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All Journal Jurnal Rekayasa Proses Jurnal MEKANIKAL Reaktor International Journal of Science and Engineering (IJSE) TEKNIK Jurnal Kesehatan Lingkungan indonesia JURNAL TEKNOLOGI KIMIA DAN INDUSTRI Prosiding Seminar Nasional Sains Dan Teknologi Fakultas Teknik Majalah Ilmiah MOMENTUM Emerging Science Journal Indonesian Journal of Chemistry JURNAL PANGAN Jurnal Pasopati : Pengabdian Masyarakat dan Inovasi Pengembangan Teknologi Bulletin of Chemical Reaction Engineering & Catalysis
Ratnawati Ratnawati
Department Of Chemical Engineering Faculty Of Engineering Diponegoro University
Aerospace Engineering Agriculture, Biological Sciences & Forestry Automotive Engineering Chemical Engineering, Chemistry & Bioengineering Chemistry Civil Engineering, Building, Construction & Architecture Computer Science & IT Control & Systems Engineering Earth & Planetary Sciences Education Electrical & Electronics Engineering Energy Engineering Environmental Science Industrial & Manufacturing Engineering Materials Science & Nanotechnology Mechanical Engineering Public Health Social Sciences

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PENGARUH SUHU UDARA PENGERING DAN KOMPOSISI ZEOLIT 3A TERHADAP LAMA WAKTU PENGERINGAN GABAH PADA FLUIDIZED BED DRYER M. A. Graciafernandy; Ratnawati Ratnawati; L. Buchori
JURNAL ILMIAH MOMENTUM Vol 8, No 2 (2012)
Publisher : Universitas Wahid Hasyim

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.36499/jim.v8i2.433

Abstract

Gabah panen dengan kadar air tinggi dapat menyebabkan penurunan kualitas gabah. Untuk menjaga kualitasnya, Pemerintah menentukan batasan kadar air maksimal yakni 14%. Proses pengeringan gabah yang diterapkan para petani di Indonesia adalah dengan cara penjemuran di bawah sinar matahari. Kendalanya adalah ketergantungan terhadap cuaca dan lamanya waktu pengeringan. Adapula pengeringan mekanik menggunakan alat pengering seperti fluidized bed dryer. Namun penggunaan suhu tinggi menyebabkan penurunan kualiatas gabah. Kajian mengenai sistem pengeringan pada suhu rendah dan waktu yang singkat perlu dilakukan untuk meningkatan kualitas gabah. Pengeringan adsorbsi dengan zeolit 3A pada fluidized bed dryer merupakan suatu modifikasi terhadap sistem pengeringan yang sudah ada. Tujuan penelitian ini untuk menentukan suhu dan komposisi zeolit terbaik yang menghasilkan waktu pengeringan tersingkat. Secara garis besar gabah panen dikeringkan dalam suatu unggun terfluidisasi pada variasi suhu 30, 40, 50 dan 60 0C, flowrate 3 m/s dengan komposisi perbandingan zeolit:gabah berturut-turut adalah sebagai berikut 0:100; 20:80; 40:60 dan 60:40 (% w). Pengamatan dilakukan terhadap penurunan kadar air serta waktu pengeringan. Pengeringan dihentikan ketika kadar air dalam gabah mencapai 14%. Waktu pengeringan tersingkat terjadi pada kompisi zeolit:gabah = 60:40 dan suhu 600C. Pengeringan ini menghemat hingga 73,07 menit dibandingkan pengeringan tanpa zeolit. Kata kunci : fluidized bed dryer, pengeringan gabah; zeolit 3A.
PENGERINGAN GABAH MENGGUNAKAN ZEOLIT 3A PADA ALAT UNGGUN TERFLUIDISASI Djoko Mulyono; Jefri Chandra Runanda; R Ratnawati; M. Djaeni
JURNAL TEKNOLOGI KIMIA DAN INDUSTRI Volume 2, Nomor 2, Tahun 2013
Publisher : Jurusan Teknik Kimia, Fakultas Teknik, Universitas Diponegoro,

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (214.533 KB)

Abstract

Indonesia sebagai negara agraris memiliki tanah yang subur dan hasil pertanian yang melimpah, salah satu hasil pertanian tersebut adalah gabah. Produksi gabah di Indonesia termasuk tiga besar penghasil gabah dunia. Penanganan gabah di Indonesia sering kali terkendala dengan masalah pengeringan. Masih banyak di Indonesia para petani menggunakan cahaya matahari sebagai media pengering, tentu hal ini tidak selalu menguntungkan karena cuaca di Indonesia tidak selalu cerah dan pengeringan menggunakan cahaya matahari ini membutuhkan waktu yang lama, sehingga dibutuhkan proses pengeringan yang lebih efisien dari segi energi dan waktu pengeringan, maka dari itu digunakan pengeringan dengan menggunakan zeolit sintetis. Pada proses pengeringan ini lebih efisien karena proses perpindahan panas dan massa terjadi secara simultan di dalam unggun terfluidisasi. Bahan yang dikeringkan dikontakkan dengan gas panas sehingga dengan panas tersebut dapat menguapkan uap air yang terdapat pada bahan dan dengan ditambahakannya zeolit sehingga udara menjadi lebih kering yang dapat mempercepat proses pengeringan sehingga lebih efisien. Pada pengeringan ini digunakan beberapa variabel diantaranya suhu 30-60oC, flow rate udara 2-5 m/s dan perbandingan gabah dan zeolit 40, 60, 80 dan 100 % gabah dan variabel yang diamati adalah 5 gr gabah setiap 5 menit. Dari hasil percobaan diperoleh temperatur yang baik untuk proses pengeringan adalah pada suhu 60oC, untuk variabel flow rate yang paling baik adalah pada kecepatan udara sebesar 5 m/s dan untuk variabel perbandingan gabah dan zeolit yang paling baik adalah pada perbandingan gabah : zeolit sebesar 40 : 60.
PENGGUNAAN TEKNOLOGI PENGERING UNGGUN TERFLUIDISASI UNTUK MENINGKATKAN EFISIENSI PENGERINGAN TEPUNG TAPIOKA Rizky Adi N; Nafiah Amalia; S Suherman; R Ratnawati
JURNAL TEKNOLOGI KIMIA DAN INDUSTRI Volume 2, Nomor 3, Tahun 2013
Publisher : Jurusan Teknik Kimia, Fakultas Teknik, Universitas Diponegoro,

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (304.292 KB)

Abstract

Drying of cassava starch using conventional method has many disadvantages, such as longer drying time, totally dependent on good weather, and inconsistent product quality. It drives this research to develop fluidized bed drying technology which is more efficient and able to operate continuously. The advantages of fluid bed dryer include ease of control, good quality of product, and free of dirt. The objectives of this research are to determine the effects of temperature and velocity of drying air to the drying process and product. The drying products were compared to the products of conventional drying. The experiment was carried out at various temperature (30, 40, 50, and 60 oC) and air velocity (2.5, 3.5, and 4.5 m/s). The results indicate that the optimum temperature for drying is 50 oC, while the air velocity is 2.5 m/s. Proximate analysis shows that the product of fluidized bed drying has better quality than that of conventional sun drying.
PENERAPAN TEKNOLOGI FLUIDIZED BED DRYER DENGAN PENAMBAHAN ZEOLIT 3A UNTUK MENINGKATKAN EFISIENSIPENGERINGAN GABAH Noor Hidayati; Utami Diah P.; Ratnawati Ratnawati; Suherman Suherman
JURNAL TEKNOLOGI KIMIA DAN INDUSTRI Volume 2, Nomor 4, Tahun 2013
Publisher : Jurusan Teknik Kimia, Fakultas Teknik, Universitas Diponegoro,

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (152.055 KB)

Abstract

Now, drying paddy  using conventional method is irrelevant to used. The need of grain increasing each year is one of the main factor that pushes scientist to invent new methods of drying paddy grain. The old method is unusefull since it takes up space, needed the sun as the drying media which causes a long drying time. One of the alternative of drying paddy grain is by using mechanic dryer. By using this type of dryer, the process of drying takes faster comparing to the old method and the distribution of grain is supplied continuously. The dryer which uses fluidized bed  can be one of the solution due to its less energy consumption, a better drying result and high drying capacity. The variable used to identify drying performance is temperature and loading weight. From the experiment, it is resulted that the best temperature for drying paddy grain is 50 C with the flowrate 3,5 m/s.
PENGGUNAAN ZEOLITE SINTETIS DALAM PENGERINGAN GABAH DENGAN PROSES FLUIDISASI INDIRECT CONTACT Affian Widjanarko; R. Ridwan; M. Djaeni; R. Ratnawati
JURNAL TEKNOLOGI KIMIA DAN INDUSTRI Volume 1, Nomor 1, Tahun 2012
Publisher : Jurusan Teknik Kimia, Fakultas Teknik, Universitas Diponegoro,

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Abstract

Drying grain commonly used in Indonesia is drying by using sunlight. Drying is still constrained by the type of season. The research objective to accelerate the use of zeolite grain drying process, determine the relationship inlet air temperature dryer drying rate, and determine the relationship of the inlet air flow rate of air at the rate of drying. The operating conditions in this experiment is the drying air temperature ((30oC; 40oC; 50oC and 60oC),  drying air flow rate (1 m / s; 1.5 m / s, 2 m / s and 2.5 m / s) and zeolite 1 kg. The research was carried out by flowing dry air at specific operating conditions and then brought into contact with the grain in the fluidized bed to obtain the water content of 12-14%. The results obtained indicate the temperature of 30oC, Nc = 0.0082, while the temperature of 60oC, Nc = 0.0138. In the air flow rate of 1 m / s, Nc = 0.0094 while the air flow rate of 2.5 m / s, Nc = 0.0118. From this data it can be concluded that the higher the temperature and the rate of air dryer, the drying rate wil be faster.
PENGGUNAAN ZEOLITE SINTETIS DALAM PENGERINGAN GABAH DENGAN PROSES FLUIDISASI INDIRECT CONTACT Affian Widjanarko; R Ridwan; M. Djaeni; R Ratnawati
JURNAL TEKNOLOGI KIMIA DAN INDUSTRI Volume 2, Nomor 2, Tahun 2013
Publisher : Jurusan Teknik Kimia, Fakultas Teknik, Universitas Diponegoro,

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (985.719 KB)

Abstract

Grain drying process being one of the constraints experienced by grain farmers in Indonesia. This is because the farmers still rely on the sun to dry their grain crops. Meanwhile, the drying is still constrained by the type of season. Drying by fluidization processes using zeolite considered an alternative to grain drying process. The purpose of this research, make use of zeolite to accelerate the drying of grain, determine the relation of drying air temperature with drying rate and determine the relation of air flow rate into the dryer with drying rate. The operating conditions in this experiment is the drying air temperature 30oC; 40°C; 50oC and 60oC), drying air flow rate (1 m/s; 1,5 m/s; 2 m/s and 2,5 m/s) and 1 kg of zeolite. The research was conducted by flowing dry air at a specific operating conditions and then contacted with the grain in the fluidized bed to obtain the water content of 12-14%. The results obtained indicate the temperature of 30oC, Nc = 0,0082, while the temperature of 60°C, Nc = 0,0138. In the air flow rate of 1 m/s, Nc = 0,0094 while the air flow rate of 2,5 m/s, Nc = 0,0118. From this data it can be concludedthatthe higher the temperature and the rate of the air dryer, the drying rate will be faster, so as to make the drying process faster.
PENINGKATAN KECEPATAN PENGERINGAN GABAH MENGGUNAKAN VERTICAL SCREW CONVEYOR DRYER Mohamad Djaeni; Cindi Yasintasia; Maharani Ratridewi; Ratnawati Ratnawati; Andri Cahyo Kumoro
Jurnal Pasopati : Pengabdian Masyarakat dan Inovasi Pengembangan Teknologi Vol 3, No 1 (2021)
Publisher : Fakultas Teknik Universitas Diponegoro

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Abstract

Ketersediaan beras yang cukup, merata dan berkualitas tinggi sangat penting bagi stabilitas ketahanan dan keamanan nasional. Beras tidak diproduksi sepanjang tahun, tetapi hanya 2 sampai 3 kali panen dalam satu tahun. Oleh karena itu untuk memenuhi kebutuhan sepanjang tahun, komoditas pertanian ini harus disimpan kering (kadar air 12 – 14%), baik dalam bentuk gabah maupun beras. Proses pengeringan gabah dengan screw conveyor dilengkapi sistem dehumidifikasi udara dengan  zeolite berbahan bakar biogas menjadi suatu pilihan untuk pengeringan gabah. Udara berkadar air rendah ini meningkatkan driving force pengeringan, sehingga proses menjadi cepat, dan efisien. Selain itu, suhu udara rendah ini, sangat tepat untuk gabah yang sensitive terhadap panas, sehingga kerusakan tekstur dan nutrisi dapat dihindari.Rancangbangun demonstrasi unit pengeringan gabah dengan screw conveyor dryer telah dilakukan dengan kapasitas terpasang 500 kg per batch. Unit pengeringan ini difabrikasi atas kerjasama Universitas Diponegoro, PT Muatiara Global Industri (Bogor), dan CV Raja Pengering (Surabaya). Alat ini menggunakan bahan bakar yang fleksibel karena dirancang dengan model knock down dengan sumber pemanas udara. Burner berbahan bakar LPG atau pun biogas bisa diganti dengan furnace berbahan bakar sekam untuk memanasi udara sebagai media pengering. Uji coba telah dilakukan pada laju 10% dari kapasitas idealnya, dengan variasi berbagai temperature. Hasil menunjukkan alat tersebut dapat meningkatkan kualitas gabah kering giling dan mempercepat proses pengeringan menjadi 90 menit dengan prosentase beras utuh saat penggilingan di atas 50%. Peningkatan efisiensi panas, dan pengggunaan bahan bakar yang lebih murah seperti biogas atau sekam sangat diperlukan agar dapat menekan biaya produksi.
Sequential Microwave-Ultrasound Assisted Extraction of Flavonoid from Moringa oleifera: Product Characteristic, Antioxidant and Antibacterial Activity Aji Prasetyaningrum; Bakti Jos; Ratnawati Ratnawati; Nur Rokhati; Teguh Riyanto; Gian Restu Prinanda
Indonesian Journal of Chemistry Vol 22, No 2 (2022)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/ijc.65252

Abstract

Moringa oleifera leaves contain secondary metabolites in flavonoid compounds known to prevent several diseases. Therefore, appropriate extraction methods are required to produce extracts with a high yield of flavonoids from Moringa. In this study, the extraction from Moringa leaves was carried out using the sequential microwave/ultrasound-assisted extraction (MUAE) method compared with sequential ultrasound/microwave (UMAE), microwave (MAE), ultrasound (UAE), and maceration (ME). The effects of the time, temperature, and percentage of ethanol were studied on total flavonoid content using AlCl3 colorimetric assay. The extracts were analyzed by Scanning Electron Microscopy (SEM), Fourier Transforms Infrared Spectrophotometry (FTIR), and High-Performance Liquid Chromatography (HPLC). The antioxidant and antibacterial activities were tested using DPPH-scavenging and disc diffusion methods. The results of SEM surface analysis on various extraction methods show differences on each surface. The FTIR spectrum showed the presence of flavonoid O–H at 3200 cm–1, C=O at 1621 cm–1, and C–O at 1019 cm–1. In the results of HPLC, MUAE extracts 16.70 mg/ 100 g flavonoid quercetin at the retention time of 4.5 min, with the highest total flavonoids (2.89 mg QE/g), the highest antioxidant activity (IC50 72.31 µg/mL), and highest antibacterial activity (S. aureus 7 mm, E. coli 2 mm).
Design of Propellant Composite Thermodynamic Properties Using Rocket Propulsion Analysis (RPA) Software Anita Pinalia; Bayu Prianto; Henny Setyaningsih; Prawita Dhewi; Ratnawati Ratnawati
Reaktor Volume 22 No. 1 April 2022
Publisher : Dept. of Chemical Engineering, Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (478.592 KB) | DOI: 10.14710/reaktor.22.1.1-6

Abstract

Rocket Propulsion Analysis (RPA) is software for predicting the performance of a rocket engine. It is usually used in conceptual and preliminary design. Heat capacity and specific impulse are two properties related to the performance of a propellant. This work aimed to design AP/HTPB-based solid propellant composite with various compositions and predict the heat capacity and specific impulse using the RPA software. The materials used were ammonium perchlorate (AP) as the oxidizer, Hydroxy-Terminated Polybutadiene (HTPB) as the fuel binder, Al powder as the metal fuel, and other additives. Four propellants with different formulations were prepared and tested for heat capacity and specific impulse. The experimental heat capacity was obtained using a differential scanning calorimeter (DSC), while the specific impulse was obtained using a bomb calorimeter. The same propellant formulations were used as the input to the RPS to predict the heat capacity and specific impulse. The results show that the experimental heat capacity of the propellant ranges from 1.576 to 4.08 J g–1 K–1, and the simulation result ranges from 1.78 to 3.48 J g–1 K–1. The overall average deviation is 16.3%. The predicted specific impulse at vacuum and sea level ranges from 231.3 to 234.0 s and from 219.8 to 220.9 s, respectively. Meanwhile, the experimental specific impulse at vacuum and sea level varies from 236.2 to 240.3 s and from 228.5 to 232.9 s, respectively. The overall average deviation is 3.7%. Therefore, the RPA is reliable for predicting specific impulse of propellant, but it is not accurate enough for predicting the heat capacity of propellant composite.
Kinetics and Thermodynamics Study of Ultrasound-Assisted Depolymerization of k-Carrageenan in Acidic Solution Ratnawati Ratnawati; Nita Indriyani
Bulletin of Chemical Reaction Engineering & Catalysis 2020: BCREC Volume 15 Issue 1 Year 2020 (April 2020)
Publisher : Masyarakat Katalis Indonesia - Indonesian Catalyst Society (MKICS)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.9767/bcrec.15.1.6738.280-289

Abstract

K-carrageenan is a natural polymer with high molecular weight ranging from 100 to 1000 kDa. The oligocarrageenan with low molecular weight is widely used in biomedical application. The aim of this work was to depolymerize k-carrageenan in an acidic solution with the assistance of ultrasound irradiation. The ultrasonication was conducted at various pH (3 and 6), temperatures (30-60 °C), and depolymerization time (0-24 minutes). The results show that the depolymerization reaction follows pseudo-first-order kinetic model with reaction rate constant of 1.856×10-7 to 2.138×10-6 s-1. The reaction rate constant increases at higher temperature and lower pH. The Q10-temperature coefficients of the depolymerization are 1.25 and 1.51 for pH 6 and 3, respectively. The enthalpy of activation (ΔH‡) and the Gibbs energy of activation (ΔG‡) are positive, while the entropy of activation (ΔS‡) is negative, indicating that the activation step of the ultrasound-assisted depolymerization of k-carrageenan is endothermic, non-spontaneous, and the molecules at the transition state is more ordered than at the ground state. The ΔH‡ and the ΔS‡ are not affected by temperature, while the ΔG‡ is a weak function of temperature. The ΔH‡ and ΔS‡ become smaller at higher pH, while the ΔG‡ increases with the increase of pH. The kinetics and thermodynamics analysis show that the ultrasound-assisted depolymerization of k-carrageenan in acidic solution is possibly through three mechanisms, i.e. bond cleavage due to cavitational effect of microbubbles, hydroxyl radical and hydrogen peroxide, as well as proton. 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 . Widayat Aat Zaki Mubarok Affian Widjanarko Affian Widjanarko Aji Prasetyaningrum Andri C. Kumoro Andri Cahyo Kumoro anggoro D.D. Anggoro Anita Pinalia Aprilina Purbasari Bakti Jos Bayu Prianto Catarina S. Budiyati Catarina Sri Budiyati Cindi Yasintasia Dewi Ayuningtyas Diah S. Retnowati Diah Susetyo Retnowati Djoko Mulyono Dyah Arum Kusumaningtyas Dyah Hesti Wardhani Fadlillah Fani Fitri Lafifa G.A. Mansoori G.A. Mansoori Gian Restu Prinanda H Hadiyanto Hargono Hargono Hartono, Damin Henny Setyaningsih Jefri Chandra Runanda Johannes Leonard Jumali Jumali L. Buchori Lestari, Novi Dian Luqman Buchori M. Djaeni Maharani Ratridewi Maria Augustine Graciafernandy Nafiah Amalia Nita Indriyani Nita Indriyani Noer Abyor Handayani Noor Hidayati Nur Rokhati Nurfiningsih Nurfiningsih Nurkhikmah, Eli Nurul Asiah Nurul Asiah Prawita Dhewi Purbo Suseno R Ridwan R. Ridwan Retno Wulandari Rizky Adi N Sadam Arrois Siti Thomas Zulaikhah Suherman Suherman Sulastri, Neng Teguh Riyanto Utami Diah P. Wiratno Wiratno Yudhy Dharmawan Yustina Linasari