Remediation of arsenic-contaminated water: high effectiveness of modified biochars from legal amazon residues

Abstract

Arsenic contamination in water poses a significant global health risk, especially in regions with mining activities, such as the Legal Amazon. This study investigated the efficacy of iron-impregnated biochar, derived from three abundant fruit wastes native to the Legal Amazon region (baru, cupuaçu, and pequi), in removing As(V) from water. The biochars were characterized by techniques including elemental analysis, Brunauer–Emmett–Teller (BET) surface area determination, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The results indicate that iron impregnation significantly modified the surface properties of the biochar, leading to an increase in surface area and the introduction of new functional groups. A response surface methodology, employing a central composite design (CCD), was utilized to optimize the adsorption process by varying the biochar dosage (g L⁻¹), the initial concentration of As(V) (µg L⁻¹), and the pH. The findings demonstrate that all three iron-modified biochars exhibit high arsenic removal efficiencies, exceeding 90% under all tested conditions. The optimal conditions for each biochar varied, suggesting that the unique surface chemistry and porosity resulting from the different biomass sources play critical roles in the adsorption performance. Furthermore, a comparative analysis revealed the differences in adsorption capacities among the biochars, with the Cupuaçu shell biochar showing the highest efficiency. Overall, these results highlight the potential of utilizing readily available fruit waste to develop sustainable and effective adsorbents for arsenic remediation. The FeCl₃ impregnation method proved simple yet effective, showing a particular promise for applications in resource-limited communities.

Graphical Abstract