INFLUÊNCIA DA CONCENTRAÇÃO DE ÁCIDO FOSFÓRICO NA OTIMIZAÇÃO DA CLARIFICAÇÃO DO CALDO DE CANA

Abstract

Clarification of sugarcane juice is an essential step in the sugar production process, directly influencing quality and efficiency. In general, sugarcane juice contains an average of approximately 250 ppm of phosphoric acid, but some cane varieties produce juice with low levels, making the treatment process more difficult. Therefore, as the concentration of phosphoric acid in the juice increases, clarification becomes more efficient. This study evaluated the influence of phosphoric acid addition to sugarcane juice during the clarification stage in sugar-ethanol mills, aiming to optimize impurity removal and improve settling efficiency. The research was conducted at a sugar-ethanol mill in Pernambuco, analyzing data on mineral impurities at cane reception, color index, pH, and P₂O₅ levels of mixed and clarified juice during the 2024/2025 harvest. In parallel, tests were carried out to assess the impact of adding different concentrations of phosphoric acid (200, 400, 600, and 800 ppm) to raw cane juice and industrial process samples collected from the same evaluation points. The average values obtained during the 2024/2025 harvest for the mixed juice were: color index 19,976; pH 5.00; and P₂O₅ 480.00 ppm, and for the clarified juice: color index 15,104; pH 7.11; and P₂O₅ 74.70 ppm. Tests on raw juice showed that an 800 ppm concentration reduced color by 30.55%. Experiments with industrial process samples indicated that 800 ppm was the ideal phosphoric acid concentration, maximizing flocculation-coagulation efficiency and reducing initial juice color and turbidity, resulting in reductions of 57.87% in color and 87.71% in turbidity for mixed and limed juice, respectively. Statistical analysis using the Tukey test (p<0.05) indicated that higher concentrations of phosphoric acid improved color and turbidity, although the differences were not statistically significant. The study also confirmed the need to monitor cane quality and operational conditions such as temperature, pH, agitation, and the point of acid addition to ensure efficient juice clarification. Therefore, this study demonstrated that it is possible to optimize the clarification of mixed and limed juice in the mill through phosphoric acid addition and operational adjustments, emphasizing the importance of monitoring input concentrations to prevent excessive use, reduce costs, and align sugar quality with sustainability.