This research improves the strength of plastic using avocado seed starch and PLA. The effect of blending avocado seed starch and PLA was optimized using the RSM approach by using two variables: water absorption and biodegradability. Mixing them using RSM gave the best result: 1.8 g of starch and 3 g of PLA. Degradable plastic has a tensile strength of 10.1 MPa, elongation at a break of 85.8%, and a Young’s modulus of 190 MPa. Infrared spectroscopy showed that the plastic had a -OH bond at 3273.20 cm⁻¹, 3502.73 cm⁻¹, and 3647.39 cm⁻¹, a CH₂ bond at 2953.52 cm⁻¹, 2945.30 cm⁻¹, and 2902.87 cm⁻¹, a C=C bond at 1631.78 cm⁻¹, and a C-O bond at 1741.72 cm⁻¹. The plastic decomposed in the soil. It was organic and hydrophilic. Thermal tests demonstrated that the plastic can withstand heat well, losing weight at 356.86 °C to 413.64 °C, forming crystals and plastic melts at 159.10 °C—the same as PLA. In the melt flow test, the sample melted before measurement, and was therefore not measurable—process conditions affected it. A water absorption of 5.763% and biodegradation rate of 37.988% were found when the samples were decomposed for 12 days. The starch and PLA fused in the morphology analysis to form a smooth surface. The RSM value was close to 1. The RSM gave the best process parameters.

When the manganese is under the acceptable limit, then the removal of Fe (II) ion, the common metallic compound contained in groundwater, is one of the most important stages in the processing of groundwater to become potable water. This study was aimed at investigating the performance of a fixed-bed adsorption column filled, with activated carbon prepared from palm kernel shells, in the removal of Fe (II) ion from groundwater. The influence of important parameters such as bed depth and the flow rate was investigated. The bed depth adsorbent was varied at 7.5, 10 and 12 cm. At a different flow rate of 6, 10 and 14 L/minute. The Atomic Absorb Spectrophotometer was used to measure the Fe (II) ion concentration, thereafter the results were confirmed using a breakthrough curve showing that flow rate and bed depth affected the curve. The mathematical model that used to predict the result was the Thomas and Adams-Bohart model. This model is used to process design, in which predicting time and bed depth needed to meet the breakthrough. This study reveals that the Thomas model was the most appropriate one, including the use of Palm Kernel Shell for processing groundwater. According to the Thomas Model, the highest capacity of adsorption (66.189 mg/g) of 0.169-mg/L of groundwater was achieved with a flow rate of 6 L/minute, with the bed depth at 14 cm.

Palm oil bottom ash utilization from mill boilers as CO2 adsorbent has been in use for few years. This study aims to examine adsorbent characteristics and capabilities of bottom ash produced from boiler combustion in palm oil industry for CO2 adsorption before and after utilization, such as compound functional group using the Fourier Transform Infra-Red (FT-IR) spectrophotometer, adsorbent morphology through Scanning Electron Microscopy (SEM), and compound amount using Energy Dispersive X-Ray Spectroscopy (EDX). The CO2 adsorption was carried out in fixed-bed column. Process variables consist of volumetric flow rate, contact time and bed height. Results showed that SiO2 compounds in the heterogeneous form with average particle size of 1073 nm, as supported by FT-IR spectrum finding indicating SiO2 signal at wavelength of 958–954 cm–1. Additionally, EDX analysis showed Silica and Oxygen content of 11.88% and 36.90%, resulting 70% CO2 adsorption capacity of 0.350 mg/g at discharge of 5 L/min, contact time of 40 min, and bed height of 12 cm. Langmuir isotherm model was obtained with R2 of 0.998, qm of 1.588, and kL of 0.144. Meanwhile, the kinetic model followed a simple first-order prototypical with R2 of 0.952, C02 of 0.260, and k1 of 0.006.

Biogas is a cost-effective, efficient, environmentally friendly, and renewable alternative energy source. While biogas contains CH₄, it also contains impurities in the form of 27–45% CO₂ gas. Therefore, it is necessary to purify biogas by removing CO₂ gas as it can reduce the calorific value of CH₄, the main component of biogas. The process of methane purification can be achieved through adsorption. Bottom ash, derived from palm oil mill waste, shows great potential for methane purification by effectively adsorbing CO₂. This research simulated the methane purification process using the computational fluid dynamics (CFD) method with the student version of the ANSYS R20 software. The study utilized an adsorbent made from bottom ash obtained from palm oil mill waste. The main objective was to investigate the performance of bottom ash as an adsorbent for removing CO₂ gas in a continuous gas flow within an adsorption column. The study involved varying the column bed height (4 cm, 8 cm, 12 cm) and gas flow rate (10 L/min, 15 L/min, 20 L/min). The results showed that the highest efficiency in removing CO₂ gas was 84.53% with a bed height of 12 cm and a flow rate of 10 L/min, while the lowest efficiency was 47.87% with a bed height of 4 cm and a flow rate of 20 L/min. Furthermore, the highest adsorption capacity for CO₂ gas was 1.64 mg/g with a bed height of 12 cm and a flow rate of 10 L/min, while the lowest capacity was 0.93 mg/g with a bed height of 4 cm and a flow rate of 20 L/min. The linearization of adsorption isotherm data indicated that the CO₂ gas adsorption process using bottom ash adsorbent followed the Langmuir model.

As with conventional cyclones, the gas-particle flow within a square cyclone is characterized by the consistent presence of turbulence. Therefore, selecting an appropriate turbulence model to accurately predict cyclone performance is crucial. This paper presents the findings of a computational fluid dynamics (CFD) study that assesses the impact of various turbulence models on the flow field, collection efficiency, and pressure drop predictions within square cyclone separators. In the simulation of the flow field, an investigation was conducted into five turbulence models falling under the Reynolds Averaged Navier-Stokes category, namely the Spalart-Allmaras, standard k–ε, RNG k–ε, standard k–ω, and Reynolds Stress models. Each turbulence model was coupled with a discrete phase model to represent solid particle flow within a square cyclone. The solution of the flow and particle transport equations was conducted using the software Ansys Fluent (version 21.1). Except for the flow field, for which experimental data were unavailable, the calculations were validated by comparing the predicted results for the square cyclone overall and grade efficiencies, and the pressure drop, with values from the literature. The findings of this simulation investigation demonstrate that all tested turbulence models exhibit comparable qualitative trends in predicting the tangential and axial velocity profiles. However, when evaluated in quantitative terms, the RNG k-ε model tends to overpredict both the tangential and axial velocities compared to the other models. Conversely, in the majority of cases, the k–ε standard turbulence model tends to underpredict these velocities in comparison to the other models. Regarding the predictions of the square cyclone performance, the Reynolds Stress Model is particularly noteworthy among the five turbulence models examined. It provides qualitative and quantitative closer agreement with the experimental data regarding the overall collection, grade efficiencies, and pressure drop. In general, while all models produced qualitatively similar trends in square cyclone performance predictions, the Reynolds Stress Model yielded the closest agreement with the experimental results, both qualitatively and quantitatively.

Continuous Stirred Tank Reactor (CSTR) atau Reaktor Alir Tangki Berpengaduk(RATB) merupakan salah satu jenis reaktor yang umumnya berbentuk bejana danbekerja secara kontinyu. Continuous Stirred Tank Reactor (CSTR) banyakdigunakan untuk reaksi-reaksi homogen fase cair tanpa katalis maupun dengankatalis. Penelitian ini bertujuan untuk mendapatkan respon terbaik kontrol PIDdengan menggunakan metode trial and error pada nilai Kc, Ti, dan Td. Metodetrial and error adalah adalah metode mencari nilai parameter dengan caramencoba-coba suatu nilai tertentu sebagai parameter sampai didapat sebuahperformansi kontrol PID yang terbaik. Sistem kontrol PID merupakan controlleruntuk menentukan presisi suatu sistem instrumentasi dengan karakteristik adanyaumpan balik pada sistem tersebut (Feed back). Adapun metodologi penelitian iniadalah membuat model steady state Continuous Stirred Tank Reactor (CSTR),kemudian mengubah model steady state menjadi model dynamic, lalu membuatmodel kontrol PID, setelah itu melakukan tuning terhadap kontrol PID danmelakukan pengujian terhadap kontrol PID, dengan melakukan gangguan padaset point. Nilai Kc = 8, Ti = 1 dan Td = 0 respon waktu rata-ratanya 0,815 menit, sebuah sistem pengendalian suhu yang dapat diterapkan untuk mendapatkanwaktu yang paling optimal. Nilai Kc = 10, Ti = 4 dan Td = 0 waktu rata-ratanya1,257 menit sebuah sistem pengendalian suhu yang memiliki waktu yang kurangoptimal. Kata Kunci: Continuous Stirred Tank Reactor (CSTR), PID, Set Point.