Wahyu Prasetyo Utomo
Department of Chemistry, Sepuluh Nopember Institute of Technology (ITS), Jl. Arief Rahman Hakim, Sukolilo, Surabaya 60111

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Characterization of mannanase-producing bacteria from sago hump Wahyuni, Sri; Khaeruni R, Andi; Lianto, Lianto; Sidarmin, Sidarmin; Holilah, Holilah; Utomo, Wahyu Prasetyo; Asranudin, Asranudin
Waste Technology Vol 4, No 1 (2016)
Publisher : Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (715.804 KB) | DOI: 10.12777/wastech.4.1.1-6

Abstract

Sago is a hardwood that can be used as source of fiber hemicellulose mannan. The abundance of mannanase waste is potential for the production of functional foods such as Manno oligosaccharides. Sago hump which is sago processing waste is very potential for growth of microorganisms because it contains lignin, cellulose, starch, minerals and vitamins that can be used as sources of carbon and energy for the growth. In this study, BLS.11-01 and BLS.11-02 isolates have been isolated and characterized from waste of sago hump. Locust bean gum was used as  substrate for measuring the activity of mannanase. Both isolates had optimum temperatures at 70°C and 60°C while they remain stable at temperature range of 30°C - 90°C. Mannanase from BLS.11-01 and BLS.11-02 had optimum pH at 6 and 7, respectively, and were also stable in wide pH range of 2-8. Co2+ was a mannanase activator for both isolates. Cu2+, Zn2+, Ni2+, Ca2+ and Fe2+ were  mannanase inhibitors for two isolates. Tween 20 (0.5% and 1.0%) and NaCl (0.5% and 1.0%) were chemical reagents that could enhance the activity of BLS.11-01 and BLS.11-02 mannanase isolates.  While tween 80 (0.5% and 1.0%), urea (0.5% and 1.0%) and SDS (0.5% and 1.0%) were chemical reagents that were not effective for both isolates mannanase activity
Properties and Toxicity of Cobalt(II) Complex with 2,4,5-triphenyl-1H-imidazole Ligand Martak, Fahimah; Cahyani, Nuari Wahyu Dwi; Nugraheni, Zjahra Vianita; Utomo, Wahyu Prasetyo
Indonesian Journal of Chemistry Vol 16, No 3 (2016)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (339.617 KB) | DOI: 10.22146/ijc.21140

Abstract

Binuclear cobalt(II) complex with 2,4,5-triphenyl-1H-imidazole ligand has been synthesized using reflux method. The yellowish green crystals with needle-like shape were obtained. Determination of molecular formula of the complex was carried out using Atomic Absorption Spectroscopy (AAS) and CHN elemental analysis. The contents of carbon, hydrogen, nitrogen and cobalt(II) in the complex were 36.28, 5.32, 4.17, and 16.64% by weight, respectively. The calculation of element composition showed that the molecular formula of complex [(H2O)5Co-L-Co(H2O)5]Cl3. The IR spectrum showed absorption peaks of Co-N and Co=O at 397.31 and 493.74 cm-1, respectively, confirming the formation of complex. The complex compound showed paramagnetic properties with μeff value of 3.18 BM. Toxicity of the complex was determined by Brine Shrimp Lethality Test (BSLT) method, and the LC50 value of the complex was 362.24 mg/L.
Preparation of CaTiO3 Asymmetric Membranes Using Polyetherimide as Binder Polymer Setyaningsih, Endang Purwanti; Machfudzoh, Maya; Utomo, Wahyu Prasetyo; Fansuri, Hamzah
Indonesian Journal of Chemistry Vol 16, No 1 (2016)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (288.743 KB) | DOI: 10.22146/ijc.21172

Abstract

Asymmetric dense and thin membranes have been prepared from powders of perovskite oxide-type CaTiO3 without cracking by phase inversion method. Polyetherimide was used as a polymeric binder in the method. The resulting green membranes, composed of CaTiO3 powder and polyetherimide binder, were sintered at 890, 1100 or 1200 °C. The crystal phase of CaTiO3 was analyzed using X-Ray Diffraction (XRD). The XRD pattern of the synthesized CaTiO3 powder was matched with the reference indicating the formation of CaTiO3 structure. Sintering at 890 °C fails to form a strong membrane. Scanning Electron Microscope (SEM) images of the membranes showed that the membrane had the asymmetric structure with dense layer on one side and porous layer on the other side. The pores in the porous layer were both finger-like and sponge-like structure. The mechanical strength of the membranes, which were determined by Vickers micro hardness method, varied from 3.5 to 25.8 Hv. The strongest membrane without any crack was resulted from sintering at 1200°C with hardness values between 19.4 and 25.8 Hv. Thermal expansion coefficients of the asymmetric membranes sintered at 1100 and 1200 °C, measured with Thermomechanical Analyzer (TMA), were 10.82 × 10-6 and 12.78 × 10-6.C-1 respectively.
KERAPATAN, KEKERASAN DAN KOEFISIEN MUAI PANAS MEMBRAN PENGHANTAR ION OKSIGEN LACO0,8FE0,2O3-δ TERSUBSTITUSI CA2+(LA1-XCAXCO0,8FE0,2O3-δ) Fansuri, Hamzah; Trengginas, Totok; Zulaicha, Vivi; Utomo, Wahyu Prasetyo; Widiastuti, Nurul; Purwanti, Endang
Reaktor Volume 16 No. 2 Juni 2016
Publisher : Dept. of Chemical Engineering, Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (704.768 KB) | DOI: 10.14710/reaktor.16.2.87-95

Abstract

Abstract DENSITY, HARDNESSAND THERMAL EXPANSION COEFFICIENTOF Ca2+-SUBSTITUTED LaCo0.8Fe0.2O3-? (La1-xCaxCo0,8Fe0,2O3-?) OXYGEN ION TRANSPORT MEMBRANE. A dense oxygen ion conductive membrane such as LaCo1-yFeyO3must be hard and has a low thermal expansion coefficient to survive harsh reaction condition in its application. Substitution of La3+ with Ca2+ is expected to improve both properties. Ca2+ substituted LaCo1-yFeyO3 powders were prepared from their respective metal oxides to become La1-xCaxCo0.8Fe0.2O3-? (LCCF), where 0.1?x?0.4, using the solid state method. X-ray diffraction data indicates that the LCCFs are highly crystalized. The LCCF was then made into a membrane by pressing the powder in a stainless steel mold by applying 6 tonnes load for 10 minutes, followed by sintering the product at 1250°C. SEM analysis results showed that the densities of all LCCF membranes are very high. Average hardnesses of LCCF 9182, 8282, 7382 and 6482 membranes, as measured by the Vicker method,are 902.08, 915.42, 1093, and 1178.6 HV, respectively. Thermal expansion tests showed that LCCF 6482 is a membrane with the lowest thermal expansion coefficient. In addition, it is also evident that the higher the number of Ca2+substituents, the higher the hardness and the lower the thermal expansion coefficient. Substitution of La3+ by Ca2+ produced denser and harder membranes, as well as low thermal expansion coefficient, which are preferable when they are applied as oxygen ion conductive membranes. Keywords: dense membrane; La1-xCaxCo0.8Fe0,2O3-?; oxigen ion transfer; perovskite  Abstrak Kekerasan tinggi dan koefisien muai panas rendah adalah sifat mekanik yang perlu dimiliki oleh membran rapat penghantar ion oksigen seperti oksida perovskit LaCo1-yFeyO3, agar dapat bertahan ketika digunakan. Substitusi La3+ oleh Ca2+ diperkirakan dapat memperbaiki kedua sifat tersebut. LaCo1-yFeyO3 tersubstitusi Ca2+disintesis dari oksida-oksida logamnya sehingga memiliki komposisi La1-xCaxCo0,8Fe0,2O3-? (LCCF) dengan 0,1?x?0,4 dengan metode solid state melalui kalsinasi pada suhu 1000°C. Data difraksi sinar-X menunjukkan bahwa serbuk LCCF yang dihasilkan memiliki kekristalan yang tinggi. LCCF tersebut selanjutnya dibuat menjadi membran yang diawali oleh pencetakan melalui penekanan serbuk LCCF dengan beban 6 ton selama 10 menit di dalam cetakan  baja tahan karat dan dilanjutkan dengan sintering hasil pencetakan pada suhu 1250°C. Hasil pengamatan dengan SEM menunjukkan bahwa kerapatan semua membran LCCF yang dihasilkan sangat tinggi. Kekerasan rata-rata membran yang diukur dengan metode Vicker adalah 902,08;  915,42; 1093; dan 1178,6 HV masing-masing untuk LCCF 9182, 8282, 7382 dan 6482. Pengujian muai panas menunjukkan bahwa LCCF 6482 adalah membran dengan koefisien muai panas tekecil. Selain itu terlihat pula bahwa semakin tinggi jumlah substituen Ca2+, semakin tinggi pula kekerasannya dan semakin rendah koefisien muai panasnya. Substitusi La3+ oleh Ca2+ menghasilkan membran dengan kerapatan tinggi serta kekerasan dan koefisien muai panas yang lebih baik dalam aplikasi LCCF sebagai membran penghantar ion oksigen. Kata kunci: membran rapat; La1-xCaxCo0,8Fe0,2O3-?; penghantar ion oksigen;  perovskit 
PENINGKATAN KETERAMPILAN PEMBUATAN DAN PEMASARAN KECAP BIJI NANGKA: ALTERNATIF BAHAN PENDAMPING MAKANAN DI KEPUTIH SURABAYA Putri, Endah Mutiara Marhaeni; Utomo, Wahyu Prasetyo; Ramadhan, Zein Firdaus; Burhan, R.Y. Perry; Rachimoellah, M.; Martak, Fahimah; Wahyudi, Agus; Zetra, Yulfi; Mujahid, M. Nadjib; Nugraheni, Zjahra Vianita
ABDIMAS ALTRUIS: Jurnal Pengabdian Kepada Masyarakat Vol 2, No 1 (2019)
Publisher : ABDIMAS ALTRUIS: Jurnal Pengabdian Kepada Masyarakat

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

Abstract

Keputih is one of the areas in Sukolilo District, Surabaya which has considerable human resources. This region is also near Institut Teknologi Sepuluh Nopember (ITS) and University of Hang Tuah (UHT). As a region that has large human resources, it is unfortunate that this region belongs to the low economic category. Due to its location  around campus compounds, the entrepreneurial sector has a lot of potentials that can be used to improve the economy in the region. This community service aimed to provide an introduction to one of the entrepreneurial opportunities through training in producing soy sauce from jackfruit seeds (beton). In this training, the community was trained how to make soy sauce by utilizing jackfruit seeds (beton) which had not been utilized well and were just thrown away. The community would also be given training for packaging so that the produced soy sauce could be marketable. It is expected that the community will be able to make soy sauce from jackfruit seeds (beton) independently. The expected impact of the community service, among others, is to open new jobs for the people of Keputih through making soy sauce from alternative ingredients so as to improve the economy of the community.