A solar photoFenton process with calcium peroxide from eggshell and ferrioxalate complexes for the degradation of the commercial herbicide 2,4-D in water
Rocío Girón-Navarro, Verónica Martínez-Miranda, Elía Alejandra Teutli-Sequeira, Ivonne Linares‐Hernández, Iván Galileo Martínez-Cienfuegos, Miriam Sánchez-Pozos, Fortunata Santoyo‐Tepole
Abstract
The present study focused on the degradation of the commercial herbicide 2,4-D in water by solar photoFenton assisted with ferrioxalate complex and calcium peroxide (CaO 2 ), using an experimental system consisting of a storage tank, a water pump, a solar reactor, and a compound parabolic concentrator (CPC), which collected solar energy of 212.102 kJ/L. The CaO 2 was synthesized from eggshells, the influence of the 2,4-D concentration, oxalic acid (H 2 C 2 O 4 ), iron (Fe 3+ ), and CaO 2 on the degradation of herbicide was evaluated by HPLC, and the intermediates such as 2,4-dichlorophenol, 1,4-benzoquinone, and oxalic acid were determined to confirm the proposed reaction mechanism. The generation of hydroxyl radicals and other reactive species, depends on the molar ratios of oxalate/Fe 3+ , CaO 2 /Fe 3+ , and CaO 2 /2,4-D. The optimum concentrations for 100 % degradation were 61.5 mg/L 2,4-D, 50.5 mg/L Fe 3+ , 100.5 mg/L H 2 C 2 O 4 , and 81 mg/L CaO 2 with 42.27 % COD and 44.09 % TOC. This study highlights the viability of the solar photoFenton process to degrade the 2,4-D herbicide and aims to promote: the recovery of organic waste such as eggshells, the complexing effect of H 2 C 2 O 4 -Fe 3+ , the CaO 2 as an alternative oxidant, and the application of renewable energy in the treatment of similar contaminants present in wastewater for future research.