Teaching Sustainable Development Concepts in the Laboratory: A Solid–Liquid Extraction Experiment

One of the principles of sustainable development is to replace chemicals traditionally derived from oil with alternative, renewable materials. For example, phenol and phenol derivatives currently used in the manufacture of wood adhesives can be replaced (at least in part) by biopolymers extracted from biomass. In this work, pine bark (a renewable resource containing easily extractable, reactive phenols) is employed as a substrate for solid-liquid extraction with dilute NaOH solutions. The kinetics of polyphenol extraction is followed spectrophotometrically. In order to convert absorbance data into concentrations, the extracted polyphenols can be measured gravimetrically for selected samples. The experimental data are interpreted by equations involving two or three regression parameters. Additional aspects illustrating the "biomass refinery" concept applied to pine bark are discussed.