The 1.PENDAHULUAN Tenaga surya merupakan sumber energi dunia, dari tenaga surya ini akan tercipta sumber-sumber energi baru dan sumber kehidupan. Energi merupakan bagian yang sangat penting dalam setiap bidang kegiatan. Selain itu energi juga merupakan komponen penting dalam pertumbuhan ekonomi, disamping modal, tenaga kerja dan bahan baku. Semakin besar dan maju suatu kegiatan akan semakin besar pula energi yang dikonsumsi. Sehingga biaya penyediaan energi mengambil bagian yang besar pula dalam kegiatan yang dilakukan. Dalam kegiatam industri biaya penyediaan energi atau yang lebih popular dikenal dengan biaya bahan bakar dapat mencapai lebih dari 40% dari biaya produksi [6]. Industri memenuhi kebutuhan energinya dari tenaga listrik dan bahan bakar fosil. Energi listrik yang terutama digunakan untuk a) penggerak, misalnya untuk menjalankan pompa, kompressor dan alat angkut yang lain; b) pemanas, misalnya untuk membuat udara panas, regenerasi penjerap dan pemanas bahan skala kecil; c) pengkondisian, misalnya penyejuk ruangan dan d) penerangan, baik untuk penerangan ruangan, penerangan area pabrik dan penerangan rumah. Hal ini dilakukan apabila tersedia cukup listrik dari perusahaan listrik negara (PLN). Sedangkan apabila tidak tersedia listrik yang cukup, maka perusahaan terpaksa harus menyediakan listrik sendiri. Bila terjadi hal yang demikian, penggunaan bahan bakar akan semakin banyak, karena kebutuhan bahan bakar disediakan untuk pembangkit tenaga listrik. Tenaga listrik tersebut digunakan sama ada di pabrik maupun di perumahan dan fasilitas lainnya. Pembakaran bahan bakar yang lainnya adalah untuk pembangkit "steam" yang banyak diperlukan dalam industri.
Electrodialysis is a separation process which ions are transported through semi permeable membranes under an influence of electric potential. In this research, electrodialysis using monovalent ion exchange membranes was applied to separate lithium ions from mixtures of lithium-cobalt aqueous solution. The study aims to examine factors that affect the performances of electrodialysis monovalent membrane, such as applied voltage, flow rate, and the concentration of cobalt as co-ion. The research was conducted using electrodialysis PC cell BED 64004, monovalent cation exchange membrane (PC-MVK) and monovalent anion exchange membrane (PC-MVA) produced by PCA-PolymerchemicAltmeier, GmbH, Heusweiler, Germany. The effect of applied voltage was studied by varying the voltage in the range of 1-4 volt/cell volt. The effects of flow rate and initial concentration of ion were studied by changing the flow rate (10, 15, and 20 L/h) and varying the ratio of initial concentration between Li and Co ions (100-100, 100-400, and 100-500 mg/L). The results exhibited that the highest separation capacity of lithium (99.40%) was obtained when using the optimum applied voltage of 1 volt/cell. Low energy consumption would be obtained when using a low voltage for the process separation. The optimum flow rate for the lithium separation using electrodialysis monovalent membrane in this research was 15 L/h. The greater flow rate reduced the current efficiency and increased the energy consumption. When the concentrations of cobalt were increased in the range of 100-500 mg/L, the results indicated a decrease of current efficiency but an increase of energy consumption showing the influence of concentration of cobalt to transportation of lithium ions and selectivity of monovalent membrane.
Glycerol can be synthesized to make 1,3-dinitroglycerin as an intermediate product to produce polyglycidyl nitrate. This study performed kinetic modeling of nitration used elementary reactions that consisting of seven reversible reactions. The aim of this present work is to find out the representing reaction of seven reactions tested. The concept work is to study the reaction rates and its relation to the position of the nitrated hydroxyl group in the molecule. Nitration of glycerol to 1,3-dinitroglycerin was studied in the temperature range 10-30 °C, the molar ratio of nitric acid to glycerol 1/1 to 7/1 and nitric acid concentration of 69%. The seven reaction terms represent the reactions that occurred in the nitration of glycerol. The position of hydroxyl group in molecule causes difference reaction rate. The primary hydroxyl group is more reactive than secondary hydroxyl group. The parameter values describe that the 1 st , 3 rd , 5 th and 7 th reaction rates are very fast. On the contrary, the 2 nd , 4 th and 6 th reaction rates are slow.
Determinations of the temperature effect on glycerol nitration processes have been done with two methods
In the present study, a kinetic model of nitration between glycerol and nitric acid was developed. The presented model describes three controlling reactions model used elementary reactions consisting of three reversible reactions. The model utilizes first order reaction according to each reactant. The nitration of glycerol was modelled by fitting the kinetic model with 6 parameters, the rate constant at an average temperature and the activation energy. The reaction rate is assumed to be governed by three reactions, i.e. the formation of MNG (mononitroglycerin), the formation of DNG (dinitroglycerin) and the formation of TNG (nitroglycerin). The aim of this work is compare two models: seven controlling reactions model and three controlling reactions model. Two models have the similar trend. The three controlling reactions model gives better fit than seven controlling reactions model. The accuracy of three controlling reactions model is higher. The advantage of the seven controlling reactions model is this model can predict all products of nitration. So this model can be used at preliminary design plant. Three controlling reactions model can be used at next step, as design of reactor.
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