Dicamba Degradation by Fenton-Like Process Using Iron/Biochar Composites

Abstract

In this work, an iron/biochar composite was evaluated as a catalyst for 3,6-dichloro2-methoxybenzoic acid (dicamba) herbicide degradation by heterogeneous Fenton-like process. The biochar was produced from pyrolysis of coffee husks. After FeII adsorption by biochar, the material was submitted to chemical reduction, via borohydride, producing zero-valent iron nanoparticles (BIO-Fe0 ). The material was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy and energy dispersive X-ray spectroscopy, Raman scattering spectroscopy, nitrogen adsorption/desorption analysis, among other techniques. The BIO-Fe0 is a heterogeneous material, and the main constituent elements are carbon (C), oxygen (O), silicon (Si), sulfur (S) and iron (Fe). The dicamba degradation was monitored by high-performance liquid chromatography and biological assays using beans (Phaseolus vulgaris) as indicator species. The commercial dicamba (500 mL; 250 mg L-1) was submitted to Fenton-like process (initial pH 3.20; BIO-Fe0 : 3 or 5 g; 1.00 mL H2O2 at 3.00 mmol L-1; 1.00 mL Al2(SO4)3 at 1.00 mol L-1; 25 °C and 5 h of reaction), presenting ca. 100% of degradation. These treated solutions were used in a biological assay. The intoxication levels were less 30%. These results show that BIO-Fe0 has the potential to be used in the dicamba degradation by Fenton-like processes.

Exploration of Eco-Friendly Hydrochar’s Potential in Advanced Oxidative Processes for Dicamba Degradation within a Circular Bio-Economy Framework

“…Control experiments were conducted specifically to assess the adsorption of dicamba by Hy-Fe, but the observed removal efficiency was surprisingly low, measuring only around 3%. These findings align with previous results obtained by our research group [33].…”

“…Control experiments were conducted specifically to assess the adsorption of dicamba by Hy-Fe, but the observed removal efficiency was surprisingly low, measuring only around 3%. These findings align with previous results obtained by our research group [33]. Comparison of dicamba degradation by biochar produced by pyrolysis (Py-Fe) and hydrochar (Hy-Fe) produced by hydrothermal synthesis (HTC).…”

“…The procedure was carried out in accordance with previous work [33]. To determine the influence of reaction time on the degradation of dicamba, 100.00 mL of dicamba solution (50.00 mg L −1 ) were placed under constant stirring with 0.20 g of Hy-Fe, 1.00 mL of H 2 O 2 (1.00 mmol L −1 ) and 1.00 mL of aluminum sulfate solution (1.00 mol L −1 ) at a temperature of 25 • C. At pre-set times, aliquots of 1.00 mL were taken from the system, which were filtered through a cellulose acetate membrane (0.45 µm pore size and 13 mm diameter) and analyzed by High Performance Liquid Chromatography (HPLC).…”

“…Thus, in H 2 O 2 was added at the onset of the reaction, along with the other reagents. The concentration used was determined based on the literature findings, considering an excess [53,54], as well as on previous work [33]. It is important to note that the reactions were consistently interrupted to conduct the analyses.…”