Estudo da influência de parâmetros operacionais na adsorção de cobre em coluna de leito fixo utilizando casca de arroz.

Abstract

With advancing industrialization, social and environmental problems have intensified, including water contamination by heavy metals, which is a major environmental concern. In this context, the search for solutions and the need to reduce copper (Cu²⁺) contamination levels have gained prominence, driving the development of efficient and sustainable wastewater treatment technologies. The overall objective of this study was to determine the optimal operating conditions for a bench-scale fixed-bed column using rice husks as an adsorbent material for Cu²⁺ removal. The methodology employed consisted of washing, drying, crushing, and sieving the rice husks, as well as preparing synthetic solutions containing Cu²⁺ at concentrations of 8, 32, and 128 mg/L. The fixed-bed column was assembled with a 30 mm inner diameter tube, 30 cm long, and adsorbent bed heights of 5, 7.5, and 10 cm were used in each test, with a flow rate of 13 mL/min. Samples were collected every 10 min during the total operating time of 360 min and analyzed by atomic absorption spectrophotometry. Operating conditions with a higher bed height (10 cm) and lower initial solution concentration (8 mg/L) provided higher removal efficiency, with removals of up to 100% and a breakthrough point of up to 150 min. At a concentration of 8 mg/L and an adsorbent bed height of 10 cm, the column did not saturate, further demonstrating the efficiency of the treatment system. However, at a concentration of 128 mg/L, early saturation occurred, with sudden breakthrough. Overall, the results of this research reinforce the potential of rice husks as a promising adsorbent, as two trials showed 100% copper removal at lower concentrations, as well as others with 97% and 90%. Therefore, the fixed-bed column can operate with high efficiency for up to 360 minutes at low concentrations. These results demonstrate the applicability of agricultural waste as a low-cost, low-environmental-impact adsorbent for the development of industrial wastewater treatment systems.