Growing plastic waste and industrial wastewater necessitate sustainable treatment solutions. This study optimized industrial wastewater treatment using activated carbon derived from high-density polyethylene (HDPE) pyrolysis char via thermal activation, eliminating the need for aggressive chemical agents. Characterization via FTIR, BET, and SEM-EDX revealed a micro-mesoporous structure with a BET surface area of 287.3 m²/g, a 90.05 atomic percent carbon content, and dominant pore sizes of 2.1 to 2.6 nm. The adsorbent performance was evaluated against laundry wastewater using a Central Composite Design and Response Surface Methodology. Statistical analysis yielded a robust model (R² = 0.9406, adequate precision = 15.54) to assess the impact of dosage, contact time, and initial concentration. Numerical optimization identified ideal conditions: 8.68 g/L dosage and 15-minute contact time for a 100 mg/L initial concentration. Experimental validation confirmed a 77.99% total dissolved solids (TDS) reduction, aligning closely with the predicted 79.48%. Post-treatment analysis indicated significant quality improvements, with COD and TOC levels decreasing to 35.8 mg/L and 21.6 mg/L, respectively, while dissolved oxygen increased from 0.6 to 4.3 mg/L. This research confirms that HDPE-derived activated carbon offers an effective, sustainable approach for both wastewater remediation and plastic waste valorization. Copyright © 2026 by Authors, Published by Universitas Diponegoro and BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).
Carbon capture from humid flue gas is problematic. Many microporous adsorbents are poisoned by water vapor. This research aims to study the effect of the Si/Al ratio on the competitive adsorption of CO₂ and H₂O in FAU-type zeolites, as well as evaluate their performance in capturing humid flue gases. Grand Canonical Monte Carlo (GCMC) simulations were performed to study the competitive adsorption of equimolar CO₂/H₂O mixtures at 298 K in two FAU zeolites: Zeolite 13X (Na₇₇, Si/Al ≈ 1.5) and Zeolite Y (Na₄₉, Si/Al≈2.92). The results showed that Zeolite 13X shows higher adsorption of CO₂ under low pressures, with the phenomenon of the roll-over occurring in the case of high pressure because of competitive adsorption with H₂O. In turn, the adsorption of CO₂ for Zeolite Y remained stable over the entire pressure range and exhibited lower H₂O uptake. Isosteric heats of CO₂ adsorption on the zeolites are 15.71 kcal/mol for Zeolite 13X and 13.23 kcal/mol for Zeolite Y. The energy of CO₂ binding in the presence of H₂O decreased by 1.14 kcal/mol for Zeolite 13X and for 2.03 kcal/mol for Zeolite Y. These findings indicate that high-silica FAU zeolites, such as Zeolite Y, are efficient CO₂ adsorbents. Copyright © 2026 by Authors, Published by Universitas Diponegoro and BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).
The development of sustainable cement alternatives has intensified interest in alkali‐activated binders formulated from abundant clay minerals. In this study, a clay-based geopolymer binder was synthesized and optimized by investigating the combined influence of activated clay loading (10-100 g), bauxite loading (0-150 g), alkaline activator dosage (0-3 g), and curing temperature (90-150 °C) on its setting time and compressive strength. A Central Composite Design (CCD) under Response Surface Methodology (RSM) was employed to model the responses and determine optimal processing conditions. The experimental results revealed that both responses were significantly influenced by the synergy between the activator dosage and raw material loading. Increasing activated clay and bauxite content accelerated geopolymerization, leading to shortened setting time, whereas excessive activator addition resulted in delayed matrix hardening due to excess soluble silicate–aluminate species. Compressive strength increased with increasing precursor loading up to a threshold level, beyond which incomplete dissolution restricted polycondensation. Regression analysis demonstrated excellent agreement between predicted and experimental values, with no transformation required, as confirmed by Box–Cox analysis. The normality and independence of residuals were verified through residual plots against predicted values and experimental runs. Optimization using a desirability function achieved a setting time of 6 h and compressive strength of 40.44 MPa at optimal conditions of activated clay (55 g), bauxite (75 g), activator dosage (1.5 g), and curing temperature (120 °C), with a global desirability of 1.000. These results confirm RSM as an effective statistical tool for tailoring the performance of clay-based geopolymers, offering a promising pathway for developing high-strength, fast-setting, sustainable binders. Copyright © 2026 by Authors, Published by Universitas Diponegoro and BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).
Hydrothermal liquefaction (HTL) of lignocellulosic biomass provides a viable route for converting wet, low-value residues into energy-dense biocrude suitable for upgrading to drop-in fuels. This review systematically covers feedstock selection and pretreatment strategies, fundamental HTL reaction pathways, and the effects of operating conditions and reactor configurations on product yields and distribution. Advances in biocrude characterization using chromatographic and spectroscopic techniques are reviewed alongside upgrading approaches, including solvent extraction, fractional distillation, catalytic hydrotreatment, and refinery co-processing. The generation, composition, and management of the aqueous phase are also examined, with emphasis on treatment challenges, environmental impacts, and potential valorization routes. Key technological barriers, including heteroatom removal, catalyst deactivation, integration of upgrading processes, and scale-up economics are critically assessed using insights from recent techno-economic and life cycle assessment studies. Based on literature reported between 2015 and 2026, this review identifies research priorities required to advance lignocellulosic HTL toward scalable, commercially viable, and sustainable fuel production. Copyright © 2026 by Authors, Published by Universitas Diponegoro and BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).
Electrodeposition is widely used in automotive painting due to its high adhesion and uniform coating. Temperature control is critical for coating quality, but stirred tanks exhibit nonlinear dynamics with large inertia and time-varying parameters. This study aims to develop an integrated control strategy combining model predictive control (MPC) with a model reference adaptive system (MRAS) to improve temperature control accuracy and robustness in a stirred electrodeposition tank. A robust MPC with N-step-free control action was designed based on an ARX-identified state-space model, and an MRAS estimator with PI adaptation was integrated to online-update the dominant time constant perturbed by stirring. Simulation and experimental results demonstrated that the proposed MPC-MRAS method achieved temperature control accuracy within ±0.2 °C, superior set-point tracking, and robust disturbance rejection compared to conventional MPC without parameter adaptation. The integrated strategy effectively compensates for model uncertainties caused by fluid agitation and operational variations, showing significant potential for industrial electrodeposition applications. Copyright © 2026 by Authors, Published by Universitas Diponegoro and BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).
