Ana Najwa Mustapa

Background: Accidental oil spills threaten ecosystems and water resources, while synthetic absorbents like polypropylene contribute to long‐term pollution. This study explores the potential of a novel biodegradable hybrid biopolymer composed of sodium alginate (ALG) and soy protein isolate (SPI) for oil spill remediation. The ALG/SPI aerogel absorbent was synthesised via a sol–gel method. Surface modification of the ALG/SPI to enhance its hydrophobicity was performed through two techniques: (i) liquid immersion and (ii) scCO ₂ adsorption. The reusability, biodegradation, and toxicity tests of the ALG/SPI absorbent were evaluated, aligning with the growing concern about sustainability and reliance on synthetic or non‐biodegradable materials. Results: ALG/SPI aerogels biodegraded rapidly (80–86% mass loss in 5 weeks) while maintaining buoyancy after oil uptake. MTMS silanisation with both techniques produced superhydrophobic/oleophilic surfaces (water contact angles: surface 124–143°, cross‐section 118–146°), enhancing oil selectivity and performance. The optimised 1% ALG/1.5% SPI (ALG/SPI 1:1.5) exhibited the highest contact angle of 143 ^o , achieving 89.8% oil–water separation efficiency with 13‐cycle reusability through MTMS liquid immersion. FTIR, TGA, and FESEM post‐testing supported an environmentally benign profile, positioning ALG/SPI aerogels as a promising alternative to synthetic absorbents. Conclusion: The ALG/SPI 1:1.5 aerogel exhibited excellent buoyancy, stable absorption across 40–120 °C, and superior environmental performance compared to synthetic sponges. With liquid immersion giving the highest hydrophobicity and scCO₂ adsorption showing potential as a greener solvent‐free alternative with comparable wettability properties, ALG/SPI emerges as a sustainable substitute for synthetic oil absorbents. © 2025 Society of Chemical Industry (SCI).

Christia vespertilionis is a medicinal herb traditionally used as a complementary and alternative medicine to treat cancer and malaria. This study investigated the effect of pre-treatments of the Christia vespertilionis plant on supercritical CO2 extraction yield and solubility. Four pre-treatments were studied: drying and grinding, doping with absolute ethanol (99%) and 80% (v/v) of ethanol/water, and microwave pre-treatment. The supercritical CO2 extraction was conducted at a constant 13.8 MPa, 40℃ with 24 mL/min flow rate in 40 min of extraction time. It was found that the dried sample after drying and grinding pre-treatment produced the highest yield of 4.56 mg/g, whereas the lowest yield was obtained for the fresh leaves’ samples treated with microwave irradiation (1.26 mg/g). Doping techniques with absolute ethanol and 80% (v/v) were comparable in the 2.64 to 2.94 mg/g. GCMS results revealed that Christia vespertilionis extract comprises antioxidants, mainly phytol, limonene, and other medicinal compounds such as α-monolaurin and l-ascorbyl 2,6-dipalmitate. This study indicates that adding co-solvent was not the primary technique in supercritical CO2 extraction to increase the extractability of compounds of interest from plant matrices.

In this work, the ionic liquid [Aliquat][Cl] was supported into alginate and silica aerogel matrices and applied as a catalyst in the cycloaddition reaction between CO₂ and a bio-based epoxide (limonene oxide). The efficiency of the alginate aerogel system is much higher than that of the silica one. The method of wet impregnation was used for the impregnation of the aerogel with [Aliquat][Cl] and a zinc complex. The procedure originated a well-defined thin solvent film on the surface of support materials. Final materials were characterised by Fourier Transform Infrared Spectroscopy, N₂ Adsorption–Desorption Analysis, X-ray diffraction, atomic absorption and Field Emission Scanning Microscopy. Several catalytic tests were performed in a high-pressure apparatus at 353.2 K and 4 MPa of CO₂.

Clinacanthus nutans Lindau (C. nutans) is a popular medicinal herb plant in Asia regions such as Malaysia, Indonesia, Thailand and China for its high polyphenols content. Various conventional extraction techniques have been use to extract bioactive compounds in C. nutans, however, the methods have limitations such as usage of organic solvent, time-consuming and low extraction yield. In this study, polyphenols content from C. nutans leaves extracted by solvent-free microwave extraction (SFME) in a vacuum condition (V-SFME) and at ambient pressure (SFME) to investigate the effect of vacuum on the extraction of polyphenols. Energy density or irradiation power per unit of sample volume is used instead of applied microwave power to determine actual energy absorbed by the microwave extraction. Effect of process parameter on the polyphenol contents: energy density of 0.073, 0.078 and 0.108 W/ml in 5, 10 and 15 min with 6 ml/g of solvent-to-feed (S/F) ratio was studied. The highest total phenol content (TPC) was obtained at 0.073 W/ml, 6 ml/g of S/F ratio and 5 min of extraction time with TPC of 24.08 ± 0.51 mg GAE/g DW at temperature of 79 °C. Results demonstrated that the TPC of C. nutans was higher when extracted under vacuum pressure compared to TPC at ambient pressure. The results suggest that V-SFME method using water under vacuum state appears as the most efficient and green technique for the extraction of polyphenols from C. nutans extract in shorter time with no use any of organic solvent to produce reasonably high TPC.

Medicinal herb Christia vespertilionis oil has been claimed to possess anti-cancer and anti-plasmodial properties and show interest in food and pharmaceutical industries. Being an important alternative medicine plant, solubility data of Christia vespertilionis oil is demanded in order to understand the separation process and is crucial for designing purposes. In this work, extraction and determination of the oil’s solubility were carried out using a green technique of supercritical carbon dioxide at a temperature range of 40 to 60℃ and 276 to 414 bar of pressure. The results demonstrated that the highest solubility was obtained at the highest temperature and pressure of 60℃ and 414 bar, respectively. For solubility prediction, experimental data were modelled using four empirical density-based models: Chrastil, del Valle and Aguilera, Adachi and Lu, and Sparks et al. models. In general, all the models were able to predict the solubility of Christia vespertilionis oil in supercritical carbon dioxide. The best fitting showed that Adachi and Lu model gave the best correlation with the lowest %AARD value of 1.61%.