Hary Sulistyo

Kinetics of sequential reaction of hydrolysis and sugar degradation of rice husk in ethanol production: Effect of catalyst concentration

This study focuses on kinetics of rice husk hydrolysis using sulfuric acid catalyst to produce sugars. The experiments were conducted at various catalyst concentrations. It turned out that during hydrolysis, degradation of sugars was encountered. The kinetics was expressed with both homogeneous and heterogeneous models. At catalyst concentration of higher than 0.44 N, heterogeneous model works better than homogeneous model, while at the lower, both models work well. In the heterogeneous model, it is observed that the mass transfer of sulfuric acid in the particles and the hydrolysis reaction control the rate of hydrolysis. The mass transfer can be described by Ficks law with the effective diffusivity of 1.4×10(-11) cm2/s, while the hydrolysis and sugar degradation rate constants follow Arrhenius equations. In addition, it was experimentally observed that the sugars produced can be converted to ethanol by fermentation using yeast.

Optimization of pretreatment of Jatropha oil with high free fatty acids for biodiesel production

A central composite rotatable design and response surface methodology were used in order to investigate the individual and combined effects of the ethanol-to-oil ratio, H2SO4 concentration, temperature and time of reaction on the reduction of free fatty acid (FFA) in jatropha oil. A quadratic polynomial model relating the reaction variables with FFA reduction was developed, presenting a good coefficient of determination (R2= 0.893). For reducing FFA to less than 1%, the optimal combination was found to be 0.62 v·v−1 ethanol-to-oil ratio (14.9 v·v−1 ethanol-to-FFA ratio), 1.7% v·v−1 H2SO4 concentration, and 79 min reaction time at a reaction temperature of 54°C. These results are of great relevance to maximize methyl esters formation by transesterification using an alkaline catalyst.

Modeling of Fixed Adsorptive Distillation in Batch Operation

Abstract This paper presents the modeling of fixed adsorptive distillation in batch operation. A combination of theoretical and empirical approaches is used to derive the model with the following procedures: (i) modeling through each sub‐unit based on ideal concepts and assumptions, (ii) addition of empirical correction factors into the model to eliminate assumptions. The model is designated to predict the model parameter, which is the composition of the second column product, as a function of three process variables (i.e. time, feed composition, and flow ratio). It is found that the two above–mentioned approaches result in a representative model with an average error percentage of 5.46%.

Biogas production from traditional market waste to generate renewable energy

The increased energy consumption and limited fossil energy sources caused industry to find energy from renewable resources. Biogas is one of the renewable energy that has a good prospect in the near future. Traditional market wastes which were represented by green mustard and white mustard were undertaken in a laboratory experiment. To produce biogas, the raw material such as white mustard and cow manure, green mustard and rice straws were mixed until C to N ratio close to 20. Inoculums starter from biodigester effluent was put into digester then water was added until 350 ml. The initial pH was measured. Fermentation process was conducted at temperature of 35°C. Volume and pH of the biogas were observed daily. Methane, total solid and volatile solid were analyzed weekly. Fermentation process was observed for 7 weeks. The accumulation of biogas production at the day 42 for white mustard (S1), white mustard with cow manure (S2), and mixed of green mustard and rice straw (S3) were 0.111L, 0.901L and 0.390L respectively. The highest methane concentration in the biogas was achieved on the day 21, which were found of 62.18% and 63.15% for S2 and S3 respectively. Meanwhile for S1 (white mustard only without cow manure) no methane was observed. In the first 7 days, the pH level were observed decrease and increase after the day of 28. However, at the end of digestion period the pH will slightly decrease. It was also developed to conduct a pilot plant within the tubular digester to generate energy in batik home industry, Imogiri, Yogyakarta, Indonesia.

Sulfuric acid hydrolysis of various lignocellulosic materials and its mixture in ethanol production

Lignocellulosic materials sustainability in ethanol production could be supported by the use of mixed raw materials. Therefore the effect of mixed raw materials to hydrolysis kinetics needs to be studied. For this purpose each raw material was hydrolyzed and the mixed raw materials were also hydrolyzed. As a result, a comparison of the kinetics models of dilute sulfuric acid hydrolysis between various lignocellulosic materials (leaf, twig, corn cob, sawdust) and its mixture was obtained. It was observed that a pseudo-homogeneous model can quantitatively describe individual materials as well as mixed materials with different levels of accuracy. Besides the kinetics model, the influence of various lignocellulosic materials on sugar yield was also investigated. The results showed that the lignin content of the raw material influenced the sugar yield of the hydrolysis. Moreover the mixed lignocellulosic materials did not proportionally provide a yield based on its composition. Some hydrolyzates were fermented to verify whether the sugars formed could be converted into ethanol using Saccharomyces cerevisiae. The fermentation results showed that high sugar concentrations of hydrolyzates did not produce high ethanol yields. The various sugar types and the chemical substance of the sugar degradation affected the ethanol yield from sugars.

Adsorption of saturated fatty acid in urea complexation: Kinetics and equilibrium studies

Urea complexation is fractionation process for concentrating poly-unsaturated fatty acids (PUFAs) from vegetable oil or animal fats. For process design and optimization in commercial industries, it is necessary to provide kinetics and equilibrium data. Urea inclusion compounds (UICs) as the product is a unique complex form which one molecule (guest) is enclosed within another molecule (host). In urea complexation, the guest-host bonding exists between saturated fatty acids (SFAs) and crystalline urea. This research studied the complexation is analogous to an adsorption process. The Batch adsorption process was developed to obtain the experimental data. The ethanolic urea solution was mixed with SFA in certain compositions and adsorption times. The mixture was heated until it formed homogenous and clear solution, then it cooled very slowly until the first numerous crystal appeared. Adsorption times for the kinetic data were determined since the crystal formed. The temperature was maintained constant at room temperature. Experimental sets of data were observed with adsorption kinetics and equilibrium models. High concentration of saturated fatty acid (SFA) was used to represent adsorption kinetics and equilibrium parameters. Kinetic data were examined with pseudo first-order, pseudo second-order and intra particle diffusion models. Linier, Freundlich and Langmuir isotherm were used to study the equilibrium model of this adsorption. The experimental data showed that SFA adsorption in urea crystal followed pseudo second-order model. The compatibility of the data with Langmuir isotherm showed that urea complexation was a monolayer adsorption.Urea complexation is fractionation process for concentrating poly-unsaturated fatty acids (PUFAs) from vegetable oil or animal fats. For process design and optimization in commercial industries, it is necessary to provide kinetics and equilibrium data. Urea inclusion compounds (UICs) as the product is a unique complex form which one molecule (guest) is enclosed within another molecule (host). In urea complexation, the guest-host bonding exists between saturated fatty acids (SFAs) and crystalline urea. This research studied the complexation is analogous to an adsorption process. The Batch adsorption process was developed to obtain the experimental data. The ethanolic urea solution was mixed with SFA in certain compositions and adsorption times. The mixture was heated until it formed homogenous and clear solution, then it cooled very slowly until the first numerous crystal appeared. Adsorption times for the kinetic data were determined since the crystal formed. The temperature was maintained constant at roo...

Effect of sodium carbonate catalyst weight on production of bio-oil via thermochemical liquefaction of corncobs in ethanol-water solution

Lignocellulosic biomass has recently received serious attention as an energy source that can replace fossil fuels. Corncob is one of lignocellulosic biomass wastes, which can be further processed into bio-oil through thermochemical liquefaction process. Bio-oil is expected to be further processed into fuel oil. In this research the effect of Na2CO3 catalyst weight on the yield of bio-oil was investigated. The composition of bio-oil produced in this process was analyzed by GC-MS. Bio-oil formation rate were analyzed through mathematical model development. First model aasumed as an isothermal process, while second model was not. It is found that both models were able to provide a good approach to experimental data. The average reaction rate constants was obtained from isothermal model, while the activation energy level and collision factors were obtained from non-isothermal model. The reaction rate will increase by addition of Na2CO3 (0 - 0.5 g) as catalyst to 250 mL system solution, then the activation ene...

Rubber mixing process and its relationship with bound rubber and crosslink density

This research studied the relationship between bound rubber and crosslink density based on rubber mixing process. Bound rubber was obtained after natural rubber was masticated and mixed with rubber chemicals and filler while crosslink density was collected after rubber compound was vulcanized. Four methods are used and each method refers to four ways of incorporating carbon black during mixing. The first method, after rubber was masticated for 5 minutes, the addition of rubber chemicals and filler was done simultaneously. Rubber was masticated for 1 minute and continued mixing of rubber chemicals and filler where mixing was different from first method. This was the second method. The third method was the same as the second method but the filler used N 660 while in the second method N 330. The last method is not the same as the first and second, the rubber is only masticated for 3 minutes and then mixed with filler and followed by rubber chemicals sequentially. The results showed that bound rubber and crosslink density were influenced by mixing and mastication process. Bound rubber dropped and crosslink density was relatively stable in the first three mixing methods for increasing carbon black at the beginning of the mixing process. Bound rubber and crosslink density stated opposite results in the fourth mixing method. The higher the bound rubber the lower the crosslink density. Without regard to mixing methods, there is a non-linear relationship between bound rubber formation and crosslink density determination

Investigation of the slow pyrolysis kinetics of oil palm solid waste by the distributed activation energy model

ABSTRACT Oil palm solid waste has promising potential as future feedstock for bioenergy generation due to its abundant availability as an impact of the increasing worlds palm oil production. In this study, non-isothermal thermogravimetry measurements under an inert atmosphere of nitrogen were conducted at heating rates of 5, 10, 15 and 20°C/min, on oil palm solid waste, including its components: empty fruit bunch (EFB), fibre, and shell. The distributed activation energy model (DAEM) was used to investigate the pyrolysis kinetic parameters, comprising activation energy and frequency factor. The activation energy and frequency factor values for EFB, fibre, and shell are from 107.17 to 227.28 kJ/mol and from 1.79E+13 to 9.87E+20 s−1; from 50.75 to 213.22 kJ/mol and from 8.40E+05 to 4.25E+15 s−1, and from 59.36 to 170.30 kJ/mol and from 1.54E+07 to 1.11E+14 s−1, respectively. It was found that the activation energy values of all components vary with the progress on conversion, and they show different trends. The DAEM can be used to determine the pyrolysis kinetic parameters and provides reasonable fit to the experimental data.

KINETIKA REAKSI HIDROLISIS

Bio-etanol merupakan salah satu bahan bakar organik yang dapat diproduksi dari pati dan selulosa. Bahan berbasis selulosa dapat ditemukan dalam limbah organik, diantaranya: grajen kayu, ranting kering, daun kering, tongkol jagung, sekam padi dan lain-lain. Langkah-langkah penting pada produksi etanol dari lignoselulosa ialah hidrolisis untuk mengkonversi hemiselulosa dan selulosa menjadi gula, fermentasi gula untuk memproduksi etanol, dan pemurnian etanol. Penelitian ini mempelajari reaksi hidrolisis ranting kering dengan asam encer pada kondisi non-isotermis. Dua ratus gram ranting kering dicampur dengan 1200 cm 3 larutan asam sulfat 0,18 N dan dipanaskan di dalam autoklaf. Selama proses hidrolisis ini, suhu akan terus naik (non-isotermis), kemudian setelah mencapai suhu tertentu dijaga tetap (suhu akhir). Hasil hidrolisis pertama diambil pada suhu 413 K dan seterusnya diambil setiap interval 5 menit. Suhu akhir divariasi pada 433 K, 453 K, 473 K dan 493 K. Metode Fehling dipilih untuk menganalisis kandungan gula di dalam sampel. Persamaan kinetika reaksi diperoleh dengan mengolah data dengan pendekatan model shrinking-core dengan ukuran partikel tetap. Nilai tetapan kecepatan reaksi meningkat sedangkan nilai tetapan transfer massa relatif tidak berubah pada berbagai suhu. Tetapan kecepatan reaksi dapat didekati dengan persamaan Arrhenius, dengan frekuensi tumbukan A r = 0,083 l/(mol.menit) dan energi aktivasi E r = 20.000 J/mol. Untuk menyelidiki langkah mana yang mengontrol laju proses, dibandingkan tetapan kecepatan reaksi dan tetapan transfer massa pada 493 K, diperoleh nilai tetapan transfer massa berkisar 0,06 l/(mol.menit), dan nilai tetapan kecepatan reaksi berkisar 0,00051 l/(mol.menit), sehingga diperoleh bilangan Hatta 0,00933. Karena bilangan Hatta < 0,02 maka dapat disimpulkan bahwa reaksi kimia lebih mengontrol daripada transfer massa.