Bicarbonate-activated Peroxide Research Articles

Activation of H2O2-HCO3- by Ca2Co2O5 for pollutant degradation.

The bicarbonate-activated hydrogen peroxide (BAP) system is widely studied for organic pollutant degradation in wastewater treatment. Ca2Co2O5, a heterogeneous catalyst containing multivalent cobalt including Co(II) and Co(III), was herein investigated as a BAP activator, and Acid Orange 7 (AO7) was used as a model pollutant. Ca2Co2O5 exhibited good activation performance. The degradation rate and the initial rate constant of the Ca2Co2O5-activated BAP system were 5.4 and 11.2 times as high as the BAP system, respectively. The removal rate of AO7 reached 90.9% in 30min under optimal conditions (AO7 20mg/L, Ca2Co2O5 0.2g/L, H2O2 1mM, NaHCO3 5mM, pH 8.5, 25℃). The Ca2Co2O5 catalyst exhibited good stability and recyclability, retaining 85% of AO7 removal rate in the fifth run. Compared to the BAP system, a lower dosage of H2O2 was required and a higher initial concentration of pollutants allowed for effective degradation in the Ca2Co2O5-BAP system. X-ray photoelectron spectroscopy was used to analyze the catalytic mechanism. The analysis showed that the good catalytic performance of Ca2Co2O5 attributes to its high proportion of oxygen vacancies and Co(III) species, and the presence of Ca. The active species O2•-, •OH, and 1O2 are responsible for the degradation, as indicated by the quenching experiments. The degradation mechanism of AO7 was speculated based on UV-Vis spectral analysis and the identification of degradation intermediates. The azo form, naphthalene and benzoic rings in the AO7 structure are destroyed in the decomposition. This research provides a feasible approach to designing effective and reusable BAP activators for pollutant degradation in wastewater treatment.

Cobalt-catalysed bicarbonate-activated peroxide as a promising system for the advanced oxidation of epirubicin in wastewaters

Epirubicin (EPI) is a common cytostatic drug often found as a pollutant in hospital wastewater. While many studies have focused on the degradation kinetics of its epimer, doxorubicin (DOX), none have reported the kinetics of EPI degradation. Herein, we report a new cost-efficient, environmentally friendly system for the advanced degradation of EPI consisting of cobalt-catalysed bicarbonate-activated peroxide. We propose a new kinetic model for EPI degradation that shows the hydroperoxyl radical is the most important reactive oxygen species (ROS) involved in the degradation process. Seven degradation products are identified using high-performance liquid chromatography coupled with mass spectrometry (HPLC-MS). The effect of surfactants, commonly found in wastewaters, is also investigated and the presence of the cationic surfactant hexadecylpyridinium chloride (CPC) in the reaction medium leads to a 6.1-fold increase in the degradation rate. Modelling the reaction kinetics using the Piszkiewicz model unveils the rate constant for the micellar degradation of EPI to be 4.66×10‐3s‐1. The ecotoxicity study of the degradation products shows a dramatic decrease in both acute and chronic toxicity. Although the level of mineralisation of the products is less than 10%, this method is still suitable as a pre-treatment of wastewaters. The same system is successfully used for the degradation of DOX, mitoxantrone, and quinizarin. In the case of DOX, a rate constant of 3.74×10‐2s‐1 is obtained, the highest reported so far.

Oxidation of Allura Red AC Using the NaHCO3-activated H2O2 System Catalyzed with Cobalt Supported on Al-PILC

The oxidation of aqueous solutions containing Allura Red AC (AR–AC) using bicarbonate-activated peroxide (BAP) and cobalt-impregnated pillared clay (Co/Al–PILC) as the catalyst was investigated. Using the CCD-RMS approach (central composite design–response surface methodology), the effects of dye, H2O2, and NaHCO3 concentrations on AR–AC degradation were studied. The decolorization, total nitrogen (TN), and total carbon (TC) removals were the analyzed responses, and the experimental data were fitted to empirical quadratic equations for these responses, obtaining coefficients of determination R2 and adjusted-R2 higher than 0.9528. The multi-objective optimization conditions were [dye] = 21.25 mg/L, [H2O2] = 2.59 mM, [NaHCO3] = 1.25 mM, and a catalyst loading of 2 g/L. Under these conditions, a decolorization greater than 99.43% was obtained, as well as TN and TC removals of 72.82 and 18.74%, respectively, with the added advantage of showing cobalt leaching below 0.01 mg/L. Chromatographic analyses (GC–MS and HPLC) were used to identify some reaction intermediates and by-products. This research showed that wastewater containing azo dyes may be treated using the cobalt-catalyzed BAP system in heterogeneous media.

Environment-friendly chemical mechanical polishing using NaHCO3-activated H2O2 slurry for highly efficient finishing of 4H-SiC (0001) surface

Silicon carbide (SiC) is recognized as one of the most promising and widely used semiconductor materials, but the current chemical mechanical polishing (CMP) process for SiC is inefficient and polluting. There is badly in need of developing an efficient and environmentally friendly CMP polishing solution for SiC. This paper proposes the use of a bicarbonate-activated hydrogen peroxide (BAP) system in SiC CMP to address the inefficiency and environmental concerns. The BAP system aims to develop an economical, environmentally friendly, efficient, and sustainable SiC CMP solution. Comparative tests were conducted to validate the material removal rate (MRR), surface roughness (Sa), and morphology of 4H-SiC samples after CMP processing. The experimental results show that the introduction of NaHCO3 induces the generation of different reactive oxygen radicals (·CO3−, ·O2−, 1O2) when combined with hydrogen peroxide (H2O2). This enhancement significantly improves the oxidation performance of the polishing solution. The average MRR after a 2-hour CMP process is measured at 220 ± 5 nm/h, which represents a remarkable 450 % increase in material removal efficiency compared to using pure H2O2 slurry. Furthermore, the surface roughness (Sa) after polishing is measured at only 0.283 ± 0.016 nm, indicating a smooth surface without noticeable scratches.

Treatment of textile wastewater using the Co(II)/NaHCO3/H2O2 oxidation system

Textile wastewater (TWW) is one of the most hazardous wastewaters for ecosystems when it is discharged directly into water streams without adequate treatment. Some organic pollutants, such as dyes in TWW, are considered refractory compounds that are difficult to degrade using conventional chemical and biological methods. The bicarbonate-activated peroxide (BAP) system is an advanced oxidation process (AOP) based on applying H2O2, which has been demonstrated to be a clean and efficient technology for dye degradation, with the advantage of operating under slightly alkaline pH conditions. In this study, response surface methodology (RSM) based on a central composite design (CCD) was used to optimize the degradation of TWW contaminated with the azo dye Acid Black 194 using the BAP system catalyzed with cobalt ions in solution (Co2+). The analysis of variance (ANOVA) technique was applied to identify significant variables and their individual and interactive effects on the degradation of TWW. The optimum reagent concentrations for degrading TWW at 25 °C and with 45 μM Co2+ were 787.61 and 183.34 mM for H2O2 and NaHCO3, respectively. Under these conditions, complete decolorization (≥99.40), 32.20 % mineralization, and 52.02 % chemical oxygen demand removal were achieved. Additionally, the acute toxicity of textile wastewater before and after oxidation was evaluated with guppy fish (Poecilia reticulata), showing a total reduction in mortality after treatment with the Co2+–BAP system. The Co2+–BAP oxidation system is a potential method for textile wastewater treatment, which, in addition to achieving complete decolorization and partial mineralization, improves biodegradability and reduces the toxicity of the treated water.

Kinetic isotope effect study of N-6 methyladenosine chemical demethylation in bicarbonate-activated peroxide system.

N-6 methyladenosine is the most abundant nucleic acid modification in eukaryotes and plays a crucial role in gene regulation. The AlkB family of alpha-ketoglutarate-dependent dioxygenases is responsible for nucleic acid demethylation. Recent studies have discovered that a chemical demethylation system using hydrogen peroxide and ammonium bicarbonate can effectively demethylate nucleic acids. The addition of ferrous ammonium sulfate boosts the oxidation rate by forming a Fenton reagent with hydrogen peroxide. However, the specific mechanism and key steps of this process remain unclear. In this study, we investigate the influence of ferrous ammonium sulfate concentration on the kinetic isotope effect (KIE) of the chemical demethylation system using LC-MS. As the concentration of ferrous ions increases, the observed KIE decreases from 1.377 ± 0.020 to 1.120 ± 0.016, indicating a combination of the primary isotope effect and inverse α-secondary isotope effect with the ion pairing effect. We propose that the initial hydrogen extraction is the rate-limiting step and observe a tight transition state structure in the formation of the hm6A process through the analysis of KIE trends. The concentration-dependent KIE provides a novel perspective on the mechanism of chemical demethylation and offers a chemical model for enzyme-catalyzed demethylation.

Bicarbonate-Activated Hydrogen Peroxide for an Azo Dye Degradation: Experimental Design

The present study investigated the degradation of an aqueous Allura Red AC (AR–AC) solution by activating hydrogen peroxide with bicarbonate using cobalt ion (Co2+) as the catalyst. Four independent variables (H2O2, NaHCO3, Co2+, and dye concentrations) were analyzed in the composite central design (CCD). AR–AC degradation was optimized using the response surface methodology (RSM). Under optimal degradation conditions (41.86 mg/L AR–AC, 5.58 mM H2O2, 2.00 mM NaHCO3, and 9.00 µM Co2+), decolorization > 99.86%, mineralization (CO2 to conversion) of 12.99%, and total nitrogen removal of 51.97% were achieved. The predicted values for the three response variables were consistent with the experimental values, with determination coefficients (R2) greater than 0.9053. Because cobalt ions (Co2+) are a source of water pollution, after oxidation, these were adsorbed on sodium bentonite (Na–Bent), obtaining a final concentration of <0.01 mg/L. Bicarbonate-activated hydrogen peroxide is a potential technology for dye wastewater treatment that operates at an alkaline pH and at ambient temperature.

(Invited) An Artificial Leaf with a Solar-to-H2O2 Conversion Efficiency

Millions of families around the world remain vulnerable to water scarcity and have no access to drinking water. Advanced oxidation processes (AOPs) are an effective way towards water purification with qualified reactive oxygen species (ROSs) while are impeded by the high-cost and tedious process in either input of consumable reagent, production of ROS, and the pre-treatment of supporting electrolyte. Herein, we couple solar light-assisted H2O2 production from water and photo-Fenton-like reactions into a self-cyclable system by using an artificial leaf, achieving an unassisted H2O2 production rate of 0.77 μmol/(min·cm2) under 1 Sun AM 1.5 illumination. Furthermore, a large (70 cm2) artificial leaf was used for an unassisted solar-driven bicarbonate-activated hydrogen peroxide (BAP) system with recycled catalysts for real-time wastewater purification with requirements for only water, oxygen and sunlight. This demonstration highlights the feasibility and scalability of photoelectrochemical technology for decentralized environmental governance applications from laboratory benchtops to industry.

Morphology-dependent activation of hydrogen peroxide with Cu2O for tetracycline hydrochloride degradation in bicarbonate aqueous solution

The design of efficient heterogeneous catalysts in bicarbonate-activated hydrogen peroxide systems (BAP) is a hot topic in wastewater treatment. In this work, Cu2O nanoparticles with different morphologies including cubic shape (c-Cu2O), octahedron shape (o-Cu2O) and spherical shape (s-Cu2O), were applied in BAP for the first time to degrade tetracycline hydrochloride (TC). Compared with Cu2+ ions and CuO, TC degradation was boosted in the presence of Cu2O in the BAP system, with the degradation rate following the order c-Cu2O > o-Cu2O > s-Cu2O. The morphology-dependent effects could be linearly correlated with the ratio of surface oxygen species (OS), but not with the surface area or Cu(I) ratio. The c-Cu2O catalyst with exposure of (100) facets contained 76.6% OS as the active site for H2O2 adsorption and activation, while the value was much lower for o-Cu2O and s-Cu2O with dominant (111) facets. The presence of HCO3− enhanced the interactions among Cu2O, H2O2 and TC, leading to facile oxidation of Cu(I) to Cu(II) by H2O2, and the formation of various reactive species such as hydroxyl radicals and Cu(III) contributed to TC degradation. This work provides a new method for enhancing H2O2 activation with heterogeneous catalysts by crystal facet engineering.

Self-cycled photo-Fenton-like system based on an artificial leaf with a solar-to-H2O2 conversion efficiency of 1.46%

Millions of families around the world remain vulnerable to water scarcity and have no access to drinking water. Advanced oxidation processes (AOPs) are an effective way towards water purification with qualified reactive oxygen species (ROSs) while are impeded by the high-cost and tedious process in either input of consumable reagent, production of ROSs, and the pre-treatment of supporting electrolyte. Herein, we couple solar light-assisted H2O2 production from water and photo-Fenton-like reactions into a self-cyclable system by using an artificial leaf, achieving an unassisted H2O2 production rate of 0.77 μmol/(min·cm2) under 1 Sun AM 1.5 illumination. Furthermore, a large (70 cm2) artificial leaf was used for an unassisted solar-driven bicarbonate-activated hydrogen peroxide (BAP) system with recycled catalysts for real-time wastewater purification with requirements for only water, oxygen and sunlight. This demonstration highlights the feasibility and scalability of photoelectrochemical technology for decentralized environmental governance applications from laboratory benchtops to industry.

Oxidative removal of Fast Green FCF and ponceaux 4R dyes by H2O2/NaHCO3, UV and H2O2/UV processes: A comparative study

In this work, we explored the use of reactive oxygen species generated by either bicarbonate activated hydrogen peroxide (BAP), UV and UV/H2O2 system for degradation of triarylmethane dye, Fast Green FCF (FG), and azo dye Ponceau 4R (P4R). The degradation rate constant is supposed to be a pseudo-first-order. By bicarbonate activated peroxide (BAP) system which generates hydroxyl radicals and superoxide anion radical (O2-) able to attack the dyes molecules, in 20 min the conversions ware up to 65% for FG and 50% for P4R, respectively. The most efficient degradation is achieved through UV irradiation in the presence of hydrogen peroxide, where the kinetic constants increase by an order of magnitude for both dyes. The total organic carbon (TOC) data showed that for chemical oxidation of FG, the mineralization degree is 86% instead in the case of P4R, the chemical oxidation with BAP system does not lead to mineralization (mineralization degree is about 5%). In the mixture, the degradation of dyes in the BAP system occurs with higher rates for both dyes; in the photolysis, the degradation of FG is slightly increased in the mixture, while the degradation of P4R is much slower. In the case of the UV/H2O2 system, the degradation of both dyes is slower in the mixture. The results obtained by HPLC-MS led to the identification of some organic intermediates and a plausible reaction mechanism for FG and P4R degradation process was proposed.

Bicarbonate activated hydrogen peroxide with cobalt nanoparticles embedded in nitrogen-doped carbon nanotubes for highly efficient organic dye degradation

The bicarbonate-activated hydrogen peroxide (BAP) with heterogeneous catalysts has been demonstrated to have a good future for organic pollutants removal in wastewater treatment. Herein, a novel catalyst, cobalt nanoparticles encapsulated in nitrogen-doped carbon nanotubes ([email protected]) was prepared by pyrolysis of Co salt and melamine, followed by acid treatment to remove excess metallic cobalt. Combining the hollow carbon nanotube structure and Co nanoparticles, the [email protected] offers excellent catalytic performance for acid orange 7 degradation in the BAP system. High stability against cobalt ions leaching from the [email protected] was observed, which is superior to the previously reported heterogeneous catalysts·H2O2 activation mechanism by [email protected] catalyst was also proposed, in which superoxide ion and single oxygen are the dominant reactive species from H2O2 decomposition by the synergistic effect of Co(0) and N species.

Synthesis and Characterization of Co/Al-PILCs for the Oxidation of an Azo Dye Using the Bicarbonate-Activated Hydrogen Peroxide System

Synthesis and Characterization of Co/Al-PILCs for the Oxidation of an Azo Dye Using the Bicarbonate-Activated Hydrogen Peroxide System

Purification of dye wastewater using bicarbonate activated hydrogen peroxide: Reaction process and mechanisms

Advanced oxidation techniques based on H2O2 activation have recently gained lots of concern for dye wastewater treatment. A green activation approach, HCO3−-H2O2 system, was employed for dye wastewater treatment in this study, and Acid Orange II (AO7) was selected as the target dye. AO7 removal performance and decomposition mechanisms were systematically explored. Almost all of the AO7 was removed within 30 min’s processing. Relatively higher reaction kinetic rate constant was obtained at a relatively lower AO7 initial concentration, appropriately larger H2O2, and HCO3− dosages, and weak alkaline conditions. O2− was the main active substances for AO7 decomposition, and OH and 1O2 also participated in the AO7 decomposition as analyzed by different scavenger tests. The attacks of these active substances to AO7 molecules resulted in the destruction of the benzene ring, naphthalene ring, and the azo groups. Finally, the removal of chemical oxygen demand reached 72% after 60 min’s oxidation treatment. The main degradation intermediates contained salicylic acid, phenol, 1,4-benzenediol, and dibutyl phthalate; and the possible decomposition pathways of AO7 in this system were proposed. Furthermore, the removal performances of different dyes in this system were all satisfactory.

Ultrasonic-assisted citrus pectin modification in the bicarbonate-activated hydrogen peroxide system: Chemical and microstructural analysis.

The modified pectin (MP) showed the improved functional properties than the native one. The aim of present study was to develop the ultrasonic accelerated bicarbonate-hydrogen peroxide system for pectin modification to generate short fragments with advanced bioactive properties. The depolymerization effects of this system on the physicochemical properties, structural features, and bioactivity of the degraded fragments were studied systematically. The results indicated that the molecular weight of pectin was reduced drastically from 1088 kDa to 33 kDa within 50 min under an optimized condition (MH2O2-MNaHCO3 = 1:2.5, 50 °C, and ultrasound intensity = 11.4 W/cm3). The resulting fragments also showed lower degree of methoxylation and rheological viscosity. The investigation on the sample structures and active oxygen species demonstrated that the highly active O2- species generated from HCO4- of NaHCO3-H2O2 acted preferentially on the GalA backbone in the HG region, while the RG-I region was maintained; and ultrasound enhanced the degradation efficiency via both chemical effects (increasing the transformation of free radicals) and mechanical effects (disaggregating polysaccharide clusters). The atomic force microscope (AFM) imaging directly verified the branched-chain morphology of pectin and the small-strand degradation fragments. Moreover, ultrasound and NaHCO3-H2O2 treatment induced high galactose content in the degraded products, contributing to an improved inhibitory activity against A549 lung cancer cells, as shown by MTT assay.

A green strategy for simultaneous Cu(II)-EDTA decomplexation and Cu precipitation from water by bicarbonate-activated hydrogen peroxide/chemical precipitation

Classical chemical precipitation technology is inefficient for the removal of heavy metal-organic complexes from wastewater. In this study, a novel and green strategy of coupling bicarbonate-activated hydrogen peroxide (BHP) oxidation and alkaline precipitation was proposed for simultaneous decomplexation of Cu-ethylenediaminetetraacetic acid (Cu-EDTA) and Cu precipitation. The Cu-EDTA decomplexation efficiency reached 92.0% within 60 min of the BHP treatment, and the decomplexation process was spontaneous and endothermic. Reactive substances such as O2−, OH, and 1O2 were identified, and O2− was predominant in the Cu-EDTA decomplexation. The weak alkaline environment provided by bicarbonate favored the generation of the reactive substances and subsequent Cu-EDTA decomplexation. Relatively higher H2O2 dosage favored Cu-EDTA decomplexation, while excessive bicarbonate dosage inhibited the reaction. TOC removal efficiency and Cu removal efficiency reached 78.4% and 68.3% after 60 min treatment, respectively. The CuO and CuN bonds in Cu-EDTA were destroyed by the reactive substances, and a series of Cu-containing intermediates, small organic molecules such as ethanamine, ethylene glycol and butanediol, and NO3− were produced. The released Cu ions were precipitated as Cu2(OH)2CO3, CuCO3, Cu(OH)2, and CuO. Possible pathways of Cu-EDTA decomplexation in this system were proposed.

Fast decolourization of Indigo Carmine and Crystal Violet in aqueous environments through micellar catalysis

Abstract Herein we report the modulating effect of sodium dodecyl sulphate (SDS), hexadecyl-pyridinium chloride (HDPC) and octylphenol ethoxylate (Triton X100) on the degradation of indigo carmine (IC) and crystal violet (CV) in bicarbonate-activated peroxide (BAP) system. Upon the addition of surfactant/BAP “surfoxidant”, the decolourization degrees of both dyes were above 60% after 5 min, and the total organic carbon removal after 15 min varied within 44–50%. While SDS has shown rather an inhibitory effect during the oxidation of CV, HDPC and Triton promoted the oxidation of both CV and IC, particularly HDPC when a 10-fold increase of the decolourization rate was obtained. This behaviour suggests the formation of active entities –kinetic micelles- acting as nano-reactors by “enclosing” reactants in small-sized aggregates with volumes ranging from 30 to 720 nm3.

Carbonate-activated hydrogen peroxide oxidation process for azo dye decolorization: Process, kinetics, and mechanisms

Advanced oxidation processes offer effective solutions in treating wastewater from various industries. This study is the first time to investigate the potential of carbonate-activated hydrogen peroxide (CAP) oxidation process for the removal of organic pollutant from highly alkaline wastewaters. Azo dye acid orange 7 (AO7) was selected as a model pollutant. The influences of various parameters on AO7 decolorization by the CAP oxidation were evaluated. Furthermore, the active species involved in AO7 degradation were explored using scavenger experiments and electron spin resonance analysis. Additionally, AO7 degradation products by the CAP oxidation were identified to elucidate possible transformation pathways. Results showed that the CAP oxidation had better AO7 decolorization performance compared to bicarbonate-activated hydrogen peroxide method. The AO7 decolorization efficiency augmented from 3.70 ± 0.76% to 54.27 ± 2.65% when carbonate concentration was increased from 0 to 50 mM at pH 13.0, and then changed slightly with further increasing carbonate concentration to 70 mM. It increased almost linearly from 5.95 ± 0.32% to 94.03 ± 0.39% as H2O2 concentration was increased from 5 to 50 mM. Moreover, trace amount of Co(II) could facilitate AO7 decolorization by the CAP reaction. Superoxide and carbonate radicals might be the main reactive oxygen species involved in the CAP process. Finally, a possible degradation pathway of AO7 by the CAP oxidation was proposed based on the identified products.

Bicarbonate-activated hydrogen peroxide and efficient decontamination of toxic sulfur mustard and nerve gas simulants

13C NMR spectra showed that peroxymonocarbonate (HCO4−) was generated in the NaHCO3-activated H2O2 solution and pH was a key factor in its production. A cycle for the bicarbonate anion was proposed as HCO3−→HCO3 → (CO2)2*→CO2(aq)→HCO4− (H2CO4)→HCO3− (HCO3) basing on the results of NMR, electron paramagnetic resonance, chemiluminescence analysis. In this cycle, (CO2)2* was the key intermediate and (CO2)2*→2CO2+hv was the rate controlling step. Thioanisole and paraoxon, the simulants of sulfur mustard gas and nerve gas, respectively, were efficiently decontaminated by the NaHCO3-activated H2O2 solution. While HCO4− was the primary oxidant for the oxidation of thioanisole, O2− generated during the decomposition of HCO4− or H2O2 led to the secondary oxidation of the sulfide. Paraoxon was degraded in the NaHCO3-activated H2O2 solution via nucleophilic substitution by OOH− and OH−, and the degradation rate increased exponentially with increasing pH. Alkali metal ions had a catalytic effect on the degradation of paraoxon. Mustard gas and soman degraded efficiently into nontoxic products in NaHCO3-activated H2O2. A pH range of 9–10 was found to be optimum for the broad-spectrum decontamination of chemical warfare agents and other eco-toxicants using NaHCO3-activated H2O2.

Feed-back action of nitrite in the oxidation of nitrophenols by bicarbonate-activated peroxide system

In this study it was found that the nitrite anion greatly increases the oxidation rate of the substituted phenols by the bicarbonate-activated peroxide (BAP) system at ambient temperature. This feed-back effect was investigated in the BAP oxidation of 2-amino-4-nitrophenol and 4-nitrophenol, where the kinetic analysis showed that the rate determining step was the elimination of a nitro group as nitrite. Complementary oxidation experiments with 2-aminophenol in BAP system, performed in the presence/absence of sodium nitrite confirmed the catalytic role of this anion. High concentrations of nitrite/BAP prevented formation of polymeric species and favoured the degradation to aliphatic fragments such as 3-oxobutanoic and acetic acid. Indirect evidence suggested in-situ generation of reactive oxygen species (ROS), other than hydroxyl, peroxyl and carbonate radicals, during the nitrite/BAP oxidation. Formation of additional ROS – peroxynitrite and nitrosoperoxycarbonate – may account the synergistic action of nitrite/BAP system. The estimated value of the apparent rate constant of the autocatalytic step for 2-amino-4-nitrophenol (kapp=(4.97±0.19)×103M−3s−1) demonstrates that fast degradation of this oxidation-resistant phenolic dye is feasible even in ambient conditions. These findings can be exploited for developing clean, cost-effective methods for the removal of phenolic dyes as alternative to current advanced oxidation processes.