Triyanda Gunawan

Indonesia’s abundant Bangka-Belitung kaolin offers a raw material for developing geopolymer membranes for wastewater treatment. In this study, the kaolin was activated at 650 °C to form metakaolin, which was then used to synthesize porous geopolymer membranes. Porosity was tailored using hydrogen peroxide (H2O2) as a foaming agent. The resulting membranes exhibited non-uniform pores with varying degrees of connectivity whose size strongly influenced mechanical and filtration performance. The smallest pores (produced by 1 wt % H2O2 addition) provided the highest compressive strength (11.7 MPa) and moderate but stable water permeability (0.95 L·m⁻2·h⁻1·bar⁻1), representing the most operationally robust membrane configuration. In contrast, the best balance between methylene blue (MB) rejection and mechanical stability was achieved at 5 % H2O2 with 2 wt % addition. MB removal was governed by combined size exclusion and adsorption interactions between MB molecules and surface hydroxyl groups (Si–OH and Al–OH) within the geopolymer framework. These interactions facilitated effective dye retention within the porous network while maintaining stable permeation behaviour. Overall, the study demonstrates that the geopolymer membranes can be engineered with tuneable porosity, mechanical integrity, and high dye-removal efficiency, highlighting their strong potential as membranes for dye wastewater purification.

This study presents a systematic and reproducible methodology for developing synthetic wastewater that mimics the bulk physicochemical characteristics of palm oil mill final effluent (SWM‐POME _FE ) at laboratory scale. The framework was established through four sequential phases: (1) physicochemical characterization of real POME _FE (R‐POME _FE ), (2) dose–response analysis of selected media, (3) iterative formulation of SWM‐POME _FE , and (4) stability and statistical validation. R‐POME _FE was characterized across 10 sampling events to establish baseline conditions for key parameters. Dose–response analyses of glucose, lignin, surfactant, unrefined red palm oil, and NH ₄ Cl were conducted to reproduce COD, BOD ₅ , color, O&G, and NH ₃ –N contributions. Three progressively refined formulations were developed through iterative adjustments, demonstrating strong agreement between experimental results (Exp‐R) and calibrated predictions (Cal‐P), with deviations ranging from 0.3% to 6.3%. Statistical similarity analysis of the final SWM‐POME _FE formulation showed that NH ₃ –N, O&G, color, and turbidity closely matched the distribution of the R‐POME _FE dataset, with mean values falling within the 95% confidence interval, interquartile range, and ±10% tolerance band. These parameters also exhibited very small standardized deviations (| z | ≤ 0.2), indicating negligible differences relative to the natural variability of the field measurements. TSS met all criteria except the interquartile range ( z = 0.76). In contrast, COD and BOD ₅ fell outside the central distribution metrics but remained within the observed field range ( z = 1.03 and 1.52, respectively). Although formal equivalence testing using the two one‐sided tests procedure did not demonstrate strict equivalence, this was attributed to the large natural variability of the field measurements. Stability assessments further confirmed the robustness of the formulation, with < 5% variation during the 5‐day short‐term test and only minor reductions after 3‐month storage, indicating that SWM‐POME _FE provides a stable physicochemical surrogate for controlled laboratory studies.

This study investigates the performance of the Pebax membrane in CO ₂ adsorption and permeation processes. The adsorption tests were conducted using a gas adsorption reactor based on the solubility approach, with adsorption capacity determined from system pressure variations. SEM characterization revealed a smooth and homogeneous surface with the presence of microvoids that contribute to an enhanced CO ₂ adsorption capacity of up to 397.53 mg/g. The linear relationship between adsorption capacity and pressure variation was used to determine the solubility coefficient, while the slope of the qt versus t ^1/2 plot provided the diffusion constant. Based on the obtained solubility and diffusion values, the calculated CO ₂ permeability of the Pebax membrane indicates strong gas transport properties, confirming its potential as one of the most promising adsorbent materials for smart decarbonization and sustainable carbon capture applications.

Calixarenes are adaptable macrocyclic hosts with tunable cavities and functionalizable rims, making them promising for selective CO ₂ capture. Modifications such as amine incorporation, metal coordination, porous polymerization, and integration into MOFs or polymer membranes enhance adsorption capacity, selectivity, and recyclability through cooperative interactions like hydrogen bonding and Lewis acid–base coordination. Hybrid frameworks provide hierarchical porosity and efficient diffusion, surpassing conventional sorbents. Challenges remain in mixed-gas adsorption, moisture tolerance, and scalable synthesis. Future research should target molecular-level understanding, stable regenerable frameworks, and multifunctional systems coupling CO ₂ capture with catalytic or electrochemical conversion.

One of the challenges in shipbuilding is managing the Bill of Materials (BOM), caused by the existence of separate BOM versions for the design, production, and maintenance stages. In addition, most BOM preparation still involves manual processes. This results in additional work in the form of BOM transformation and repeated verification, as the multiple manually created BOM versions are highly prone to data inconsistencies and duplication. This study aims to simplify BOM preparation by developing a CAD-integrated add-on program capable of automatically generating BOM from ship section design. The proposed add-on program is expected to provide a solution for facilitating BOM data transfer between shipyard divisions, thereby reducing the risk of data inconsistencies and speeding up decision-making in ship construction. The research method includes collecting material data (ship profiles and plates), creating profile and plate model templates, designing the add-on program, and developing a user guide for the add-on. The add-on program will consist of three components: Drawing Tool for modeling, Part Identification for marking structural components in the ship section design, and BOM Calculation for calculating the Bill of Materials from the structural components in the ship section design. The expected outcome of this research is the development of an add-on program capable of automatically generating a BOM from a ship’s section design, demonstrated through a case study on the cargo oil tank section in the parallel middle body of a tanker.

Efficient ethanol–water separation is vital for sustainable biofuel production, yet conventional techniques remain energy-intensive. This work presents synergistic sodium alginate (SA)/Pebax composite membranes supported on ceramic tubes for high-performance pervaporation. By tuning SA/Pebax ratios (5 : 1 to 3 : 2) and applying glutaraldehyde crosslinking, the membranes exhibit enhanced thermal stability, mechanical strength, and hydrophilicity. FTIR and SEM confirm successful blending and uniform morphology, while AFM reveals controlled surface roughness. Increasing the Pebax composition in the polymer blend improved thermal stability while reducing the swelling degree. Tensile strength tests showed that the 4 : 1 ratio provided a balanced performance, with a tensile strength of 12.04 MPa and elongation of 30.65%. At 50 °C and 90 wt% ethanol feed, the SA/Pebax (4 : 1) membrane achieves a flux of 133 g m⁻² h⁻¹ and a separation factor of 281, raising the separation factor from 5 for pure SA to 281 (56 times). These findings demonstrate that SA/Pebax composite membranes provide opportunities for energy-efficient solutions for water/ethanol separation, aligning with sustainable chemical processing goals.