Multiple Solid–Liquid Extraction: Determination of Extraction Yield through UV–Vis Spectroscopy

Abstract

A class of 18 students attending the last year of an Italian high school was divided into groups and performed the extraction of pigments contained in hibiscus tea. Each group worked at a different temperature and carried out multiple extractions using distilled water as a solvent. By means of UV−vis spectroscopy it was possible to determine the yield of each individual extraction and then to study the effect of temperature on the extraction itself. The method is easy to implement, it does not require the use of hazardous reagents or special safety precautions, and it is very cheap. The laboratory part was carried out in 3 h time, while the analysis and data processing took about 4 h. On an educational level, the students learned to process and analyze large amounts of data, and they became familiar with the UV−vis spectrophotometer and eventually had to solve the problems independently.

A Simple and Colorful Experiment to Show Nanowire Membrane Construction for Molecule Separation

“…Molecule separation and purification are extremely significant processes in the chemical industry and also provide lots of input in teaching. , Students’ separation and purification experiments mainly focus on paper chromatography, − column chromatography, − layer chromatography, − liquid–liquid extraction, − solid–liquid extraction, − and adsorption, − while little attention is being paid to an advanced separation techniquemembrane filtration. According to the statistics of the Journal of Chemical Education , there are plenty of publications concerning chromatography, while there is only one paper reporting about membrane filtration experiments in the past decade …”