Photodegradation Conditions Research Articles

Enhanced removal and destruction of per- and polyfluoroalkyl substances (PFAS) mixtures by coupling magnetic modified clay and photoreductive degradation

The widespread presence of per- and polyfluoroalkyl substances (PFAS) in the environment poses significant challenges due to their persistence and adverse health effects. This study investigates an innovative approach to PFAS removal and destruction using a combined adsorption and photoreductive degradation system. Magnetic modified clay (MMC) was synthesized and employed as an adsorbent for six regulated PFAS, achieving high adsorption efficiencies of nearly 100 % for each PFAS. Subsequent photoreductive degradation was optimized in both reductant concentrations and pH to enhance PFAS breakdown under the 285 nm UV light. The study demonstrated the potential of MMC to effectively adsorb PFAS and facilitate their degradation through a photochemical process, achieving substantial defluorination efficiency. Under optimal photodegradation conditions with 50 mM Na2SO3 and 10 mM KI at pH 12, the overall defluorination efficiency reached 66.5 ± 1.1 % after 48 h. Regeneration and reuse of MMC were also evaluated, showing promising results for the sustainable treatment of PFAS-contaminated water. This combined approach offers a cost-effective and environmentally friendly solution for mitigating PFAS pollution.

Novel S-scheme WO3/ZnO-modified g-C3N4 heterojunction for optimizing norfloxacin photodegradation condition via DoE: Synthesis, characterization, and mechanism evaluation

Norfloxacin, an antimicrobial agent, has been recurrently observed in municipal wastewater facilities, posing a conjectured threat to human health and environmental integrity. Herein, novel ternary heterojunction of WO3/ZnO-modified g-C3N4 was fabricated utilizing the impregnation technique for the organic pollutant degradation, presenting a significant challenge. XRD, XPS, TEM, HR-TEM, SEM, EDS, BET, EIS, Mott-Schottky, ESR, PL, photocurrent, and DRS techniques were used to explore the structural, morphological, textural, and optical features of the produced materials. In this ternary system, ZnO served as an electron transfer conduit, facilitating the formation of a heterojunction interface between the semiconductor constituents. Establishment of the S-scheme within the charge transfer dynamics of the heterojunction markedly augmented charge separation, enhancing the efficacy of the photocatalytic activity. Under optimized conditions via the DoE software (i.e.; photocatalyst dosage: 0.54 g/L, NOR concentration: 25.87 mg/L, Irradiation time: 41.71 min and pH: 6.9), 97.19 % of NOR elimination was achieved by the optimized 20-WZC photocatalyst with a pseudo-first-order kinetic model (k = 0.05 min−1). ESR data, alongside quenching experiments, corroborated the pivotal involvement of O2−, OH, and h+ in the NOR degradation mechanism. The investigation of NOR's potential decontamination pathways was performed using HRLC-MS. TOC analysis revealed a significant mineralization of 82.45 %, indicating the conversion of NOR into H2O, CO2, and other degradable substances. The optimized photocatalyst also demonstrated notable efficiency in the degradation of Tetracycline: 98.15 %, Ciprofloxacin: 93.27 %, Methylene Blue: 98.89 %, and Enrofloxacin: 91.54 % pollutants. The photocatalytic activity of the 20-WZC catalyst remained consistently high, without significant reduction, over five successive cycles.

Construction of PANI@V2O5-ZnIn2S4 Z-scheme heterojunction photocatalysts for highly effective degradation of industrial dyes and antibiotics

From an environmental protection, the highly effective photodegradation of organic dyes and antibiotics in wastewater needs to be solved expeditiously. Fortunately, the construction of Z-scheme heterojunction for photocatalytic degradation is considered to be an effective method. In this paper, after the fabrication of V2O5 by calcination and loading of PANI on its surface by aniline polymerization, a novel PANI@V2O5-ZnIn2S4 composite photocatalysts prepared by one-pot synthesis method and used for the degradation of industrial dyes (crystalline violet, Congo red) and antibiotics (tetracycline-TC). Under the optimal photodegradation conditions, the 30 wt% PANI@V2O5-ZnIn2S4 heterojunction photocatalysts resulted in more than 95 % degradation of CR, CV and TC solutions after 32 min of irradiation. The optimal photodegradation conditions of the simulated pollutants in real aqueous environments catalyzed by the as-synthesized photocatalysts were explored via response surface methodology (RSM). Multiple material characterization techniques, such as FESEM, HRTEM, XPS valence band spectrum, photoelectrochemistry, radical trapping experiments and EPR tests verified the existence of Z-scheme heterojunction. Especially, the coating of conductive PANI on the V2O5 surface can further improve the separation and transfer efficiency of photogenerated charge carriers, thereby enhancing the photocatalytic activity of the semiconductor photocatalyst. This study will provide a robust option for the design and construction of Z-scheme heterojunctions photocatalysts for environmental pollution remediation.

Heterojunction-Based Photocatalytic Degradation of Rose Bengal Dye via Gold-Decorated α-Fe2O3-CeO2 Nanocomposites under Visible-Light Irradiation

Developing photocatalytic nanomaterials with unique physical and chemical features using low-cost and eco-friendly synthetic methods is highly desirable in wastewater treatment. In this work, the magnetically separable α-Fe2O3-CeO2 nanocomposite (NC), with its respective metal oxides of α-Fe2O3 and CeO2 nanoparticles, was synthesized using a combination of hexadecyltrimethylammonium bromide (CATB) and ascorbic acid via the hydrothermal method. To tune the band gap, the heterojunction nanocomposite of α-Fe2O3-CeO2 was decorated with plasmonic Au nanoparticles (Au NPs). The various characterization methods, such as FTIR, UV-vis DRS, XRD, XPS, TEM, EDX, SEM, and PL, were used to determine the properties of the materials, including their morphology, elemental composition, optical properties, band gap energy, and crystalline phase. The nanocomposite of α-Fe2O3-CeO2@Au was utilized to remove Rose Bengal (RB) dye from wastewater using a photocatalytic technique when exposed to visible light. A comprehensive investigation of the impact of the catalyst concentration and initial dye concentration was conducted to establish the optimal photodegradation conditions. The maximum photocatalytic efficiency of α-Fe2O3-CeO2@Au (50 mg L−1) for RB (20 ppm) dye removal was found to be 88.9% in 120 min under visible-light irradiation at a neutral pH of 7 and 30 °C. Various scavengers, such as benzoquinone (BQ; 0.5 mM), tert-butyl alcohol (TBA; 0.5 mM), and ethylenediaminetetraacetic acid (EDTA; 0.5 mM), were used to investigate the effects of different free radicals on the photocatalytic process. Furthermore, the reusability of the α-Fe2O3-CeO2@Au photocatalyst has also been explored. Furthermore, the investigation of the potential mechanism demonstrated that the heterojunction formed between α-Fe2O3 and CeO2, in combination with the presence of deposited Au NPs, led to an enhanced photocatalytic efficiency by effectively separating the photogenerated electron (e−)–hole (h+) pairs.

Synergistic photoactivity regulation of Bi2WO6 with highly exposed {0 0 1} facets and oxygen vacancies by base-metal-ion dopant for enhanced reduction of pharmaceutical compounds

Herein, base metal-doped Bi2WO6 nanosheets with a large proportion of exposed {001} facets and oxygen vacancies were prepared and exhibited greatly enhanced photoactivity for removing four kinds of pharmaceutical compounds under visible-light irradiation. Results in this study indicated that both Zn- and Cu-doped nanosheets possessed optimal photocatalytic activity due to their improved light-harvesting ability and transport efficiency of photo-induced carriers, but Cu-doped nanosheets showed better activity than Zn-doped samples attributed to the existence of high-oxidation-state Cu3+ ions. Meanwhile, it was found that the optimal photodegradation condition for the metal ion-doped photocatalysts was neutral pH, 10 mg/L of pollutants concentration and 0.3 g/L of catalyst dosage. The degradation rate of Zn-doped samples was different from Cu-doped ones, while the Zn-doped samples showed almost 100 % degradation rate for hydrocortisone and 87.8 % for atenolol but the Cu-doped ones showed 100 % for hydrocortisone, 99.3 % for bezafibrate, and 82.1 % for carbamazepine. It was found that O2− and 1O2 were the dominant active species for photodegradation and the breakdown products were identified to be hypotoxic generally.

Emerging silver-doped strontium titanate nanostructures as photocatalysts for the degradation of organic pollutants under visible light

The primary objective of this research is to explore a novel and straightforward method, known as one-pot hydrothermal synthesis, for producing photocatalyst nanocomposite materials consisting of perovskite-based silver doped strontium titanate (Ag–SrTiO3). The investigation focused on assessing the photocatalytic effectiveness and recyclability of these nanocomposites when employed to eliminate ciprofloxacin (CIP) antibiotics under visible-light exposure. The XRD of the Ag–SrTiO3 exhibited a highly crystalline nature with stacked cube morphology, which was also revealed through the SEM technique. The TEM analysis showed the characteristics of the materials such as particle shape, and the SAED pattern confirmed the crystalline phases. The essential reaction parameters, including the amount of catalyst used, the solution's pH level, and the initial pollutant concentration, were altered to identify the most favorable conditions for photodegradation. Furthermore, this composite catalyst displayed excellent stability and could be reused, achieving an 84.5 % removal of CIP after five consecutive cycles. Through scavenger tests, it was determined that photogenerated holes (h+) and superoxide free radicals (•O2) played key roles in the degradation process. This research offers valuable insights into designing highly efficient nanomaterials for the removal of antibiotic degradation from wastewater, and it proposes a possible reaction mechanism.

Modeling and Optimization of a Green Process for Olive Mill Wastewater Treatment

The olive mill wastewater (OMW) treatment process is modeled and optimized through new design of experiments (DOE). The first step of the process is coagulation–flocculation using three coagulants (modeled with the mixture design) followed by photo-degradation (modelled with the full factorial design). Based on this methodology, we successfully established a direct correlation between the system’s composition during the coagulation–flocculation step and the conditions of the photo-catalytic degradation step. Three coagulants are used in this study, Fe3+ solution, lime, and cactus juice, and two parameters are considered for the photo-degradation conditions: dilution and catalyst mass. Utilizing a sophisticated quadratic model, the analysis of the two observed responses reveals the ideal parameters for achieving maximum efficiency in coagulation–flocculation and photo-degradation processes. This is attained using a quasi-equal mixture of limewater and cactus juice, exclusively. To achieve an optimal photo-catalytic degradation, it is essential to maintain a minimal dilution rate while employing an elevated concentration of TiO2. It was found that the experimental tests validations were in good concordance with the mathematical predictions (a decolorization of 92.57 ± 0.90% and an organic degradation of 96.19 ± 0.97%).

Degradation of amoxicillin residue under visible light over TiO2 doped with Cr prepared from tannery wastewater

The degradation of amoxicillin residue has been performed using TiO2 photocatalyst doped with Cr prepared from tannery wastewater under visible light exposure. The incorporation of Cr metal into TiO2 structure was conducted via hydrothermal method. From the characterization results, it is found that doping Cr from the tannery wastewater into TiO2 structure has been successfully shifted the light absorption into visible region. Among the various Cr content in the TiO2-Cr photocatalyst, TiO2-0.33Cr (medium level) shows the highest ability in the visible light absorption, suggesting it to be the best photocatalyst. It is also clearly proven that in the presence of TiO2-0.33Cr photocatalyst, the degradation of amoxicillin can reach almost 100 % after the third cycles. Furthermore, this study also investigated the optimum condition for photodegradation of amoxicillin as the prevalent antibiotic residue in batch technique. The concentration of amoxicillin after the photodegradation process was determined using a UV–visible spectrophotometer. The result identifies the optimal condition for the amoxicillin photodegradation is reached at pH 6, with 10 mg of the photocatalyst mass per 30 mL of the sample solution, and an irradiation time at 90 min. The photodegradation of amoxicillin using TiO2-0.33Cr follows the pseudo-first order kinetic model with kinetic constant (k) is high as 0.004 min−1.

Stability-Indicating Liquid Chromatography Method for Rifaximin and LC-MS Characterization of its Potential Degradants

Rifaximin (RFX) is a structural analog of rifampin that has been shown to be a gastrointestinal-selective antibiotic with broad-spectrum antibacterial properties, a pronounced safety profile, and limited drug interactions. Crohn’s disease, diarrhea, hepatic encephalopathy, irritable bowel syndrome, and traveler’s diarrhea caused by non-invasive diarrheagenic Escherichia coli, can all be treated with rifaximin. FDA has designated RFX as an orphan drug for the treatment of hepatic encephalopathy. There is a substantial need for analytical quality monitoring of Rifaximin to ensure the safety and efficacy of treatment. To generate degradants, forced degradation study of the drug was carried out in acid, alkali, oxidative, thermal, and photolytic stress conditions. The optimum separation of the drug, and its degradants was achieved on an Inertsil ODS-3V C18 column (250 X 4.6 mm X 5 μm) under gradient elution conditions using, 10 mM potassium dihydrogen orthophosphate (pH 5.0 ± 0.05) as mobile phase A, and acetonitrile as mobile phase B, at a flow rate of 1.0 mL/min. The run time was 41 minutes and the detection wavelength was 258 nm. The method was validated in accordance with the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human use Guidelines. The drug was stable in neutral hydrolysis, photo and dry heat degradation conditions. The percentage degradation observed during acid, alkali hydrolysis and oxidative stress conditions were 70.46, 15.11 and 24.18, respectively. The degradants were investigated by LC-MS which indicated the presence of four (m/z 784.2, 744.5, 784.3, 753.8), three (m/z 744.5, 784.3, 753.8) and five (m/z 772.4, 838.4, 744.5, 753.8, and 801.9) degradants in acid, alkali and oxidative stress conditions, respectively. The structures of degradants were elucidated using Liquid chromatography–mass spectrometry (LC-MS) and Liquid chromatography tandem mass spectrometry (LC-MS/MS) analyses.

Visible-Light-Induced Photocatalytic Degradation of Rhodamine B Dye Using a CuS/ZnS p-n Heterojunction Nanocomposite under Visible-Light Irradiation

The aim of this work was to investigate a new, simple, one-pot combustion synthesis technique for creating sulphur-based CuS/ZnS p-n heterojunction nanocomposite photocatalysts. This study examined the photocatalytic activity and reusability of these nanocomposites in removing rhodamine B (RhB) dye under visible-light irradiation. Various methods of characterisation were employed to determine the properties of the materials, including particle morphology, crystalline phases, and bandgap energy. The intrinsic reaction parameters, such as catalyst loading, the pH level of the solution, and initial pollutant concentration, were varied to establish the optimal photodegradation conditions. The results showed that a binary CuS/ZnS catalyst with a 10 g L−1 loading, at pH 5, degraded 97% of 5 ppm RhB dye after 270 min of visible light irradiation. Additionally, this composite catalyst exhibited excellent chemical stability and reusability, achieving 83% RhB dye removal after five recycling runs. Scavenger tests identified the photogenerated holes (h+) and superoxide free radicals (•O2) as the primary reactive species responsible for degradation. This study provides valuable insight into the design of highly efficient nanomaterials for removing organic pollutants in wastewater, and a possible reaction mechanism is proposed.

Optimization of photocatalytic parameters using Doehlert experimental design to improve the photodegradation of Orange G

The development of a method for the soft and ecological synthesis of ZnO is a key research area in materials science and engineering. Herein, a simple and ecofriendly gelation method via biopolymer (sodium alginate) was investigated to highly control the size, morphology, and porosity of synthesized ZnO nanoparticles (ZnO NPs). The characterization techniques used confirmed the formation of pure ZnO with a wurtzite structure and an average particle size of 44.8 nm. Furthermore, the effect of different parameters (solution pH, ZnO quantity and dye concentration) on the photocatalytic performances of ZnO NPs was evaluated using the design of experiments. A three-factor Doehlert design experiment was conducted to investigate the optimal conditions for Orange G photodegradation using ZnO NPs. The Doehlert design was used as a statistical method to systematically vary the values of these three factors and evaluate their effects on photodegradation. The experimental results showed that the optimal photodegradation conditions obtained at a ZnO quantity of 1.03 g/L, an orange G concentration of 39.4 µM, and an initial pH of 4.2.

Ag/AgCl/Bi2O3/BiFeO3@zeolite for photocatalytic degradation of levofloxacin hydrochloride

A kind of easily recyclable and composite photocatalyst based on Ag/AgCl/Bi2O3/BiFeO3 (AABB) and modified zeolite (MZ)/activated carbon (AC) were made, and investigated for the degradation of levofloxacin hydrochloride (Lev-HCl) in wastewater. The structures and morphologies of AABB@loading materials were firstly characterized. The results showed that under visible light, the optimal conditions for photodegradation were: mass ratio of MZ to AABB 3:2, AABB@MZ dosage 1–1.2 g/L, initial concentration of Lev-HCl <18 mg/L. Under these conditions, 72.09%∼ Lev-HCl could be degraded within 1.5 h. In addition, AABB@MZ could be easily recovered by gravity settling for 30 min and reused three times with 74.7% recovery rate. Photoluminescence (PL) combined with electron paramagnetic resonance (EPR) showed that photocatalysts mainly produced ·O2− and ·OH, which played a major role in the degradation process. Finally, a possible catalytic mechanism for AABB@MZ was suggested.

Degradation of Metronidazole from Aqueous Environment Using Hydrothermally Synthesized ZnO, N-Doped ZnO, and ZnO/AC Nanoparticles

ZnO, ZnO (calcined at 400°C), nitrogen-doped ZnO nanoparticles, and activated carbon (AC) impregnated with ZnO (ZnO/AC) nanocomposites were synthesized by the hydrothermal method. The structural, morphological, and optical properties of the synthesized complexes were studied by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transformation infrared analysis (FTIR), Brunauer−Emmett−Teller (BET) analysis, and UV-visible spectroscopy analysis. The degradation of the antibiotic metronidazole (MNZ) from aqueous solutions was examined by the photocatalytic process of those synthesized complexes. Among the four complexes, ZnO/AC was confirmed to be a capable prospective both as an efficient photocatalyst and as an adsorbent. The optimal photodegradation condition obtained was 0.9 g/L and pH = 9. After 300 minutes, 99% of MNZ was removed by ZnO/AC. Finally, gas chromatography-mass spectroscopy was conducted to identify the degradation intermediates.

Electrospun Sn-doped TiO2: Synthesis, structural, optical and catalytic performance as a function of Sn loading and calcination temperatures

A series of tin (Sn)-doped titania (TiO2) composites were prepared by electrospinning and then calcined at temperatures of 500 °C, 600 °C, and 700 °C. The morpho-structural and optical properties of the resulting composites were assesed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) spectroscopy. In this way, the effect of the dopant amounts and calcination temperatures on the composition, morphology, band gap energy (Eg) of the prepared composites was established, as well as their photocatalytic activity towards ciprofloxacin (CIP) photodegradation. The kinetics of ciprofloxacin photodecomposition reactions was analyzed. Herein, it is reported that the nanostructured material based on ([1.5%]Sn:TiO2) sintered at 500 °C shows a remarkable photocatalytic activity with a removal efficiency of about 100% and a rate constant of 9.685 × 10−2 min−1. The photocatalytic stability of this material was evaluated by reusability tests with five cycles under identical conditions for CIP photodegradation. In-depth structural investigations were undertaken to explain this remarkable photocatalytic activity towards water decontamination.

Factors influencing the photodegradation of acid orange 8 by nitrocellulose membranes

Nitrocellulose membranes (NCM) have broad application prospects in the field of organic wastewater treatment. In this research, acid orange 8 was used as the target pollutant, and the effects of factors, such as concentration, light intensity, anions, and cations, on the photodegradation of acid orange 8 were investigated under simulated sunlight by NCM. The results showed that the degradation rate constant of acid orange 8 in the NCM system was 1.94 × 10−3 min−1, which was 27.3 times that in the pure water. The photodegradation rate increases with decreasing concentration in the range of 20–120 μmol/L for acid orange 8. The photodegradation rate increased with increasing NCM area. The degradation effect of acid orange 8 increased with the increase of light intensity. Acidic conditions were favorable for the degradation of acid orange 8. The optimal conditions for photodegradation of acid orange 8 were the solution concentration of 20 μmol/L, membrane area of 17.35 cm2, light intensity of 481 μmol/(m2s), and pH value of 3.0. The effect of different components in water on the photodegradation of acid orange 8 was different. Ca2+, Mg2+, and NO3− could promote the photodegradation of acid orange 8, while CO32- could inhibit the photodegradation. The effect of degrading acid orange 8 by NCM under light conditions is obvious, which can provide a new method for the removal of acid orange 8 in wastewater.

ANALYTICAL METHOD DEVELOPMENT AND VALIDATION FOR THE ESTIMATION OF CYAMEMAZINE TARTRATE IN FORMULATION BY RP-HPLC WITH STABILITY INDICATING

High-performance liquid chromatography (HPLC) technique for cyamemazine tartrate (CYMT) was developed and validated according to the International Conference on Harmonization (ICH) Q2 (R1) guidelines. The developed and validated method for estimating CYMT from a bulk and its pharmaceutical dosage form was found to be a simple, precise, accurate, fast, and stable reverse phase HPLC (RP-HPLC) approach. For chromatographic separation, a Hypersil BDS C18 (250 mm × 4.6 mm, particle size: 5 μm) column was employed with a mobile phase of methanol and buffer (80:20 v/v) flow rate at 1.0 ml/min at room temperature. For detection, a wavelength of 270 nm was utilized. With a run period of 10 min, the CYMT was eluted at 4.38 min. With a correlation coefficient (r2) of above 0.9996, and limits of detection and quantitation (LOD and LOQ) of 0.27 and 0.80 μg, respectively, the method exhibited a dynamic linear response across 30–90 μg/ml. The repeatability of batch injections for intra- and inter-assay precision and accuracy testing was likewise satisfactory. The stability of CYMT was studied under thermal, acid, alkali, and oxidation conditions, as well as photodegradation conditions. The stability of the approach is demonstrated by the presence of CYMT and its breakdown products. The recommended technique exhibited great linearity, accuracy, precision, robustness, LOD, LOQ, and system suitability within the acceptance limit. The study’s findings indicate that the method is rapid, simple, accurate, exact, and linearly stable, implying that an HPLC method for CYMT has been developed and validated, and that it may be used for routine quality control analysis.

Photocatalytic activity of ZnO-PbS nanoscale toward Allura Red AC in an aqueous solution: Characterization and mechanism study

A binary ZnO-PbS catalyst in nanoscale was prepared and characterized via some identification techniques of XRD, DRS, BET, photoluminescence, and SEM-EDX techniques. The average size for ZnO, PbS, and ZnO-PbS was about 17.4, 19.5, and 22.5 nm by the Scherrer model, and 22.7, 23.5, and 18.5 nm by the Williamson-Hall model, respectively. ZnO and the coupled catalyst showed absorption edge wavelengths of 379 nm and 537 nm corresponding to Eg of 3.27 eV and 2.31 eV. The pHpzc of as-synthesized PbS, ZnO, and ZnO-PbS were obtained to be 6.0, 7.2, and 6.7, respectively. Synergistic photocatalytic activity of the binary sample, concerning the semiconductors alone, was achieved toward Allura Red AC (AR) as a dye pollutant model that varied with the change in the amount of the semiconductors in the coupled sample. The best activity was reached when moles of ZnO in the coupled system were four times greater than the other. Optimal conditions for RF photodegradation were: dose: 0.9 g/L, ZnO: PbS mole ratio: 4:1, CAR: 2 ppm, pH 5.

Study of Forced Degradation Behaviour of a Novel Anti-Platelet Drug of Vorapaxar by Uplc-Ms/Ms

A sensitive, precise, specific, linear and stability indicating isocratic UPLC-MS/MS method was developed for the analysis of vorpaxar as per ICH guidelines Q1A (R2). Various forced degradation studies were conducted to establish an impurity profile for vorpaxar. Degradation products were produced upon exposing vorpaxar to different degradation conditions (acidic, basic, oxidative, photolytic, aqueous and thermal); the chromatographic separation was achieved with 5mM Ammonium Format Buffer (pH: 4.0): Methanol: Acetonitrile, (40:30:30, % v/v) using the Pursuit XRs-100Å, C18, 4.6 x 50 mm, 10 µm analytical column. The total analysis time was 3.5 min and flow rate was set to 0.2 ml/min. The mass transitions of vorapaxar and vorapaxar-D5 obtained were m/z 591.4/447.2 and 498.6/447.2. The standard curve shows correlation coefficient (r2) greater than 0.999 with a range of 35.0-105.0 pg/ml using linear regression model. The drug showed instability in the solution state (under acidic, alkaline and oxidative stress conditions), but it was relatively stable in the solid-state, at thermal and photo degradation conditions.

Tuning of Sm3+ and Er3+-doped TiO2 nanofibers for enhancement of the photocatalytic performance: Optimization of the photodegradation conditions

Titanium dioxide (TiO2)-based nanofibers doped with samarium (Sm3+) and erbium (Er3+) at doping levels tuned in the range of 0.05–1.0% were prepared by the electrospinning-calcination method. The produced materials were well characterized by X-ray diffraction, SEM, EDX, and UV–vis diffuse reflectance spectroscopy. These one-dimensional nanostructures showed a crystalline structure with values of fiber diameters values between 60 and 100 nm. The best catalyst sample of this study was formulated as TiO2:Sm (0.1%) and sintered at 600 °C. And, it was employed to intensify the photocatalytic process under visible-light irradiation. Likewise, the chemometric approach was applied to optimize the process. The results revealed that the rate constant for the photo-degradation of a cationic organic pollutant was significantly improved (k = 3.496 × 10−1 min−1). In terms of the reaction half-life, the intensification and optimization of the process led to a decrease in the half-life of the reaction from 68 to 2 min. And, these are outstanding findings for the photo-degradation process under visible-light irradiation. In addition, the total organic carbon (TOC) removal efficiencies were found to be 69.95% and 72.30% for the mineralization of MB and CIP, respectively, after a 360 min reaction time, which are significant results. Moreover, this material demonstrated remarkable photocatalytic activity for the degradation of ciprofloxacin (CIP) with a 99.6% removal efficiency and a rate constant of 4.292 × 10−1 min−1. Finally, the stability and reusability of this catalyst were demonstrated during five repetitive cycles of the CIP photodegradation.

Photodegradation of tetracycline and doxycycline under visible radiation using MIL-MIL101Fe (NH2) @g-C3N4@CoFe2O4/GO as photocatalyst

Today, the use of antibiotics around the world poses many threats to the environment and humans. Antibiotics are potentially environmental pollutants that play an important role in causing pollution with the development of new technologies and increasing use of these products. Photodegradation of antibiotics is a promising way to solve the contamination of antibiotics in water. In this study, the photodegradation efficiency of nanocomposites of contaminants such as tetracycline and doxycycline antibiotics was investigated using nanocomposites of CoFe2O4@GO, MIL-101Fe (NH2), g-C3N4, MIL-101Fe (NH2) @g-C3N4 and MIL-101Fe (NH2) @ g-C3N4@ CoFe2O4 / GO. The best efficiency of degradation was obtained by MIL-101Fe (NH2) @g-C3N4@CoFe2O4/GO (90% and 80% for tetracycline and doxycycline respectively). Photodegradation conditions of effective photocatalyst were optimized by experimental design (version 11) and results were found as follow: initial antibiotic concentration of 20 ppm, pH = 5, the dosage of photocatalyst 40 mg and irradiation time of 65 min. The quadratic model was proposed as a suitable model with coefficient of determination R2 = 0.9982, 0.962 for tetracycline and doxycycline respectively. The photocatalysts were characterized by X-ray diffractometer (XRD), field emission scanning electron microscope (FE-SEM), UV-Vis spectroscopy and Fourier transform infrared spectroscopy (FT-IR) techniques. Zeta potential was also used to determine the surface charge. The final products of degradation process were analyzed by 1HNMR, MS and UV-Vis spectroscopic techniques.