This work is designed as an experience for organic and analytical chemistry laboratories in environmental science courses. Coffee grounds were chosen because they are easily available, they are a fine example of a waste product, and the students are familiar with them.
The coffee bean is a source of a number of by-products. By comparing the physicochemical characteristics of coffee oil (from the grounds) with those of common oils, it is found that coffee oil shows similarity to palm oil. We hydrolysed the coffee oil and obtained a soap that had good detergent and foaming properties similar to olive oil soap or commercial products. Another beneficial aspect of the coffee bean results from the high content in organic matter (C = 48.9%) of the degreased coffee grounds, which allows their utilization to improve the fertility of soils. The total nitrogen content of the residue is higher than that of many composts and is similar to the nitrogen content of some commercial products employed for house plants.
The economical, technical, and environmental advantages that frequently can derive from the recovery of some by-products of foods and beverages, such as the coffee grounds in this example, are evident.
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