Biosorption process using Cereus jamacaru DC, Cactaceae for Pb²⁺ removal from aqueous systems

Lead is a highly toxic metal associated with many human health diseases that can be caused by several environmental changes. Innovative sustainable solutions for water remediation have been recently encouraged by using renewable, low-cost and earth-abundant biomass materials to ensure public health conditions. In this article, Cereus jamacaru DC (popularly known as Mandacaru) was investigated as a biosorbent in the Pb²⁺ removal from aqueous solution using a two-level factorial design. The analysis of variance suggested a significant and predictive model (R² = 0.9037). The maximum efficacy of Pb²⁺ removal in the experimental design was 97.26%, being the optimized conditions: pH 5.0, contact time 4 h without adding NaCl. The Mandacaru was divided into three types according to the plant structure and this parameter did not present a significant interference in the biosorption process. This result corroborates with slight differences in the total soluble proteins, carbohydrates and phenolic compounds found in the Mandacaru types investigated. FT-IR analysis revealed the presence of O-H, C-O and C = O groups that were responsible for the ion biosorption process. The optimized procedure was capable to remove 97.28% of the Pb²⁺ added in the Taborda river water sample. The kinetic adsorption results show the pseudo-second-order model, suggesting chemisorption process. Thus the treated water sample can be considered in accordance with technical standards issued by CONAMA Resolution Num. 430/2011 and Ordinance GM/MS Num.888/2021 of WHO. In this way, the Mandacaru proved to be an efficient, fast and easy-to-apply bioadsorbent in Pb²⁺ removal and has great environmental application potential.