ASEAN Journal of Chemical Engineering

The Development of Tubular Photobioreactor for Microalgae Cultivation

2024-12-22T10:57:07+07:00

In a tubular photobioreactor, microalgae cells obscure one another (Self-shading), leading to the microalgae at the bottom of the tube getting less light. The objective of this research was to design and develop Tubular Photobioreactor with 93.5 liters for microalgae cultivation. The experiments had two steps. The first step was designing the solar receiver by inserting the fin into each tube wall as follows: 12-34, 1-2-3-4, 1234, and 13-24. Then, FLUENT software was used to simulate flow behavior inside the tube by Computational Fluid Dynamics by observing the pressure drop, the amount of energy consumption, and the swirling velocity to select the best fin-type. The best fin-type with the growth rate equation is introduced in the next step to simulate the microalgae's growth and movement using the user-defined function technique. The comparison of a tubular photobioreactor is investigated between fin and without fin by observing biomass production. The results showed that algae's optimum inlet velocity is 0.15 meters per second with the tubes containing fin-type 13-24. When simulating the growth behavior of microalgae, results show that the tubes without fins had lower biomass content than the 13-24 fin-type, which were 0.675 and 0.806 grams per liter, respectively, because the 13-24 fin-type will make well microalgae distribution leading to increase the light distribution too. Tubular photobioreactor fins type 13-24 had more biomass production, up to 19.4 percent.

Effect of Al Concentration over ZnO-Al2O3 Physicochemical Characteristics and Removal of Remazol Red RB

2024-12-22T10:57:07+07:00

ZnO is one of the widely used semiconductors due to its high photocatalytic activity. The inactivity of ZnO in the visible range could be enhanced by combining the ZnO with Al. In this study, the photocatalytic activity of ZnO-Al₂O₃ on Remazol Red RB was investigated. The effect of the ratio mass of ZnO-Al₂O₃ (1:0.05, 1:0.07, and 1:0.10) was also evaluated. The photocatalyst would be characterized using XRD, SEM-EDX, and UV-Vis DRS. The characterization showed that photocatalysts were successfully synthesized. The XRD analysis showed that the optimum ratio mass of ZnO-Al₂O₃ was achieved by 1:0.05, with the smallest crystal size of 13.3 nm. The SEM analysis showed that the surface of ZnO-Al₂O₃ (1:0.05) was easily granulated with smaller particle sizes than ZnO, and the shape tends to clump with the composites. The EDX analysis of ZnO-Al₂O₃ confirmed the presence of Zn, O, and Al elements. The photodegradation study showed that the optimum conditions were obtained at a contact time of 180 minutes at pH 6 with 91.04% dye removal. In addition, the effect of the initial concentration of the dye was achieved at 50 ppm with a dye removal of 89.26%. The study showed that the ZnO-Al₂O₃ exhibited adequate removal of Remazol red RB.

Auto Regressive eXogenous (ARX) System Identification of Batch Milk Cooling Process

2024-12-22T10:57:08+07:00

The dynamic model of the milk cooling process from 36°C to 4°C using chilled water available at 2°C has been carried out. The cooling water temperature is kept constant by using a refrigeration unit. The process being studied was a Packo brand milk cooling tank belonging to KUD SAE Pujon (Malang - Indonesia). A fundamental heat balance method was used to derive the model, leading to a first-order transfer function process. For a 2 hours cooling process then, the gain and time constant values are 1.00 and 42.3548 mins respectively, or G(s)=1/(42.3548s+1) (first order process). Deriving system transfer function through a mechanistic model is considered difficult; therefore, in this paper, we explored process identification via Auto Regressive eXogenous (ARX). Transient simulations could then be performed to identify the dynamic behavior of the cooling process. The system was then identified using several orders of the Auto Regressive eXogenous (ARX) model, and then the results were re-tested on different forms of perturbations and obtained quite accurate results. The transfer function identified through the ARX111 is G(s)=1/(42.3729s+1) (first order process), while via ARX441, the 5^th order process was obtained: G(s)=(0.02361s^4+0.000371s^3+0.2331s^2+9.27×10^(-7) s+0.0005826)/(s^5+0.03932s^4+9.873s^3+0.2331s^2+0.02468s+0.0005826). These models particularly useful for process control design and analysis.

Effect of Carrier Agents and Operational Parameters on the Physical Quality of Spray-Dried Tomato Powder: A Review

2024-12-22T10:57:08+07:00

Tomatoes are one of the most frequently consumed crops in the world, and they can be cultivated all year using present production methods. Tomatoes are produced for either manufacturing tomato paste, tomato pulp, tomato sauce, and ketchup or consumed as fresh fruit. However, excessive moisture levels in tomatoes generally result in increased water activity that promotes quality degradation and increases enzymatic activity, which leads to microbial growth. Therefore, the spray drying method is used to produce dried food powder, which may reduce postharvest losses while adding value to the raw product. The purpose of the paper is to review scientific research on the influence of carrier agents and operational parameters of spray-drying fruit extracts on physicochemical qualities such as moisture content, hygroscopicity, solubility, bulk density, water activity, and color difference. The current paper reviews the various formulation and process factors that impact the physicochemical characteristics of tomato powder microparticles produced by spray drying in order to find the optimum parameters to produce tomato powders with a high and effective product yield with improved powder qualities.

Electrochemical Behaviour of Silica Deposited on Stainless Steel by Electrophoretic Deposition

2024-12-22T10:57:09+07:00

The purpose of this paper is to evaluate the characteristics of corrosion protection of stainless steel substrates coated with silica by electrophoresis with pulsed direct current (PDC) and constant direct current (CDC) with anodization. Electrophoresis was carried out using silica sol from sodium silicate solution as an electrolyte solution. Stainless steel functioned as an anode and carbon as a cathode with a constant electrode distance of 2 cm. The amplitude, duty cycle, and anodization effect on stainless steel corrosion protection characteristics were evaluated. The samples were characterized by linear polarization and electrochemical impedance spectroscopy (EIS) to see the characteristics of metal corrosion protection and scanning electron microscopy (SEM) analysis to see the morphology of the coating. This study showed that PDC electrophoresis and CDC accompanied by anodization could obtain silica film with good corrosion protection characteristics (high pore resistance and low admittance). Linear polarization results showed that metal corrosion protection behavior was increased by anodization. Similar results were obtained by EIS analysis which showed that pore resistance increased by anodization. The highest pore resistance obtained by the constant current with anodization is 543 ohms, and the lowest admittance is 0.0217. Corrosion protection characteristics are also influenced by the amplitude and duty cycle during electrophoresis. Silica film with a high pore resistance and a low admittance were obtained at a frequency, amplitude, and duty cycle of 80 Hz, 0.5 volts, and 60%, respectively. The silica film produced by pulsed electrophoresis resulted in better coating characteristics than by constant current with anodization, which is seen from the pore resistance value and its admittance.

Effects of Nucleation and Crystal Growth Rates on Crystal Size Distribution for Seeded Batch Potash Alum Crystallization Process

2024-12-22T11:04:40+07:00

The driving force of the cooling crystallization process is supersaturation, where the supersaturation level during the crystallization process is crucial to grow the crystal sufficiently. Nucleation and crystal growth rates are two concurrent phenomena occurring during crystallization. Both are supersaturation functions that determine the growth of seed crystals and the formation of fine crystals. Trade-offs between nucleation and crystal growth are essential for achieving the large size of seed crystals with the minimum number of fine crystals. Thus, the objective of this study is to analyze the effects of nucleation and crystal growth rates on final product quality, which is crystal size distribution (CSD). Modeling of the crystallization process using a potash alum case study is highlighted and simulated using Matlab software. Then, the effects of nucleation rate, crystal growth rate, and both nucleation and crystal growth rates on CSD are evaluated using local sensitivity analysis based on the one-factor-at-a-time (OFAT) method. Based on simulation results for all strategies, a low combined rate delivers the best performance of the final CSD compared to others. Its primary peak has a mean crystal size of 455 µm with 0.0078 m³/m volume distribution. This means that the grown seed crystals are large with high volume distribution compared to the nominal strategy, which is at the mean crystal size of 415 µm and 0.00434 m³/m. Meanwhile, the secondary peak has the mean crystal size of 65 µm, 0.00028 m³/m in volume distribution. This corroborates the least number of fine crystals at the considerably small size compared to nominal’s (0.00151 m³/m, 35 µm). Overall, the low nucleation and crystal growth rates strategy provides useful insights into designing temperature profiles during the linear cooling crystallization process, whereby achievable supersaturation levels in obtaining large crystals with fewer crystal fines are provided via simulation.

Comparison of Maseration and Sonication Method on Flavonoid Extraction from Mango Leaves: Effect of Solvent Ratio

2024-12-22T11:07:19+07:00

Mango leaf extract has proven to contain flavonoids that serve as antioxidants. In this study, a comparison between traditional maceration and sonication on flavonoid extraction from mango leaf was investigated. The various ratios of ethanol and acetone were utilized as solvents (1:5, 1:10, and 1:15). The sonication process, which uses an ultrasonic cleaning bath set at 40 ^oC, takes 30 minutes as contrasted to the maceration procedure of 36 hours treatment at room temperature. The flavonoid test using aluminum (III) chloride (AlCl₃) colorimetric technique shows that acetone provides greater solvent power than ethanol. According to this study, the optimal ratios for the maceration and sonication procedures are 1:10 and 1:15, respectively. The maceration process resulted in the optimum extract of 0.186 mgQE/g dry leaves. Meanwhile, using a 1:15 acetone solvent ratio and the sonication method, the highest concentration of flavonoid components was discovered, reaching 0.143 mgQE/g dry material with 54 times shorter time.

A Comparative Study on The Electrochemical Properties of Hydrothermal and Solid-State Methods in The NCM Synthesis for Lithium Ion Battery Application

2024-12-22T10:57:10+07:00

In this article, we report and compare the synthesis method of the active cathode materials based on nickel‐cobalt‐manganese (NCM) for lithium-ion battery application. We evaluate the hydrothermal and solid-state reaction method in NCM-622 synthesis, the material characterizations, and the battery performance. Based on the analytical results using X-ray diffraction (XRD), particles synthesized using hydrothermal and solid-state methods exhibit a highly crystalline NCM phase. NCM particles synthesized using solid-state reaction exhibit high-rate performance up to 10 C. The electrochemical impedance spectroscopy analysis shows that the charge transfer resistance (Rct) of NCM synthesized by the solid-state reaction (SSR) method was 25.9% lower than hydrothermal. Meanwhile, the ionic diffusivity of the SSR sample was 38.5% higher than the hydrothermal sample. These two factors lead to better performance when tested in a lithium-ion battery.

Application of Refuse-Derived Fuel (RDF) Plant in Piyungan Landfill Municipal Solid Waste Management

2024-12-22T10:57:11+07:00

Piyungan Landfill is the biggest landfill in the Yogyakarta Province that still operates in overcapacity condition. A new alternative is highly required in solid waste management in the landfill, which can reduce the volume of the waste coming into it and decrease the need for a new landfill area. Refused-derived fuel (RDF) plant is one of the technological alternatives in solid waste management that has the potential to reduce the volume of solid waste and change the waste into fuel. The study analyzed the potential of the application of the RDF to reduce the volume of solid waste in the Piyungan landfill and its economic feasibility. The results of the analysis showed that during the operational period of the RDF plant, the volume of the solid waste coming into the landfill could be annually reduced by 43% on average. The results of the economic analysis show that the RDF plant in the Piyungan Landfill is feasible to apply with an NPV of IDR 281.46 billion, an IRR of 24%, and a payback period of 6 years.

Development of Cavity Matrix Combustor for Biogas Application

2024-12-22T10:57:11+07:00

The use of conventional fossil fuels has limitations in energy resources and environmental problems such as greenhouse gas, air pollution, etc. Biogas has sustainable and renewable characteristics that can be used as an alternative energy source to alleviate these problems. In this study, we proposed a novel cavity matrix combustor that directly enables the combustion of what is produced in small and medium-sized biogas facilities without separation or purification. We also identified combustion characteristics for changes in air ratio, gas feed rate, biogas ratio, and exhaust gas recirculation rate and proposed optimal operating conditions based on this. The performance test result showed that the cavity matrix combustor is excellent for biogas combustion. The optimal operating conditions for the combustor are: the biogas ratio is 60% of CH₄ and 40% of CO₂, the air ratio is 1.1, the gas feed rate is 30L/min, and the exhaust gas recirculation rate is 100%. At this time, the combustion efficiency was 87%, and the unburned components were CO, UHCs, which are 0.01% and 0.05%, respectively, and NOx was 1ppm.

The Effect of Power on Nitrate Synthesis and The Emission Intensities of Reactive Species Using Anodic Plasma Electrolysis

2024-12-22T10:57:12+07:00

Nitrates are used as fertilizer to fulfill nutrients for plants. Anodic plasma electrolysis technology can be an effective and environmentally friendly solution in nitrogen fixation into nitrate compounds. This research aimed to determine the effect of controlling voltage and power in nitrate synthesis using plasma electrolysis with air as the raw material injected at the anode. The material used is an electrolyte solution of 0.02 M K₂SO₄, the electrodes used are in the form of tungsten and stainless steel, and a nitrate reagent is used for the nitrate test. The results of the study showed that at 400 W, the optimal rate was 0.8 L men^-1 with 1889 mg L^-1 of nitrate formed. While at 500 W and 600 W, the optimal rate of 1 L men^-1 with nitrate formed was 2213 mg L^-1 and 2453 mg L^-1. The emission intensities of reactive species N, N₂*, N₂⁺,•OH, •H, and •O at an optimal rate of 0.8 L men^-1 400 W 700 V in 20139 au, 28540 au, 18023 au, 30863 au, 12547 au, 49800 au. The addition of air injection will increase the oxygen input into the plasma zone, which can produce reactive species •O and nitrogen produces reactive species N, N₂*, N₂⁺forms NO. The formed NO compounds can be oxidized to NO_2, and the reaction between NO₂ and reactive species •OH forms nitrates.

Characteristics of Rapid Visco Analyzer Carrageenan Extract with Enzymatic Pretreatment of Kappaphycus striatum

2024-12-22T10:57:12+07:00

Carrageenan is a polysaccharide compound extracted from red seaweed and is widely used by food, cosmetic, and advanced materials industries because of its good properties as an environmentally friendly stabilizer. Carrageenan extraction generally uses alkaline treatment for one full day, where the treatment is to obtain carrageenan quality with good gel characteristics. The use of cellulase enzymes is thought to accelerate the desulfuration process of seaweed, where cellulase enzymes are used to break down cellulose in seaweed cell walls. By using a rapid visco analyzer (RVA), carrageenan was tested to see the pattern and viscosity value. This study aims to determine the effect of enzymatic pretreatment on the profile of carrageenan with a shorter alkalization process compared to the alkalization commonly used by the industry. The results showed that enzymatic treatment before KOH alkalization would produce a carrageenan profile with a viscosity value of 272-360 cP, whereas the NaOH alkalization only reached 19-24 cP. The results of the test using RVA showed that the addition of an enzymatic process could change the physicochemical properties, such as viscosity and gel point of the carrageenan alkalinized with KOH. However, there was no significant difference in the properties when treated by alkalization using NaOH, which can be described from the value of the gelling point of carrageenan treated by cellulose enzyme. Adding enzymes to KOH will accelerate the gelation process, which occurs at an average temperature of 42.78^oC. Meanwhile, carrageenan without enzymatic addition has an average gelation value of 37.48^oC.

Characterization of Cellulose Acetate Membrane at Different Thicknesses on Sucrose Concentration by Forward Osmosis

2024-12-22T10:57:13+07:00

Forward osmosis (FO) requires a specific membrane structure for applications like juice concentration. The phase inversion method was used to make cellulose acetate (CA) FO membranes. The solvents used were acetone and 1,4-dioxane. Additives included polyvinylpyrrolidone (PVP), methanol, and maleic acid were used in the preparation of CA membrane, which make it easier to improve a FO membrane's permeability. The performance of fabricated FO membrane and their morphology were evaluaed with different casting thicknesses of 150, 200, and 250 µm. Experiment works begins with an hour of membrane flux testing, deionized water was used as feed solution and 1 M NaCl as draw solution. The membrane was then used to concentrate 0.5 M sucrose with NaCl for 240 minutes (2 M). Contact angle, porosity, and scanning electron miscroscopy (SEM) were used to characterize membrane properties and morphology. High water flux (2.25 L/m²hr) and high porosity (75.86%) were found at 200 µm casting thickness. Water permeability of sucrose concentration at 200 µm casting thickness had the highest flux (2.39 L/m²hr). The results also show that flux values vary with membrane thickness. All membranes were hydrophilic with contact angles below 90°. A 200 µm casting thickness produces a membrane with smooth and evenly distributed pores, according to morphology analysis. Structural parameter (S) values had a proportional relationship with the FO membrane thickness, which thinner membrane potentially reduces the internal concentration polarization (ICP).

Extraction of Rutin from the Leaf of Male Carica papaya Linn. using Microwave-Assisted and Ultrasound-Assisted Extractive Methods

2024-12-22T10:57:13+07:00

The extraction yield of rutin from the male Carica papaya Linn leaf using Microwave-Assisted Extraction (MAE) and Ultrasound-Assisted Extraction (UAE) methods were investigated and compared. Extraction parameters were analyzed to determine the effects on the yield of rutin. The efficiencies of both extractive methods were also compared. In MAE, the effect and square effect of ethanol mixture concentration, along with its interaction effect with the solid-liquid (S/L) ratio, was found to have significantly influenced the rutin yield. The square effect of particle size was also determined to be important in MAE. In UAE, the effect and square effect of ethanol mixture concentration was found to be crucial to the yield of rutin. The square effect and its interaction effect with extraction time were noticeably significant in UAE. A higher optimized yield of rutin (4.06 ± 0.2 mg/g) was obtained using UAE at an ethanol mixture concentration of 51.5%, sonication time of 70.5 min, the particle size of 355 µm, and S/L ratio of 1:108.6 wt/wt papaya leaf/ethanol mixture despite having longer extraction time and higher energy requirement per gram of rutin than MAE. In contrast, MAE was found to be more efficient by having a higher yield obtained per hour of extraction (27.38 g/h), lower energy consumption (10 W/h), and lower energy required per gram of ruin (3.65 W.h/g). In terms of a greener extraction technique, MAE would be a better fit by consuming lesser extraction solvent and energy to extract rutin from papaya leaf.

Industrial Application of Rice Husk as an Alternative Fuel in Cement Production for CO2 Reduction

2024-12-22T10:57:13+07:00

The cement industry generally spends about 30-40% of production costs to provide energy for production. It forces the cement industry to look for cheaper and widely available alternative energy sources to increase its competitiveness. The dominance of fossil fuels poses another problem for the cement industry in the form of high CO₂ emissions. To overcome this, PT Indocement Tunggal Prakarsa (ITP) Tbk, Palimanan Unit, is committed to continuously looking for alternative energy sources by utilizing rice husks in the suspension preheater unit. This study aims to evaluate the performance, especially the reduction of CO₂ emissions and the economic benefits of energy substitution applications using rice husks. Based on the calculation in 2020, there will be an increase of 37% in 2021, and the total energy of rice husks will reach around 1,996,671 GJ. It is equivalent to using fossil fuel coal of approximately 106,450 tonnes. The contribution of rice husks to primary energy consumption seems to continue to increase yearly. A significant increase occurred between 2020 - 2021, and the contribution of rice husks reached 23%. Rice husks usage has reduced CO₂ emissions by almost 220,000 tons of CO₂e and brought production cost benefits to around 40 billion by 2021. Therefore, the substitution of coal fuel using rice husk has proven to be effective in reducing CO₂ emissions in the cement production process. By still paying attention to the reliability of the process and the quality of the cement products produced, these efforts can be continuously encouraged to realize cement products that are more environmentally friendly.