Fully Automated Weighing of Liquid Substances with a Laboratory Robot

Polyphenols from Red Vine Leaves Using Alternative Processing Techniques

The extraction kinetics of polyphenols, which are leached from red vine leaves, are studied and evaluated using a laboratory robot and nonconventional processing techniques such as ultrasonic (US)-, microwave (MW)-, and pulsed electric field (PEF)-assisted extraction processes. The robotic high-throughput screening reveals optimal extraction conditions at a pH value of 2.5, a temperature of 56 °C, and a solvent mixture of methanol:water:HCl of 50:49:1 v/v/v. Nonconventional processing techniques, such as MW- and US-assisted extraction, have the fastest kinetics and produce the highest polyphenol yield. The non-conventional techniques yield is 2.29 g/L (MW) resp. 2.47 g/L (US) for particles that range in size from 450 to 2000 µm and 2.20 g/L (MW) resp. 2.05 g/L (US) for particles that range from 2000 to 4000 µm. PEF has the lowest yield of polyphenols with 0.94 g/L (450–2000 µm), resp. 0.64 g/L (2000–4000 µm) in comparison to 1.82 g/L (2000 to 4000 µm) in a standard stirred vessel (50 °C). When undried red vine leaves (2000 to 4000 µm) are used the total phenol content is 1.44 g/L with PEF.

Adsorption of oleic acid dissolved in isopropanol–water mixtures on hydrotalcite

Fatty acids are an interesting class of educts for chemical processes as they are available from renewable resources. For obtaining high-purity fatty acids, efficient separation techniques are needed. An interesting option is adsorption. In the present work, therefore, the adsorption of oleic acid on hydrotalcite, a readily available adsorbent, is studied. The focus is on studying the influence of the composition of the solvent on the adsorption. Adsorption isotherms are reported for oleic acid in pure isopropanol and mixtures of isopropanol and water at temperatures between 278 and 308 K. Even though the solubility of oleic acid in isopropanol is higher than in mixtures of isopropanol and water, the highest capacity of the adsorber is found for pure isopropanol. The reasons are discussed. No significant influence of the temperature was observed.