On the biodegradability of nitrophenols and their reaction products by catalytic hydrogenation*

Abstract

BACKGROUND: Catalytic hydrogenation is gaining interest as an emerging technology for the detoxification of industrial effluents containing pollutants such as nitrophenols. This technique achieves high conversion levels under ambient‐like conditions of temperature and pressure, leading to less harmful products than the starting compounds. RESULTS: Complete conversion of 2‐nitrophenol, 4‐nitrophenol and 2,4‐dinitrophenol was achieved in short reaction times at 25 °C and 1 atm, using Pd/Al2O3 and Rh/Al2O3 catalysts. The rates of disappearance followed the sequence: 2,4‐dinitrophenol > 2‐nitrophenol > 4‐nitrophenol, the Pd catalyst being more active than the Rh one. The corresponding amino‐compounds were identified as the only reaction products. From a Microtox test the reaction products appeared more toxic than the starting compounds. Nevertheless, respirometric tests with conventional activated sludge yielded EC50 values for the aminophenols about double those of the nitrophenols. Biodegradability tests showed that the monoaminophenols can be degraded by non‐acclimated sludge, whereas no degradation was observed for the nitrophenols and 2‐amino‐4‐nitrophenol, the reaction product from 2,4‐dinitrophenol hydrogenation. CONCLUSION: Catalytic hydrogenation of wastewater containing nitrophenols gives rise to byproducts less toxic and more easily biodegradable by an activated sludge. Copyright © 2012 Society of Chemical Industry

CWPO of bisphenol A with iron catalysts supported on microporous carbons from grape seeds activation

“…Inhibition was also estimated in terms of EC 50 , defined as the concentration of the toxicant causing a 50% reduction of the exogenous SOUR (specific oxygen uptake rate) obtained in the presence of sodium acetate as sole carbon source. The biodegradability assays were carried out following the typical operating conditions of an activated sludge process, measuring toxicant removal and the activity of microorganisms [52,53]. In a close reactor were incorporated the unacclimated sludge and the target compound, and the SOUR profile was obtained interrupting the air supply and measuring the dissolved oxygen decay in a range of 0.3 mg L -1 .…”

Bioremediation

“…Abiotic catalytic hydrogenation aimed at improving the treatability of nitrophenols in wastewater was investigated by Diaz et al 6 Catalytic nitrophenol hydrogenation using Aluminasupported rhodium and palladium catalysts produced aminoand nitro-amino phenols. Monoaminocompounds were found to be better degradable in an anaerobic sludge than their mother compounds.…”

“…They span from the characterization of archaeal and bacterial community responses to different environments 5,7,10 -13 , the elucidation of metabolic pathways 9 , novel analytical technologies 3 and environmental nano-technology 4 to the exploitation of organisms for environmental biotechnology from yet less well characterized environments 8 or geographical regions 14,15 . In addition, a number of abiotic approaches to increase pollution attenuation efficacy are introduced, including electrochemistry 1 and catalytic hydrogenation 6 , soil amendments to modify processes governing interactions between pollutants and plants 16,19 or microbes, offering the possibility of waste re-use 2 and, eventually, laser-based plant biotechnology 18 .…”

Aqueous Reactions of Sulfate Radical-Anions with Nitrophenols in Atmospheric Context

“…Much of the nitrophenol chemistry has been studied for the sake of advanced oxidation processes aimed at mitigation of nitrophenols in aquatic and industrial environments [60]. The technologies considered include: Fenton and photo-Fenton reactions based on H 2 O 2 [34,61], TiO 2 based photocatalysis [62][63][64], electrocatalysis [65], photo-electrocatalysis [66,67], and wet catalysis [68,69]. Among the latter, a promising process was proposed which utilized reactions of nitrophenols with sulfate radical-anions generated by the cobalt-mediated decomposition of peroxymonosulfate anions [70].…”