasse fibers/PP at 25/75. SEM study found a greater number of fibers oriented perpendicular to the tension direction.
Archive | 2018
Hariyati Purwaningsih; Rochman Rochiem; Muhammad Suchaimi; Wikan Jatimurti; Alvian Toto Wibisono; Budi Agung Kurniawan
Low Temperature Hot Corrosion (LTHC) is type of hot corrosion which occurred on 700-800°C and usually on turbine blades. So, as a result the material of turbine blades is crack and degredation of rotation efficiency. Hot corrosion protection with the use of barrier that separate substrate and environment is one of using metal surface coating, wire arc spray method. This study has a purpose to analyze the effect of nozzle distance and gas pressure on FeCrBMnSi coating process using wire arc spray method on thermal resistance. The parameter of nozzle distance and gas pressure are used, resulted the best parameter on distance 400 mm and gas pressure 3 bar which has the bond strength of 12,58 MPa with porosity percentage of 5,93% and roughness values of 16,36 µm. While the examination of thermal cycle which by heating and cooling continuously, on the coating surface is formed oxide compound (Fe3O4) which cause formed crack propagation and delamination. Beside that hardness of coating surface is increase which caused by precipitate boride (Fe9B)0,2
Materials Science Forum | 2018
Juliana Anggono; Suwandi Sugondo; Rassy Alim; Hariyati Purwaningsih; Aria Wibawa
Many auto manufacturers such as Mercedes Benz, Toyota and DaimlerChrysler have already embraced natural fiber composites into both interior and exterior parts and are looking to expand the uses of this composites. They have to balance the changing public demands of greater comfort, better driving performances, and higher safety standards with the environmental requirements. Based on the preliminary study using 20 to 30 wt.% NaOH treated sugarcane bagasse fibers to make biocomposites with polypropylene matrix, the tensile strength obtained was variably, in the range between 8.31 to 20.59 MPa. A further study was required to improve the strength of the composites in comparison with the specified flexural strength required by the industry for automotive parcel tray. The sugarcane bagasse fibers obtained from the sugar mill were used and alkali treated with 10% v/v NaOH at various soaking time of 2, 4, and 6 hours. Biocomposite samples were prepared from 25/75 wt.% ratio sugarcane fibers/polypropylene (PP). The highest tensile strength of 14.35 MPa was obtained from the samples with sugarcane fibers receiving two-hour alkali treatment. However, the highest flexural strength (37.78 MPa) was gained on the samples made from sugarcane fibers with 4 hours alkali treatment. This value has met the strength specification of two materials for current parcel trays which were made from monomaterial of polypropylene and woodboard composite which their flexural strengths were 35.6 MPa and 37.57 MPa, respectively. Structural studies using scanning electron microscopy (SEM) on the fracture surface of tensile tested samples show two different orientations of bagasse fibres in PP matrix, i.e. a group was in longitudinal orientation and other in transversal orientation.
Jurnal Teknik ITS | 2018
Ni Komang Alit Juliani; Hariyati Purwaningsih; Diah Susanti; Vania Mitha Pratiwi
Penelitian ini bertujuan untuk menganalisa pengaruh efektifitas leaching dalam menghasilkan silika, dan menganalisa pengaruh penambahan senyawa template OA (Octyl Amine) pada pembentukan mesopori silika nanopartikel. Penelitian ini menggunakan bahan dasar sekam padi yang di leaching menggunakan asam kuat yaitu HNO3, HCl, dan H2SO4. Berdasarkan hasil pengujian EDX kadar silika yang paling tinggi dihasilkan pada leaching menggunakan HNO3 sebesar 39.21 (wt%). Gugus fungsi hasil FTIR menjelaskan adanya gugus siloksan. Hasil XRD menunjukkan bahwa silika mesopori silika nanopartikel hasil proses ekstraksi mempunyai fasa amorfus. Hasil SEM pada mesopori silika nanopartikel memiliki bentuk partikel yang lebih kecil dan penyebarannya merata. Dari hasil TEM didapatkan ukuran partikel pada mesopori silika nanopartikel berkisar antara 16-80nm. Mesopori silika nanopartikel memiliki diameter pori rata-rata sebesar 12.6 nm. Penggunaan OA berhasil untuk menyeragamkan ukuran partikel.
Architectural Science Review | 2018
Christina Mediastika; Luciana Kristanto; Juliana Anggono; Fefen Suhedi; Hariyati Purwaningsih
ABSTRACT For buildings in tropical climates, the use of open windows for natural ventilation can not only provide low cost and low energy comfort but also provide thermal delight for occupants. However open windows let in environmental noise. The size and location of windows in walls are key but this study set out to determine whether there are any window forms that can effectively reduce the level of sound ingress into a building. A top-hung window was chosen for this study looking at the dimensions of the window opening and its orientation in relation to the environmental noise source. The top-hung form was selected for its potential to balance the functions of allowing airflow while potentially blocking and reducing noise levels with its window pane angle. The window pane was tested in a laboratory at three opening angles: 0° (closed), 5°, and 10° to let the outdoor air in. The angles were also tested in three different orientations in relation to the noise source position: perpendicular, sideways 60°, and sideways 90°. The test was conducted at 1/3 octave band frequency as specified by ASTM E90-09 to obtain the transmission loss, then ASTM E1332-90 was referred to calculate the outdoor-indoor transmission class (OITC) of the specimens. The study revealed that window orientation and extent of the openings and window pane angle have little effect on noise reduction. The paper concludes with a discussion of how higher levels of natural ventilation can be achieved, particularly in noisy urban areas. The top-hung window, once open, barely blocks environmental noise. However, when the window was closed, the perpendicular orientation offered more noise reduction when compared windows placed sideways to the noise source. The adjustable pane-angle of a top-hung window placed perpendicular to the airflow, and thus the noise source, seemed to have the most potential to balance the functions of allowing airflow when opened and reducing significant noise when closed. Nonetheless, an open window that through its design alone can significantly reduce the ingress of ambient noise into a building is still an issue.