Gac fruit (Momordica cochinchinensis Spreng.) is a prominent source of carotenoids, renowned for its exceptional concentration of these compounds. This study focuses on optimizing the extraction of active components from the aril of gac fruit by evaluating the effects of extraction temperature, solid–liquid ratio, and extraction time. The primary objective is to maximize the yield of gac oil while assessing its antioxidant capacity. To analyze the kinetics of the solid–liquid extraction process, both first-order and second-order kinetic models were employed, with the second-order model providing the best fit for the experimental data. In addition, the potential of gac fruit peel as a precursor for biochar production was investigated through carbonization. The resultant biochars were evaluated for their efficacy in adsorbing crystal violet (CV) dye from aqueous solutions. The adsorption efficiency of the biochars was found to be dependent on the carbonization temperature, with the highest efficiency observed for BCMC550 (91.72%), followed by BCM450 (81.35%), BCMC350 (78.35%), and BCMC250 (54.43%). The adsorption isotherm data conformed well to the Langmuir isotherm model, indicating monolayer adsorption behavior. Moreover, the adsorption kinetics were best described by the pseudo-second-order model. These findings underscore the potential of gac fruit and its byproducts for diverse industrial and environmental applications, highlighting the dual benefits of optimizing gac oil extraction and utilizing the peel for effective dye removal.

Erythromycin (ERY), an antibiotic widely used in human and veterinary medicine, persists in the environment due to its low degradability, accumulating in wastewater and soil. This study presents a novel adsorbent synthesized by magnetically modifying calcined natural bentonite with Fe₃O₄ nanoparticles to enhance ERY removal. The modification increased the surface area, with the highest adsorption observed at pH 11. Adsorption studies revealed that the Dubinin–Radushkevich isotherm model and pseudo-first-order kinetic model best described the adsorption behavior. Response surface methodology (RSM) was employed to optimize key parameters, including adsorbent dosage, temperature, and contact time. The quadratic model indicated optimal conditions of 41.9 mg adsorbent, 29.1 °C, and 9.6 h of contact time, yielding a maximum ERY removal efficiency of 96.2%. Density functional theory (DFT) analysis provided a molecular-level understanding of the adsorption mechanism, identifying strong interactions between ERY, Fe₃O₄, and bentonite. The theoretical binding energy aligns with experimental results, confirming the role of magnetic modification in promoting ERY adsorption. This study demonstrates a promising approach for mitigating ERY contamination in aqueous environments.

Discarded cigarette filters represent a widespread cellulose-acetate waste stream with the potential for conversion into functional carbon materials. In this study, discarded cigarette filters were converted into magnetic porous carbon for diethyl phthalate (DEP) adsorption through hydrothermal carbonization, H₃PO₄ activation at 300 °C, and subsequent Fe(II)/Fe(III) coprecipitation. Activation increased the Brunauer–Emmett–Teller (BET) specific surface area of the hydrochar from 5.96 to 312.47 m² g⁻¹, while magnetic modification further increased it to 542.41 m² g⁻¹. The incorporation of Fe-containing species was confirmed by X-ray photoelectron spectroscopy, and magnetic functionality was demonstrated by superconducting quantum interference device measurements and separation using an external magnet. DEP removal by the resulting material (MAC-11) was influenced by the initial DEP concentration, solution pH, adsorbent dosage, and temperature. Response surface methodology identified a candidate operating condition of 30.4 °C, 14.6 mg adsorbent, and 236 min, under which an independent confirmation experiment achieved 87.7% DEP removal, compared with a model prediction of 85.0%. The pseudo-second-order model provided a better empirical description of the adsorption kinetics than the pseudo-first-order model, while both the Langmuir and Freundlich models described the concentration-dependent adsorption data. Although magnetic modification reduced DEP adsorption relative to the nonmagnetic activated carbon (AC-300), MAC-11 retained appreciable adsorption performance while acquiring magnetic separability. These findings demonstrate the feasibility of converting discarded cigarette filters into magnetically responsive porous carbon through comparatively low-temperature activation, highlighting the trade-off between adsorption performance and magnetic recoverability.