Rochmadi Rochmadi

Universitas Gadjah Mada | UGM · Department of Chemical Engineering

Noni fruit (Morinda citrifolia L.) contains many beneficial bioactive ingredients and is used in traditional medicines and health supplements in tropical and subtropical countries. However, the fruit rots easily, so it must be rapidly processed to isolate bioactive ingredients with antioxidant, antimicrobial, anti-inflammatory, and anti-cancer effe...

Gamma radiation have become attention since their high potential for degrading compounds, especially organic pollutants. In this research, gamma radiation was studied for degrading the Reactive Orange-16 (RO-16) dye, a toxic and carcinogenic pollutant. The radiolytic degradation process was studied in a batch reactor with a gamma-ray dose rate of 2...

Using rice husk ash as a cheap in-situ catalyst under certain pyrolysis operating conditions can affect the yield of rice husk pyrolysis products. The two-stage semi-global kinetic models were often used to predict these yields. This research aims to study the effect of rice husk ash catalyst addition, heating rate, and pyrolysis temperature on the...

Microwave-assisted pyrolysis (MAP) offers a promising alternative to fast pyrolysis for scaling up biomass conversion processes, facilitating accelerated reactions without significant temperature elevation. This study investigated the optimum process parameters for MAP of Sargassum sp., the predominant macroalgae in Indonesia. Parameters explored i...

Indonesia, renowned for its tropical marine environments, boasts a rich diversity of macroalgae, with Sargassum being a major contributor. Currently, the primary application of Sargassum revolves around alginate extraction, prompting a systematic exploration of alternative end-products for optimal utilization. Thermochemical conversion of Sargassum...

Introduction The demand for lithium-ion batteries (LIBs) is rapidly increasing due to the growth of the electronics and electric vehicle industries. Even though the batteries are rechargeable, their storage capacity decreases, and they eventually end up being wasted. Recycling the spent LIBs is necessary to reduce the environmental impact and utili...

The mechanical properties of hydrogels are crucial in wound dressing application. Starch-based hydrogels have deficiencies in mechanical strength and gel stability. These shortcomings can be addressed by employing crosslinking techniques with oxidized sucrose. A design of experiments approach was used to optimize the tensile strength of the product...

Gondorukem yang diperoleh dari sadapan pohon pinus disebut gondorukem non-modifikasi yang memiliki kelemahan mudah teroksidasi oleh oksigen di udara terbuka. Oleh karena itu gondorukem perlu dimodifikasi untuk meningkatkan stabilitas oksidatifnya, salah satunya dengan metode esterifikasi. Pentaeritritol rosin ester merupakan produk turunan gondoruk...

Epoxidized oleic acid can be transformed into vegetable oil-based polyesters through a self-polymerization reaction. This study aims to develop the kinetic model for the polymerization reaction between epoxide and carboxyl groups and the product characterization regarding its functional groups, molecular weight, and thermal stability. The polymeriz...

The present study investigates the effects of nanoparticle geothermal silica (NGS) on the mechanical properties and vulcanization characteristics of rubber compounds with various filler loadings. The rubber compounds were filled with 0, 20, 30, and 40 phr of silica. The properties of NGS were analyzed using transmission electron microscopy, particl...

Astaxanthin is an antioxidant compound that can be extracted from the microalgae Haematococcus pluvialis using the microwave-assisted extraction (MAE) method. Purification of the astaxanthin compound can be conducted using a low-pressure column chromatography (LPCC) method. However, the mathematical model illustrating the adsorption and desorption...

The purification of terephthalic acid recovered from an alkali-reduction wastewater by reactive crystallization was investigated. The crude terephthalic acid was reacted with sodium hydroxide solution to form a salt of disodium terephthalate, then acidified with sulfuric acid to get the terephthalic acid with higher purity. Effects of time, pH, con...

Thermal properties are important factors to determine the proper manufacturing, processing, and storing of biocomposites. Therefore, the thermal properties of the biocomposite made from acetylated betung bamboo pulp and polypropylene (PP) were investigated. The biocomposite was manufactured by hot pressing at 180 oC for 2 minutes and the fiber cont...

The addition of clay to polypropylene (PP) has been known to improve the mechanical properties of PP/clay composites. There are several important variables that affect the increase in tensile strength properties of PP/clay composites. However, the optimum conditions for these variables are not known. The important variables are material composition...

Methanolysis of epoxidized Tung oil (ETO) with the minimum initial concentration of epoxy of 3.9199 mmol/gram was carried out for 4 hours. Sulfuric acid was used as a catalyst. This study aims to evaluate the effect of the mole ratio of methanol to ETO in the synthesis of Tung oil-based polyols and to characterize the resulted polyols. Methanolysis...

Microalgae is one of source biofuel to substitute the fossil energy. One of the problems of oil extraction is the method of extraction which produce higher oil yield. Ultrasound assisted extraction is one of method to extract algae oil from algae biomass. The problem of this method of extraction is solvent. In this paper, the extraction uses mixed...

Ash-based catalysts, as low-cost materials, are applicable in biomass pyrolysis and play a role in lowering the activation energy. This study enriched the insights of different method of catalyst addition into biomass in the catalytic pyrolysis. The addition of rice husk ash as a catalyst into rice husk pellets allows for better solid-solid contact...

This research described the effect of the mortar volume ratio on the mechanical behavior of Class CI fly ash-based geopolymer concrete. The absolute volume ratio parameters were designed to determine the effects on the mechanical properties of the geopolymer concrete. The volume ratio of the mortar to coarse aggregate voids (Rc) was increased by 0....

Epoxy resin as a polymer material with good mechanical and electrical characteristics and resistance from corrosion and moisture resistance are considered to have the potential to be applied in defense field. The research aimed to investigate the kinetics of the reaction between bisphenol A diglycidyl ether (DGEBA) and terephthalic acid (TPA). The...

Astaxanthin is an antioxidant that is sensitive to environmental conditions. This study aimed to determine the effect of temperature and lighting on the concentration of astaxanthin, then derive the kinetic equation for its degradation. The half-life was calculated to determine the astaxanthin degradation time at which its concentration drops to ha...

Levulinic acid, a versatile chemical building block, was derived from C6-sugar galactose using sulfuric acid as the catalyst. Galactose is monosaccharide of polysaccharides constituent that is mostly contained in third generation biomass, macro-microalgae. It currently receives high attention to be a source of renewable feedstock. The effect of tem...

Multi-walled carbon nanotubes (MWCNTs) are known as efficient drug carriers. To improve their interaction with other materials, surface modification of MWCNTs is necessary. In this work, MWCNTs were functionalized with acid and polysaccharides (chitosan and gelatin). The functionalization process was done via modification with acid solutions of nit...

Cellulose is the primary substance of sugarcane bagasse and is essential for producing chemicals such as levoglucosan (LG), which can be synthesized through various methods, such as cellulose hydrolysis catalyzed by a Brønsted acid. This recent research was preceded by a preliminary study on glucose hydrolysis into LG with hydrochloric acid (HCl) a...

This paper reports on a pH responsive material and a mathematical model for a drug release study. This material can be applied as a tumor drug carrier, because the tumor tissue has a different pH (5.7–7.8) compared to the healthy tissue (7.3–7.4). Maleic anhydride (MA) is introduced into the chitosan (CTS) backbone to create a polyampholyte chitosa...

A study on the effect of mixing process parameters of nanostructured silica/SBR composite on cure characteristics, mechanical properties, morphology, and vulcanization kinetics was performed. The mixing process was carried out in an internal mixer with 3 (three) investigated parameters, namely: initial mixing temperature (70 - 100°C), mixing time (...

The thermogravimetric behaviors and the kinetic parameters of uncatalyzed and catalyzed pyrolysis processes of a mixture of powdered raw rice husk (RRH) and its ash (RHA) in the form of pellets were determined by thermogravimetric analysis at three different heating rates, i.e., 5, 10, and 20 K/min, from 303 to 873 K. This research aimed to prove t...

Porous carbon plays important role in the application of energy storage materials e.g. supercapacitors. Along with the importance to find a perfect carbon precursor, lignin from biomass depicts its advantages as a carbon source. However, wood-based lignin-derived carbon typically displayed a low capacitance due to small pore size and purely capacit...

Multi-walled Carbon Nanotube (MWCNT) pure is easy to form aggregate, making it difficult to apply as a drug carrier since it can be toxic to the body. It can be overcome by functionalization using surfactants, like cetyltrimethyl ammonium trichloro-monobromo-cerate (CTACe) and polyethylene glycol (PEG). First, MWCNT was functionalized with CTACe su...

The propellant binder is one of the important components in three-component-based propellants. Three-component-based propellants contain oxidizer, binders, and additives. Refers to spesific impulse value and combustion rate, polyglycidyl nitrate is a very promising energetic polymer as a propellant binder. Polyglycidyl nitrate has the potential to...

Currently, fossil fuels are still the primary fuel source and reducing agent in the steel industries. The utilization of fossil fuels is strongly associated with CO2 emissions. Therefore, an alternative solution for green steel production is highly recommended, with the use of biomass as a source of fuel and a reducing agent. Biomass’s growth consu...

Glucose is one of the primary derivative products from lignocellulosic biomass, which is abundantly available. Glucose has excellent potential to be converted into valuable compounds such as ethanol, sorbitol, gluconic acid, and levulinic acid (LA). Levulinic acid is an exceptionally promising green platform chemical. It comprises two functional gr...

This study explores the modification of lignin with surfactants, which can be used as a template to make mesoporous structures, and can also be used in combination with manganese oxide to produce manganese oxide/lignin-derived carbon. Organosolv extraction, using ethanol (70%) at 150 °C, was carried out to extract lignin from oil palm wood. Lignin...

Epoxides from vegetable oils are currently gaining more attention to replace petroleum-based monomers for polymer synthesis. As one of unsaturated fatty acids derived from vegetable oil, Oleic acid can be converted into epoxidized oleic acid by chemical epoxidation. Epoxidized oleic acid is a bifunctional monomer that has the potential to be used a...

Low-pressure column chromatography (LPCC) is commonly used on a great scale of astaxanthin purification. To get the optimum effectiveness and accuracy of this purification process, the adsorption capacity data of adsorbents were needed. Silica gel and aluminum oxide, in batches, have been tested. Standard astaxanthin dissolved in acetone was adsorb...

The aim of this study was to determine the characterization of ionic and covalent interactions to form a crosslinking network with chitosan as a wall material of microcapsules. Red ginger oleoresin microcapsule was prepared by emulsion crosslinking method. Red ginger oleoresin was mixed and stirred with chitosan solution to form an emulsion, then a...

Chemical functionalization is carried out on Single-Walled Carbon Nanotubes (SWCNT) to improve its surface interaction when used for final application such as for drug carriers. This research compared the effectiveness of ultrasonic treatment and stirring in the functionalization process. Both methods were conducted at room temperature. The functio...

The growth of textile industry is accompanied by the increase of wastewater containing synthetic dyes. Without proper treatment, synthetic dyes may possess environmental burden. Here, removal of methylene blue as the model compound of synthetic dye has been investigated with the aid of flocculants. Combination of two types of flocculants: Sodium Li...

Polyol is the main raw material to produce polyurethane which is widely used in the commercial and industrial fields. The use of candlenut oil to become polyols by epoxidation process is a new alternative method, which has advantages: renewable raw materials and biodegradable polymer. The purpose of this research is to study the rate of reaction of...

Glucose is the primary derivative of lignocellulosic biomass, which is abundantly available. Glucose has excellent potential to be converted into valuable compounds such as ethanol, sorbitol, gluconic acid, and levulinic acid (LA). Levulinic acid is a very promising green platform chemical. It is composed of two functional groups, ketone and carbox...

Epoxidation of the unsaturated fatty acids (UFA) in Tung oil provides a very interesting opportunity in the research and development of advanced materials. Tung oil is one of non-edible vegetable oils and epoxidized Tung oil (ETO) also provides benefits in terms of renewable and eco-friendly. This research evaluated the influences of acetic acid's...

This research was conducted to study changes in functional groups after oxidation of porous carbon synthesized from palm kernel shell and their effects on the performance of material for an electric double-layer capacitor (EDLC). Porous carbon was prepared by pyrolysis of palm kernel shell at a temperature of 800 °C and steam activation. Surface mo...

This study analyzes the effects of rotor speed, mixing time, and initial temperature on the curing characteristic, mechanical and dynamical properties, as well as the morphology of nanostructured silica/natural rubber composites. The rotor speed, mixing time, and initial temperature settings of the mixer were adjusted in the range of 40–100 rpm, 15...

The processing, curing, mechanical, and morphological characteristics of natural rubber (NR) filled with nanostructured silica (NS) were discussed in this paper. NS was synthesized at 60-90°C using bagasse ash as raw material. NR was mixed with NS using Haake Rheomix equipped with roller rotors. Curing kinetics of NR compounds was studied using the...

Astaxanthin is a natural antioxidant, and the highest content of this compound is found in Haematococcus pluvialis microalgae. Microwave-assisted extraction (MAE) is one of the environmentally friendly extraction methods and has many advantages. This study aims to investigate the extraction of astaxanthin through the MAE method using various solven...

In this study, chitosan-based carrier of red ginger oleoresin was prepared using the emulsion cross-linking technique with sodium tripolyphosphate (TPP) as a cross-linking agent. The effect of chitosan and TPP concentration, as well as pH on the encapsulation efficiency, particle size and characterization of chitosan microcapsule was determined. Th...

CaCO 3 hydrogel incorporation into Plaster of Paris (POP) formulations decreased the resorption rate of the POP after implantation in the body. Although an inflammatory process is required as part of wound healing, the accumulation and activation of inflammatory cells in the POP–hydrogel CaCO 3 implant area needs to be controlled. Therefore, cinnam...

Bagasse ash as one of the sugar mill wastes can create a serious environmental problem. Hence, we adopted a strategy to reduce the waste by utilizing its silica content. Nanostructured silica was synthesized from bagasse ash via sodium silicate route. The effect of synthesis temperature and pH on the morphology, primary particle size, pore size, th...

The application of conventional fertilizer, especially for inorganic fertilizer, has low efficiency due to the fast release of its nutrients into the environment. Also, it has a high operating cost caused by multiple fertilization processes in one of the planting periods. One of the possibilities to overcome this limitation is applying organic fert...

Tung oil with an iodine value (IV) of 99.63 g I2/100 g was epoxidized in-situ with glacial acetic acid and hydrogen peroxide (H2O2), in the presence sulfuric acid as catalyst. The objective of this research was to evaluate the effect of mole ratio of H2O2 to unsaturated fatty acids (UFA), reaction time and catalyst concentration in Tung oil epoxida...

Abstract. Combining an anti-inflammatory agent derived from a plant essential oil, such as cinnamaldehyde, with bioabsorbable and osteoconductive material as a bone substitute is a challenge in biomedical technology. In this study, cinnamaldehyde, a good anti-inflammatory agent with an aromatic α, β-unsaturated aldehyde derived from cinnamon, was...

Lignocellulosic biorefinery is a promising alternative for petroleum refinery that has potential to meet a sustainable variety of needs in the future. One product of lignocelullosic biorefinery is levulinic acid (LA) which is a precursor for the production of many chemicals. Cellulose from lignocellulosic biomass is hydrolyzed to glucose, then hydr...

Plastics based on low-density polyethylene (LDPE) blends generally have limited miscibility, and it is difficult to obtain a homogeneous blend. Although they show excellent properties, their thermal degradation rate is a concern. This work aims to realize a homogeneous blend with higher chitosan concentration, thus expected to increase its degradat...

Oleic acid is a mono-unsaturated fatty acid that can be found abundantly in various vegetable oils and potentially attractive to be used as raw material for epoxide chemical. In-situ epoxidation of oleic acid was conducted in batch reactor using peroxy-formic at 30-60°C. Pseudo-steady-state-hypothesis (PSSH) was applied to develop the kinetic model...

As a byproduct of the physical refinement of crude palm oil, palm fatty acid distillate or PFAD has a potential to be transformed into monoglycerides by means of irreversible esterification with glycerol over a cation exchange resin catalyst. Irreversibility of the esterification can be assured by continuous azeotropic removal of water by adding xy...

As fossil fuels were depleting at an alarming rate, the development of renewable energy has become necessary. One of the promising renewable energy to be used is biodiesel. The interest in using third-generation feedstock, which is microalgae, is rapidly growing. The use of third-generation biodiesel feedstock will be more beneficial as it does not...

Porous carbon has been widely used for many applications e.g., adsorbents, catalysts, catalyst supports, energy storage and gas storage due to its outstanding properties. In this paper, characteristics of porous carbon prepared by carbonization of lignin from various biomasses are presented. Various biomasses, i.e., mangosteen peel, corncob and coc...

Microalgae have been considered as a potential candidate for biodiesel feedstock. Single-stage simultaneous extraction–transesterification process is proposed for simpler and more effective biodiesel conversion. In this study, the experiment of biodiesel production from microalgae Spirulina sp. was performed in a batch-stirred reactor using palm oi...

The pyrolysis characteristics of Spirulina platensis residue (SPR) with silica–alumina catalysts were investigated using thermogravimetric analysis (TGA). The effects of differing amounts of catalysts on thermochemical behavior and kinetics parameters (pre-exponential factor in Arrhenius equation [A] and activation energy [Ea]) were studied. The ex...

Problems associated with the development of the first and second generations of biofuel, especially regarding its raw materials and complex processes, have led to the evolution of the third generation one, a microalgae-based bio-oil through pyrolysis. This research explored the effect of temperature ranging between 300−700 °C and the presence of Si...

Riboflavin (Vitamin B 2 ) plays an important role in the human tissue development, the production of red blood cells and helps release energy by breaking down proteins, fats and carbohydrates. Riboflavin cannot be produced the human body therefore must be supplied outside via dairy food. Riboflavin is very sensitive and unstable to environmental in...

Nowadays, energy consumption has increased as a population increases with socio-economic developments and improved living standards. Therefore, it is necessary to find a replacement for fossil energy with renewable energy sources, and the potential to develop is biofuels. Bio-oil, water phase, gas, and char products will be produced by utilizing Sp...

Polystyrene is a type of plastic that is widely used in daily life. It is applied for decoration, food packaging, and electronic packaging process. However, the use of polystyrene has become a problem for the environments because its properties are difficult to be degraded by nature. Pyrolysis method can be regarded as one of the environmentally fr...

Riboflavin ( Vitamin B 2 ) plays an important role in the development of human body tissue, the production of red blood cells and helps release energy derived from protein. Riboflavin cannot be produced and stored by the human body therefore must be supplied outside via food. Riboflavin is very sensitive and unstable to environmental influence such...