Desenvolvimento de catalisador do tipo fenton a base de biochar de casca do fruto do cafeeiro aplicado na degradação de corantes

Abstract

Technological advancements have led to increasingly complex wastewater compositions, necessitating effective and sustainable treatment methods. Advanced Oxidation Processes (AOPs), such as heterogeneous Fenton, stand out due to their efficiency, catalyst reusability, and broad pH operational range. Biochar (BC), derived from the pyrolysis of agro-industrial residues like coffee husks, has shown promise as an effective adsorbent and catalyst for degradation processes due to its high specific surface area and oxygenated functional groups. This study synthesized an iron-functionalized biochar solid catalyst for the degradation of methylene blue (MB) via the heterogeneous Fenton process. Coffee husks sourced from the agro-industrial sector of Monte Carmelo – MG were pyrolyzed at 300, 500, and 700 oC, followed by chemical activation with 0.1 mol L-1 HNO3 and impregnation with 0.15 mol L-1 FeCl3, resulting in heterogeneous catalysts. Structural characterization through Surface Area and Porosity Analysis (ASAP) revealed that BC500trat@Fe exhibited the highest specific surface area, enhancing interactions with contaminants. X-ray diffraction (XRD) confirmed the presence of iron oxides anchored to the carbonaceous matrix, while infrared spectroscopy (IR) identified relevant functional groups for adsorption. Photocatalytic assays demonstrated that BC500trat@Fe achieved the highest degradation rate (62.6%), with a point of zero charge (pHPZC) close to neutrality (6.78), favoring both adsorption and degradation of the dye. The Bangham-Modified-Gompertz (BMG) kinetic model provided the best fit (R2 = 0.999), suggesting a synergistic adsorption-degradation mechanism. Furthermore, reuse tests indicated that the catalyst maintained its efficiency after four cycles, highlighting its feasibility for large- scale applications. The bioassay test indicated that the degradation method using the BC500trat@Fe catalyst did not produce toxic by-products, confirming the safety of the process and the absence of adverse effects on biological organisms. The results confirm the efficiency of the system in degrading methylene blue dye without compromising environmental quality. In conclusion, iron-functionalized biochar, particularly BC500trat@Fe, exhibits high potential for the degradation of organic pollutants, serving as a viable and sustainable alternative for industrial wastewater remediation.