Degradation Efficiency Of Carbamazepine Research Articles

Bio-electrochemical degradation of carbamazepine (CBZ): A comprehensive study on effectiveness, degradation pathway, and toxicological assessment

Recent attention on the detrimental effects of pharmaceutically active compounds (PhACs) in natural water has spurred researchers to develop advanced wastewater treatment methods. Carbamazepine (CBZ), a widely recognized anticonvulsant, has often been a primary focus in numerous studies due to its prevalence and resistance to breaking down. This study aims to explore the effectiveness of a bio-electrochemical system in breaking down CBZ in polluted water and to assess the potential harmful effects of the treated wastewater. The results revealed bio-electro degradation process demonstrated a collaborative effect, achieving the highest CBZ degradation compared to electrodegradation and biodegradation techniques. Notably, a maximum CBZ degradation efficiency of 92.01% was attained using the bio-electrochemical system under specific conditions: Initial CBZ concentration of 60 mg/L, pH level at 7, 0.5% (v/v) inoculum dose, and an applied potential of 10 mV. The degradation pathway established by identifying intermediate products via High-Performance Liquid Chromatography-Mass Spectrometry, revealed the complete breakdown of CBZ without any toxic intermediates or end products. This finding was further validated through in vitro and in vivo toxicity assays, confirming the absence of harmful remnants after the degradation process.

Kinetic model-based optimization in electro-activated sulfite system for carbamazepine degradation: Aeration and multiple dosages of sulfite

Electro-activated sulfite system (E-SO32−) was an emerging advanced oxidation technology, but its kinetics and process optimization have been overlooked. This study developed a first-principle kinetic model to investigate carbamazepine (CBZ) degradation and optimized this process by aeration and multiple dosages of SO32−. A low aeration rate (140 mL/min) remarkably accelerated sulfate radical (SO4•−) generation because of the enhanced rate of sulfite radical (SO3•−) reacting with oxygen. Thus, the degradation efficiency of CBZ improved from 71 % to 84 % and the electrical energy per order (EE/O) decreased from 4.55 to 2.32 kWh/m3/order at current density of 103 A/m2 and initial dosage of SO32− of 4 mM. However, further increasing the aeration rate diminished the enhancement of SO4•− generation rate due to the limited SO3•− generation, and excessive aeration resulted in decreased degradation efficiency and increased cost of aeration due to the direct oxidation of SO32− by oxygen. Consequently, matching of SO32− concentration, current density and aeration rate was crucial to maximize the generation rate of SO4•−. The most optimal strategy was at current density of 75 A/m2, aeration rate of 100 mL/min and SO32− concentration of 1.1 mM with multiple dosages. 95 % of CBZ was removed in 20 min, 18 % higher than that in single dosage. Finally, the optimal strategy for CBZ degradation was successfully applied in different water matrixes and real wastewater and well predicted by the kinetic model. Furthermore, degradation pathways of CBZ, including hydroxylation and deamidation, were elucidated from density functional theory and LC-MS detection. The toxicity of most intermediates decreased, while some intermediates possessed higher toxicity than CBZ. Overall, the firstly proposed combined strategy of aeration and multiple dosages of SO32− significantly facilitated the application of E-SO32− system in contaminants degradation.

Degradation of Carbamazepine in Water by UV-activated Sulfite Process

In this study, the degradation efficiency and mechanism of carbamazepine (CBZ), a typical emerging contaminant in water, in the UV/sulfite process were investigated. The effects of different concentrations of dissolved oxygen [ρ(DO)] on the degradation of CBZ by UV-activated sulfite were investigated. Additionally, under a simulated natural water environment-controlled initial ρ(DO) of (8.0 ±0.2) mg·L-1, the effects of different process parameters (sulfite dosages and reaction pH) and water environmental factors (the presence of HCO3-, Cl-, and humic acids) on the degradation of CBZ were comprehensively analyzed. The results showed that the UV/sulfite process efficiently degraded CBZ with a degradation rate of 85.3% during the 30 min reaction time and followed the pseudo-first order kinetic model with the constant of 0.055 7 min-1. Using the electron spin resonance detection, reactive species quenching tests, and the competition kinetics, the sulfate radicals (SO4-·) and hydroxyl radicals (·OH) in the UV/sulfite process were determined to be the main reactive species and were responsible for the degradation of CBZ with contribution rates of 43.9% and 56.1%, respectively. In addition, the degradation efficiency of CBZ decreased with the increasing concentration of HCO3-, and the presence of Cl- had little effect on the degradation of CBZ, whereas the presence of humic acids significantly inhibited the degradation of CBZ. Moreover, the accumulation of sulfate during the reaction was significantly lower than the limit of the Standard for Drinking Water (GB5749-2022). Additionally, the sulfite consumption rate constant was 0.004 4 min-1, which was significantly lower than the degradation rate constant of CBZ, indicating that sulfite could be activated efficiently by UV light to degrade CBZ in water.

Photocatalytic persulfate activation by highly dispersed nano-TiO2 supported by silica for efficient carbamazepine degradation

A silica-loaded nano-TiO2 composite (A-SiO2/TiO2) was prepared by wet-grinding method, using industrial silica (A-SiO2) as the carrier. A-SiO2/TiO2 was used for photocatalytic activation of peroxymonosulfate (PMS) to degrade carbamazepine (CBZ). The A-SiO2/TiO2 containing 20 wt% nano-TiO2 resulted in the CBZ degradation efficiency of 94.83 % after 90 min simulated sunlight irradiation with the presence of PMS. The main reactive species during CBZ degradation in the system of photocatalytic PMS activation by A-SiO2/TiO2 were O2•−, •OH and SO4•−. Compared to nano-TiO2, A-SiO2/TiO2 exhibits enhanced dispersion, increased surface active sites and improved photo-generated carrier separation efficiency, which contributed to enhanced degradation performance.

Activation ability of Yellow River (Huanghe) suspended sediment to degrade carbamazepine pollutants in water environment using peroxymonosulfate: Performance, mechanism, and potential toxicity evaluation

By constructing a novel heterogeneous persulfate activation system, the ability of Yellow River’s suspended sediment (SS) to promote in-situ oxidative degradation of carbamazepine (CBZ) by peroxymonosulfate (PMS) in water environment was investigated. Our results have shown that the SS could efficiently activate PMS to remove carbamazepine pollutants from water environment. In the SS/PMS system (without any other catalysts), at the SS dosage and PMS concentration of 4 g/L and 6 mM, respectively, the CBZ degradation efficiency could reach 81.7 % within 6 h at natural pH, compared with 15.6 % in PMS alone system. During the CBZ degradation process, the SO4− and OH were the dominant radicals in SS/PMS system. The Fe-O complexation and π-π* stack-up on the surface of SS were the main active sites to activate the PMS. The degradation intermediates and potential pathways in the reaction process were analyzed by density functional theory (DFT) calculation and liquid chromatography mass spectrometry (LC–MS). Further, the ECOSAR results confirmed the decreased biological toxicity of CBZ after degradation in SS/PMS system. These findings demonstrated the efficient application of Yellow River’s suspended sediment for in-situ remediation of antibiotics contaminated water, with more availability and economic feasibility, especially suitable for treating wastewater from antibiotic manufacturing companies.

The visible optical driving N-S co-doped La2Ti2O7 activated peroxydisulfate for carbamazepine removal: Mechanism and performance

Carbamazepine (CBZ) as an “emerging pollutant”, which poses a threat to human health. Photocatalytic activation of peroxydisulfate (PDS)-based advanced oxidation processes (AOPs) can deep oxidation of CBZ pollutants through the generation of free radicals with high redox potential. However, most of common photocatalysts only have a narrow band gap, which limits their application under visible light. In order to broaden the band gap of photocatalysis, herein we report the N-S co-doping in La2Ti2O7 (N-S LTO) is viable, and then evaluate the visible light activation of PDS to remove the pollutants of CBZ. Compared with pure LTO and N or S mono-doped LTO, the degradation efficiency of CBZ in N-S LTO/PDS/Vis system was 2.18, 1.45, and 1.41 times improved, respectively, under the visible light irradiation condition. Furthermore, the mechanism of CBZ degradation under N-S LTO/PDS/Vis processes was explored and revealed that the HO• and SO4•− were the main substances for the breakage of CBZ molecules. The further physicochemical characterization of samples convinced the active sites in N-S LTO for PDS motivation and oxidation processes with the best separation and migration ability of carriers than other samples. Finally, combined with density functional theory (DFT) calculations, the detailed degradation pathways of CBZ were proposed. This work not only provides insight into the construction of photocatalysts with co-doping for PDS activation, but also brings an inspiration of CBZ degradation in water treatment.

Peroxyacetic acid activation by cobalt-doped peanut shell biochar for efficient CBZ degradation: Role of organic radicals, singlet oxygen, and high-valent cobalt species

Peroxyacetic acid (PAA) oxidant has a broad application prospect to be combined with biochar in the treatment of organic pollutants due to its excellent characteristics of eco-friendly and easy activation. In this study, peanut shell biochar-loaded Co nanoparticles (Co-BC-850) catalysts were prepared through pyrolysis to activate PAA for carbamazepine (CBZ) degradation. The pyrolysis temperature significantly affected the CBZ degradation efficiency of the catalysts. The experimental results revealed that the Co-BC-850 catalyst exhibited the highest CBZ degradation efficiency. Within 20 min, a CBZ degradation rate of 99.9% was achieved with Co-BC-850 concentration of 50 mg/L and PAA concentration of 1 mM. The Co-BC-850/PAA system achieved high degradation performance for CBZ at a pH ranging from 5.0 to 9.0, even in the presence of inorganic anions. The analysis of the Co-BC-850/PAA system revealed a complex interplay of reactive species (RSs). Organic radicals (R-O•), singlet oxygen (1O2), and high-valent cobalt species (Co(IV)) collaboratively contributed to CBZ degradation. These findings revealed the intricate mechanism of CBZ degradation via Co-BC-850-activated PAA, thereby elucidating potential degradation pathways. This study demonstrates the promising application of biochar PAA-based AOPs and offers a sustainable and effective solution for the degradation of CBZ and other potential pharmaceutical compounds in water.

Recyclable magnetic AgBr/BiOBr/Fe3O4 photocatalytic activation peroxymonosulfate for carbamazepine degradation: Synergistic effect and mechanism

In order to effectively curb the various hazards posed by carbamazepine (CBZ) to aquatic ecosystems, a recyclable magnetic AgBr/BiOBr/Fe3O4 composite photocatalytic material was successfully synthesized in this study. When the content of Fe3O4 was 5 wt% (ABF-5), the ABF-5/Vis/PMS system was formed under peroxymonosulfate (PMS) and visible light (Vis). The system was able to degrade 96.84 % of CBZ within 30 min, with good photocatalytic synergy and degradation effect. Meanwhile, the system also showed a satisfactory degradation effect on CBZ in real water bodies such as reservoir water and hospital wastewater. In the ABF-5/Vis/PMS system, CBZ was degraded mainly by cleavage, hydroxylation, oxidation, and decarboxylation, and the active substances such as 1O2, O2−, h+ played a major role in the degradation process. After five cycles of experiments, the degradation efficiency of CBZ remained above 85 %. Moreover, ABF-5 can be quickly separated and easily reused under an external magnetic field with good stability. In summary, the recoverable magnetic ABF-5 has good potential for practical application and could provide novel perspectives methods, and ideas for the treatment of persistent organic pollutants treatment in water ecosystems.

Efficient degradation of carbamazepine using a modified nickel-foam cathode (Ni-FM/CNTs) in penetrating electro-Fenton process

A modified nickel-foam (Ni-FM) cathode coated with multi-walled carbon nanotubes (Ni-FM/CNTs) was synthesized for carbamazepine (CBZ) highly energy-efficient degradation in penetrating electro-Fenton. Scanning Electron Microscopy (SEM) and X-ray diffractometer (XRD) test proves that multi-walled CNTs were successfully coated on the surface of nickel foam. The linear sweep voltammetry (LSV) results revealed the greater electrochemical activity of Ni-FM/CNTs compared to Ni-FM. The H2O2 accumulation performance tests showed that Ni-FM/CNTs cathode had higher H2O2 accumulation performance than Ni-FM cathode, and the H2O2 yield of Ni-FM/CNTs was 5.7 times higher than that of Ni-FM after 1 h of electrolysis. The reaction rate of CBZ degradation in penetrating electro-Fenton process was 2.5 times that of planar electro-Fenton process because the flow-through process enhanced O2 mass transfer and promoted the production of H2O2. The Box-Behnken Design response surface method was used to analyze the factors affecting the degradation efficiency of CBZ in the penetrating electro-Fenton process. The CBZ degradation efficiency could reach 100%, and electric energy consumption was 0.4356 Wh/L at current density of 9 mA/cm2, pH = 3, concentration of Fe2+ was 0.3 mM, and the through-flow velocity of 60 mL/min. The quenching experiment and EPR test results confirmed the degradation of CBZ was mainly the oxidation of·OH, and O2-·is the prerequisite for the production of·OH. Eight possible degradation products of CBZ degradation were identified and the probable degradation route was proposed. The ECOSAR program was used to predict the toxicities of CBZ and its degradation products, and the consequences revealed that the electro-Fenton process has a detoxification effect on CBZ, but may also produce more toxic organic compounds than the parent compound.

Oxidized pyrite as an efficient Fenton reagent to generate active species for the degradation of carbamazepine in a wide pH range

Few studies have reported the catalytic activity of oxidized pyrite. In the paper, oxidized pyrite was first explored as a Fenton reagent to generate active species to degrade carbamazepine (CBZ) in a wide pH range (3.0–11.0). The results showed that oxidized pyrite exhibited excellent catalytic performance on the activation of H2O2 to degrade CBZ with high stability. The influences of oxidized pyrite loading, H2O2 concentration, CBZ concentration, initial pH and co-existing ions on the degradation efficiency of CBZ were studied in detail. The main active species for the degradation of CBZ were HO, O2-, e- and 1O2, which were generated from the comprehensive effects of homogeneous Fenton, heterogeneous Fenton and photo-Fenton reaction. Furthermore, a possible pathway for CBZ degradation was proposed based on the intermediates detected from UPLC-MS/MS. Finally, the potential for practical utilization of oxidized pyrite was confirmed by degrading CBZ in tap water and secondary effluent water. The obtained results provide a new idea for the environment purification using natural pyrite.

Fe3O4 decorated with α-cyclodextrin for enhanced peroxymonosulfate(PMS)-activated degradation of PPCPs

In this work, novel Fe3O4@α-CD nanoparticle was synthesized for the catalytic activation of peroxymonosulfate (PMS) towards carbamazepine (CBZ) degradation. The effect of α-CD content, Fe3O4@α-CD dosage and PMS concentration on the catalyst activity were systematically evaluated. The results showed the synergistic effect between α-CD and Fe3O4 can greatly improve the removal efficiency of CBZ in the Fe3O4@α-CD/PMS system. CBZ removal efficiency gained 73.37% in 5 min at pH 7.0 with PMS 1 mM, Fe3O4@α-CD load 0.4 g/L and CBZ 10 μM. The variation in the removal efficiency of different PPCPs under the same conditions mainly ascribed to the adsorption of α-CD and the activation of PMS by Fe3O4 to generate free radicals, in which sulfate radical (SO4·−) and hydroxyl radicals (·OH) was determined as the reactive species in the Fe3O4@α-CD/PMS system. Density functional theory (DFT) calculations was also utilized to optimize the structure of composite and confirmed that the charge distribution mainly concentrate on Fe3O4. As deduced from the LC-MS analysis, the possible CBZ degradation pathways were proposed. CBZ degradation efficiency still reached 54% after three cycle, which indicates that Fe3O4@α-CD catalyst has a good reusability potential and practical applications.

Novel ternary catalyst Ag2O/NCDs@ porous tubular g-C3N4 as efficient visible-light-driven peroxymonosulfate activator

The photo-induced peroxymonosulfate (PMS) activation method for the removal of emerging pollutants is regarded as a promising technique, and designing an effective and stable catalyst is the key. In the current work, a novel Ag2O nanoparticle and nitrogen-doped carbon dots (NCDs) modified porous tubular carbon nitride (Ag2O/NCDs@PTCN) catalyst was synthesized. The morphology, composition, and optical activities of the Ag2O/NCDs@PTCN were analyzed by TEM, XRD, XPS, and UV–vis, respectively. Catalytic degradation test results showed that the degradation efficiency of carbamazepine by Ag2O/NCDs@PTCN/Vis-PMS (0.1452 min−1) was greatly enhanced compared with Vis-PMS (0.0014 min−1). A series of mechanistic analysis indicated that both non-radical and radical played an important role in (1O2, h+, and O2•-) carbamazepine degradation. In addition, the Ag2O/NCDs@PTCN/Vis-PMS system showed low silver ion leaching, high adaptability to solution pH, and low toxicity of degradation products. This research may provide a green and hopeful practical application potential for degrading the persistent organic pollutants in the aquatic environment.

The catalytic activity of different Mn(III) species towards peroxymonosulfate activation for carbamazepine degradation

In this study, the catalytic activity of soluble Mn(III) ions, soluble Mn(III)-pyrophosphate (PP), and solid Mn(III) (α-MnO2) towards peroxymonosulfate (PMS) activation was investigated through carbamazepine (CBZ) degradation. The degradation efficiency of CBZ was negligible when soluble Mn(III) ions or Mn(III)-PP were used as catalysts, while 99.7% of CBZ was degraded in the α-MnO2/PMS system with no soluble Mn(III) ions detected. The degradation efficiency of CBZ reduced by 18% with the solid Mn(III) content decreasing. Hence, the solid Mn(III) made the major contribution to PMS activation. This study supported a better understanding of the role of Mn(III) in PMS activation.

LaRuO3 perovskites as effective and reusable heterogeneous catalysts to activate peroxymonosulfate for carbamazepine degradation

Sulfate radical-based technologies have been frequently applied to degrade pharmaceutical and personal care products (PPCPs). Metal-based catalysts have shown great potential for activating persulfate (PS) and peroxymonosulfate (PMS) to degrade PPCPs. In this study, a Ru-based perovskite (ARuO3, A = La, Ba, Ce, Sr) was synthesized by the sol–gel method and used as a catalyst to activate PMS for the degradation of carbamazepine (CBZ). Results demonstrated that the A-site cations had a significant influence on the catalytic performance of the perovskite, and the degradation efficiency of CBZ in descending order for different Ru-based perovskites was as follows: La > Ba > Sr > Ce. LaRuO3 was selected as the optimal catalyst for CBZ degradation. LaRuO3 efficiently activated PMS to degrade CBZ in a neutral environment. The reaction rate constant had a positive linear correlation with the concentration of PMS in a range between 0.1 mM and 0.5 mM. ESR analysis and radical quenching experiments confirmed the existence of 1O2, •OH, and SO4•− in the LaRuO3/PMS system, and SO4•− played the most significant role in decomposing CBZ. The recycling experiment and XPS spectra suggested the stability of LaRuO3.

Oxidation of micropollutants by visible light active graphitic carbon nitride and ferrate(VI): Delineating the role of surface delocalized electrons

The treatment of recalcitrant micropollutants in water remains challenging. Ferrate(VI) (FeVIO42−, Fe(VI)) has emerged as a green oxidant to oxidize organic molecules, however, its reactivity with recalcitrant micropollutants are sluggish. Our results demonstrate enhanced oxidation of carbamazepine (CBZ) by three types of visible light-responsive graphitic carbon nitride (g-C3N4) photocatalyst in absence and presence of ferrate(VI) (FeVIO42−, Fe(VI)) under mild alkaline conditions. The g-C3N4 photocatalysts were prepared by thermal process using urea, thiourea, and melamine and were named as CN-U, CN-T, and CN-M, respectively. The degradation efficiency of CBZ, in both visible light-g-C3N4 and visible light-g–C3N4–FeVIO42- systems followed the order of CN-U > CN-T > CN-M. The mechanisms for this trend was elucidated by measuring physiochemical properties of the microstructures with various surface and analytical techniques. Results suggest the dominating role of specific surface area and surface delocalized electrons of microstructures in degrading CBZ. Crystallinity, morphology, and surface functional groups may not directly associate with CBZ degradation. The CN-U has higher specific surface area and surface delocalized electrons than CN-T and CN-M and therefore the highest degradation efficiency of CBZ. The surface electrons likely generated O2●- and 1O2 in the visible light-g-C3N4 system. The additional oxidants, FeV and FeIV in the visible light-g–C3N4– FeVIO42− system led to higher degradation efficiency than the visible light-g-C3N4 system. Results suggest that the surfaces of g-C3N4 may be prepared preferentially with high levels of delocalized electrons at the surface of microstructures to enhance degradation of micropollutants.

Removal of contaminants of emerging concern from secondary-effluent reverse osmosis retentates by continuous supercritical water oxidation- parametric study and conceptual design

The continuous removal of TOC and the degradation efficiency of carbamazepine and 17β-estradiol were investigated using actual secondary municipal-effluent RO-retentate solutions. A specific set of operating parameters were applied within the supercritical water oxidizing conditions: temperature range 420–480 °C, 25.1 MPa, hydraulic retention time (HRT) of 1–2 min, excess oxidant molar-ratio of 3–10 and presence of a homogenous catalyst (IPA) at 50–100 mg/L. > 99% organic carbon mineralization, along with complete degradation of model pollutants, was observed at 450 °C/1 min/OC= 5–10 and 100 mgIPA/L. The outlet estrone concentration, 1.03 ± 1.14 ng/L, representing estrogenic pollutants, dropped to the "no effect" range. A model for a SCWO plant treating secondary-municipal-effluent-RO-retentate for a city of 100,000 capita-equivalent was developed, based on a shell & tube SCWO flow reactor, showing > 75% energy-efficiency. The model yielded that for the extreme case of a zero caloric-value feed-solution, the total OPEX and CAPEX would be < $6.0 ± 2.5 per m3 of secondary effluents, i.e., two orders of magnitude lower than the reported environmental shadow-price associated with CECs (contaminants of emerging concern). Further work is required on the continuous and efficient separation of the salt-matrix, which can lead to higher overall heat transfer coefficients and enable further reduction in capital costs.

Facile synthesis of a novel AgIO3/BiVO4 photocatalyst with two-step charge separation to enhance visible-light-driven photocatalytic performance for carbamazepine degradation

• A novel visible-light-driven AgIO 3 /BiVO 4 photocatalyst was fabricated. • The two-step charges separation in AgIO 3 /BiVO 4 enhanced the photocatalytic activity. • The different crystal facets in decahedral BiVO 4 facilitated the charges spatial pre-separation. Rapid recombination of photo-generated electron-hole in photocatalyst limits the improvement in photocatalytic activity. A novel visible-light-driven AgIO 3 /BiVO 4 photocatalyst with two-step charge separation enhancing photocatalytic activity was fabricated. The composite with optimum molar ratio of 40% AgIO 3 to BiVO 4 has a narrow band gap of 2.28 eV, which is smaller than that of BiVO 4 (2.41 eV). The composite presented 99.38% degradation efficiency of rhodamine B in 40 min under visible light irradiation, which is higher than 1% and 9% degradation efficiencies by BiVO 4 and AgIO 3 , respectively. In addition, a 97.86% degradation efficiency of carbamazepine was achieved in 60 min. Thus, the significant enhancement of photocatalytic activity depended on the two-step charge separation in AgIO 3 /BiVO 4 . The first step was the spatial pre-separation among different crystal facets in decahedral BiVO 4 . Photo-generated electrons accumulated on {0 1 0} facets. Moreover, photo-generated holes on {1 1 0} facets facilitated the production of •OH radicals. The second separation was achieved by the type Ⅱ heterojunction structure of AgIO 3 /BiVO 4 . Photo-generated electrons in conduction band were transferred from BiVO 4 {0 1 0} facets to AgIO 3 , and holes in valence band accumulated on BiVO 4 {1 1 0} facets. This work provides an effective method to further decrease electron-hole recombination in photocatalysts and promote their environmental application in contaminated water purification.

Ultraviolet-Light-emitting-diode activated monochloramine for the degradation of carbamazepine: Kinetics, mechanisms, by-product formation, and toxicity

Monochloramine (NH2Cl) oxidant combined with a Ultraviolet (UV)-Light-emitting-diode (LED) light source forms a new advanced oxidation process (AOP), which can achieve high-efficiency degradation of carbamazepine (CBZ). The degradation of CBZ displayed pseudo-first-order reaction kinetics (R2 > 0.98, kCBZ = 0.0043 cm2 mJ−1 at pH 7). The degradation of CBZ was dependent on UV-LED wavelength, with maximum degradation efficiency observed at 265 nm since it was the lowest wavelength studied among UV-LEDs. Variation in pH across the range, which might be expected under normal environmental conditions (pH 6–8), and the presence of Cl− had no significant effect on the degradation efficiency of CBZ, while the presence of HCO3− and natural organic matter (NOM) inhibited degradation. Electron paramagnetic resonance (EPR) experiments detected OH in the system. Probe compounds were used to distinguish the contribution of reactive chlorine species (RCS). It was proved that OH and Cl played major roles and OH was responsible for around 50% of the observed degradation of CBZ. Eight transformative products (TPs) in the degradation process of CBZ were identified, with a generally decreasing toxicity. The concentration of disinfection by-products (DBPs) formed during CBZ degradation was all within limits of WHO and China standard for drinking water. Although the concentration of nitrogen-containing DBPs (N-DBPs) was the lowest, N-DBPs were the main contributors to toxicity, and these would require more attention in practical applications. UV-LED/NH2Cl AOP was identified as an effective way to degrade pharmaceutically active compounds.

A green solar photo-Fenton process for the degradation of carbamazepine using natural pyrite and organic acid with in-situ generated H2O2

Pyrite is widely used in Fenton reaction for degradation of pollutants and exhibits great potential for environmental remediation, however, its efficiency is greatly compromised by extra H2O2 and pH adjustment. Herein, a pyrite based green solar photo-Fenton system for carbamazepine (CBZ) treatment is constructed, involving the use of simulated sunlight and natural organic acids with in situ-generated H2O2 and without extra pH adjustment. The addition of organic acids including tartaric acid (TA), citric acid (CA), and ascorbic acid (AA) can form complex with iron in pyrite, which promotes the Fe(II) dissolution. Upon irradiation, pyrite could be excited to produce photoelectrons, which would reduce oxygen to produce H2O2 through a two-step route assisted by organic acids. The simulated sunlight and organic acids promoted the in-situ production of H2O2 and Fe(II) species, sustaining an efficient Fenton reaction. This produced massive hydroxyl radical (OH), as demonstrated by the active species capture experiment. Compared with no degradation of CBZ under pure pyrite, the degradation efficiency of CBZ reached to 70%, 60%, and 53% in pyrite/TA, pyrite/CA, pyrite/AA within 30 min under simulated solar light irradiation, respectively. This work reports the first use of natural pyrite, a typical Fe-mineral semiconductor, to produce OH for CBZ degradation through natural additive assisted Fenton reaction excluding the adding extra H2O2 and pH adjustment.

Insights in the Aqueous and Adsorbed Photocatalytic Degradation of Carbamazepine by a Biosourced Composite: Kinetics, Mechanisms and DFT Calculations

Although the degradation of carbamazepine (CBZ) in the aqueous phase was widely studied for a better comprehension of its photocatalytic behavior in the aqueous solution, the knowledge about its photodegradation adsorbed on solid surfaces is yet very limited. In this work, the combination of two processes (adsorption and photocatalysis) has been applied for the degradation of CBZ adsorbed on TiO2 and activated carbon AC/TiO2 and aqueous phase. The degradation efficiency of CBZ could reach 100%, and 99% in CBZ dissolved and adsorbed parts, respectively. Moreover, the CBZ mineralization starts at 4 h of irradiation. Hydroxy radical (·OH) has an essential role in CBZ degradation, and It accompanies a synergistic effect of the photogenerated hole (h+) and oxygen active species during the reaction. Thereafter, the transformation products and possible degradation pathways of CBZ were identified by LC/MS-Qtof. Density functional theory calculation successfully predicts the degradation mechanism of CBZ molecule by means of Fukui indexes, including the ring hydroxylation, photocyclization, C–C and C–N bond cleavage processes.