Hasil Pencarian  ::  Simpan CSV :: Kembali

Abstrak :
Kebutuhan akan energi listrik semakin meningkat. Hal ini menyebabkan perlunya alternatif penghasil energi listrik yang ramah lingkungan. Microbial fuel cell (MFC) merupakan salah satu alternatif penghasil energi listrik yang cukup menjanjikan. Pada penelitian ini dilakukan preparasi untuk sistem microbial fuel cell (MFC) dengan menggunakan elektroda busa karbon yang dimodifikasi nanopartikel emas dan difungsionalisasikan dengan mercapto acetic acid (MAA). Elektroda busa karbon dimodifikasi nanopartikel emas berhasil disintesis melalui metode hidrotermal menggunakan HAuCl4 dan trisodium sitrat. Berdasarkan hasil karakterisasi larutan hidrotermal menggunakan UV-Visible Spectrometer (UV-Vis) dan Transmission Electron Microscopy (TEM) menunjukkan bahwa nanopartikel emas berhasil disintesis dan juga hasil karakterisasi elektroda dengan menggunakan X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) dan Scanning Electron Microscope (SEM) menunjukkan elektroda berhasil dimodifikasi menggunakan AuNP dan MAA. Studi awal elektrokimia dengan metode Cyclic Voltammetry (CV) dengan rentang potensial -1,5 sampai 1,3 dengan scan rate 10 mV/s dilakukan untuk mengkonfirmasi bahwa elektroda busa karbon termodifikasi memiliki sifat elektro aktif terhadap glukosa, yang merupakan substrat atau bahan bakar pada sistem MFC ini. Kinerja MFC dievaluasi dengan menggunakan kurva polarisasi dan didapatkan hasil bahwa elektroda busa karbon yang dimodifikasi nanopartikel emas serta difungsionalisasikan dengan MAA (CF/Au-MAA) menghasilkan densitas arus dan densitas daya sebesar 4470,47 mW/m2 dan 813,6 mW/m2 sedangkan untuk elektroda busa karbon/emas (CF/Au) densitas arus dan densitas daya sebesar 392,48 mA/m2 dan 225,6 mW/m2 ......The need for electrical energy is increasing. This causes the need for an alternative to produce electrical energy that is environmentally friendly. Microbial fuel cell (MFC) is a promising alternative for producing electrical energy. In this study, a microbial fuel cell (MFC) system was prepared using carbon foam electrodes modified with gold nanoparticles and functionalized with mercapto acetic acid (MAA). Gold nanoparticle modified carbon foam electrode was successfully synthesized by hydrothermal method using HAuCl4 and trisodium citrate. Based on the results of characterization of hydrothermal solutions using UV-Visible Spectrometer (UV-Vis) and Transmission Electron Microscopy (TEM), it shows that gold nanoparticles were successfully synthesized and also the results of electrode characterization using X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscope (SEM) showed that the electrodes were successfully modified using AuNP and MAA. Early electrochemical studies using the Cyclic Voltammetry (CV) method with a potential range of -1.5 to 1.3 with a scan rate of 10 mV/s were carried out to confirm that the modified carbon foam electrodes have electro-active properties against glucose, which is the substrate or fuel in this MFC system. The performance of MFC was evaluated using a polarization curve and the results showed that the carbon foam electrode modified with gold nanoparticles and functionalized with MAA (CF/Au-MAA) resulted in a current density and power density of 4470.47 mW/m2 and 813.6 mW/m2 while for carbon foam/Au electrodes (CF/Au) the current density and power density are 392.48 mA/m2 and 225.6 mW/m2.

Abstrak :
Sorghum merupakan tanaman serealia yang sangat potensial untuk dibudayakan di Indonesia karena punya keunggulan dibandingkan dengan tanaman pangan yang lain. Di dalam limbah sorghum (malai dan tangkai) banyak terkandung hemiselulosa yang apabila dihidrolisis akan menghasilkan monomermonomernya. Salah satu monomer yang dihasilkan adalah xilosa yang merupakan bahan baku pembuatan xilitol. Pada penelitian ini digunakan malai dan tangkai sorghum mandau sebagai bahan untuk pembuatan xilitol. Bahan tersebut dihidrolisis menggunakan asam sulfat (H2SO4) 0,3M pada suhu 121°C dengan waktu optimum 35 menit. Hasil pengukuran kadar xilosa dalam hidrolisat pada kondisi optimum 25,70 % (w/w) untuk malai dan 20,56 % tangkai. Hidrolisat optimum ini yang akan digunakan sebagai substrat dalam proses fermentasi oleh Candida fukuyamaensis UICC Y-247 khamir penghasil enzim xilose reduktase. Hidrolisat kemudian detoksifikasi dengan menambahkan arang aktif 1% (w/v) untuk menghilangkan senyawa toksik yang dapat menghambat pertumbuhan khamir. Produk xilitol hasil fermentasi tanpa kosubstrat, konsentrasi tertinggi didapatkan waktu fermentasi 12 jam dengan persen konversi xilitol 12,88% untuk malai dan 10,88% tangkai. Produk xilitol hasil fermentasi dengan kosubstrat 7,5%, konsentrasi tertinggi pada waktu fermentasi 12 jam dengan persen konversi xilitol 18,04 untuk malai dan 16,50 tangkai. Sedangkan produk xilitol hasil fermentasi dengan kosubstrat 15%, konsentrasi tertinggi waktu fermentasi 12 jam dengan persen konversi xilitol 8,22% untuk malai 4,88% tangkai. ......Sorghum is plant which is potential to be cultivated in Indonesia since it has many advantages compared with other plants. Sorghum?s waste (stem and branch) contains which can be hydrolyzed giving its monomers hidrolized, to produce xylose. One of the monomers is xylose which the materials of xylitol. In this research, stem and branch of sorghum are used as souce is the source for xylitol production. The material was hydrolyzed using sulfuric acid (H2SO4) 0,3M At 121 degree Celcius with optimal duration of 35 minutes. The result of measurement of xylosa contained in hydrolyzed at optimal condition 24,90 % for stem and 20,56 % for branch. This hydrolyzed was used as substrate for the process of fermentation by Candida fukuyamaensis UICC Y-247 khamir is the producer of "xylose reductate" enzyme. The hydrolyzed is then decolorized by adding active carbon 1 % (w/v) to remove toxin substance which can fermentation process by khamir growth. The product of xylitol fermentation without kosubstrat, from the highest fermentation duration 12 hours with percent coversion of xylitol 12,88 % for stem and 10,88 % or branch. The product of xylitol from fermentation with kosubstrat 7,5 %, from the highest concentration on fermented duration 12 hours with percentage of xylitol convention 18,04 for stem and 16,50 for branch. Where as the product of xylitol fermentation with 15 % kosubstrat, with the highest yealds fermentation duration 12 hours with the percentage of xylitol convention is 8,22 % for stem and 4,88 % for branch.

Abstrak :
Xilitol merupakan pemanis alami yang bersifat antikariogenik dan memiliki indeks glikemik rendah. Xilitol dapat diproduksi dari xilosa, baik melalui proses kimiawi ataupun proses fermentasi. Xilitol dihasilkan melalui proses fermentasi xilosa oleh Candida fukuyamaensis UICC Y-247. Xilosa diperoleh dari hidrolisis hemiselulosa dalam limbah sorgum manis yang telah dihilangkan senyawa ekstraktif dan ligninnya. Hidrolisis dilakukan secara kimiawi dengan katalis asam sulfat 0,3 M. Penelitian ini dilakukan untuk mengetahui pengaruh penambahan kosubstrat terhadap yield xilitol. Yield xilitol tertinggi diperoleh dari fermentasi malai jam ke-12 sebesar 188 ppm dengan konversi xilosa menjadi xilitol 20,29%. Penambahan kosubstrat L-arabinosa 150 ppm menaikkan yield xilitol hingga 347 ppm dengan konversi sebesar 37,37%. Penambahan kosubstrat D-glukosa 150 ppm menghasilkan xilitol 287 ppm dengan konversi 30,93%. ......Xylitol is a natural sweetener that has anti-cariogenic properties and has a low glycemic index. Xylitol can be produced from xylose, either through a chemical process or fermentation process. Xylitol was produced through a process of xylose fermentation by Candida fukuyamaensis UICC Y-247. Xylose derived from hemi-cellulose hydrolysate of sweet sorghum waste in which the lignin and extractive compounds had been removed. The hydrolysis was done chemically with sulfuric acid catalyst 0.3 M. This research was conducted to determine the effect of adding cosubstrate on xylitol yield. The highest xylitol yield obtained from the fermentation tassel at the hour 12 by 188 ppm with the conversion of xylose into xylitol 20.29%. The addition of L-arabinose cosubstrate 150 ppm increased xylitol yield up to 347 ppm by a conversion of 37.37%. The addition of D-glukosa cosubstrate 150 ppm produced xylitol 287 ppm by a conversion of 30,93%.

Abstrak :
ABSTRACT
In order to shorten the measurement time of biochemical oxygen demand (BOD), a BOD sensor based on yeast metabolism was developed. Local yeast, Indonesian Origin, Candida fukuyamaensis UICC Y-247, was used as a transducer. The yeast was immobilized as a thin film in ag arose matrix with the auxiliary of Nafion® acting as the membrane for ion exchange process. The film was then attached to gold-modified glassy carbons and used as transducer on the working electrodes. The measurements were conducted by observing the depletion of glucose concentration using multipulse amperometric method and then converte d to BOD values. Optimum condition was observed in a waiting measurement time of 30 min at an applied potential of 450 mV (vs. Ag/AgCl). Linearity was shown in glucose concentration range of 0.1?0.5 mM, which was equivalent to BOD concentration range of 10?50 mg/L. A detection limit of 1.13 mg/L BOD could be achieved. Good repeatability was shown by a relative standard deviation (RSD) of 2.7% (n = 15). However, decreasing current response of ~50% was found after 3 days. Comparing to the conventional BOD measurement, this BOD sensor can be used as an alternative method for BOD measurements.

Abstrak :
Penelitian ini dilakukan untuk membuat xilitol dari limbah batang/malai sorgum manis CTY-33. Xilitol dibuat melalui proses fermentasi xilosa menggunakan Candida fukuyamaensis UICC Y-247 penghasil enzim xilosa reduktase yang mereduksi xilosa menjadi xilitol. Xilosa didapat dari hidrolisis hemiselulosa dalam limbah batang/malai sorgum manis CTY-33 yang telah dilakukan delignifikasi. Hasil xilosa tertinggi dengan 30 ml larutan H2SO4 0,3M dicapai pada waktu hidrolisis 35 menit yaitu 22,71% dalam hidrolisat malai sorgum manis CTY-33, dan 15,30% dalam hidrolisat batang sorgum manis CTY-33. Yield xilitol tertinggi dicapai pada fermentasi jam ke-12 yaitu 191,07 ppm dari malai, dan yield xilitol dari batang 31,48 ppm. Penambahan kosubstrat glukosa menaikkan kadar xilitol, hasil tertinggi dicapai pada jam ke-12. Penambahan kosubstrat glukosa 300 ppm pada malai menghasilkan xilitol sebesar 291,17 ppm (konversi xilosa menjadi xilitol 38,86 %). dan penambahan kosubstrat glukosa 150 ppm pada batang sebesar 173,44 ppm (konversi xilosa mnjadi xilitol 26,20. ......Producing xylitol from the straw / panicle of sweet sorghum CTY -33 wastes was done. The xylitol produced through the fermentation process of xylose using Candida fukuyamaensis UICC Y-247 which reduced xylose to xylitol using xylose reductase enzyme. The hemicellulose in the straw/panicle sweet sorghum CTY-33 wastes was hydrolized by 30 mL sulfuric acid 0,3 M after delignification. The highest xylose in the hydrolyzate of panicle during 35 minutes was 22.71 % and from straw was15.30 %. The highest xylitol yield reached in 12-hours fermentation, panicle xylitol yield was 191.07 ppm and straw xylitol yield was 31.48 ppm. When glucose added as co-substrat, the xylitol yield increased. The panicle xylitol yield became 291.170 ppm (the xylose conversion to xylitol was 38,86 %) when it added glucose 300 ppm, and the straw xylitol yield became 173.44 ppm (the xylose conversion to xylitol was 26,20 %) when it added glucose 150 ppm.