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"Cultivation of chlorella vulgaris buitenzorg with alteration of light illumination using a maximum carbon dioxide trnasfer rate (CTR) base curve syccessfully enhanced the CTR value up to 1.74 times compared to alteration of light illumination with a growth base curve...."

"ABSTRAKEnergi cahaya merupakan salah satu faktor penting yang dibutuhkan dalam

kultivasi Chlorella vulgaris. Namun penggunaan energi cahaya dengan cahaya

lampu membuat peningkatan biaya produksi yang cukup signifikan. Siklus terang

gelap alami matahari dapat dimanfaatkan sebagai sumber energi yang potensial

untuk kultivasi Chlorella vulgaris. Pada penelitian ini dilakukan proses kultivasi

Chlorella vulgaris dalam fotobioreaktor skala pilot 150 L di luar ruangan

menggunakan siklus pencahayaan terang gelap matahari. Pada proses kultivasi

luar ruangan tersebut, kultur Chlorella vulgaris dapat tumbuh dengan baik pada

kisaran temperatur 25- 40 oC dengan nilai Optical Density tertinggi 0,702 yang

dicapai pada jam ke-168. Setelah kultivasi selama 200 jam dilakukan pengujian

kandungan esensial dengan jumlah lipid sebesar 5,4 % berat kering, protein

sebesar 50,36 % berat kering, total klorofil sebesar 1,8306 ppm serta β-karoten

sebesar 0,686 ppm. Kualitas yield biomassa yang dihasilkan dengan

menggunakan pencahayaan terang gelap alami memang tidak sebaik pencahayaan

kontinu. Namun proses kultivasi dengan sistem terang gelap dapat dikaji lebih

lanjut untuk mendapatkan hasil yang lebih ekonomis

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ABSTRACT

Light energy is one of the important factors needed in the cultivation of Chlorella vulgaris. However, the use of light energy by halogen lamp increase cost of production significantly. Natural light dark cycle of the sun can be harnessed as a potential energy source for the cultivation of Chlorella vulgaris. In this research the cultivation of Chlorella vulgaris in a 150 L pilot scale photobioreactor outdoor lighting using light dark cycle of the sun. At the outdoor cultivation of Chlorella vulgaris culture was able to grow well in the temperature range 25-40° C with the highest Optical Density reached 0.702 at the hours to 168. After cultivation for 200 hours testing essential to the lipid content of dry weight, protein of dry weight, total chlorophyll, and B-carotene are 5,4% ;50,36%; 1,8306 ppm and 0,686 ppm, respectively. The quality of the biomass yield produced by using natural dark light illumination is not as good as continuous lighting. But the process of cultivation with natural light dark cycle can be studied further to obtain more economical results."

"There are many researches to solve the effects of global warming caused by great amount of CO2 in the air. One of the effective alternatives to reduce this gas in atmosphere is by using micro alga Spirulina platensis due to its ability of CO2 fixation and the very useful biomass that it produced. Spirulina platensis contains high protein and can cure diseases such as cancer and cholesterol reduction. In considering of these benefits, this research focused on increasing the biomass production of Spirulina platensis by alteration of light illumination during microbial growth. The cultivation holds in a series of photo-bioreactors at 29"C and I atm where each of photo-bioreactor has volume of 500 ml., using Conwy medium as nutrition. 3% CO2 is the carbon source for the cultivation with superficial velocity 1.2 m/h. Phillips Halogen lamp 20W/12V/50Hz is the source for illumination. The cultivation using constant intensity of light illumination was also be done as a control. Cultivation of Spirulina platensis with alteration illumination method successfully increased the biomass production 55.1 % higher than constant intensity of light illumination. The energy of producing biomass in alteration of light illumination method lower than continuous intensity illumination which was only 21.6 % than constant intensity of light illumination. Kinetic studies of this microbial growth at alteration of light illumination also concluded that specific growth rate and bicarbonate concentration as essential compound followed Ierusalemsky kinetic model equation."

"Light is one of the most important factor in plant tissue culture. The growth and development of plant in vitro are affected by light quality. This study examines the influence of different light qualities on the in vitro growth and development of oil palm shoots. Oil palm shoots were cultured in Murashige & Skoog medium under either white fluorescent lamp, white light-emitting diode (LED), red LED, blue LED, combination of red and blue LED, or in darkness. The results show that the growth and development of oil palm shoots are influenced by the light quality. Root initiation and shoot elongation were good under red light, while chlorophyll and sugar content was better produced under white and blue light than red light. In addition to white fluorescent lamp, the combination of red and blue LED resulted in higher growth parameter compared to other light treatments, but the results were not significantly different."

"Mikroalga telah dikenal memiliki kemampuan untuk melakukan fiksasi CO2 melalui proses fotosintesis dan mengubah CO2 secara langsung menjadi senyawa karbon atau biomassa seperti polisakarida, protein, atau lipid yang bernilai cukup ekonomis. Penelitian mengenai proses fiksasi CO2 dengan memanfaatkan kemampuan fotosintesis mikroalga Spirulina platensis merupakan salah satu aternatif yang diusulkan untuk mengatasi permasalahan gas rumah kaca, yang telah menjadi permasalahan yang serius akhir-akhir ini. Proses fiksasi CO2 dan produksi biomassa menggunakan Spirulina platensis ini dilakukan dengan menggunakan medium Conwy dalam sebuah fotobioreaktor dengan perlakuan alterasi pencahayaan dan pencahayaan konstan. Fotobioreaktor yang digunakan tersusun secara seri dan tunggal dengan volume masing-masing 500 ml dan 1.500 ml. Proses tersebut berlangsung pada kondisi : suhu 29_C, kecepatan superfisial gas sebesar 1,2 m/jam, kandungan CO2 3% volume dalam aliran udara dan intensitas cahaya berkisar antara 1,48 Watt/m2 ?5,76 Watt/m2. Secara umum hasil yang diperoleh dalam penelitian ini adalah dengan semakin banyak konfigurasi reaktor dan semakin tingginya intensitas cahaya yang diterima oleh sel dalam medium, peningkatan jumlah sel yang terjadi juga semakin tinggi. Besarnya peningkatan jumlah sel ini berbanding terbalik dengan kemampuan fiksasi CO2. Laju fiksasi CO2 dan laju pertumbuhan sel yang tertinggi dicapai dengan menggunakan reaktor susun seri melalui perlakuan alterasi pencahayaan. Peningkatan fiksasi CO2 ditandai dengan meningkatnya nilai rata CTR dan qCO2 hingga mencapai 5,53 g/dm3 h-1 dan 41,77 h-1. Model pendekatan secara empiris terhadap laju fiksasi CO2 mengikuti persamaan Haldane dan persamaan Ierusalemsky.

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Microalgae has known for its ability to fix CO2 with photosynthesize and convert into biomass product such as polysacharide, protein, or lipid. The research of CO2 fixation using Spirulina platensis has become a promising alternative to reduce green house effect. CO2 fixation process and biomass production with Spirulina platensis was cultivated in photobioreactor with fixed and alteration of light illumination with Conwy as a medium. Two configuration of photobioreactors are arranged in single and three stages serial photobioreactor with reactor volume of photobioreactors are 1.500 mL and 500 mL/reactor, orderly. The fixation experiment were carried out in : Temperatur 29_C , gas supervicial velocity 1,2 m/hour, CO2 concentration : 3 % volume and range of light intensity 1,48 Watt/m2 ? 5,76 Watt/m2. The experimental findings for this system show that the increasing of reactor number and accepted light intensity in medium will be rise the number of cell in reactor. The rate of cell growth was oppposite to CO2 fixation rate. The highest of CO2 fixation and cell growth rate was reached in three stages serial photobioreactor with alteration light of illumination. The highest mean value of CTR and qCO2 could reach 5,53 g/dm3 h-1 dan 41,77 h-1. The empirical equation models of CO2 fixation rate follow Haldane and Ierusalemsky equation."

"ABSTRAKDisertasi ini membahas tentang metode yang praktis dan biaya murah untuk membuat fotokatalis Ag/N ko-doped TiO2 bersifat responsif terhadap cahaya sinar tampak dan diterapkan sebagai elektroda sistem fotoelektrokatalitik. Penelitian ini diawali sintesis film N-doped TiO2 pada permukaan kaca konduktif SnO2F dengan metode sol-gel menggunakan titanium tetraisopropoksida Ti OC4H9 4 sebagai prekursor TiO2. Berdasarkan hasil karakterisasi diketahui doping N pada struktur kisi TiO2 telah berhasil, namun demikian aktivitas fotokatalisisnya masih rendah. Tahapan penelitian berikutnya, film N-doped TiO2 disintesis di atas permukaan logam Ti dengan metode anodisasi menggunakan foil Ti dalam elektrolit etilen glikol yang mengandung amonium florida NH4F; 0,3 , air 0,3 dan trietilamina 0,02 . Potensial diatur tetap 40 V selama 60 detik, hingga didapatkan amorfous Ti OH 6 dan trietilamina tersolvasi di permukaannya. Perlakuan kalsinasi terhadap amorfous Ti OH 6 pada suhu 450oC kondisi atmosferik N2 selama 3 jam, menyebabkan beberapa atom O disubstitusi oleh atom N dalam struktur kisi TiO2 membentuk kristal N-doped TiO2 yang memiliki band gap 2,7 eV. Untuk meningkatkan aktivitas fotokatalisis di daerah sinar tampak, permukaan N-doped TiO2 didekorasi dengan partikel Ag secara deposisi elektrokimia, menggunakan larutan AgNO3-EDTA dengan potensial deposisi 1V dan variasi waktu 5-25 detik, hingga didapatkan fotokatalis Ag/N ko-doped TiO2. Hasil pengukuran XRD memperlihatkan Ag/N ko-doped TiO2 terdiri dari kristal anatase, dan diamati puncak difraksi pada daerah 2 Theta 44,8o yang merupakan karakteristik Ag 111 , membuktikan bahwa partikel Ago telah terdeposisi pada matrik N-doped TiO2. Foto FESEM memperlihatkan morfologi permukaan N-doped TiO2 berbentuk nanotube, yang memiliki tebal dinding tube rata-rata 15 nm, diameter mulut tube 70 nm dan tinggi 900 nm. Hasil pengukuran HRTEM memperlihatkan partikel Ago berukuran 15-40 nm dan mapping EDX membuktikan bahwa nanopartikel Ago terdistribusi merata di permukaan N-doped TiO2 dengan rasio atom 0,61 . Spektrum XPS N 1s pada daerah binding energi 400,6 eV membuktikan keberadaan atom N dalam matrik Ag/N ko-doped TiO2 sebagai indikasi pembentukan ikatan N-Ti-O yang didukung hasil pengukuran FTIR. Spektrum XPS Ag 3d memperlihatkan puncak serapan ganda yang terpisah pada binding energi 368,6 eV dan 374,6 eV, dengan energi pemisahan 6,0 eV, memperkuat bukti bahwa Ag terdeposisi sebagai partikel Ago. Partikel Ago terdeposisi meningkatkan kemampuan N-doped TiO2 menyerap sinar tampak l=550 nm sebagai kontribusi serapan surface plasmon resonance SPR . Tahapan penelitian selanjutnya, Ag/N ko-doped TiO2 digunakan sebagai elektroda kerja sistem fotoelektrokatalitik FEK dengan pemberian bias potensial. Berdasarkan uji kinerja elektroda pada degradasi larutan MB secara fotoelektrokatalisis FEK , terbukti bahwa elektroda Ag/N ko-doped TiO2 memiliki aktivitas fotokatalisis yang tinggi, mampu mendegradasi larutan MB pada konsentrasi 10 ppm selama 4 jam, memberikan rasio MB terdegradasi 92 , lebih tinggi dibandingkan dengan N-doped TiO2 dan TiO2 masing-masing mampu mendegradasi 56 dan 14 . Pemberian bias potensial 0,2 V pada permukaan elektroda Ag/N ko-doped TiO2, mampu meningkatkan aktivitas FEK degradasi MB, memberikan konstanta laju FEK k=9x10-3/menit , yang mana 4,5 kali lebih cepat dibandingkan dengan proses fotokatalisis FK tanpa pemberian bias potensial k=2x10-3/menit . Beberapa faktor yang mempengaruhi FEK degradasi MB telah dievaluasi, yakni pH optimum adalah 9,0 ; bias potensial optimum 0,2 V dan konsentrasi awal larutan MB optimum 10 ppm. Elektroda Ag/N ko-doped TiO2 yang dikembangkan memiliki kestabilan yang tinggi, setidaknya 5 kali pemakaian masih memperlihatkan aktivitas fotokatalitik yang baik sehingga sangat ekonomis untuk diterapkan dalam mendegradasi polutan organik.

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ABSTRACTThe dissertation discusses practical and inexpensive methods for synthesis of Ag N co doped TiO2 photocatalysts responsive to visible light and used as photoelectrocatalytic electrodes system. Initial phase of this study was synthesized N doped TiO2 film on SnO2 F conductive glass surface with sol gel method using titanium tetraisopropoksida Ti OC4H9 4 as TiO2 precursor. Based on the characterization results known doping N on TiO2 lattice structure has been successful, however photocatalysis activity is still low. The next stage of the study, the N doped TiO2 film was synthesized on the surface of the Ti metal by anodizing method using a Ti foil in an ethylene glycol electrolyte containing ammonium fluoride NH4F 0.3 , water 0.3 and triethylamine 0.02 . The anodizing process is carried out at a potential of 40 V for 1 hour, forming an amorphous Ti OH 6 and triethylamine dissolved on its surface. Calcined treatment of amorphous Ti OH 6 at 450 C atmospheric conditions N2 for 3 hours, causing some O atoms substituted by N atom in lattice structure of TiO2 to form N doped TiO2 crystals having band gap of 2.7 eV. This method is very effective and efficient, where the N doping process takes place optimally and simultaneously with the formation of TiO2 crystal. To improve the photocatalysis activity in visible light region, the surface of N doped TiO2 was decorated with Ag particles by electrochemical deposition method, using AgNO3 EDTA solution with a potential deposition 1V and a time variation 5 25 second, to obtain Ag N co doped TiO2 photocatalyst. The XRD measurements showed that Ag N co doped TiO2 consisted of anatase crystals, and observed the diffraction peak at 2 Theta 44.8o region which is characteristic of Ag 111 , proving that the Ago particle has been deposited on an N doped TiO2 matrix. FESEM images show the surface morphology of N doped TiO2 in the form of nanotubes, which have an average thickness of 15 nm tube wall, 70 nm diameter mouth tube and 900 nm height. The HRTEM measurements show that Ago particles of 15 40 nm and EDX mapping demonstrate that Ago nanoparticles are evenly distributed on the surface of N doped TiO2 with an atomic ratio of 0.61 . The XPS N 1s spectrum in the energy binding region of 400.6 eV proves the presence of N atoms in the Ag N co doped TiO2 matrix as an indication of N Ti O bond formation supported by FTIR measurements. The XPS Ag 3d spectrum shows a separate double absorption peak on energy bindings of 368.6 eV and 374.6 eV, with a 6.0 eV separation energy, reinforcing evidence that Ag is deposited as an Ago particle. The Ago particle enhances the ability of N doped TiO2 to absorb the visible light l 550 nm as a contribution of surface plasmon resonance SPR absorption. The next step of this research, the Ag N co doped TiO2 is used as the electrode of photoelectrocatalytic PEC system and potential bias was applied. Based on the electrode activity test on the degradation of MB solution by photoelectrocatalysis PEC , it is proved that the Ag N co doped TiO2 electrode has high photocatalytic activity, capable of degrading the MB solution at 10 ppm concentration for 4 hours, giving a degradable MB ratio of 92 higher compared with N doped TiO2 and TiO2 respectively were able to degrade 56 and 14 . The potential bias was applied 0.2 V on the surface of the Ag N co doped TiO2 electrode, capable of increasing the PEC activity of MB degradation, gives PEC rate constants k 9x10 3. min 1 , which is 4.5 times faster than by photocatalysis PK without potential bias k 2x10 3.min 1 . Several factors affecting the PEC degradation of MB have been evaluated, ie optimum pH is 9.0 optimum potential bias of 0.2 V and initial concentration of optimum MB solution is 10 ppm. The Ag N co doped TiO2 electrode developed has a high stability of photocatalytic activity, at least 5 times the use still showing good photocatalytic activity so it is very economical to apply in degrading organic pollutants. "

"Industri tekstil merupakan penyumbang terbesar limbah zat warna ke dalam air, contohnya zat warna metilen biru yang bersifat racun, karsinogenik, dan tidak dapat terurai secara alami. Salah satu teknik mengurangi kadar metilen biru adalah melalui degradasi secara fotokatalitik dengan menggunakan semikonduktor. CuBi2O4 merupakan semikonduktor tipe-p dengan celah pita yang sempit (1,5 – 1,8 eV) dapat digunakan sebagai fotokatalis untuk degradasi metilen biru karena memiliki respon cahaya tampak. Penambahan logam mulia Paladium (Pd) dapat meningkatkan kinerja aktivitas fotokatalitik CuBi2O4 karena dapat menekan rekombinasi pasangan e− dan h+. Penelitian ini, telah berhasil mensintesis CuBi2O4 melalui metode solvotermal, dan mensintesis nanokomposit Pd/CuBi2O4 dengan variasi perbandingan rasio mol Pd:CuBi2O4 (1:1, 1:2, dan 2:1) melalui metode presipitasi dan reduksi. CuBi2O4 dan Pd/CuBi2O4 hasil sintesis telah dibuktikan melalui karakterisasi dengan XRD, TEM, FTIR, dan UV-Vis DRS. Uji sifat katalis dilakukan pada larutan Metilen Biru dengan variasi penambahan massa katalis sebesar 5 mg, 10 mg, dan 15 mg, serta variasi kondisi (fotolisis dan adsorpsi). Persentase degradasi metilen biru paling optimum adalah pada katalis Pd/CuBi2O4 (2:1) 10 mg, yaitu sebesar 82,63% dengan laju degradasi 8,9 × 10-3 min-1.

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Textile industry is the largest contributor of colorant waste into water, for instance, the toxic, carcinogenic, and non-biodegradable dye methylene blue. One of the techniques to reduce the concentration of methylene blue is through photocatalytic degradation using a semiconductor. CuBi2O4 is a p-type semiconductor with a narrow bandgap (1.5 - 1.8 eV) that can be utilized as a photocatalyst for methylene blue degradation due to its visible light response. The addition of the noble metal Palladium (Pd) can enhance the photocatalytic activity of CuBi2O4 by suppressing the recombination of electron-hole pairs (e− dan h+). In this research, CuBi2O4 has been successfully synthesized through the solvothermal method, and Pd/CuBi2O4 nanocomposites have been synthesized with various ratios of Pd:CuBi2O4 (1:1, 1:2, and 2:1) using the precipitation and reduction method. CuBi2O4 and Pd/CuBi2O4 synthesized products have been characterized using XRD, TEM, FTIR, and UV-Vis DRS. The catalytic properties test was performed on Methylene Blue solutions with varying catalyst masses of 5 mg, 10 mg, and 15 mg, as well as different conditions (photolysis and adsorption). The optimum percentage of methylene blue degradation was observed with the catalyst Pd/CuBi2O4 (2:1) 10 mg, which was 82.63%, with a degradation rate of 8,9 × 10-3 min-1."