Degradation Of Acetaminophen Research Articles

Mechanism of action of the heterojunction structure of the photocatalyst ZnO-g-C3N4@TiO2 and its application to the degradation of acetaminophen

Acetaminophen, a non-steroidal anti-inflammatory drug, is one of the most abundant drugs and personal care products in natural water bodies, and the amount of acetaminophen (APAP) has increased dramatically during COVID-19. Photocatalysis is an advanced oxidation technology with high degradation and mineralization capacity and is environment-friendly, and it is important to design new photocatalysts to improve APAP removal efficiency and investigate the mechanism of photocatalytic oxidation. In this study, two kinds of photocatalysts, g-C3N4@TiO2 (gT) and g-C3N4@TiO2@ZnO (gTZ) were prepared by the sol–gel method and sol–gel heat condensation method. Secondly, they were systematically characterized by SEM, XRD, BET, XPS, UV–vis DRS, steady-state photoluminescence (PL) spectroscopy, and contact angle, and their energy band structures were analyzed and inferred to be composite type II heterojunction photocatalysts. The photocatalytic efficiency was investigated by degrading the pollutants APAP and azo dyes. The degradation rates of gT and gTZ for APAP were 70.6% and 92.4% under 254 nm UV light, respectively. Finally, the main radicals of gTZ for the degradation of APAP were hydroxyl radicals (•OH), which were investigated by the free radical capture, and then eight intermediates for the photocatalytic degradation of APAP were obtained by HPLC-MS/MS, which led to the photocatalytic degradation pathway.

Photocatalytic Degradation of Acetaminophen in Aqueous Environments: A Mini Review.

Over the past few decades, acetaminophen (ACT), a typical nonsteroidal anti-inflammatory drug (NSAID), has gained global usage, positioning itself as one of the most extensively consumed medications. However, the incomplete metabolism of ACT leads to a substantial discharge into the environment, classifying it as an environmental contaminant with detrimental effects on non-target organisms. Various wastewater treatment technologies have been developed for ACT removal to mitigate its potential environmental risk. Particularly, photocatalytic technology has garnered significant attention as it exhibits high efficiency in oxidizing and degrading a wide range of organic pollutants. This comprehensive review aims to systematically examine and discuss the application of photocatalytic technology for the removal of ACT from aqueous environments. Additionally, the study provides a detailed overview of the limitations associated with the photocatalytic degradation of ACT in practical applications, along with effective strategies to address these challenges.

Cu3(hexaamino triphenylhexane)2/reduced graphene oxide composites with boosting electron-transfer properties for acetaminophen electrocatalytic degradation

Electron-transfer properties, as great contributors for electrocatalytic oxidation on the anode, are crucial to pollution degradation. The strong relationship between electron-transfer properties and active species (such as radicals) generation of anode catalysts suggests a new strategy for pollution-degradation efficiency improvement. In this study, a novel composite of Cu3(hexaamino triphenylhexane)2 [Cu3(HITP)2] and reduced graphene oxide (RGO) was synthesized to construct electron-transfer pathways between the two layers. Benefiting from the connection formed through RGO-O-N-Cu, the electron transfer from RGO to Cu3(HITP)2 was accelerated. The resettled charge distribution led the C atoms in the RGO layer, and the Cu and C atoms in Cu3(HITP)2 layer acted as the main surface active sites. O2•–, 1O2, and reactive chlorine were then triggered to boost the degradation of acetaminophen. The source of O2•– and 1O2 was more likely from surface oxygen groups rather than dissolved O2. Overall, this research provided a perspective proof of conductive Cu3(HITP)2/RGO composite construction with 2D/2D structure for electrocatalytic-oxidation improvement.

SUSTAINABLE BIOREMEDIATION OF ACETAMINOPHEN USING BACTERIA: A CRITICAL REVIEW

Acetaminophen is a common antipyretic and analgesic pharmaceutical contaminant and has become one of the most emerging contaminants in the environment. Bioremediation is the suitable method to degrade acetaminophen as it is sustainable, mimics nature and is low-cost. The bioremediation of acetaminophen is performed by identifying the bacterial characteristics and the source of the bacteria involved in the degradation of acetaminophen. Based on this review study, gram-negative bacteria showed the highest efficiency in degrading acetaminophen by Pseudomonas aeruginosa strain HJ1012 and Cupriavidus necator with an efficiency of 99% and 100%, respectively. In addition, synergistic or antagonistic interaction among bacteria in mixed culture is a gap of study. The findings from the previous study showed that the optimum conditions are pH 7.0, temperature ranges between 30–40°C, and a poor culture medium of minimal salt solution. Furthermore, the study sheds light on enzyme involvement and characterisation of acetaminophen degradation pathways toward less harmful intermediates are addressed in order to achieve sustainable development goals through environmental security and health safety. These identified research gaps offer fundamental knowledge and shed insight into upcoming mechanism and application studies.

Enhanced organic contaminants degradation via coupling molybdenum powder with tripolyphosphate in Fe(Ⅱ)-based peroxymonosulfate activation

To overcome the challenges of pH application range, slow cycling of Fe(III)/Fe(II) and low oxidant activation efficiency, we propose a strategy of combining molybdenum powder (Mo) cocatalyst with sodium tripolyphosphate (STPP) to accelerate peroxymonosulfate (PMS) activation and achieve efficient degradation of acetaminophen (ACT). The ACT degradation efficiency and rate were 99.7% and 0.065 min−1, respectively, which were significantly improved compared to the system without Mo due to the abundance of active sites of Mo that accelerate the dissolved Fe species complexed with STPP. Additionally, the degradation efficiency remained above 95%, and there was only a slight change in morphology after 5 cycles, demonstrating the excellent co-catalytic performance and reusability of Mo. The several oxidizing active substances (OH, SO4−, 1O2, Fe(Ⅳ)) were synergistically worked for ACT removal, which were investigated the origin and activation mechanism via multiple measures. Satisfactorily, the system exhibited desirable anti-jamming capability and superiority in the removal of various contaminants. ACT degradation intermediate products were measured and proposed three degradation pathways according to the results of liquid chromatograph-mass spectrometer (LC-MS). The development of combining Mo and STPP for organic pollutant degradation is significant in broadening the application range of PMS-AOPs in environmental remediation.

Chicken litter-derived catalyst for persulfate activation to remove acetaminophen: An organic-waste-to-wealth strategy

Extracting value from organic waste (e.g., chicken litter) to deliver high-end products should become an essential disposal strategy in the future. Herein, chicken litter was employed as the feedstock to produce a catalyst for peroxydisulfate (persulfate) activation for potential wastewater treatment applications. Three different chicken litter samples were prepared to investigate the effects of inorganic species contained in chicken litter on the catalyst performance: (1) chicken litter without pretreatment, (2) chicken litter washed with 0.05 M HCl, and (3) chicken litter washed with 0.25 M HCl. When the chicken litter-derived catalyst was used for persulfate activation, acetaminophen (ACP) was effectively removed, suggesting a synergic effect. When utilizing the catalyst derived from chicken litter without undergoing HCl pretreatment, the degradation efficiency of ACP reached 84.1%, surpassing that of the pretreated catalysts. The ACP degradation efficiency further improved to 93.8% and 93.9% with increased catalyst dose and persulfate concentration. The reactive oxygen species present during the ACP degradation were analyzed using chemical scavengers. O2•− radicals showed a dominant effect on ACP degradation. ACP degradation was greatly suppressed when HCO3− and humic acid coexisted. Furthermore, combustible byproducts of the catalyst production process can be potentially used to supply energy to the process, which would help lower the overall energy requirement.

Alkaline lignin-derived N-doped biochars as peroxymonosulfate activators for acetaminophen degradation: Performance and catalytic bridging mediated Electron-Transfer mechanism

Carbon-catalyzed persulfate activation processes are promising techniques for oxidizing aqueous organic pollutants, while high-performance and low-cost carbocatalysts are urgently needed. To address this issue, nitrogen-doped biochar catalyst from alkaline lignin was developed to activate peroxymonosulfate (PMS) for acetaminophen (APAP) degradation. The optimized N-doped biochar achieved a complete removal of 50 ppm APAP within 15 min under the conditions of 0.1 g/L catalyst and 0.5 mM oxidant across a wide pH range of 4–10. Notably, the optimized N-doped biochar exhibits remarkable stability, retaining 75% APAP removal after four cycles. Moreover, a comprehensive investigation, including quenching tests, electron paramagnetic resonance measurements, and electrochemical analyses, elucidated the electron-transfer mechanism involved in the nonradical N-doped biochar/PMS system. Surprisingly, the results indicated that the primary species responsible for APAP oxidation was an activated state of N-doped biochar with electron deficiency generated from the interactions between the catalyst and PMS. This work not only provides cost-effective and high-performance biochar catalyst for selectively removing APAP from actual water body, but also sheds new light on the electron-transfer mechanism involved in nonradical carbon/PMS systems.

Optimized Cu2O-{100} facet for generation of different reactive oxidative species via peroxymonosulfate activation at specific pH values to efficient acetaminophen removal

Abstract Activation of peroxymonosulfate (PMS) to degrade persistent organic contaminants has received increasing attention in wastewater purification. In this study, Cu2O catalysts with different exposed crystal facets were prepared, characterized, and evaluated for acetaminophen (ACE) degradation through PMS activation. The experimental results showed that cubic Cu2O with {100} facets exhibited remarkable activity on ACE removal by PMS activation in wide pH range of 3–11. DFT calculations indicated that Cu2O-{100} displayed higher electron transfer efficiency and PMS adsorption ability, further improving PMS activation. The radicals quenching experiments and electron paramagnetic resonance (EPR) results illustrated that singlet oxygen (1O2) was dominant reactive oxidative species (ROSs) during oxidation reactions and the relevant generation pathways were distinctly elucidated. Finally, the possible PMS activation mechanisms were discussed for ACE degradation in a wide pH range. This study will provide new insights to disclose PMS-based advanced oxidation processes (AOPs), and offer a new approach for wastewater purification by non-radical reactions.

Photocatalytic Activity of the Blends Based on TiO2 Nanoparticles and Reduced Graphene Oxide for Degradation of Acetaminophen.

The aim of this work is to highlight the influence of blends based on TiO2 nanoparticles and reduced graphene oxide (RGO) on the photodegradation of acetaminophen (AC). To this end, the catalysts of TiO2/RGO blends with RGO sheet concentrations equal 5, 10, and 20 wt. % were prepared by the solid-state interaction of the two constituents. The preferential adsorption of TiO2 particles onto the RGO sheets' surfaces via the water molecules on the TiO2 particle surface was demonstrated by FTIR spectroscopy. This adsorption process induced an increase in the disordered state of the RGO sheets in the presence of the TiO2 particles, as highlighted by Raman scattering and scanning electron microscopy (SEM). The novelty of this work lies in the demonstration that TiO2/RGO mixtures, obtained by the solid-phase interaction of the two constituents, allow an acetaminophen removal of up to 95.18% after 100 min of UV irradiation. This TiO2/RGO catalyst induced a higher photodegradation efficiency of AC than TiO2 due to the presence of RGO sheets, which acted as a capture agent for the photogenerated electrons of TiO2, hindering the electron-hole recombination. The reaction kinetics of AC aqueous solutions containing TiO2/RGO blends followed a complex first-order kinetic model. Another novelty of this work is the demonstration of the ability of PVC membranes modified with Au nanoparticles to act both as filters for the removal of TiO2/RGO blends after AC photodegradation and as potential SERS supports, which illustrate the vibrational properties of the reused catalyst. The reuse of the TiO2/RGO blends after the first cycle of AC photodegradation indicated their suitable stability during the five cycles of pharmaceutical compound photodegradation.

Catalytic behavior of nitrous acid for acetaminophen transformation during the freezing process

This study demonstrates the transformation of acetaminophen by reactive nitrous acid in a frozen solution and its abnormal stoichiometry. The chemical reaction between acetaminophen and nitrous acid (AAP/NO2− system) was negligible in the aqueous solution; however, the reaction rapidly progressed if the solution started to freeze. The ultrahigh performance liquid chromatography–electrospray ionization tandem mass spectrometry measurements showed that polymerized acetaminophen and nitrated acetaminophen were formed in the proceeding reaction. Electron paramagnetic resonance spectroscopy measurements showed that nitrous acid oxidized acetaminophen via a one-electron transfer reaction producing acetaminophen-derived radical species, which is the cause of acetaminophen polymerization. We demonstrated that a relatively smaller dose of nitrite than acetaminophen caused significant acetaminophen degradation in the frozen AAP/NO2− system and revealed that the dissolved oxygen content notably affected acetaminophen degradation. We showed that the reaction occurs in a natural Arctic lake matrix (nitrite and acetaminophen spiked). Considering that the freezing phenomenon is common in the natural environment, our research provides a possible scenario for the freezing chemistry of nitrite and pharmaceuticals in environmental chemistry.

Deep Eutectic Solvent-Assisted Synthesis of a Strontium Tungstate Bifunctional Catalyst: Investigation on the Electrocatalytic Determination and Photocatalytic Degradation of Acetaminophen and Metformin Drugs

In this work, we propose a modified solid-state approach for the sustainable preparation of a SrWO4 bifunctional catalyst using thymol-menthol-based natural deep eutectic green solvents (NADESs). Various spectroscopic and morphological techniques analyzed the as-synthesized SrWO4 particles. Acetaminophen (ATP) and metformin (MTF) were selected as the model drug compounds. The electrochemical detection and photocatalytic degradation of ATP and MTF upon ultraviolet-visible (UV-vis) light irradiation in the presence of as-prepared SrWO4 particles as an active catalyst are examined. The present study displayed that the proposed catalyst SrWO4 has enhanced catalytic activity in achieving the optimum experimental conditions, and linear ranges of ATP = 0.01-25.90 μM and MTF = 0.01-25.90 μM, a lower limit of detection (LOD) value (ATP = 0.0031 μM and MTF = 0.008 μM), and higher sensitivity toward ATP and MTF determination were obtained. Similarly, the rate constant was found to be k = ATP = 0.0082 min-1 and MTF = 0.0296 min-1 according to the Langmuir-Hinshelwood model, benefitting from the excellent synergistic impact of the SrWO4 catalyst toward the photocatalytic degradation of the drug molecule. Hence, this work offers innovative insights into the applicability of the as-prepared SrWO4 bifunctional catalyst as an excellent functional material for the remediation of emerging pollutants in water bodies with a recovery range of 98.2-99.75%.

Atomically dispersed Cu-N3 on hollow spherical carbon nitride for acetaminophen degradation: Generation of 1O2 from H2O2

Discharge of recalcitrant pharmaceuticals into aquatic systems has caused severe impacts on public health and ecosystem. Advanced oxidation processes (AOPs) are effective for eliminating these refractory pollutants, for which single-atom catalysts (SACs) become the state-of-the-art materials owing to the maximized exposure of active metal sites. In this work, hollow spherical graphitic carbon nitride (hsCN) was fabricated to incorporate copper species to develop Fenton-like catalysts for acetaminophen (ACT) removal. Through pyrolysis of supramolecular assemblies derived from melamine-Cu complex and cyanuric acid, single atom Cu-N3 sites were anchored on hsCN by N-coordination to obtain SACu-hsCN. In virtue of the atomically dispersed Cu-N3 sites as well as the hollow structure of hsCN providing smooth channels for the interactions between single Cu atoms and reactants, the optimal 5.5SACu-hsCN removed 94.8% of ACT after 180 min of Fenton-like reactions, which was superior to that of 5.5AGCu-hsCN with aggregated Cu particles on hsCN (56.7% in 180 min). Moreover, 5.5SACu-hsCN was still active after four cycles of regeneration. The mechanism investigation demonstrated that both hydroxyl radicals (OH) and singlet oxygen (1O2) contributed to ACT degradation in 5.5SACu-hsCN/H2O2 system, in which non-radical 1O2 played the dominant role.

Ultra-sonic assisted synthesis of nitrogen rich-g-C3N5 @MoO3 Z-scheme system for efficient removal of acetaminophen in aqueous environment via photo- and electro-catalytically

Herein, a nitrogen-rich g-C3N5 @MoO3 hybrid material has been prepared via an ultrasonic method, and its photo- and electro-catalytic properties were confirmed through the degradation and determination of acetaminophen (AP) were reported. The as-prepared materials were confirmed using some analytical techniques including XRD, FT-IR, DRS, BET, XPS, SEM, TEM, EDX, and mapping analysis. In addition to that, the electron transfer properties as well as recombination were confirmed by photocurrent and impedance spectroscopy. The optimized g-C3N5 @MoO3 (10%) photocatalyst shows an excellent electron transfer and reduces the recombination rate of electron and hole pairs which was confirmed by the degradation of AP in the aqueous environment. The degradation rate and kinetic constant were calculated and presented. The radical scavengers test was investigated and proposed the degradation mechanism of g-C3N5 @MoO3 (10%) via Z-scheme. In addition, the g-C3N5 @MoO3 (10%) catalyst was fabricated on GCE and utilized for the detection of AP via electrochemically (CV, DPV, and impedance). The limit of detection and sensitivity of the prepared g-C3N5 @MoO3 were investigated thoroughly and presented. The electro-catalytic mechanism was also proposed and studied. These higher photo- and electro-catalytic properties of g-C3N5 @MoO3 (10%) are due to the higher surface area and synergistic effect between both g-C3N5 and MoO3. Hope this method and fabrication of materials could be an effective way to prepare new nanomaterials with high performance.

Augmented photocatalytic degradation of Acetaminophen using hydrothermally treated g-C3N4 and persulfate under LED irradiation

Photocatalytic degradation of organic pollutants in water using graphitic carbon nitride and persulfate under visible light (g-C3N4/PS system) has been studied. Here, we demonstrate augmentation of photocatalytic degradation of Acetaminophen (AAP) using hydrothermally treated g-C3N4 and PS under 400 nm LED irradiation (HT-g-C3N4/PS system). A pseudo-first-order rate constant (kobs, 0.328 min−1) for degradation of AAP using HT-g-C3N4/PS system was determined to be 15 times higher compared to g-C3N4/PS system (kobs, 0.022 min−1). HT-g-C3N4 showed a higher surface area (81 m2/g) than g-C3N4 (21 m2/g). Photocurrent response for HT-g-C3N4 was higher (1.5 times) than g-C3N4. Moreover, Nyquist plot semicircle for HT-g-C3N4 was smaller compared to g-C3N4. These results confirm effective photoelectron-hole separation and charge-transfer in HT-g-C3N4 compared to g-C3N4. AAP degradation using HT-g-C3N4/PS system was significantly inhibited with O2.− and h+ scavengers compared to 1O2,SO4.− and HO. scavengers. ESR results revealed O2.− formation in HT-g-C3N4/PS system. Moreover, photocurrent measurements reveal AAP oxidation by h+ of HT-g-C3N4 was effective than g-C3N4. HT-g-C3N4 was reused for five cycles in HT-g-C3N4/PS system. Augmented photocatalytic degradation of AAP by HT-g-C3N4/PS system compared to g-C3N4/PS is attributed to effective photoelectron hole separation of HT-g-C3N4 that generates O2.− and h+ for oxidation of pollutant. Importantly, electrical energy per order (EEO) was 7.2 kWh m−3 order−1. kobs for degradation of AAP in simulated groundwater and tap water were determined as 0.029 and 0.035 min−1, respectively. Degradation intermediates of AAP were proposed. AAP ecotoxicity against marine bacteria Aliivibrio fischeri was completely removed after treatment by HT-g-C3N4/PS system.

Single-atom Ag-loaded carbon nitride photocatalysts for efficient degradation of acetaminophen: The role of Ag-atom and O2

Carbon nitride has been extensively used as a visible-light photocatalyst, but it has the disadvantages of a low specific surface area, rapid electron–hole recombination, and relatively low light absorbance. In this study, single-atom Ag was successfully anchored on ultrathin carbon nitride (UTCN) via thermal polymerization, the catalyst obtained is called AgUTCN. The Ag hardly changed the carbon nitride's layered and porous physical structure. AgUTCN exhibited efficient visible-light photocatalytic performances in the degradation of various recalcitrant pollutants, eliminations of 85% were achieved by visible-light irradiation for 1 hr. Doping with Ag improved the photocatalytic performance of UTCN by narrowing the forbidden band gap from 2.49 to 2.36 eV and suppressing electron–hole pair recombination. In addition, Ag doping facilitated O2 adsorption on UTCN by decreasing the adsorption energy from −0.2 to −2.22 eV and favored the formation of O2·−. Electron spin resonance and radical-quenching experiments showed that O2·− was the major reactive species in the degradation of Acetaminophen (paracetamol, APAP).

Effective photodegradation of acetaminophen by V2O5 nanocrystals under simulated solar radiation

Vanadium pentoxide (V2O5) can absorb light in both ultraviolet (UV) and visible regions making it an important material for the photocatalytic degradation of environmental pollutants under solar radiation. Herein, V2O5 nanocrystals have been chemically synthesized using two different capping agents viz. cetyl trimethyl ammonium bromide (CTAB) and polyvinylpyrrolidone (PVP), and they are found to be effective photocatalysts under simulated solar radiation (SSR) for degradation of acetaminophen, which is an emerging environmental pollutant. The CTAB-capped and PVP-capped V2O5 nanocrystals degraded 65% and 71% of aqueous acetaminophen after 270 min of irradiation, respectively. The chemical oxygen demand (COD) of the acetaminophen-polluted water decreased significantly after photocatalysis. The photocatalysts were found to be usable for two consecutive cycles without significant changes in degradation efficiencies. Moreover, the solution pH influenced photocatalysis. The mechanism of the photocatalysis process has been presented considering the split nature of the V2O5 conduction band.

Visible light photocatalytic activity of a FeCo metal-organic framework for degradation of acetaminophen and 2,4-dichlorophenoxyacetic acid and a nematode-based ecological assessment

The present work reports the solvothermal synthesis of a bimetallic (FeCo) metal-organic framework (MOF) for the sunlight-driven photocatalytic degradation of acetaminophen (AAP) and 2,4-dichlorophenoxyacetic acid (2,4-D). The FeCo-MOF was confirmed by various analytical techniques. The as-prepared FeCo-MOF displayed improved light absorbance in the visible region and a bandgap energy of 1.73 eV. Photoluminescence spectra showed that the FeCo-MOF exhibited a lower charge carrier recombination rate than bare Fe- or Co-MOFs. The FeCo-MOF achieved a maximum AAP conversion rate (rate constant 0.031/min) of 97.4% in 180 min than bare Fe-MOF (66%) or Co-MOF (73%). A scavenger study showed that the superoxide anion radicals were responsible for the degradations of AAP and 2,4-D. The catalyst proved stable after five recycles with no change in AAP degradation efficiency. On the other hand, under the same conditions, the FeCo-MOF photodegraded 2,4-D by 79.8%. A kinetic study showed that the degradations of AAP and 2,4-D exhibited pseudo-first-order kinetics. In addition, the ecotoxicity results showed that degraded 2,4-D altered the survival, development, reproduction, intracellular redox status, and expression pattern of stress-responsive genes in the Caenorhabditis elegans model.

Electrochemical activation of peroxymonosulfate by 3D printed blue TiO2 nanotube arrays reactive electrochemical membrane for efficient degradation of acetaminophen

Electrocatalytic technology (EC) is a promising strategy for peroxymonosulfate (PMS) activation due to its environmental safety and energy conservation. Herein, 3D printed blue TiO2 nanotube arrays (3DP-BTNAs) reactive electrochemical membranes (REM) were designed as anode and cathode in EC and EC/PMS systems. EC/PMS system displayed superior performance for acetaminophen (ACT) degradation and detoxication. The ACT degradation in EC/PMS system was 3.70 times faster than that in EC system. Quenching experiments suggested that singlet oxygen (1O2) mediated nonradical pathway was responsible for ACT degradation in EC/PMS system, while hydroxyl radical (•OH) was the predominant reactive oxygen species (ROS) in EC system. Our study first provided direct evidence that PMS activation on cathode was mainly triggered by superoxide radical (O2•-). PMS was reduced by O2•- derived from O2 reduction on cathode, and subsequently converted into ROS for organics oxidation. However, PMS tended to adsorb on anode and formed 3DP-BTNAs-PMS* complex for organics degradation. The influencing factors (e.g., PMS dosage, flow rate) on ACT degradation in EC/PMS system were evaluated, and the obtained optimal kinetic constant and lowest energy consumption were 0.135 min−1 and 0.27 Wh/L, respectively. In addition, eight degradation products were identified and possible degradation pathways of ACT were proposed to be the cleavage of C-N bonds and benzene ring. This study is dedicated to the rational design of highly porous REM material by 3DP technology for wastewater treatment and the in-depth mechanism of PMS activation over BTNAs electrode in EC/PMS system.

Enhancing Removal of Pollutants by Combining Photocatalysis and Photo-Fenton Using Co, Fe-Doped Titanate Nanowires

Aiming to improve their photocatalytic performance, titanate nanowires (TNW) were modified by Fe and Co (co)-doping, FeTNW, CoTNW and CoFeTNW samples, using a hydrothermal methodology. XRD characterization agrees with the existence of Fe and Co in the lattice structure.and the existence of Co2+ together with the presence of Fe2+ and Fe3+ in the structure was confirmed by XPS. The optical characterization of the modified powders shows the impact of the d-d transitions of both metals in the absorption properties of TNW, mainly in the creation of additional 3d energetic levels within the prohibited zone. The effect of the doping metal(s) in the recombination rate of photo-generated charge carriers suggests a higher impact of Fe presence when compared to Co. The photocatalytic characterization of the prepared samples was evaluated via the removal of acetaminophen. Furthermore, a mixture containing both acetaminophen and caffeine, a well-known commercial combination, was also tested. CoFeTNW sample was the best photocatalyst for the degradation of acetaminophen in both situations. A mechanism for the photo-activation of the modified semiconductor is discussed and a model proposed. It was concluded that both Co and Fe are essential, within the TNW structure, for the successful removal of acetaminophen and caffeine.

A continuous photo-Fenton-like process using persulfate salts for the degradation of acetaminophen under solar irradiation at circumneutral pH

The demand for sustainable and feasible water treatment technologies (WTT) increases with the growing realization of the magnitude of the damage that our indiscriminate wastewater disposal strategy has caused the Environment. Considering the increasing costs of energy, the development of solar-driven processes is key to ensuring the economic feasibility of WTT for industries of all sizes. In this direction, this paper reports the development of a photo-Fenton-like system based on the persulfate ion and the use of solar irradiation as its coactivator for use in continuous processes. Using acetaminophen as model contaminant (C0 = 5 ppm), we showed that under optimal conditions and circumneutral pH (pH ∼5.6), a removal of 94% was achievable with a residence time of 3.3 min. Economically, this translates into a collector area per order of 11.4 m2/(m3 order), in line with the best numbers found in the literature. We showed that this was achieved due to the improved concentration of sulfate radicals, SO4•−, formed in the system, when compared to the same process carried out in a small-scale batch reactor. Our results, obtained under controlled conditions using a solar simulator, were validated under natural sunlight, confirming the feasibility of our proposed intensification strategy.