The production of ethanol via syngas fermentation obtained from lignocellulose gasification provides a method for completely utilizing all of the carbon content from lignocellulosic feedstock. The low mass transfer rate of less soluble CO and H2 gas to liquid has been considered a major bottleneck in the overall process; however, microporous membrane has been proposed as a gas diffuser to improve gas-to-liquid mass transfer. In this study, a liquid batch of syngas fermentation employing Clostridium ljungdahlii with continuous gas supply was obtained using the configuration of a bioreactor connected to microporous hydrophobic polypropylene hollow fiber membrane (HFM) as a gas diffuser. Liquid recirculation between the fermentation vessel and membrane module was applied to enhance the gas-liquid contact as well as cell-recycle. The fermentation performance with and without HFM was compared and evaluated by cell growth, CO utilization, ethanol yield, and productivity. A higher ethanol yield, 0.22 mol/mol, was achieved using the system of an HFM-supported bioreactor with a higher ethanol titer of 1.09 g/L and an ethanol-acetate molar ratio of 1.43 mol/mol. The obtained result demonstrates that an HFM-supported bioreactor is the best fermentation system compared to stirred tank reactor (STR) without a membrane.
Contamination of lead (Pb) in water due to domestic and industrial activities can endanger the environment and human health. One of the heavy metal waste treatments is adsorption using microorganisms (biosorption). In this study, dried microalgae Aphanothece sp. used as biosorbent for binding Pb in aqueous solution. Biosorbent was prepared from the 14 days cultivation of microalgae in a photobioreactor system which was then dried and mashed to the size of 45 mesh. Pb metal biosorption experiments were carried out in a batch system at various initial concentration variations (3.9–18.6 mg/L) and contact times (30–180 minutes) to find the optimum conditions of the biosorption process. The concentration of Pb in solution was analysed using the Atomic Absorption Spectroscopy (AAS). The results of the experiment showed that the highest removal efficiency of Pb metal in the initial concentration variation of 18.6 mg/L and contact time of 30 minutes was 99.9 % with an absorption capacity of 185.64 mg/g. Pb metal adsorption data at equilibrium conditions follows the Langmuir isotherm model equation with R2>0.9. Biosorption kinetics using dried biomass of Aphanothece sp. following the pseudo second-order kinetics model. The results of this study provide an overview of the potential microalgae as Pb metal biosorbent in wastewater treatment on a larger scale.
Liquid smoke is a preservative solution that can be used safely. This grade 1 product can be also used as food preservative. The aim of this article is to discuss and examine the previous experiment’s results by literature review. The outcome of this article is expected to be regenerated by other research using the existing variable which is discussed on this article or using new variable. Based on the result. There are some variables that effect the final quality of liquid smoke. Some of them are pyrolisys temperature, pyrolisys time, adsorbant type and activator type. Pyrolisys temperature used was arround 250 °C – 300 °C with resulted pH 1.41 to 2.25. While for pyrolisys temperature was arround 4 – 5 hours with phenol content arround 3.04% to 4.08%. The type of adsorbant used was zeoilte and quartz sand, which the acid total having both increment and decrement phenomenon. Activator type used were salt activator such as NaCl , NaHCO, CaCl2, Na2SO4 and base activator (NaOH) which producing the most percent acid total.
<p><strong>ABSTRAK.</strong> <em>Carbon nanodots</em> (CNDs) merupakan nanomaterial yang berukuran dibawah 10 nm. CNDs memiliki keunggulan diantaranya yaitu fotostabilitas tinggi, biokompatibilitas baik, toksisitas yang rendah, mudah dibuat, dan ramah lingkungan. Sumber karbon yang digunakan berasal dari molase karena murah dan mudah didapat serta merupakan hasil samping dari pengolahan tebu. Pada penelitian ini digunakan metode pemanasan terbantukan gelombang mikro atau <em>Microwave Assisted Extraction</em> (MAE) yang memberikan hasil suspensi yang homogen, pemanasan efisien, dan waktu yang singkat. Waktu iradiasi mempengaruhi energi gap CNDs dari molase yang dihasilkan. Waktu yang optimum untuk sintesis CNDs dari molase menggunakan metode MAE yaitu selama 3 menit. Efek fluoresensi telah diamati untuk suspensi CNDs yang mengubah warna kuning menjadi warna biru dibawah sinar UV 366 nm. Karakterisasi menggunakan spektrofotometri UV-Vis menunjukan serapan maksimum CNDs dari molase pada panjang gelombang 255 nm dengan energi gap sebesar 4,55 eV.</p><p><strong>Kata kunci:</strong></p><p align="left"><em>carbon nanodots</em>, <em>microwave, </em>molase</p><p><strong><br /></strong></p><p><strong>ABSTRACT. </strong>Carbon nanodots (CNDs) are nanomaterials with a size below 10 nm. CNDs have advantages such as high photostability, good biocompatibility, low toxicity, easy to manufacture, and environmentally friendly. The carbon source used comes from molasses because it is cheap and easy to obtain and is a by-product of sugarcane processing. In this study, the Microwave Assisted Extraction (MAE) method was used which gave homogeneous suspension results, efficient heating, and short time. The irradiation time affects the energy gap of the CNDs of the molasses produced. The optimum time for the synthesis of CNDs from molasses using the MAE method is 3 minutes. Fluorescence effects have been observed for suspensions of CNDs which turn yellow to blue under 366 nm UV light. Characterization using UV-Vis spectrophotometry showed the maximum absorption of CNDs from molasses at a wavelength of 255 nm with an energy gap of 4.55 eV.</p><p><strong>Keywords:</strong></p><p align="left">carbon nanodots, microwave, molasses</p><p> </p>
ABSTRAKPada penelitian ini, sistem kultur suspensi sel wortel (Daucus carota L.) digunakan sebagai model untuk mengetahui pengaruh variasi pH terhadap pertumbuhan biomassa sel serta laju konsumsi substrat amonium dalam medium. Kalus ditumbuhkan selama 24 hari dalam sistem batch pada medium cair MS (Murashige dan Skoog) dengan penambahan 4,5 x 10-6 M kinetin dan 4,5 x 10-6 M 2,4-D serta kondisi pH awal medium berbeda yaitu pH 4,5; 5,8 dan 7,5. Perubahan pH medium diamati setiap 3 hari sekali disertai dengan pengukuran berat biomassa sel dan kandungan amonium dalam medium. Hasil pengamatan menunjukkan bahwa laju pertumbuhan spesifik biomassa sel paling tinggi terjadi pada kultur dengan kondisi pH awal medium 4,5 yaitu 0,08 hari-1 sedangkan paling rendah pada kondisi pH awal medium 5,8 (kontrol) yaitu 0,02 hari-1. Variasi pH awal medium menyebabkan perubahan dan fluktuasi nilai pH dalam medium sehingga mempengaruhi tingkat penyerapan substrat amonium dalam medium. Laju konsumsi amonium tertinggi terjadi pada kultur perlakuan pH awal medium 4,5 yaitu sebesar 0,088 mM/hari. Penggunaan amonium untuk pertumbuhan biomassa juga paling efektif pada kultur dengan kondisi pH awal medium 4,5 dengan nilai perolehan biomassa per substrat amonium mencapai 0,875 g sel/mM amonium. Penelitian ini dapat memberikan gambaran mekanisme dan efisiensi penyerapan media pada medium pertumbuhan sehingga dapat diterapkan untuk pengendalian sistem produksi terutama sistem bioreaktor. Kata kunci : amonium; batch; Daucus carota L.; pH; pertumbuhan sel ABSTRACT In this experiment, a carrot (Daucus carota L.) cell suspension system was used as a model to determine the effect of pH variations on cell biomass growth and the rate of consumption of ammonium substrates in the medium. Callus was grown for 24 days in a batch system on MS liquid medium (Murashige and Skoog) with the addition of 4.5 x 10-6 M kinetin and 4.5 x 10-6 M 2,4-D and the initial pH of the medium was different, namely pH 4,5; 5.8; and 7.5. Changes in the medium's pH were observed every three days, accompanied by cell biomass weight measurements and ammonium content in the medium. The observations showed that the highest specific cell growth rate occurred in cultures with medium pH initial conditions of 4.5, 0.08 days-1, while the lowest at medium pH conditions of 5.8 (control), 0.02 days-1. Variations in the initial pH of the medium cause changes and fluctuations in the medium's pH value so that it affects the rate of absorption of ammonium substrates in the medium. The highest ammonium consumption rate occurred in the culture medium initial pH treatment equal to 0.088 mM/day. The use of ammonium for biomass growth is most effective in cultures with an initial pH medium condition of 4.5 with the acquisition value of biomass per ammonium substrate, reaching 0.875 g cells/mM ammonium. This research can provide an overview of the mechanism and efficiency of media absorption in the growth medium to be applied to control production systems, especially in bioreactor systems.
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