Natural clay and commercial activated charcoal: properties and application for the removal of copper from cachaça

Abstract

The influence of contact time and the amount of adsorbent on the removal of copper from distilled cachaça was evaluated. The adsorption of copper was favored by a 1:50 ratio of mass of adsorbent (g) to volume of sugar cane spirits (mL). An equilibration time of 120 min for clay and 360 min for activated charcoal resulted in the removal of 68.7% and 98.3% of the copper, respectivamente. The isotherms were studied in the range of copper concentrations of 0 to 2000 mg L−1. The amount of copper adsorbed per unit weight of clay was 10.8 mg g−1, and for charcoal, it was 5.9 mg g−1. The isotherm results were tested in the Langmuir and Freundlich models and were found to adapt better to the Freundlich model. The removal of copper by clay and activated charcoal could be explained by a pseudo-second-order kinetic model. Given the organic and inorganic complexity of cachaça, the influence of this process on the flavor of the beverage was also evaluated. To this end, the analyses of aldehydes, higher alcohols, furfural, esters and volatile acidity were performed according to the methods established by the Ministry of Agriculture, Livestock and Supply. The results showed that the samples treated with clay adsorbed 3.6, 8.7, 9.4, 2.2 and 3.9% of the aldehydes, higher alcohols, furfural, esters, and volatile acidity, respectively. For the samples treated with activated charcoal, the results were 6.5, 15.3, 95.31, 2.0 and 34.0% for the aldehydes, higher alcohols, furfural, esters, and volatile acidity, respectively.