Agus Prasetya

Fixed‐Bed Adsorption Study of Metal Ions on Bagasse Fly Ash (BFA)

Bagasse fly ash (BFA) has become a prospective low cost adsorbent preference for remediating wastewater containing many types of contaminant from organic compounds to toxic metal ions. The abundant availability and its unique characteristics such as large surface area and mesoporous pore size become the major reasons for utilizing BFA as adsorbents. In this paper, the continuous adsorption of Cr(VI), Cu(II) and Ni(II) into fixed bed column of bagasse fly ash (BFA) at room temperature were conducted. The experimental data are represented by breakthrough curves. Fundamental constants which govern the rate of adsorption, such as effective diffusivity of metal ions, have estimated by fitting the data with a breakthrough curve model. The effective diffusivity can be used to predict breakthrough curves in any other adsorption conditions. Meanwhile, the intensive material characterizations have been conducted before the adsorption experiments which successfully reveal the material uniqueness.

Application of Coconut-Shell Activated Carbon as Heterogeneous Solid Catalyst for Biodiesel Synthesis

Biodiesel is a bio-based fuel for diesel engine synthesized from renewable oils isolated from oil crops or animal. Biodiesel can be produced through transesterification where the process involves a catalyst and an alcohol. The most common catalyst for this process is homogeneous liquid catalyst. However, this catalyst system suffers from environmental problems. In order to eliminate the problem, we developed potassium loaded on coconut-shell activated carbon (K/AC) as heterogeneous solid catalyst which is easily regenerated, leading to more secure and more environmental friendly application. The purpose of the present work is to demonstrate the biodiesel synthesis from palm oil using K/AC catalyst in stirred tank reactor. Reaction variables such as methanol-oil molar ratio and temperature were optimized to reach the highest conversion for 4 hours reaction time. The highest reaction conversion, 26.98%, was obtained at methanol-oil molar ratio of 6:1 and reaction temperature of 60 °C. Furthermore, the value of collision factor, activation energy and standard enthalpy change of reaction obtained are 5.40 x 103 dm6.(mol.gcat.min)-1, 16.113 cal/mol and 5499.40 cal/mol, respectively.

Performance Evaluation of Household Pyrolytic Stove: Effect of Outer Air Holes Condition

Renewable energy is the future energy for the substitution of the depleting fossil fuels. In Indonesia, biomass is one of promising renewable energy due to its abundant availability. Biomass can be converted into energy by thermochemical process, such as pyrolysis. In the implementation, pyrolysis can be applied in household cookstove, called pyrolytic stove. Pyrolytic stove will be proposed for people still cooking over an open biomass fire. This paper studied the pyrolysis of Indonesian teak using household pyrolytic stove. The effect of outer air holes on the performance of household pyrolytic stove was investigated. The increasing of cross section area of outer air holes effected on the higher of biomass combustion releasing energy for pyrolysis and cooking. Furthermore, the optimum outer air holes condition in the stove was fully open with the minimum of char product and the maximum of energy recovered for cooking.

Effect of temperature and biomass-water ratio to yield and product characteristics of hydrothermal treatment of biomass

Hydrothemal treatment is a thermochemical process that converts biomass into a coal-like materials called hydrochar by applying elevated temperature to biomass in a suspension with water under saturated pressure for a certain time. With this conversion process, easy to handle fuel with well-defined properties can be created from biomass residues, even with high moisture content. In this research, the effects of temperature (200-330°C) and biomass to water ratio (5%-20%) at initial pressure of 1.0 MPa to hydrothermal treatment of biomass (in the form of sawdust) were examined. All samples were then characterized in terms of yield, proximate analysis, calorific value,and changes in functional groups by FTIR. Approximately 52-69% of the original material was recovered as hydrochar. The gross calorific value ranged from 5472-7032 cal/g compared 5180 cal/g in the raw material. Fixed carbon ranged from 26.035-wt% compared with 26.269 wt% in the raw material.

Optimum Conditions for the Formation of Glycidyl Nitrate from 1,3-Dinitroglycerin

One of the utilization of glycerol as byproduct of the biodiesel industry is to produce polyglycidyl nitrate, the most energetic polymer. The synthesize of polyglycidil nitrate from glycerol includes three steps: nitration, cyclization and polymerization. The aim of this study is to obtain the optimum conditions of cyclization. The cyclization was carried out in a 5 ml reactor and equipped with Hickman distillation head and nitrogen purge with the variables are mole ratio of sodium hydroxide/glycerol of 1/1 to 1.5/1, reaction temperature of 283.15 to 293.15 K and sodium hydroxide concentration of 15%. Each sample was analyzed by gas chromatography to determine the composition of products. The optimum conditions are temperature of 288.15 K and the mole ratio of sodium hydroxide /glycerol of 1.5.

Study of waste management towards sustainable green campus in Universitas Gadjah Mada

Waste management is a part of the green campus achievement program. Universitas Gadjah Mada has a Standard Operating Procedure for managing produced waste. Waste produced by each building or work unit is temporarily accommodated in the waste depot before dumped into the landfill. This research aims to study the waste management system in UGM, in accordance with the concept of a green campus. The concept of green campus to improve the efficiency of waste management needs to be supported by various parties. The success of the green campus program relies on an integrated approach, a sustainable implementation that involves stakeholders of the university. In actualizing the concept of a green campus, the university has its own waste processing system. The organic produced waste is processed into compost, while plastic waste is converted into alternative fuel. Overall, the waste management system that UGM owns is ineffective and inefficient, it was proved by the fact that there is still much waste dumped into the landfill. UGM provides a laboratory that is specialized to process waste that is produced by UGM. It is planned to be able to reduce the amount of waste that is dumped into the landfill. According to the results, vermicomposting technology, the manufacture of liquid fertilizer from leachate, and the manufacture of the composite from a mixture of leaves and paper were offered as solutions.

Simultaneous Hydrolysis and Fermentation of Sweet Sorghum Varieties (FS501 and KCS105) into Bioethanol Using Saccharomyces steineri – A Kinetics Study

In this study, kinetics of bioethanol production by fermentation of three different substrates, which were artificial substrate and the juice of two sweet sorghum varieties (FS501 and KCS105) using Saccharomyces steineri, were examined using two proposed models by assuming that simultaneous hydrolysis and fermentation occurred. Fermentation of the substrate of FS501 and KCS105 juices showed better data fitting by using the modified version of the kinetics model while the fermentation of artificial substrate which was free of any other components followed Philippidis’s kinetics model. This difference was caused by the change of the yeast behavior in the form of the reduction of both the rate of fructose and/or glucose consumption by the yeast and the rate of fructose and or glucose conversion into ethanol during lag phase. As the consequence, sucrose hydrolysis seems very dominant in the FS501 and KCS105 juices fermentation during the lag phase. The change of behavior of the yeast was estimated being caused by the existence of “impurities” such as acetic acid, glycerol, nitrogen, phosphor, and potassium in the FS501 and KCS105 juices. From statistical analysis using correlation coefficient (between kinetics parameters and “impurities”), acetic acid was the most influential component to change the behavior.

Performance of continuous stirred tank reactor (CSTR) on fermentative biohydrogen production from melon waste

This research was meant to investigate performance of continuous stirred tank reactor (CSTR) as bioreactor for producing biohydrogen from melon waste through dark fermentation method. Melon waste are commonly generated from agricultural processing stages i.e. cultivation, post-harvesting, industrial processing, and transportation. It accounted for more than 50% of total harvested fruit. Feedstock of melon waste was fed regularly to CSTR according to organic loading rate at value 1.2 - 3.6 g VS/ (l.d). Optimum condition was achieved at OLR 2.4 g VS/ (l.d) with the highest total gas volume 196 ml STP. Implication of higher OLR value is reduction of total gas volume due to accumulation of acids (pH 4.0), and lower substrate volatile solid removal. In summary, application of this method might valorize melon waste and generates renewable energy sources.