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In the present work, green synthesis of some basic phase transfer nanocatalysts (PTC) with tuneable and quantifiable hydrophobic/hydrophilic properties was achieved. Hydrophobic derivatization of fumed silica (FS) carried out by chemical covalent attachment of commercially available stearic acid (SA) into the FS matrix, followed by microwave assisted loading of calcium oxide (CaO) as the basic active sites. Mechanogriding was performed for the hydrophobic derivatization of FS. As-prepared modified supports and catalysts were characterized by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), dynamic light scattering (DLS), powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), and static water contact angle (WCA) measurement. Surface coverage ratio (Θ), modification efficiency and ratio of hydrophobic surface area to hydrophilic surface area (HPho/HPhi) were also calculated. Microwave assisted loading preceded a highly uniform dispersion of CaO on the surface of fumed silica. The basic catalytic properties of the functional non-porous nanocomposites were evaluated in a model transesterification -type (biodiesel) reaction. In the presence of the modified support, a more favorable conformation orientation of the immiscible reactants (methanol-oil) in the presence of active sites (CaO), was provided, leading to an interfacial activation mechanism. The latter led to a significant increase in both active site stability and mass transfer efficiency between two immiscible reagents. Quantitative conversion of the reactants to biodiesel (96% versus 50% for the unmodified one) was achieved at 62 °C, 6:1 methanol to oil molar ratio, 2 wt% of CaO and 4 h of reaction time.

Ultrasound-assisted extraction (UAE) of oil from tea seeds, and the effects of some operating parameters such as ultrasonic power, extraction time, extraction temperature and solvent to solid ratio on the yield of tea seed oil were investigated; some of the results were compared with those of the conventional method. It was found that UAE requires a shorter extraction time and a reduced solvent consumption. The yield of tea seed oil increased with the increase of the ultrasonic power and decreased as the temperature increased. The fatty acid compositions of the oils extracted by the ultrasound-assisted method and the conventional method were analyzed using gas chromatography. The result showed no significant affect on the compositions of the tea seed oil by the application of ultrasound. PRACTICAL APPLICATIONS The ultrasound-assisted extraction (UAE) can enhance the extraction efficiency, facilitating solvent penetration into the plant material and allowing the intracellular product release. Ultrasound also agitates the solvent used for extraction, thus increasing the contact surface area between the solvent and the targeted compounds by permitting greater penetration of the solvent into the sample matrix. Therefore, UAE reduces extraction time as well as solvent consumption. In addition, UAE can be carried out at a lower temperature, thus avoiding thermal damage to the extracts and minimizing the loss of bioactive compounds. Therefore, it may serve as an effective method for extraction of oil from tea seeds.

This study examines subcritical water extraction (SCWE) of caffeine from black tea leaf. The effects of various operating conditions such as water temperature (100, 125, 150 and 175C), water flow rate (1, 2 and 4 g/min), mean particle size (0.5, 1 and 2 mm) on extraction yield and rate were determined. SCWE at 175C, water flow rate of 2 g/min and mean particle size of 0.5 mm were found to be able to recover 3.82% (w/w) of caffeine present in the black tea leaf within 3 h of extraction. In comparison to the SCWE, conventional hot water extraction showed 3.30% (w/w) extraction yield. It was found also that pressure had no effect on extraction yield and rate. PRACTICAL APPLICATIONS Recently, subcritical water has become of great interest as an alternative solvent for extraction of natural active compounds. Subcritical water, as a green solvent, can be used in many different fields of applications. In recent years, extraction of flavors, fragrances and antioxidant components from plant materials, and hydrolysis of carbohydrates, vegetable oils and fatty acids have been widely investigated by many researchers. Using subcritical water for analytical purposes, for soil remediation and applying it as a reaction media are some other interesting fields for practical applications. Subcritical water is an excellent solvent for caffeine as well as many other organic compounds but is safer than the organic solvents that are used for caffeine extraction.

The solubility of l-(+)-ascorbic acid in water, ethanol, methanol, propan-2-ol, acetone, acetonitrile, ethyl acetate, and tetrahydrofuran was measured by a gravimetrical method from (293 to 323) K, and the solubility data were correlated against temperature. The solubility of l-(+)-ascorbic acid in water and methanol was high compared with other solvents.

The aim of this study was to investigate the isolation of caffeine from tea waste using subcritical water extraction (SCWE) method. The effect of various operating conditions such as water temperature (100,125,150, 175 and 200C), water flow rate (1, 2 and 4 g/min), mean particle size (0.25, 0.5, 1 and 2 mm) and pressure (20, 30 and 40 bar) on extraction yield and rate were determined. SCWE at 175C, water flow rate of 4 g/min and mean particle size of 0.5 mm was found to be able to recover 0.77% (w/w) of caffeine present in the tea waste within 1.5 h of extraction. In comparison with the SCWE, conventional hot water extraction showed 0.46% (w/w) extraction yield. It was found also that pressure had no effect on extraction yield and rate. A sustainable and environmentally friendly procedure has been used for the Fourier transform infrared determination of caffeine in tea waste extracted samples. PRACTICAL APPLICATIONS Subcritical water extraction (SCWE), as a green solvent, can be used in many different fields of applications. It can be used to extract antioxidant compounds from rosemary plants as well as to extract whitening agents and azo dyes in samples. Additionally, soil can be remediated through SCWE of dioxins. Recently, subcritical water has become of great interest as an alternative solvent for extraction of natural active compounds. In recent years, extraction of flavors, fragrances and antioxidant components from plant materials, and hydrolysis of carbohydrates, vegetable oils and fatty acids have been widely investigated by many researchers. Using subcritical water as a reaction media are some other interesting fields for practical applications.

The solubility of salicylic acid in water, ethanol, carbon tetrachloride, ethyl acetate, and xylene was measured by a gravimetrical method from (298 to 348) K, and the solubility data were correlated against temperature. The experimental solubility of salicylic acid in water and ethyl acetate was compared with the literature data. The solubility of salicylic acid in ethanol and ethyl acetate was high compared with other solvents.