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"Objectives of this research are mainly to study impacts of acidity strength (by varying amount of precipitant and loading Al-Si) and the effect of nickel particle size (by varying calcinations temperature) on decomposition reaction performances. In this research, high-nickel-loaded catalyst is prepared with two methods. Ni-Cu/Al catalysts were prepared with co-precipitation method. While the Ni-Cu/Al-Si catalyst were prepared by combined co-precipitation and sol-gel method. The direct cracking of methane was performed in 8mm quartz fixed bed reactor at atmospheric pressure and 500-700°C. The main results showed that the Al content of catalyst increases with the increasing amount of precipitant. The activity of catalyst increases with the increasing of catalyst?s acidity to the best possible point, and then increasing of acidity will reduce the activity of catalyst. Ni-Cu/4Al and Ni-Cu/11Al deactivated in a very short time hence produced fewer amount of nanocarbon, while Ni-Cu/15Al was active in a very long period. The most effective catalyst is Ni-Cu/22Al, which produced the biggest amount of nanocarbon (4.15 g C/g catalyst). Ni catalyst diameter has significant effect on reaction performances mainly methane conversion and product yield. A small Ni crystal size gave a high methane conversion, a fast deactivation and a low carbon yield. Large Ni particle diameter yielded a slow decomposition and low methane conversion. The highest methane conversion was produced by catalyst diameter of 4 nm and maximum yield of carbon of 4.08 g C/ g catalyst was achieved by 15.5 nm diameter of Ni catalyst."

"Objectives of this research are mainly to study impacts of acidity strength (by varying amount of precipitant and loading Al-Si) and the effect of nickel particle size (by varying calcinations temperature) on decomposition reaction performances. In this research, high-nickel-loaded catalyst is prepared with two methods. Ni-Cu/Al catalysts were prepared with co-precipitation method. While the Ni-Cu/Al-Si catalyst were prepared by combined co-precipitation and sol-gel method. The direct cracking of methane was performed in 8mm quartz fixed bed reactor at atmospheric pressure and 500-700°C. The main results showed that the Al content of catalyst increases with the increasing amount of precipitant. The activity of catalyst increases with the increasing of catalyst?s acidity to the best possible point, and then increasing of acidity will reduce the activity of catalyst. Ni-Cu/4Al and Ni-Cu/11Al deactivated in a very short time hence produced fewer amount of nanocarbon, while Ni-Cu/15Al was active in a very long period. The most effective catalyst is Ni-Cu/22Al, which produced the biggest amount of nanocarbon (4.15 g C/g catalyst). Ni catalyst diameter has significant effect on reaction performances mainly methane conversion and product yield. A small Ni crystal size gave a high methane conversion, a fast deactivation and a low carbon yield. Large Ni particle diameter yielded a slow decomposition and low methane conversion. The highest methane conversion was produced by catalyst diameter of 4 nm and maximum yield of carbon of 4.08 g C/ g catalyst was achieved by 15.5 nm diameter of Ni catalyst."

"Flex matala biofilter dengan luas permukaan 365 m2/m3 (M365) dan 190 m2/m3 (M190) digunakan sebagai carrier bkteri dalam produksi biohidrogen menggunakan reaktor CSTR. Reaktor CSTR yang dilengkapi dengan biofilter (CSTR-PBF) didesain dan dioperasikan untuk memproduksi gas biohidrogen dengan bahan baku limbah pabrik minuman sebagai substrat pada konsentrasi 10 ? 30 g total glukosa/L dan waktu tinggal 8 jam ? 0,5 jam. Carrier atau biofilter dipasang pada bagian tengah fermentor (60 mm dari dasar fermentor) yang berfungsi untuk menghindari washout. Hasil menunjukkan bahwa konsentrasi substrat 15 ? 20 g/L memberikan yield dan Laju produksi gas biohidrogen (LPH) yang tinggi. Biofilter M365 memberikan kinerja produksi hidrogen yang lebih baik dibanding dengan biofilter M190. HRT 0,5 jam memberikan LPH yang paling tinggi, yakni 124,87 L H2/L/hari, namun yieldnya 1,17 mol H2/mol glukosa. Di sisi lain, kondisi yang memberikan yield tertinggi dicapai pada waktu tinggal 4 jam dengan LPH sebesar 13,74 L H2/L/hari dan yield sebesar 1,82 mol H2/mol glukosa. Kondisi operasi yang direkomendasikan adalah waktu tinggal 1 jam dan konsentrasi substrat 20 g glukosa/L dengan LPH 88,69 L H2/L/hari, konversi substrat, 91,85 % dan yield 1,42 mol H2/mol glukosa. Pada waktu tinggal yang rendah, yakni 1 jam dan 0,5 jam terdapat perbedaan distribusi konsentrasi biomassa pada bagian atas, tengah dan bawah reaktor. Produk cair terbesar adalah asam butirat dan asam asetat dengan rasio 1,41 mol asam butirat/mol asam asetat sampai dengan 5,66 mol asam butirat/mol asam asetat.

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A flex-matala packed biofilter with specific surface area M365 m2/m3 (M365) and 190 m2/m3 (M190) were used as a bacteria carrier in a Continuous Stirred Tank Reactor (CSTR) in this study. The continuous stirred tank reactor with packed biofilter (CSTR-PBF) was designed and operated under sugary wastewater substrate at concentration of 10 g total sugar/L ? 30 g total glukosa/L and hydraulic retention time (HRT) 8 h - 0.5 h to assess the biohydrogen producing ability. Biofilter was installed at 60 mm height from the bottom of bioreactor (middle of the bioreactor). The biofilter played a role in avoiding biomass washout. It was found that substrat concentration of 15 ? 20 g glucose/L lead the hydrogen production performa. Biofilter M365 produced the higher hydrogen production rate and yield. The condition producing the higher hydrogen production rate was at HRT 0.5 h with hydrogen production rate (HPR) of 124.87L H2/L/d, and yield of 1.17 mol H2/mol glucose. On the other hand, the condition producing the higher yield obtained when the fermentor operated at HRT 4 h, which hydrogen production rate and yield were 13.74 H2/L/d, and yield of 1.42 mol H2/mol glucose. Operation condition suggested for hydrogen production was HRT 1 h and 20 g total glucose/L which HPR, susbtrate conversion and yield were 88.69 H2/L/d; 91.85 % and 1.42 mol H2/mol glucose. There was difference distribution of biomassa on top, middle and bottom part of the bioreactor observed at HRT 1 h to 0,5 h. Butyric acid and acetic acid were the main liquid product that the ratio was 5.66 mol butyric/mol acetic. A flex packed biofilter used in CSTR system is a better approach to accumulate biomass concentration in bioreactor for enhancing biohydrogen production rate comparison with other kinds of bioreactor."

"Upaya untuk memproduksi hidrogen masih sedikit dari sumber yang terbarukan. TiO2 dalam bentuk nanotube arrays dengan dopan Boron yang disintesis dengan metode anodisasi untuk produksi hidrogen telah diinvestigasi. Perlakuan termal katalis B-TiO2 nanotube arrays (B-TNTAs) dilakukan dengan kalsinasi reduksi dengan gas hidrogen pada suhu 500oC selama 2 jam. Analisis SEM menunjukkan morfologi nanotube arrays tiap konsentrasi boron seragam. Analisis UV-Vis DRS menunjukkan B-TNTAs memiliki absorbansi yang besar pada jangkauan panjang gelombang sinar tampak dengan band gap energy yang relatif rendah yaitu menjadi 2,9 eV. Analisis XRD menunjukkan hasil 100% kristal anatase murni. Melalui proses fotokatalisis, hidrogen mampu dihasilkan hingga 48959 μmol/m2 setelah 4 jam pengujian dengan katalis 7,5 mM B-TNTAs.

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Attempts to produce hydrogen is still slightly from renewable sources. TiO2 nanotube arrays in the form of boron dopants synthesized by anodizing method for hydrogen production has been investigated. Catalyst-thermal treatment of TiO2 nanotube arrays B (B-TNTAs) performed by calcination reduction with hydrogen gas at a temperature of 500oC for 2 hours. SEM analysis showed the morphology of nanotube arrays by uniform boron concentration. UV-Vis DRS analysis showed B-TNTAs has a large absorbance in the visible wavelength range with a band gap energy is relatively low, to 2.9 eV. XRD analysis produces 100% anatase crystals. Through a photocatalytic process, hydrogen is able to produce up to 48959 μmol/m2 after 4 hours of testing with catalyst 7.5 mM B-TNTAs."

"ABSTRAKGas hidrogen banyak diperoleh dari proses elektrolisis yang memerlukan energi listrikyang besar. Elektrolisis plasma adalah teknologi baru dalam meningkatkan produktifitashidrogen sekaligus menekan kebutuhan listrik. Penelitian ini dilakukan untuk mengujiefektivitas proses elektrolisis plasma dengan penambahan aditif (larutan metanol danetanol) yang dinyatakan sebagai jumlah produk hidrogen per satuan energi listrik yangdikonsumsi dengan memvariasikan temperatur, tegangan listrik dan konsentrasi larutanKOH. Efektivitas proses ini dibandingkan dengan efektivitas elektrolisis Faraday danelektrolisis plasma tanpa penambahan aditif. Hasil percobaan menunjukkan kenaikankonsentrasi KOH dan tegangan listrik menyebabkan kenaikan jumlah produk hidrogen.Proses elektrolisis plasma pada penelitian ini dapat meningkatkan efektivitas proseshingga 5 kali lipat lebih tinggi dibandingkan dengan elektrolisis plasma tanpapenambahan aditif.

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ABSTRACTHydrogen is commonly produced by electrolysis which consumes a great deal of energy.Plasma electrolysis is a new technology that can increases hydrogen productivity whilelowering electrical energy needs. This research aimed to test the effectiveness of theplasma electrolysis process with methanol and ethanol addition which is expressed as thenumber of products of hydrogen per unit of electrical energy consumed by investigatedtemperature, electrical voltage and the concentration of KOH solution. Then, theeffectiveness of this process compared with the effectiveness of electrolysis Faraday.Results showed an increase of KOH concentration and the voltage causes an increase inthe hydrogen product. Plasma electrolysis process in this research can improve theeffectiveness of processes to 5 fold higher compared plasma electrolysis withoutmethanol and ethanol addition."

"Produksi hidrogen dengan menggunakan metanol atau gliserol sebagai elektron donor pada fotokatalis TiO2, TiNT, Pt/TiO2 dan Pt/TiNT pada suhu reaksi dari 30 oC sampai dengan 70 oC telah diteliti. Metanol dan gliserol efektif sebagai elektron donor untuk produksi hidrogen secara fotokatalisis. Penggunaan metanol lebih unggul 10% dari gliserol pada semua katalis dalam total produksi hidrogen. Produksi hidrogen terbaik ditunjukkan oleh fotokatalis Pt(1%)/TiNT dengan metanol sebagai elektron donor, yaitu sebesar 2306 µmol/gcat, sementara total hidrogen dengan gliserol sebesar 2120 µmol/gcat. Penggunaan dopan Pt pada fotokatalis menghasilkan produksi hidrogen dua kali lebih besar dibandingkan dengan tanpa dopan.

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Hidrogen production with methanol or glycerol as sacrificial agent using TiO2, TiO2 Nanotubes, Pt/TiO2 and Pt/TiO2 Nanotubes photocatalysts at reaction temperature 30 oC to 70 oC have been investigated. Methanol and glycerol were effective for hydrogen production and the best result was methanol with Pt(1%)/TiO2 that have 2306 µmol/gcat, meanwhile with glycerol only produce 2120 µmol/gcat. The other photocatalyst also have the same pattern, which metanol give 10% higher result on total hydrogen production. Catalyst with Pt give twice higher hydrogen production rather than with no Pt."

"Sianida telah digunakan sejak lama dalam proses pengektrasian emas dengan metoda pelindian (leaching). Sianida juga dikenal sebagai bahan kimia berbahaya dan mematikan. Oleh karena itu, International Cyanide Management Code (ICMC) didirikan untuk mengontrol penggunaan siandia dalam industri. Kanowna Belle Gold Mine (KBGM) telah terdaftar dalam ICMC sejak tahun 2008 dan kemudian diperbaharui pada Desember 2012. Menurut ICMC, konsentrasi sianida yang dibuang ke tempat pembuangan akhir (tailings) harus 80% di bawah 50 ppm dan 95% di bawah 78 ppm. Pembuangan di atas 78 ppm yang berkepanjangan dapat menyebabkan pelanggaran atas kode yang sudah ditetapkan dan disepakati oleh perusahaan. Batas konsentrasi sianida yang dibuang ke tailings di KBGM lebih tinggi dari batas normal dikarenakan tipe air yang digunakan dalam proses adalah air dengan tingkat garam yang tinggi (hyper saline water). Tujuan utama skripsi ini adalah untuk meneliti dan memaksimalkan keefektifan dari hidrogen peroxida dalam proses penghancuran sianida di tailings KBGM selama berlangsungnya proses pelindian batuan refractory dan free milling. Penelitian dilakukan dengan menggunakan sampel yang diambil saat refractory dan free milling untuk kemudian dilakukan pengujian skala lab dan nyata (plant trial). Sampel yang diambil dari setiap eksperimen lalu dites menggunakan metoda picric acid, yaitu metoda yang menggunakan warna sebagai indikator tingkat konsentrasi sianida di dalam larutan. Semakin merah warna larutan, menunjukkan semakin tinggi konsentrasi sianida di dalam larutan tersebut. Dampak dari kombinasi penggunaan H2O2 dan CuSO4 sebagai katalis dalam proses penghancuran sianida dilakukan secara skala lab dan nyata menggunakan metoda yang sama dengan penelitian sebelumnya. Ditemukan bahwa kombinasi dari H2O2 dan CuSO4 ternyata dapat mempercepat proses penghancuran sianida sebanyak 20-32% dengan 100 g/t H2O2 dan skala perbandingan dari sianida terhadap CuSO4 sebesar 2:1. Perbedaan dalam karakteristik batuan dan kondisi pelindian pada pemprosesan batu refractory and free milling menyebabkan dua model berbeda yang harus diterapkan di dalam sistem DCS. Untuk model refractory, persamaan yang harus diterapkan adalah 𝒚 =(−𝟎. 𝟎𝟕𝟏𝟒𝒙 + 𝟔. 𝟎𝟔𝟏𝟗)𝟏. 𝟐𝟕𝟑, sedangkan persamaan untuk model free milling adalah 𝒚 =(−𝟎. 𝟗𝟎𝟒𝟒𝒙 + 𝟗𝟕. 𝟖𝟓𝟖)𝜶. Persamaan untuk model free milling masih harus diselidiki lebih lanjut dengan melakukan plant trial untuk mendapatkan correction factor (α).

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Cyanide has been widely used in gold leaching processing plants for over one hundred years and is known by its characteristic to be a deadly poisonous chemical. To control cyanide usage in the mining industry, the International Cyanide Management Code (ICMC) was established. Kanowna Belle Gold Mine (KBGM) has been certified under the ICMC since 2008 and has recently been re-certified in December 2012. Under the Code, 80% of the time WAD cyanide discharge must be below 50 ppm and 95% of the time must be below 78 ppm. Prolonged discharge above 78 ppm is considered a breach of the ICMC. Greater usage of cyanide allowed in KBGM due to the usage of hyper saline water as the processing plant results in higher WAD cyanide discharge concentration.

The main objective of this report was to determine the effectiveness of WAD cyanide detoxification using hydrogen peroxide in KBGM tailings slurries during refractory and free milling ore leaching. The experiment was conducted during refractory and free milling ore slurries for both lab experiment and plant trial. The sample solutions were than analysed using picric acid method, which is a colorimetric method where higher WAD cyanide concentration solution was represented with deeper orange-red colour.

The impacts of H2O2 concentration and copper sulphate (CuSO4) as a catalyst on WAD cyanide destruction were investigated using small scale laboratory bottle roll tests. A plant trial was then conducted. It was found that the WAD cyanide destruction was optimum when the H2O2 dose was 100 g/t with 2:1 WAD cyanide to CuSO4 ratio. The combination was able to increase the removal rate by 20-32%.

Different ore characteristics and leaching conditions between refractory and free milling slurries resulted in two separate detoxification model to be applied in the DCS system. The equation for the model that should be installed during refractory leaching is 𝒚 = (−𝟎. 𝟎𝟕𝟏𝟒𝒙 + 𝟔. 𝟎𝟔𝟏𝟗)𝟏. 𝟐𝟕𝟑 and the equation model that should be installed during free milling leaching is 𝒚 = (−𝟎. 𝟗𝟎𝟒𝟒𝒙 + 𝟗𝟕. 𝟖𝟓𝟖)𝜶. The equation for the free milling slurry still needs to be investigated further by conducting a plant trial to find the correction factor (α)."

"Numerical modelling of hydrogen production by means of methanol decomposition in a thermocatalytic reactor using corrugated foil made of the Ni3Al intermetallic phase is shown in the paper. Experimental results of the flow analysis of mixtures containing helium and methanol in a thermocatalytic reactor with microchannels were used for the initial calibration of the CFD calculations (calculations based on the Computational Fluid Dynamics method). The reaction of the thermocatalytic methanol decomposition was modelled based on experimental data, considering the size of the active surface. The drop in the methanol concentration at the inlet to the reactor, ten millimetres in front of the thermocatalytic region, is associated with the diffusion of streams of other components, mainly hydrogen and carbon monoxide. The commercial CFD code was expanded by User Defined Functions (UDFs) to include surface chemical reaction rates in the interphase between the fluid and the solid. Extrapolation of data by means of the implemented numerical model enabled the assessment of the minimum length of microreactor channels and prediction of the optimal dimension at the system outlet. The results obtained by means of numerical calculations were calibrated and compared with the experimental data, confirming a satisfactory consistency of the data"