Mineralization Of Acetaminophen Research Articles

Investigation of CuCoFe-LDH as an efficient and stable catalyst for the degradation of acetaminophen in heterogeneous electro-Fenton system: Key operating parameters, mechanisms and pathways

Pharmaceuticals, as anthropogenic pollutants in a wide range of water sources, generally require specific treatment methods for degradation. A trimetallic layered double hydroxide (CuCoFe-LDH) was successfully fabricated by coprecipitation and applied as a novel heterogeneous electro-Fenton (EF) catalyst for the degradation of acetaminophen (ACT) from aqueous environments. The EF experiments showed that the CuCoFe-LDH/EF process achieved 100% of ACT degradation efficiency within 60 min at pH = 5, catalyst dosage of 0.50 g/L, current density of 10 mA/cm2 and initial ACT concentration of 20 mg/L. An impressive (>80%) mineralization of ACT was obtained over a wide pH range (pH 3–9) after 180 min. Meanwhile, the role of ·OH and O2.- were certified by radical quenching experiments and electron paramagnetic resonance (EPR) analysis. Through mechanism exploration, the coexistence of Cu and Co on Fe-based LDHs can accelerate the interfacial electron transfer and promote the formation of the reactive oxygen species (ROS), thus facilitating the EF process. Furthermore, the degradation by-products and possible degradation pathways of ACT in the CuCoFe-LDH/EF process were proposed. The reusability test and the treatment of various typical organic pollutants experiments indicated that the CuCoFe-LDH/EF process has excellent stability and broad application prospects. This work provides a valuable reference for the treatment of pharmaceuticals by the heterogeneous EF process in a wide range of pH.

Heterogeneous catalytic ozonation and peroxone-mediated removal of Acetaminophen using natural and modified hematite-rich soil, as efficient and environmentally friendly catalysts

Hormuz Red Soil (HRS), as a naturally hematite-containing mineral was used to enhance the catalytic ozonation process (COP) of Acetaminophen (ACT) elimination. The surface properties and particle size of HRS mainly composed of ɑ-Fe2O3 were modified via calcination (C-HRS) demonstrating notable catalytic activity. The catalytic activity of C-HRS was evaluated for the ozonation of ACT under various conditions. Complete degradation of 50 mg L−1 ACT was obtained within 10 min at natural conditions with 1.0 g L−1 of C-HRS which was > 10 times faster than single ozonation process (SOP). The C-HRS accelerated the decomposition of ozone to hydroxyl radical on the catalyst’s surface. Moreover, the C-HRS efficiently catalyzed the peroxone reaction for the degradation and mineralization of ACT. The C-HRS exhibited high stability and reusability in consecutive catalytic cycles. This work offers a new, effective, and low-cost catalyst for accelerating of ozone decomposition that can be used in oxidation of pollutants.

Fast mineralization of acetaminophen by highly dispersed Ag-g-C3N4 hybrid assisted photocatalytic ozonation

Highly dispersed Ag-g-C3N4 hybrid was synthesized successfully by a simple calcination method in present study. The samples were characterized by TEM, XRD, XPS, BET and UV–vis DRS. The results indicate that Ag element are existent as metallic silver and highly dispersed in the matrix of g-C3N4 nanosheet. It was used as active catalyst for photocatalytic ozonation of acetaminophen (ACE) (solar light/Ag-g-C3N4/O3). The results showed that the apparent rate constant of mineralize ACE by solar light/4% Ag-g-C3N4/O3 during 120 min is almost 2 times as large as that with solar light/g-C3N4/O3. The mechanism of photocatalytic ozonation with 4% Ag-g-C3N4 was further confirmed. In this system, Ag acts as not only a good photo-generated electron acceptor for photocatalysis but also a beneficial decomposition center for ozone. Subsequently, holes and hydroxyl radicals both make contribution to the mineralization of ACE in solar light/4% Ag-g-C3N4/O3 process. A superior synergistic effect was observed in mineralization of ACE according to the synergy index of 5.3. Furthermore, Effects of various pH values and silver contents on the ACE mineralization were evaluated. The pathway of ACE degradation in photocatalytic ozonation system with 4% Ag-g-C3N4 was also proposed.

The accelerated biodegradation and mineralization of acetaminophen in the H2O2-stimulated upflow fixed-bed bioreactor (UFBR)

The biodegradation and mineralization of acetaminophen (ACT) was evaluated in the upflow fixed-bed bioreactor (UFBR) inoculated with a biomass containing mixture of Pseudomonas spp. and Bacillus spp. as the dominant bacteria under H2O2 stimulation. The effect of various main operational variables was evaluated on the performance of the UFBR for ACT removal. The maximum ACT removal was obtained at the H2O2:ACT molar ratio of 14. H2O2 induced the bacteria in biofilm for the in-situ generation of peroxidase resulted in the acceleration of ACT decomposition into more biodegradable intermediates. Over 99% of ACT and 72% of its TOC at initial ACT concentrations up to 300 mg/L could be eliminated under optimum H2O2:ACT molar ratio in the batch UFBR within 12 h recirculation time. The specific biodegradation rate of ACT increased from 1.0 to 4.1 mg ACT/gbiomass.h when the inlet loading rate was increased from 8.3 to 41.7 g ACT/m3.h. In addition, the complete biodegradation and TOC removal of ACT was observed in the continuous UFBR at the hydraulic retention time of 6 h and the presence of 1–20 g/L salinity without inhibition. The presence of H2O2 could efficiently stimulate the production of bacterial peroxidase, which in turn resulted in the acceleration of ACT biodegradation and mineralization. Therefore, the H2O2-stimulated UFBR is an efficient and viable technique for in-situ production of peroxidase used for acceleration of ACT biodegradation.

Synergistic effect of ferrous ion and copper oxide on the oxidative degradation of aqueous acetaminophen at acid conditions: A mechanism investigation

A synergistic effect of Fe(II) and copper oxide (CuO) was observed on the degradation of acetaminophen (ACT) in the presence of O2. The results showed that 89% of ACT (50mg/L) was degraded within 6h by 10mM Fe2+ with 5g/L CuO powder at pH 3.0, among which about 30% of ACT was mineralized. The sorbed Fe(II) on the CuO surface which is more reactive than the dissolved Fe(II) was capable of reducing both Cu(II) and O2. The resulting Cu(I) significantly accelerated the destruction of ACT by serving as an electron-mediator between the sorbed Fe(II) and O2. In addition, the hydrogen peroxide (H2O2), hydroxyl radical (OH) and superoxide anion radical (O2−) were identified as the main reactive oxygen species (ROSs) generated in Fe(II)/CuO suspension by Electron paramagnetic resonance (EPR) technique and quenching studies; however, only OH was found to have caused the decomposition and mineralization of ACT. First O2− was generated by reduction of O2 through a one-electron transfer pathway. Then the generated O2− mediated the production of H2O2, which further decomposed into OH by Cu(I)- and Fe(II)-catalyzed Fenton reactions. The effects of Fe(II) concentration, CuO dose, solution pH and the degradation pathway were investigated, respectively.

Oxidation of acetaminophen in the contaminated water using UVC/S 2 O 8 2− process in a cylindrical photoreactor: Efficiency and kinetics of degradation and mineralization

Acetaminophen (ACT) is widely used as an important antipyretic drug around the world and is frequently found in the water as an emerging contaminant. The focus of this study was on demonstrating the degradation and mineralization of ACT using the UVC/S2O82− process in a cylindrical photoreactor under different experimental conditions. The results indicated that the ACT degradation increased from 7% to 83% within 60 min when the solution pH was decreased from 10 to 3. The pseudo-first-order rate constant of ACT degradation at initial concentrations of 25, 50 and 100 mg/L in aqueous solution observed to be 1.20, 1.35 and 1.5 mg/L min, respectively, at optimum solution pH of 3 and S2O82− dosage of 0.36 g/L. The mineralization degree of min 50 mg/L ACT in the UVC/S2O82− process within 90 min under optimum operational conditions was 84.3% in distilled water and 78.5% in tap water. The oxidation by sulfate radical was the main mechanism involved in the degradation of ACT in the UVC/S2O82− process. Accordingly, it can be concluded that the UVC/S2O82− process is an efficient process for degradation and mineralization of such pharmaceutical compounds as ACT.

Correlation between degradation pathway and toxicity of acetaminophen and its by-products by using the electro-Fenton process in aqueous media

The evolution of the degradation by-products of an acetaminophen (ACE) solution was monitored by HPLC-UV/MS and IC in parallel with its ecotoxicity (Vibrio fischeri 81.9%, Microtox® screening tests) during electro-Fenton (EF) oxidation performed on carbon felt. The aromatic compounds 2-hydroxy-4-(N-acetyl) aminophenol, 1,4-benzoquinone, benzaldehyde and benzoic acid were identified as toxic sub-products during the first stage of the electrochemical treatment, whereas aliphatic short-chain carboxylic acids (oxalic, maleic, oxamic, formic, acetic and fumaric acids) and inorganic ions (ammonium and nitrate) were well identified as non-toxic terminal sub-products. Electrogenerated hydroxyl radicals then converted the eco-toxic and bio-refractory property of initial ACE molecule (500 mL, 1 mM) and subsequent aromatic sub-products into non-toxic compounds after 2 h of EF treatment. The toxicity of every intermediate produced during the mineralization of ACE was quantified, and a relationship was established between the degradation pathway of ACE and the global toxicity evolution of the solution. After 8 h of treatment, a total organic carbon removal of 86.9% could be reached for 0.1 mM ACE at applied current of 500 mA with 0.2 mM of Fe2+ used as catalyst.

Copper–catalyzed activation of molecular oxygen for oxidative destruction of acetaminophen: The mechanism and superoxide-mediated cycling of copper species

In this study, the commercial zero-valent copper (ZVC) was investigated to activate the molecular oxygen (O2) for the degradation of acetaminophen (ACT). 50 mg/L ACT could be completely decomposed within 4 h in the ZVC/air system at initial pH 3.0. The H2O2, hydroxyl radical (OH) and superoxide anion radical (O2−) were identified as the main reactive oxygen species (ROSs) generated in the above reaction; however, only OH caused the decomposition and mineralization of ACT in the copper-catalyzed O2 activation process. In addition, the in-situ generated Cu+ from ZVC dissolution not only activated O2 to produce H2O2, but also initiated the decomposition of H2O2 to generate OH. Meanwhile, the H2O2 could also be partly decomposed into O2−, which served as a mediator for copper cycling by reduction of Cu2+ to Cu+ in the ZVC/air system. Therefore, OH could be continuously generated; and then ACT was effectively degraded. Additionally, the effect of solution pH and the dosage of ZVC were also investigated. As a result, this study indicated the key behavior of the O2− during Cu–catalyzed activation of O2, which further improved the understanding of O2 activation mechanism by zero-valent metals.

Photocatalytic Degradation of Acetaminophen

The photocatalytic degradation of a common analgesic (acetaminophen) with titanium dioxide irradiated with low energy ultraviolet light (365 nm) was studied in order to determine the effect of several parameters such as catalyst’s weight, photochemical effect, and initial concentration. The results indicate that acetaminophen is degraded in the order of 4% by the photochemical effect. The presence of titanium dioxide in optimal amounts increases the rate of reaction and the overall conversion. The kinetic study demonstrated that photocatalytic degradation of acetaminophen follows a pseudo first order reaction rate which could be represented by a model similar to Langmuir-Hinshelwood equation. Accordingly, the results confirmed that the degradation of acetaminophen proceeds even while other intermediate organic products (IOP) are being formed; some of these organic products were identified by High Performance Liquid Chromatography (HPLC). These products (OIP) remain in the solution for a while before being degraded to CO2. Furthermore, the experimental results indicate that the mineralization of acetaminophen can be described by an overall kinetic rate equation obtained from the experimental values of total organic carbon (TOC).