Oxidative photodegradation of herbicide fenuron in aqueous solution by natural iron oxide α-Fe₂O₃, influence of polycarboxylic acids

Abstract

The photodegradation of the herbicide fenuron (1,1-dimethyl-3-phenylurea) by using a natural iron oxide (NIO), α-Fe2O3, in aqueous solution at acidic pH has been undertaken. The NIO was characterized by the Raman spectroscopy method. The degradation pathways and the formation of degradation products were studied. A high-pressure mercury lamp and sunlight were employed as light source. Fenuron photodegradation using NIO with oxalic acid followed the pseudo-first-order kinetics, the optimal experimental conditions were [oxalic acid]0 = 10(-3) M and [NIO] = 0.1 g L(-1) at pH 3. A UVA/NIO/oxalic acid system led to a low fenuron half-life (60 min). The results were even better when solar light is used (30 min). The variables studied were the doses of iron oxide, of carboxylic acids, the solution pH and the effect of sunlight irradiation. The effects of four carboxylic acids, oxalic, citric, tartaric and malic acids, on the fenuron photodegradation with NIO have been investigated, oxalic acid was the most effective carboxylic acid used at pH 3. A similar trend was observed for the removal of total organic carbon (TOC), 75% of TOC was removed. The analytical study showed many aromatic intermediates, short-chain carboxylic acids and inorganic ion.

Organic matter and iron oxide nanoparticles: aggregation, interactions, and reactivity

“…Hydroxyl radicals formed through a photo-induced Fenton reaction enhance the photocatalyst ability of iron oxide nanoparticles, and this process could be exploited as a viable remediation technology. 173 Common hydroxyl radical sources include H 2 O 2 174 and oxalic acid, [175][176][177][178][179][180][181][182] with successful contaminant degradation observed with goethite, 174,178 hematite, [175][176][177][178]180,182 maghemite, [180][181][182] and lepidocrocite. 179 Rates of contaminant degradation may increase in the presence of OM due to the formation of hydroxyl radicals by photo-irradiation of the OM.…”

Two Coordination Polymers Synthesized from Various N-Donor Clusters Spaced by Terephthalic Acid for Efficient Photocatalytic Degradation of Ibuprofen in Water under Solar and Artificial Irradiation

“…The results show an inhibition in the phototransformation phenomena at a concentration of 10 –3 mol L –1 , inducing a reduction rate of 28.8% after 1 h of solar irradiation. This can be explained by an enhanced competition for the adsorption and by the trapping of OH radicals according to the reaction: 29 …”

“…Study of the IBP/CPs/H 2 O 2 System. One way of improving the photocatalytic efficiency of polymers relies on the addition of electron acceptors such as hydrogen peroxide in the reaction medium 28,29 IBP/CPs/H 2 O 2 system. In fact, in the heterogeneous phase, the photocatalytic processes for the degradation of ibuprofen under different conditions are illustrated in Figure 9.…”

Photodegradation of pesticides using compound-specific isotope analysis (CSIA): a review

“…The photocatalytic degradation of IPU 107 was studied in the presence of natural iron oxide, oxalic acid, and under UV irradiation. A recent study described the enhanced degradation of IPU by solar light in aqueous systems in the presence of TiO 2 , as well as diuron, 108,109 linuron, 110 monolinuron, 111 chlorotoluron, 112 monuron, 113 fenuron, 114 fluometuron, 115 and their main metabolites. Although the phototransformation process may contribute to the degradation of IPU, biodegradation appears to be the main phenomenon responsible for its natural attenuation in the environment.…”