Wahyudi Budi Sediawan

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.

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%.

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...

Effects of Various Pretreatment Variables on Hydrolysis of Lignocellulose to Produce Sugar in Bioethanol Production

This research intends to explore the effect of pretreatment on lignoselulose to be used as raw material for bioethanol production. Pretreatment prepares lignocellulose compounds to be more easily hydrolyzed. Several variables were tested on oil palm empty fruit bunch (OPEFB) i.e. temperature, NaOH concentration, and particle size. According to the method of size reduction, there are two types of pretreatment which were milling and cutting. The first pretreatment type consisted of milling and screening resulting -+10-30, -30+40, -40+80, and-80 mesh. Each size fractions were then soaked in water at 90 °C for 2 hours. Meanwhile the second type consisted of cutting to 1 cm length followed by soaking in NaOH solutions for 2 hours. The operating temperatures at the second type were varied at 90 °C, 120 °C, 150 °C, 170 °C while the NaOH concentrations applied were 0%, 0.5%, 1%, 2%, 5%, 10%.The pretreated OPEFB was then hydrolyzed using cellulase produced by Aspergillusniger grown in situ. It was revealed that the relatively good pretreatment condition was milling to-80 mesh followed by soaking in hot water at 90 °C. It gave the highest produced sugar concentration at 15 g/L while other type resulted only 5.8 g/L.

Mathematical Modelling of Oryzanol Separation from Rice Bran Oil by Silica-Based Batch Adsorption: Equilibrium and Mass Transfer Rate

Mathematical modelling of batch adsorption of Oryzanol separation from Rice Bran Oil (RBO) has been set-up and tested by generated experimental data. The proposed model takes into account mass transfer and equilibrium phenomena. The effects of intra-particle gradient were considered, so the adsorption rate is controlled by the rate of solute mass transfer from the bulk liquid to the surface of particles and the intra-particle diffusion. In this model, the rate of Oryzanol mass transfer from the bulk liquid to the surface of the particle is described by film theory, while the intra-particle diffusion is assumed to be through the liquid inside the pore. Furthermore the Oryzanol in the liquid in the pore was assumed to be in equilibrium with the Oryzanol on the adjacent pore surface, in which equilibrium model applied was coefficient distribution approach. The values of the parameters involved in the models were obtained by curve fitting to the experimental data. It turned out that model proposed can quantitatively describe the batch adsorption of Oryzanol adsorption from rice bran oil with silica gel.

The effects of intra-particle concentration gradient on consecutive adsorption-desorption of oryzanol from rice bran oil in packed-column

Utilization of valuable trace components in agriculture by product such as rice bran oil is interesting to be explored. Among the valuables, oryzanol, a healthy nutrition for cardiovascular prevention, is the most promising one. Literature studies suggest that adsorption-desorption is a prospective method for oryzanol isolation. Design of commercial scale adsorption-desorption system for oryzanol needs a quantitative description of the phenomena involved. In this study, quantitative modeling of the consecutive adsorption-desorption in packed column has been proposed and verified through experimental data. The offered model takes into account the intra-particle concentration gradient in the adsorbent particle. In this model, the rate of mass transfer from the bulk of the liquid to the surface of the adsorbent particle or vice versa is expressed by film theory. The mass transfer of oryzanol from the liquid in the pore of the particle to the adjacent pore surface is assumed to be instantaneous, so solid-liqu...

The influence of chicken eggshell powder as a buffer on biohydrogen production from rotten orange (Citrus nobilis var. microcarpa) with immobilized mixed culture

This research observed the influence of chicken eggshell on hydrogen production from anaerobic fermentation of rotten orange (Citrus nobilis var. microcarpa) using batch method at 36 °C and pH 7. Fermentation material were varied in several types, the first type was meat and peel of oranges with VS of 59.152 g.L−1 in A, B, C, and D compositions. The second type was orange meat added with peel (OMP) with VS of 36.852 g.L−1. The immobilized ingredients used in the experiment consisted of 2 % (w/v) alginate and active carbon with the ratio of 1:1. 3.2 g chicken eggshell powder was added to the first type of material (substrates A, B, C, and D). Results showed that pH during fermentation process using chicken eggshell as a buffer was constant at 5.5; however, without the use of chicken eggshell, the pH decreased to 3.8 and increased slightly before it stayed stable at 4.0. The total amount of gas produced in sample using the chicken eggshell was 46,35 mL.mg VS−1 and in sample produced without the eggshell, it...

Biohydrogen production from rotten orange with immobilized mixed culture: Effect of immobilization media for various composition of substrates

Enriched–immobilized mixed culture was utilized to produce biohydrogen in mesophilic condition under anaerobic condition using rotten orange as substrate. The process was conducted in batch reactors for 100 hours. Microbial cultures from three different sources were subject to a series of enrichment and immobilized in two different types of media, i.e. calcium alginate (CA, 2%) and mixture of alginate and activated carbon (CAC, 1:1). The performance of immobilized culture in each media was tested for biohydrogen production using four different substrate compositions, namely orange meat (OM), orange meat added with peel (OMP), orange meat added with limonene (OML), and mixture of orange meat and peel added with limonene (OMPL). The results show that, with immobilized culture in CA, the variation of substrate composition gave significant effect on the production of biohydrogen. The highest production of biohydrogen was detected for substrate containing only orange meet, i.e. 2.5%, which was about 3-5 times higher than biohydrogen production from other compositions of substrate. The use of immobilized culture in CAC in general has increased the hydrogen production by 2-7 times depending on the composition of substrate, i.e. 5.4%, 4.8%, 5.1%, and 4.4% for OM, OMP, OML, and OMPL, respectively. The addition of activated carbon has eliminated the effect of inhibitory compounds in the substrate. The major soluble metabolites were acetic acid, propionic acid, and butyric acid.