Synthesis and Application of Activated Carbon from Pecan Nutshells (Carya illinoinensis) for the Removal of Excess Copper in Distilled Beverage

This study aimed to develop activated carbon from pecan nutshells for use as an adsorbent to remove excess copper from artisanal cachaça produced in small-scale distilleries. The process included grinding the shells, classifying particle sizes, chemically activating the material with ZnCl2 (1:0.5 w/w), drying at 105 ± 1 °C, carbonizing in a muffle furnace, and washing with 6 M HCl followed by vacuum filtration. The resulting activated carbon was characterized in terms of moisture content, degree of carbonization, and iodine number. Adsorption tests were performed using two particle size fractions (10 g/L), agitating 0.1 L of cachaça with the adsorbent at room temperature (25 ± 1 °C) for up to 60 min. The initial copper concentration in the beverage was 11.30 mg/L, which exceeds regulatory limits. The activated carbon showed significant adsorption capacity, particularly the sample with the highest iodine number, achieving over 90% copper removal and reducing the copper concentration to 0.97 mg/L. These findings demonstrate the potential of pecan shell-derived activated carbon as an effective, sustainable solution for treating copper contamination in distilled beverages. A preliminary cost analysis indicated an estimated production cost of US$ 3–5 per kg, considerably lower than that of commercial activated carbons, further supporting the practical applicability of the proposed material.