To reduce the level of CO 2 content in air, effort on converting CO 2 to useful products is required. One of the alternatives includes CO 2 fixation to produce biomass using Chlorella vulgaris Buitenzorg. Chlorella vulgaris Buitenzorg is applied for production of food supplement. Chlorella vulgaris Buitenzorg is also easy to handle due to its superior adaptation. Currently, Chlorella vulgaris Buitenzorg has been analyzed by some experts for its cellular composition, its ability to produce high quality biomass and the content of essential nutrition. A series of experiments was conducted by culturing Chlorella vulgaris Buitenzorg using Beneck medium in bubbling column photobioreactor. The main variation in this experiment was photoperiodicity, where growth of Chlorella vulgaris Buitenzorg was examined during photoperiodicity condition. The difference between CO 2 gas concentration of inlet and outlet of the reactor during operational period, was compared to the same experiment under continuous illumination. Under photoperiodicity of 8 and 9 h/d, the culture cell densities (N) were approximately 40 % higher than under continuous illumination. Final biomass density of Chlorella vulgaris Buitenzorg at 9 h/d illumination was 1.43 g/dm 3 , around 46% higher than under continuous illumination. Specific carbon dioxide transfer rate (q CO2 ) in photoperiodicity was 50-80% higher than under continuous illumination. These experiments showed that photoperiodicity affects the growth of Chlorella vulgaris Buitenzorg The specific growth rate (µ) by photoperiodicity was higher than that by continuous ilumination while the growth period was two times longer. Based on the experiments, it can be concluded that photoperiodicity might save light energy consumption. The prediction of kinetic model under continuous illumination as well as under photoperiodicity illumination showed that Haldane model became the fitted kinetic model.
In this research, we studied the preparation of nanochitosan from the addition of potassium persulfate as an initiator for monomer polymerization and monocarboxylic acid-namely acetic acid, lactic acid, and formic acid-to a chitosan solution. To obtain the dried form of chitosan nanoparticles, we investigated the effects of oven and spray drying systems toward the physicochemical properties and morphology of chitosan nanoparticles. Successfully prepared chitosan nanoparticles were characterized by Fourier transform infrared spectroscopy (FTIR), Field Emission Scanning Microscopy/Energy Dispersive X-ray Analysis (FESEM-EDX), and a particle size analyzer (PSA). The structures of nanochitosan prepared in different acids were quite similar based on the FTIR spectra. By increasing the concentrations of potassium persulfate, the yields of chitosan nanoparticles also increased. The concentration of potassium persulfate had a significant influence on the production of chitosan nanoparticles. The lowest concentration of potassium persulfate (0.6 mmol) did not produce an observable formation of chitosan nanoparticles. By using formic acid and potassium persulfate in various concentrations from 1.2-3.0 mmol, chitosan nanoparticles were obtained. A particle size distribution of chitosan nanoparticles was produced from a formic acid solution having a smaller size compared to others. The acidity effect of monocarboxylic acids in the formation of chitosan nanoparticles was better compared to the addition of other acids. Furthermore, synthesized chitosan nanoparticles (50-110 nm) produced from formic acid solutions have potential applications for drug carrier purposes.
Research around using algae as a natural source of carotenoids has been intense in the 21st century, given the wide applications of carotenoids in the pharmaceutical, health, and food industries. This study aimed to get the highest yield of carotenoids from Chlorella vulgaris by ultrasound extraction. This study evaluated two parameters: the extraction solvent (ethanol, acetone, and diethyl ether were tested) and the solid-to-solvent ratio (1:30, 1:50, and 1:100 were tested). The carotenoid extracted from C. vulgaris was lutein, and its compounds were identified by UV-Vis spectroscopy. The highest carotenoid yield was achieved using ethanol at 1.146±0.082 mg/g and a solid-to-solvent ratio of 1:100 (g/mL). This research shows the use of a specific extraction solvent along with a solid-to-solvent ratio is significant to determine carotenoids yield desired. Further study of other parameters (e.g., temperature and ultrasound intensity) is necessary for the optimum extraction condition.
Contradictions have been reported on the effect of organic solvents, especially toluene, on enzymatic ring-opening polymerization (eROP) of L-lactide. Studies have shown that log P, a common measure of hydrophilicity, affects enzyme activity. This study examines the effect of solvents with various log P values on the eROP of L-lactide, performed using Candida rugosa lipase (CRL). N,N-dimethylacetamide (DMA), 1,2-dimethoxybenzene, 1,4-dimethoxybenzene, diphenyl ether, and dodecane were used as the organic solvents. The eROP in ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) was also conducted to compare its performance with the organic solvents. The results show that [BMIM][PF6]− mediated eROP gave better conversion and molecular weight than the organic solvent-mediated eROP. In this study, the effects of solvents hydrophilicity are discussed, including the possibility of hexafluorophosphate ion ([PF6]−) hydrolysis to occur.
PT Pertamina Hulu Energi West Madura Offshore (PHE WMO) berupayameningkatkan produksi minyak, salah satu cara yaitu melakukan optimalisasi pipa penyalur dari PHE-30 menuju fasilitas proses PPP dengan mengurangi slug flow pada pipa penyalur tersebut. Saat ini produksi minyak, gas dan air dari lapangan PHE-30 sebesar 2.070 Bopd, 5,1 MMscfd dan 10.800 Bwpd. Produksi minyak dari lapangan PHE-30 dapat dioptimalkan dengan menjaga gas liquid ratio (GLR) pada pipa penyalur tersebut. Optimalisasi ditujukan untuk menjaga fasilitas proses tetap aman dan terhidar dari kondisi shutdown atau terhenti sementara akibat terjadinya slug flow yang terjadi disepanjang pipa penyalur.Slug flow terjadi karena ketidakseimbangan perbandingan antara distribusi laju alir gas dan laju alir liquid pada pipa penyalur atau dapat disebut dengan gas liquid ratio (GLR).Perbedaan GLR ini disebabkan oleh tingginya air terproduksi dari dalam sumur PHE-30. Analisa dilakukan dengan menggunakan software Pipesim untuk melakukan simulasi flow regime pada pipa penyalur dari PHE-30 menuju PPP. Parameter yang digunakan yaitu laju alir minyak, gas dan air serta kecepatan superficial gas dan liquid. Hasil menunjukkan bahwa dengan pengurangan air terproduksi dari lapangan PHE-30 dengan GLR 2.463 scf/bbl, dapat merubah kondisi flow regime dari yang sebelumnya slug flow menjadi stratified flow.
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