Degradation Of Ibuprofen Research Articles

Functional characterization of an efficient ibuprofen-mineralizing bacterial consortium

Ibuprofen (IBU) is a widely used non-steroidal anti-inflammatory drug (NSAID), which has attracted widespread attention due to its high frequency of environmental detection, non-degradability and potential ecological risks. However, little is known about the functional characterization of the highly efficient IBU-mineralizing consortium. In this study, an IBU-mineralizing consortium C6 was obtained by continuous enrichment of the original consortium C1 accumulated the metabolite of 2-Hydroxyibuprofen (2HIBU). Methylobacter, Pseudomonas, and Dokdonella spp. were significantly enriched in the consortium C6. Streptomyces sp. had a relative abundance of about 0.01 % in the consortium C1 but extremely low (< 0.001 %) in the consortium C6. Subsequently, two IBU degraders, Streptomyces sp. D218 and Pseudomonas sp. M20 with detection of 2HIBU or not, were isolated from the consortia C1 and C6, respectively. These results imply that the degradation of IBU in the consortia C1 and C6 may be mainly mediated by key players of Streptomyces and Pseudomonas, respectively. This study showed that the composition of the core functional strains of the bacterial community structure was changed by continuous enrichment, which affected the degradation process of IBU. These findings provide new insights into our understanding of the biotransformation process of NSAIDs and provide valuable strain resources for bioremediation.

Engineered ball-milled colloidal activated carbon material for advanced oxidation process of ibuprofen: Influencing factors and insights into the mechanism

This study explores a simple and efficient, physically modified ball-milled activated carbon (ACBM) preparation from granular activated carbon (GAC), which can be demonstrated for groundwater application. The colloidal stability of the ACBM plays a vital role in the activation of peroxymonosulfate (PMS) and the degradation of pollutants. Adsorption kinetics and isotherm studies explain that the ACBM has more active sites and maximum adsorption capacity (qmax = 509 mg g−1) on the surface of the materials than GAC. The 92% of ibuprofen degradation was achieved at 240 min along with 0.1 g L−1 of ACBM, 5 mM of PMS, and 6.3 of initial solution pH. A chemical scavenger and electron spin resonance spectra also confirmed the formation of reactive oxygen species such as radicals (O2•–, HO•, SO4•–) and non-radical (1O2) in the ACBM/PMS system. Three major degradation pathways, hydroxylation, demethylation, and decarboxylation involved in ibuprofen degradation. Nearly 13 degradation by-products were detected during the ACBM/PMS oxidation of ibuprofen. The toxicity analysis of oxidation by-products of ibuprofen was also discussed by computational simulation employing the ecological structure-activity relationships software. The ACBM/PMS system was successfully applied to the natural groundwater system for ibuprofen degradation. Hence, the ACBM/PMS system is an excellent catalyst for real groundwater applications.

New insights into the degradation mechanism of ibuprofen in the UV/H2O2 process: role of natural dissolved matter in hydrogen transfer reactions.

Ibuprofen (IBU), a widely used antipyretic and analgesic, has been frequently detected in various natural water systems. Advanced oxidation processes (AOPs) are effective ways to remove pollutants from water. The degradation of IBU under UV/H2O2 conditions in the presence of various kinds of natural dissolved matter was investigated using density functional theory (DFT). The eco-toxicological properties were predicted based on a quantitative structure-activity relationship (QSAR) model. The calculated results showed that two H-abstraction reactions occurring at the side chain are predominant pathways in the initial reaction. H2O, NH3, CH3OH, C2H5OH, HCOOH and CH3COOH can catalyze the H transfer in the degradation process through decreasing the energy barriers and the catalysis effects follow the order of NH3 > alcohols > acids > H2O. The catalysis effects differ under acid or alkaline conditions. The overall rate coefficient of the reaction of IBU with ˙OH is calculated to be 5.04 × 109 M-1 s-1 at 298 K. IBU has harmful effects on aquatic organisms and human beings and the degradation process cannot significantly reduce its toxicity. Among all products, 2-(4-formylphenyl)propanoic acid, which is more toxic than IBU, is the most toxic with acute and chronic toxicity, developmental toxicity, mutagenicity, genotoxic carcinogenicity and irritation/corrosivity to skin. The findings in this work provide new insights into the degradation of IBU and can help to assess its environmental risks.

Heterogeneous catalytic activation of peroxydisulfate toward degradation of pharmaceuticals diclofenac and ibuprofen using scrap printed circuit board.

Pharmaceutical residues have been identified as a priority contaminant due to their toxicity to organisms and the ecosystem as representative refractory organic compounds in water. Therefore, using efficient treatment methods to remove them from wastewater has become a crucial topic of research. Advanced oxidation processes (AOPs) based on the sulfate radical have gained increased attention in recent years due to their superior performance and adaptability in the decomposition of refractory organic contaminants. In this work, scrap printed circuit boards (PCBs) were used to prepare a low-cost and efficient heterogeneous peroxydisulfate (PDS) catalytic activator via thermal treatment with an air combustion non-carbonized catalyst (NCC) and pyrolysis with a nitrogen carbonized catalyst (CC) for the removal of diclofenac (DCF) and ibuprofen (IBF) from water at circumneutral pH. The synthesized catalysts were characterized by several analytical techniques. The effects of various experimental parameters on the removal efficiency were examined. Under optimum conditions, the degradation efficiency reached 76% and 71% with NCC and 63% and 57.5% with CC within 60 min for DCF and IBP, respectively. The mineralization efficiency as measured by TOC removal reached up to 65% after 60 min treatment. The degradation kinetics for both catalysts followed the pseudo-first-order model. Results from quenching tests showed that the reactive oxidizing species (ROS), including 1O2 > SO4˙- > ˙OH, were generated mainly in the NCC/PDS and CC/PDS systems. Overall, the prepared catalysts were found to be effective and reusable for PDS activation for the removal of pharmaceutical pollutants from water. This study provided a promising, robust and efficient heterogeneous catalytic PDS activation based on the strategy of "waste-treats-waste" for the removal of pharmaceutical pollutants from water.

Enhanced degradation of ibuprofen in an integrated constructed wetland-microbial fuel cell: treatment efficiency, electrochemical characterization, and microbial community dynamics.

Over the past few decades, there has been a growing concern regarding the fate and transport of pharmaceuticals, particularly antibiotics, as emerging contaminants in the environment. It has been proposed that the presence of antibiotics at concentrations typically found in wastewater can impact the dynamics of bacterial populations and facilitate the spread of antibiotic resistance. The efficiency of currently-used wastewater treatment technologies in eliminating pharmaceuticals is often insufficient, resulting in the release of low concentrations of these compounds into the environment. In this study, we addressed these challenges by evaluating how different influent ibuprofen (IBU) concentrations influenced the efficiency of a laboratory-scale, integrated constructed wetland-microbial fuel cell (CW-MFC) system seeded with Eichhornia crassipes, in terms of organic matter removal, electricity generation, and change of bacterial community structure compared to unplanted, sediment MFC (S-MFC) and abiotic S-MFC (AS-MFC). We observed that the addition of IBU (5 mg L-1) resulted in a notable decrease in chemical oxygen demand (COD) and electricity generation, suggesting that high influent IBU concentrations caused partial inhibition for the electroactive microbial community due to its complexity and aromaticity. However, CW-MFC could recover from IBU inhibition after an acclimation period compared to unplanted S-MFC, even though the influent IBU level was increased up to 20 mg L-1, suggesting that plants in CW-MFCs have a beneficial role in relieving the inhibition of anode respiration due to the presence of high levels of IBU; thus, promoting the metabolic activity of the electroactive microbial community. Similarly, IBU removal efficiency for CW-MFC (i.e., 49-62%) was much higher compared to SMFC (i.e., 29-42%), and AS-MFC (i.e., 20-22%) during all experimental phases. In addition, our high throughput sequencing revealed that the high performance of CW-MFCs compared to S-MFC was associated with increasing the relative abundances of several microbial groups that are closely affiliated with anode respiration and organic matter fermentation. In summary, our results show that the CW-MFC system demonstrates suitability for high removal efficiency of IBU and effective electricity generation.

Интенсификация процесса биодеструкции ибупрофена с использованием факторного анализа и кинетического моделирования

Ibuprofen ranks as one of the most frequently detected pharmaceutical pollutants in water across many countries. Previous studies identified conditions for actinobacterial degradation of ibuprofen and developed a chromatographic analysis technique, enabling the measurement of residual ibuprofen levels during bio-degradation. However, the impact of a complex interplay of factors on the dynamics of ibuprofen biodegradation remains insufficiently explored. The objective of this study was to enhance the biodegradation process of ibu-profen through a multifactorial experiment that controled key parameters and to predict changes in substance content and the time needed for process optimization using kinetic modeling. As a result of this study, varying the concentrations of glucose, n-hexadecane, inoculum, and pH values has enabled a remarkable reduction in the biodegradation process duration for ibuprofen (0.1 g/L), from 10 days to just 2 days when employing cosub-strates in quantities of 1.0 g/L, 10.0 ml/l, and adhering to the turbidity standard NTU-5, along with pH stabiliza-tion at 6.5. By applying the kinetic equation of the first-order derivative, dx/dt = –k x-1, we determined the pa-rameter ‘k’ for the ibuprofen biodegradation rate to be 138.88÷146.84%2/h. The half-life (t1/2) was calculated as 25.54÷27.00 hours, and the process’s endpoint, t1/100, was refined to 34.05÷36.00 hours under the optimized conditions.

Synthesis, characterization, and application of 2D/2D TiO2-GO-ZnFe2O4 obtained by the fluorine-free lyophilization method for solar light-driven photocatalytic degradation of ibuprofen

In this study, we report the potential of 2D/2D TiO2-GO-ZnFe2O4 photocatalyst obtained using the fluorine-free lyophilization technique for the degradation of ibuprofen belonging to the group of active pharmaceutical ingredients (API). The improved ibuprofen degradation under simulated solar light was achieved in the presence of a composite of 2D TiO2 combined with GO and embedded ZnFe2O4, which additionally provides superparamagnetic properties and enables photocatalyst separation after the photodegradation process. After only 20 min of the photodegradation process in the presence of 2D/2D TiO2-GO-ZnFe2O4 composite, more than 90% of ibuprofen was degraded under simulated solar light, leading to non-toxic and more susceptible to biodegradation intermediates. At the same time, photolysis of ibuprofen led to the formation of more toxic intermediates. Furthermore, based on the photocatalytic degradation analysis, the degradation by-products and possible photodegradation pathways of ibuprofen were investigated. The photodegradation tests and electronic spin resonance analyses indicated the significant involvement of superoxide radicals and singlet oxygen in the ibuprofen photodegradation process.

BN/Fe3O4/MIL-53(Fe) ternary nanocomposite for boosted ibuprofen degradation by visible light assisted photocatalytic activation of persulfate

In this paper, ternary nanocatalysts BN/Fe3O4/MIL-53(Fe) (BNCFe) were derived from ion-based metal organic framework (MIL-53(Fe)) and boron nitride (BN) composites through calcination, and used for the photocatalysis of ibuprofen (IBP) with the addition of persulfate (PS). After calcination, the obtained BNCFe composites had roughly surface structure, larger aperture and narrower band gap compared with BN/MIL-53(Fe), which could improve the photocatalytic performance of the composites. The coexistence of BN, Fe3O4 and MIL-53(Fe) in the synthesized catalyst was confirmed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) characteristics. BNCFe composites obtained at calcination temperature of 350 °C showed the best catalytic activity and the degradation efficiency of IBP reached 100% within 180 min. The addition of HCO3− hindered the decomposition of IBP, while Cl− promoted the degradation efficiency of IBP at low concentration and inhibited it at high concentration. In addition, quenching experiments and electron spin resonance results showed that three strong oxidizing free radicals (O2·−, ·OH and SO4·−) played a crucial role in the photocatalytic process. Finally, the distribution of electrostatic potential showing that the side chain was the most easily attacked sites of free radicals, and the reasonable degradation pathways of IBP were proposed based on the intermediate product analysis and density functional theory (DFT) calculations. It was expected that this BN/Fe3O4/MIL-53(Fe) (BNCFe) ternary heterojunction photocatalyst would be a promising candidate for IBP treatment.

Treatment of Water Contaminated with Non-Steroidal Anti-Inflammatory Drugs Using Peroxymonosulfate Activated by Calcined Melamine@magnetite Nanoparticles Encapsulated into a Polymeric Matrix.

In the present study, calcined melamine (CM) and magnetite nanoparticles (MNPs) were encapsulated in a calcium alginate (CA) matrix to effectively activate peroxymonosulfate (PMS) and generate free radical species for the degradation of ibuprofen (IBP) drug. According to the Langmuir isotherm model, the adsorption capacities of the as-prepared microcapsules and their components were insignificant. The CM/MNPs/CA/PMS process caused the maximum degradation of IBP (62.4%) in 30 min, with a synergy factor of 5.24. Increasing the PMS concentration from 1 to 2 mM improved the degradation efficiency from 62.4 to 68.0%, respectively, while an increase to 3 mM caused a negligible effect on the reactor effectiveness. The process performance was enhanced by ultrasound (77.6% in 30 min), UV irradiation (91.6% in 30 min), and electrochemical process (100% in 20 min). The roles of O•H and SO4•- in the decomposition of IBP by the CM/MNPs/CA/PMS process were 28.0 and 25.4%, respectively. No more than 8% reduction in the degradation efficiency of IBP was observed after four experimental runs, accompanied by negligible leachate of microcapsule components. The bio-assessment results showed a notable reduction in the bio-toxicity during the treatment process based on the specific oxygen uptake rate (SOUR).

Hollow lanthanum ferrite perovskite for the enhanced adsorption-photo-Fenton catalytic activity of degradation of ibuprofen

Hollow lanthanum ferrite perovskite for the enhanced adsorption-photo-Fenton catalytic activity of degradation of ibuprofen

Integrated electro-Fenton system based on embedded U-tube GDE for efficient degradation of ibuprofen

Ibuprofen (IBP) is a carcinogenic non-steroidal anti-inflammatory drug (NSAID). It is of certain hazard to aquatic animals and may cause potential harm to human health. As traditional methods cannot effectively remove such a pollutant, many advanced oxidation processes (AOPs) have been developed for its degradation. The electro-Fenton process has the advantages of strong oxidative ability, a synergistic effect of various degradation processes, and a wide application range. This study developed a high-performance gas diffusion electrode (GDE) for electrochemical hydrogen peroxide (H2O2) production. The optimum system performance was found at the current density of 10 mA cm−2, pH of 7.0, and air flow rate at 0.6 L min−1, where the accumulation of H2O2 could reach as high as 769.82 mg L−1. The computational fluid dynamics (CFD) simulation results revealed a fast mass-transfer property in this electro-Fenton system with U-tube GDEs, which resulted in a deep-level degradation (∼100%) of the pollutant (IBP) and a low-concentration degradation of 10 mg L−1 within a 120-min reaction period. The high-performance liquid chromatography-mass spectrometry (LC-MS) studies demonstrated that the hydroxyl radicals were the primary active species in the electro-Fenton system and that the degradation intermediates of IBP were mainly 1-(4-isobutylphenyl) ethanol and 2-hydroxy-2-(4-isobutyl phenyl) propanoic acid through four probable electro-Fenton degradation pathways. This report provides a facile and efficient way to construct a high-performance electro-Fenton reactor, which could be effectively used in advanced oxidation processes (AOPs) to remove emerging contaminants in wastewater and natural water.

Catalytic oxidation of ibuprofen over bulk heterojunction photocatalysts based on conjugated donor-acceptor configured benzoselenadiazole molecule

The use of photocatalysts for acquiring direct photon energy from sunlight is a promising way to clean the environment, particularly the remediation of contaminants from water. In this work, firstly π-conjugated organic semiconductor configuring benzoselenadiazole, 4-(3,5-bis(trifluoromethyl) phenyl)-7-(5′-hexyl-[2,2′-bithiophen]-5-yl)-benzo [c] (Kümmerer, 2009; Chen et al., 2018; Randeep et al., 201) selenadiazole, abbreviated as (RTh-Se-F), was synthesized. The designed RTh-Se-F with an extended π-conjugation showed good optical properties in the visible region and estimated a low optical band gap of ∼2.02 eV . The molecular orbitals i.e. HOMO (−5.33 eV) and LUMO (−3.31 eV) for RTh-Se-F organic semiconductor were suitably aligned to energy levels of (Madhavan et al., 2010Madhavan et al., 2010)-Phenyl-C71-butyric acid methyl esters (PC71BM) which resulted in the broadening of absorption and covering of entire visible region. RTh-Se-F was integrated with varied weight percentages (wt %) of PC71BM to obtain bulk heterojunction (BHJ) and applied as efficient visible light driven BHJ photocatalyst for an effective oxidation of ibuprofen. RTh-Se-F@PC71BM (1:2, wt %) BHJ photocatalyst showed the superior ibuprofen degradation of ∼93% within 90 min under visible light illumination. The maximum degradation rate by BHJ photocatalyst might be accredited to the broadening of absorption capacity and improved lifetime of photogenerated electron-hole pairs which might be resulted from high absorption properties of RTh-Se-F organic semiconductor.

Environmentally Friendly Fabrication of High-Efficient Fe-ZnO/Citric Acid-Modified Cellulose Composite and the Enhancement of Photocatalytic Activity in the Presence of H2O2

In the present study, a novel Fe-ZnO/citric acid-modified cellulose composite (x%Fe-ZnO-y%CAC) was synthesized using an environmentally friendly hydrothermal method. The obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–vis diffuse reflectance spectroscopy (DRS), Fourier transform infrared spectroscopy (FTIR), nitrogen physisorption, and electrochemical and photocurrent density analyses. The influence of the additives from the series of x%Fe-ZnO-y%CAC photocatalysts with Fe content from 0 to 5% and CAC content from 0 to 80% on photocatalytic degradation of ibuprofen (IBU) under simulated solar light was investigated. The photocatalyst 0.5%Fe-ZnO-40%CAC showed high photocatalytic activity of 0.0632 min−1 first-order kinetic rate constant and 46% TOC reduction of IBU under simulated solar light irradiation. Additionally, H2O2-assisted photocatalytic process was investigated for facilitating the IBU degradation in the presence of 0.5%Fe-ZnO-40%CAC; the first-order kinetic rate constant was 2.7 times higher compared to the process without addition of H2O2. Moreover, the effect of radical scavengers was examined to explain the degradation mechanism of IBU by synthesized photocatalysts supported with H2O2. The demonstrated system provides a low-cost and green approach to improve the photocatalytic activity of x%Fe-ZnO-y%CAC photocatalysts.

A facile fabrication a novel photocatalyst (Fe-TUD-1) with enhanced photocatalytic degradation of ibuprofen

A facile fabrication a novel photocatalyst (Fe-TUD-1) with enhanced photocatalytic degradation of ibuprofen

Photodegradation of ibuprofen using 5-10-15-20-tetrakis(4-bromophenyl) porphyrin conjugated to graphene quantum dots

Ibuprofen (IBU) is a common anti-inflammatory drug that is consumed by many individuals in the world. As such, analytical studies have detected high concentrations of the drug in many waterbodies, which poses a risk of harmful effects on the environment and public health. The hydroxyl radical technologies, a collective of techniques also known as advanced oxidation processes (AOPs), can be utilized to degrade this emerging pollutant. In this study, the photodegradation of ibuprofen using 5,10,15,20-tetrakis(4-bromophenyl) porphyrin conjugated to graphene quantum dots was investigated using a custom-built photoreactor. Three different concentrations of IBU (200, 300 and 500 μM) were utilized as initial concentrations. The pH of the IBU was varied between acidic (pH 3.0), natural (pH 5.0) and alkaline (pH 9.0) to note the effect on IBU degradation as a function of time. The Highest ФΔ was obtained for InTBrP- GDQs (ФΔ = 0.80), followed by InTBrP (ФΔ = 0.74). The photodegradation efficiency of the TBrP-GQDs and InTBrP-GQDs were determined to be 43.2 and 76.1% respectively.

Visible light degradation of ibuprofen using PANI coated WO3@TiO2 photocatalyst

A PANI-coated heterojunction of WO3@TiO2 nanocomposite was fabricated in three stages. The performance evaluation of the prepared photocatalyst for the degradation of ibuprofen was performed under visible light. Characterization of the photocatalyst using X-ray diffraction (XRD) analysis showed that the TiO2 prepared constituted of the anatase phase. Furthermore, results from in situ XRD analysis of WO3 show that it consisted of monoclinic and orthorhombic crystalline structures. These phases were not affected by the incorporation of PANI as revealed by XRD analysis. Results from Transmission electron microscopy (TEM) examination showed that sphere-like WO3 and TiO2 nanorods of different sizes were prepared In addition, fabrication of a heterojunction of WO3@TiO2 wrapped in PANI was shown by TEM analysis. Results from photoluminescence studies indicate that coupling TiO2 with WO3 enhanced the charge separation and the degradation performance of the nanocomposite. Supporting the heterojunction on PANI enhanced the degradation efficiency as indicated during the performance evaluation process. Diffuse reflectance spectra (DRS) calculations of the PANI/WO3@TiO2 catalysts showed that they can be used under visible light. The experimental results of X-ray Photon Spectroscopy (XPS) analysis showed the presence of elements W, C, O, Ti, and N. Solution pH influenced the degradation process and the maximum degradation efficiency was attained at pH 9. The degradation followed the Langmuir-Hinshelwood kinetic model with a Kinetic constant of 3.5 × 10−2. The rate of degradation increased in the presence of bicarbonate/carbonate ions and persulfate ions.

Catalytic Ozonation of Ibuprofen in Aqueous Media over Polyaniline-Derived Nitrogen Containing Carbon Nanostructures.

Catalytic ozonation is an important water treatment method among advanced oxidation processes (AOPs). Since the first development, catalytic ozonation has been consistently improved in terms of catalysts used and the optimization of operational parameters. The aim of this work is to compare the catalytic activity of polyaniline (PANI) and thermally treated polyaniline (PANI 900) in the catalytic ozonation of ibuprofen solutions at different pH values (4, 7, and 10). Catalysts were thoroughly characterized through multiple techniques (SEM, Raman spectroscopy, XPS, pHPZC, and so on), while the oxidation process of ibuprofen solutions (100 mgL−1) was assessed by several analytical methods (HPLC, UV254, TOC, COD, and BOD5). The experimental data demonstrate a significant improvement in ibuprofen removal in the presence of prepared solids (20 min for PANI 900 at pH10) compared with non-catalytic processes (56 min at pH 10). Moreover, the influence of solution pH was emphasized, showing that, in the basic region, the removal rate of organic substrate is higher than in acidic or neutral range. Ozone consumption mgO3/mg ibuprofen was considerably reduced for catalytic processes (17.55—PANI, 11.18—PANI 900) compared with the absence of catalysts (29.64). Hence, beside the ibuprofen degradation, the catalysts used are very active in the mineralization of organic substrate and/or formation of biodegradable compounds. The best removal rate of target pollutants and oxidation by-products was achieved by PANI 900, although raw polyaniline also presents important activity in the oxidation process. Therefore, it can be stated that polyaniline-based catalysts are effective in the oxidation processes.

Novel FeVO4/CuS heterojunction nanocomposite as a high-performance visible-light-active photocatalyst for ibuprofen degradation in aquatic media

Herein, we report the fabrication of type-II FeVO4/CuS heterojunction nanocomposite by a versatile reflux-assisted co-precipitation procedure. The hybrid FeVO4/CuS heterostructure with a band gap of 1.95 eV, demonstrated excellent degradation efficiency of ibuprofen antibiotic (∼95%) after 90 min of visible-light irradiation, which displayed remarkably enhanced photocatalytic degradation (1.75 fold higher) in comparison to pristine FeVO4 structure. The superior photocatalytic performance of the FeVO4/CuS nanocomposite is associated with hierarchical flower-like architectures, great visible-light harvesting, and poor electron-hole recombination due to the fabrication of type-II heterojunction. In addition, we introduced an obvious photocatalytic destruction mechanism, which indicated that superoxides (•O2−) and holes (h+) were the invasive species in antibiotic degradation on the FeVO4/CuS photocatalyst. Consequently, the as-prepared FeVO4/CuS heterojunction photocatalyst is a promising candidate for the development of future photocatalysts towards the elimination of antibiotics under sun light irradiation at short process time.

Mechanism of the improved Fe(III)/persulfate reaction by gallic acid for ibuprofen degradation

Gallic acid (GA), a natural plant polyphenol, was applied as amendment of Fe(III)/persulfate (PS) system for ibuprofen (IBP) degradation in this study. The impacts of all agentia (GA, Fe(III), PS) concentration and initial pH values on IBP removal efficiency were investigated, and their corresponding observed pseudo-first-order rate constants (kobs) were calculated. The addition of GA has significantly improved elimination efficiency of IBP due to the enhanced Fe(III)/Fe(II) cycle. Electron paramagnetic resonance (EPR) results confirmed that SO4•−, HO• and O2•− were involved in GA/Fe(III)/PS system. However, quenching experiments further affirmed the impact of SO4•− and HO• towards IBP decomposition instead of O2•−, with contribution ratio to IBP removal was 69.12% and 30.88%, respectively. SO4•− was the main radicals formed by directly activation of PS with Fe(II), while HO• was the transformation product of SO4•−. Based on instrumental analysis (stopped-flow UV–vis spectrum and MS) and theoretical calculation, the potential reaction mechanism between GA and Fe(III) in the presence of PS was further proposed. GA complexed with Fe(III) firstly and the Fe(III)-GA complex was then converted into quinone substance, accompanied by the generation of Fe(II). Furthermore, the application of GA extended the optimal pH range to neutral as well, which made it a promising treatment in practical application.

TiO2–Fe3O4 Composite Systems—Preparation, Physicochemical Characterization, and an Attempt to Explain the Limitations That Arise in Catalytic Applications

In this work, a composite material based on titanium(IV) oxide and iron(II,III) oxide was prepared using mechanothermal method. The obtained composite system was thoroughly characterized using techniques such as scanning electron microscopy, X-ray powder diffraction, thermogravimetric analysis, and nanoparticle tracking analysis. The acute toxicity of the composite material was evaluated with Microtox. In addition, the material’s photocatalytic potential was studied in photodegradation tests of ibuprofen. The composite system revealed magnetic properties of potential usage in its recovery after photocatalytic tests. However, the photocatalytic activity of TiO2–Fe3O4 was lower than that of bare TiO2. In the photocatalytic tests performed under UV (365 nm) light, a 44% reduction of initial ibuprofen concentration in the sample was noted for bare TiO2, while for TiO2–Fe3O4 composite, only a 19% reduction was observed. In visible light (525 nm), both materials achieved statistically insignificant photodegradation rates, which was contrary to the anticipated effect for TiO2–Fe3O4. The observation was explained by a side oxidation reaction of Fe3O4 to Fe2O3 by the generated reactive oxygen species (ROS) in the photocatalytic process, which significantly diminished the amount of available ROS for ibuprofen degradation. The oxidation process appearing within TiO2–Fe3O4 was evident and easily observed as the color of the material turned from gray to brown. Acute toxicity assay performed with the use of Microtox revealed reduced toxicity of TiO2–Fe3O4 (32% inhibition of the Aliivibrio fischeri bacteria cell viability according to bioluminescence emitted) when compared to bare Fe3O4 (56% inhibition), whereas bare TiO2 was non-toxic. In the study, the processes occurring during the photocatalytic reaction were analyzed and discussed in the context of the available literature data.