Removal Of Naproxen Research Articles

Effective removal of naproxen from aqueous solutions by CWAO process using noble metals supported on carbon nanospheres catalysts

In this research the technical feasibility of catalytic wet air oxidation reactions (CWAO) with a novel ruthenium supported onto carbon nanospheres (CNS-Ru) catalyst for the degradation of a non-steroidal anti-inflammatory drug (NSAID), naproxen (NPR), has been tested. The operating conditions of the reaction, the different loads of ruthenium in the catalyst, the reuse of the material, the reaction kinetics and the degradation mechanism of the pollutant were studied. The complete degradation of the compound was reached in one cycle at the following conditions: 130 °C, 20 bar, [NPR]0 = 20 mg∙L−1, [CNS-Ru] = 0.75 g∙L−1, 2%wt. of ruthenium and an initial pH of 7.0. At these conditions, the efficiency for the pollutant degradation of a platinum-based catalyst (CNS-Pt) as well as its reusability were also tested. In this sense, better results regarding to the NPR degradation were obtained with the CNS-Ru material. Nevertheless, both catalysts could be considered stable after 4 consecutive runs. Furthermore, two potential kinetic models were investigated in order to simulate the degradation of NPR in both WAO and CWAO processes. Thus, the detection of 13 reaction compounds allowed to propose a degradation mechanism for NPR by CWAO. The efficiency of both catalysts was tested in a real hospital wastewater matrix; it was also proved that the NPR degradation decreased in comparison to that one found for the ultrapure water solutions, and that CNS-Ru catalyst achieved a higher pollutant degradation rather than that obtained for CNS-Pt catalyst.

Electro-assisted naproxen adsorption followed by its electrodegradation and simultaneous electroreactivation of the activated carbon electrode

In this work, the adsorption of a pharmaceutical pollutant, Naproxen (NPX), on activated carbon electrodes was improved through electroadsorption treatment under anodic polarization. After that, the contaminant was electrochemically degraded favoring the reactivation of the adsorbent material. The electroadsorption tests were performed with selected anodic potentials up to 1.1 V vs. NHE. The NPX removal increased from 14.2 mg/g (32.3%), during adsorption without electric potential, to 18.3 mg/g (42.7%) and 20.3 mg/g (47.1%) at 0.7 and 1.1 V vs. NHE, respectively, at an initial NPX concentration of 10 mg/L, in 0.05 M KNO3 solutions at pH 7. The presence of NPX on the electrode was confirmed by differential pulse voltammetry. The electrochemical oxidation of NPX followed an ECE mechanism confirmed by the analysis of voltamperometric parameters. The degradation mechanism was studied at different electrolysis times whose products were extracted by solvent and analyzed by HPLC-MS. Additionally, the reuse of the electrode was studied by the analysis of its textural properties, surface chemical analysis and in a new electroadsorption process. It was observed that the reactivated electrode increased its adsorption capacity up to 38 mg NPX/g (83 %) at 0.7 V and 41 mg NPX/g (84 %) at 1.1 V.

Optimization of photocatalytic degradation of naproxen from aqueous solutions with UV/ZnO process: Response Surface Methodology (RSM)

<p>The aim of this study was to optimize the removal of Naproxen (NPX) by the UV/ZnO photocatalytic process using response surface methodology based on Central Composite Design (CCD). The effect of parameters such as ZnO concentration, contact time, pH, temperature, and initial NPX concentration were studied. The ANOVA results indicated high coefficient values of adjusted R2 (0.9843) and predicted R2 (0.9695). The quadratic model with the highest R-squared designation was chosen to predict the NPX removal efficiency of the UV/ZnO process. Under optimal conditions that include an optimum initial NPX concentration of 21.59 mg/L, ZnO concentration of 371.15 mg/L, contact time of 73.92 min, pH of 6.87, and temperature of 24.35°C, a NPX removal efficiency value of 71.19% was obtained. The results show that the removal of NPX is most affected by the variables- initial NPX concentration, time, pH, and ZnO concentration, respectively, but temperature as a variable does not have a significant effect on the efficiency of the process. Moreover, the NPX photodegradation kinetics can be explained through the pseudo-first-order model. The UV/ZnO photocatalytic method has high potential for the removal of NPX, and that CCD is an appropriate method to optimize the operating conditions for NPX photodegradation.</p>

Facile synthesis of solar light-driven Z-scheme Ag2CO3/TNS-001 photocatalyst for the effective degradation of naproxen: Mechanisms and degradation pathways

The development of efficient solar light-driven catalyst materials is considered a promising strategy for the photocatalytic eradication of contaminants. Herein, a novel Z-scheme Ag2CO3/TNS-001 nanocomposite photocatalyst with excellent solar-light response was synthesized using a simple hydrothermal and deposition reaction. The morphology, chemical structure, and optical property of Z-scheme composites were systematically investigated by TEM, XRD, FI-IR, XPS, and UV–vis, etc. techniques. The Ag2CO3/TNS-001 exhibited superior photocatalytic activity for removal of naproxen (NAP) under solar light irradiation, demonstrating kinetics of 40.7, 23.9, and 6.9 times higher than that of Ag2CO3, P25, and TNS-001, respectively. This remarkably improved photocatalytic efficiency was attributed to the synergistic effects of highly active (001) facets, efficient solar light response, and enhanced separation of photogenerated carriers. The scavenging experiments indicated that h+ was the dominant species during the photocatalytic degradation of NAP. Together with the analyses of EPR and band structure, a potential Z-scheme mechanism was confirmed. Moreover, the degradation pathway of NAP was revealed via intermediate detection and density functional theory (DFT) calculations. The chlorella acute toxicity test further indicated that mineralization translated to a reduction in the toxicity of the NAP solution. This work offers a promising strategy for the design of efficient Z-scheme photocatalysts, while exploring new insights into the elimination of emerging organic pollutants.

Isolation of Cultivable Bacteria Associated with the Root of Typha latifolia in a Constructed Wetland for the Removal of Diclofenac or Naproxen

In this work, we designed at the level of microscale, subsurface flow wetlands planted with Typha latifolia, and used to remove diclofenac and naproxen from solutions that contained them. The wetlands were operated for 105 days with a hydraulic residence time (TRH) of 5 days. In these conditions, the removal efficiencies for diclofenac and naproxen were 98.4% and 97.7%, respectively. Moreover, we identified cultivable bacteria associated with the roots of plants exposed to either diclofenac or naproxen. We obtained 898 isolates that clustered in 9 morphotypes from the roots of Typha latifolia exposed to diclofenac, and 563 isolates grouped in 7 morphotypes, in the case of naproxen. All isolates were identified by 16S ribosomal sequencing. The BLASTn analysis indicated that 16 morphotypes showed an identity higher than 95% with the 16S rDNA gene of bacteria belonging to the genus Pseudomonas. Biochemical characterization based on plant growth-promoting activities suggests that bacteria contribute to plant growth in the wetland conditions. The results indicate that Typha latifolia and bacteria associated with their roots removed diclofenac and naproxen in subsurface flow wetlands.

Roles of structure defect, oxygen groups and heteroatom doping on carbon in nonradical oxidation of water contaminants

A rational design of structure-tailored and functionalized nanocarbons for peroxymonosulfate (PMS) activation is important in metal-free catalysis for degradation of water contaminants. In this work, we employed ionic liquids (ILs) for synthesis of porous carbon materials (PCMs) as a PMS activator for oxidative removal of naproxen and systematically investigated the functions of structure defects, oxygen functional groups and heteroatom doping toward the catalytic oxidation. A positive linear correlation between reaction rate constants and carbon defect ratios of PCMs revealed that the structural defects played an important role in PMS activation. Electron paramagnetic resonance (EPR) spectra, radical quenching experiments and electrochemical analysis tests verified nonradical-dominated oxidations via electron transfer and 1O2. Structural vacancies, ketonic C=O groups and graphitic-N atoms on carbons have been revealed to be the active sites for the nonradical pathways via direct electron transfer or generation of O2•−/1O2. This work provides new insight into the reaction mechanism and structure-performance relationships of the catalytic centers in nonradical oxidation.

Quantification, removal and potential ecological risk of emerging contaminants in different organic loads of swine wastewater treated by integrated biological reactors

This study aims to evaluate the dynamics and their ecological risks for aquatic species of lipid regulator, nervous stimulant, anti-inflammatory and endocrine disrupters in an upflow anaerobic sludge blanket (UASB), submerged aerated biological filters (SABF) and horizontal subsurface flow constructed wetland (HSSF-CW) reactors that treat swine wastewater. Four organic loads of swine wastewater (SW) were used according to changing the chemical oxygen demand. 13 contaminants were quantified, standing out the endocrine disruptors, lipid regulator and anti-inflammatory. In phase III, 8318.4 ng L−1 of 4-ocylphenol was found at the influent of the UASB reactor and removal from 1877.1 to 13.7 ng L−1 in the bisphenol A system. With the maximum organic load, there was a reduction among all the treatment units, with concentrations between 1877.1 and 13.7 ng L−1 of bisphenol A and had naproxen removal of 94.5% and 2,7 ng L−1 after treating phases II and III. It was found that 24.6% of the contaminants presented a high ecological risk, with maximum values of 27.4 (4-nonylphenol, phase II), 24.6 and 5.9 (17β-estradiol, phase IV and I, respectively), 13.4 (4-ocylphenol, phase III) and 4.4 (estrone, phase IV) in the influent system. The reduction of ecological risk potentials was optimized by SABF and HSSF-CW. The effect oxygen availability and microbiological activities optimized the reduction of ecological risks on zebrafish (Danio rerio) and cnidarian (Hydra attenuata) species, moreover, the reduction of mass flows and ecological risks of the emerging contaminants are associated with the use of biological reactors in series and organic stabilizations.

Single-atom silver induced amorphization of hollow tubular g-C3N4 for enhanced visible light-driven photocatalytic degradation of naproxen

In this work, a novel strategy for building single-atom silver-induced amorphous graphitic carbon nitride (g-C3N4) with a hollow tubular morphology is developed. By forming a tubular supramolecular gel, silver is successfully isolated by the nitrogen atoms in both melamine and nitrate anions, impeding agglomeration in the subsequent thermal polymerization. The high density of single-atom-dispersed silver (atomic ratio up to 11.6%) selectively breaks the hydrogen bonds in layered g-C3N4, leading to a fully amorphous structure. Silver-induced full amorphization not only enhances the visible light absorption of g-C3N4 but also accelerates charge transfer, endowing the as-prepared photocatalyst having the optimal silver content with 52 times higher surface area specific naproxen (NPX) removal activity than pure g-C3N4. Both density functional theory (DFT) calculations and steric effects are applied to explain the degradation pathway of NPX. The toxicity of NPX is reduced by sufficient irradiation. This work provides useful insights into the design and morphology control of single metal ion-dispersed g-C3N4 for environmental applications.

Removal of cimetidine, ketoprofen and naproxen by heterogeneous catalytic ozonation over volcanic sand at low pH

This work presents experimental results on the catalytic effect of volcanic sand on the simultaneous removal of naproxen, ketoprofen, and cimetidine by ozonation. Catalyst characterization included XRD, EDX, XRF, SEM and physisorption analysis. Removal assays at laboratory scale in a semi-batch reactor showed enhanced removal by the presence of the catalyst at pH 4, but no difference was found at higher pH values. Furthermore, the immobilization of different amounts of TiO2 (2.5 % and 5.0 %) on the sand surface revealed that TiO2 exerted an adverse effect on the catalytic activity at pH 4, lowering ketoprofen removal by up to 41.3 %. Likewise, the highest and fastest removal at pH 4 was obtained using a catalyst dose of 1 g/L and dosing ozone at 15 mg/L (72.5 % ketoprofen; 90.7 % total pharmaceuticals), reaching more than 80 % total elimination after only one minute of treatment. Catalyst reusability evaluated over 5 cycles demonstrated efficient elimination of the pharmaceuticals, with only slight decrease in ketoprofen elimination. Finally, heterogeneous catalytic ozonation of ketoprofen was applied in a real wastewater matrix, obtaining a removal of 75.9 % after 40 min of reaction; this represents a similar efficiency to that achieved in synthetic wastewater.

Blue LED light-driven photoelectrocatalytic removal of naproxen from water: Kinetics and primary by-products

Here, we demonstrate the viability of a ZnO/TiO2/Ag2Se thin-film composite synthesized on FTO to degrade the drug naproxen in aqueous solutions by visible-light photoelectrocatalysis (PEC). The experiments were made with 100 mL of solutions containing 5 mg L−1 drug and 50 mM Na2SO4 at natural pH, using a cell equipped with a Pt wire as cathode and the composite as photoanode exposed to a 36 W blue LED lamp. Total degradation was achieved after 210 min of electrolysis at anodic potential of +1.0 V/Ag|AgCl. This resulted from the oxidative action of hydroxyl radicals formed via direct anodic water discharge and through mediated water oxidation by photogenerated holes. The degradation rate decreased at higher naproxen concentration, but the treatment efficiency became higher due the deceleration of the parasitic reactions involving hydroxyl radicals. In chloride medium, the photoanode showed a large ability to produce active chlorine, which contributed to the oxidation of the target molecule. LC-QToF-MS analysis of treated solutions revealed the generation of four primary naphthalenic by-products, from which the initial degradation route of naproxen is proposed.

Rapid and efficient removal of naproxen from water by CuFe2O4 with peroxymonosulfate.

Naproxen, a widely used nonsteroidal anti-inflammatory drug, has been detected in many environmental matrixes and is regarded as an emerging pollutant. Sulfate radical(SO4·-) -based advanced oxidation processes have attracted wide attention due to their high efficiency and applicability in the removal of emerging contaminants. In this study, CuFe2O4 was used as an efficient catalyst to activate peroxymonosulfate to oxidize naproxen. The results suggested that 92.3% of naproxen was degraded and 50.3% total organic carbon was removed in 60min in the presence of 0.3g·L-1 CuFe2O4 and 2mM peroxymonosulfate. This degradation system showed strong adaptability in a wide pH range from 4.0 to 10.0. Free radical scavenger experiments and electron spin resonance analysis indicated that 1O2,·OH, andSO4·- are the main active species. Finally, the potential degradation pathways of naproxen were proposed by detecting and analyzing the degradation products with ultra-high-performance liquid chromatography combined with mass spectrometry. The results of this study suggest that the CuFe2O4-activated peroxymonosulfate system is a promising technology for the removal of naproxen from natural water.

Evaluation of cold-weather wastewater nitrification technology for removal of polar chemicals of emerging concern from rural Manitoba wastewaters

Aerated lagoons, typically used by small communities, often provide limited removal of wastewater nutrients. Given increasingly stringent wastewater standards, it is imperative that effective, but economical and easy-to-operate, treatment technologies be developed. The Submerged Attached Growth Reactor (SAGR®) is a treatment process developed to perform nitrification near freezing temperatures. Previous tests on full-scale installations have shown that SAGR could consistently remove ammonia to below current Canadian standards and provide additional total suspended solids and biochemical oxygen demand removal. In this study, we evaluated removal of polar chemicals of emerging concern (CECs), including pharmaceuticals, personal care products, and pesticides, at SAGR installations in two Manitoba First Nations communities (MCN and LPFN) under cold winter conditions. Both showed some removal of diclofenac, naproxen, clarithromycin, metoprolol, and trimethoprim, likely by biotransformation. Average naproxen removal was 21% (2.53 × 103 ng L−1) in MCN and 64% (1.58 × 103 ng L−1) in LPFN. Atenolol was well-removed by SAGR, by 80% on average (range of 64%–94%). Clarithromycin, metoprolol, and trimethoprim removal was similar within and between systems, ranging from 54% to 76% (30.8–3.07 × 102 ng L−1 removed). Carbamazepine was detected in nearly all samples, but was not well-removed, consistent with other treatment studies. Overall, results showed that SAGR technology could moderately remove CECs, while providing the designed treatment performance for other parameters. This work will help to improve our understanding of wastewater treatment in small and/or remote communities with limited infrastructure and challenging cold-weather conditions.

Activated carbon embedded alginate beads for removing nonsteroidal anti-inflammatory drug naproxen from wastewater: equilibrium, kinetics, thermodynamics, desorption, and reusability.

In the present study, activated carbon/alginate (AC/ALG) beads were successfully synthesized with different AC:ALG ratios of 1.0-3.0 (w/v) and used for the adsorption of the nonsteroidal anti-inflammatory drug naproxen from wastewater. The beads were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) analysis, and adsorbent dosage, initial pH, initial naproxen concentration, and contact time in removal efficiency were investigated. Maximum naproxen removal percentage was achieved using 350 mg of AC/ALG beads with a ratio of 3.0% (w/v) within six hours and naproxen removal performance was determined to be 98.0%. Freundlich, Temkin, and Dubinin-Radushkevich (D-R) isotherm models were fitted to the equilibrium data better than the Langmuir model. According to kinetics results, the equilibrium time for the AC/ALG beads was reached in four hours and the kinetic model was determined by the pseudo-second-order equation. The thermodynamic parameters were calculated and enthalpy of naproxen adsorption was found to be positive for all AC/ALG beads. After the adsorption process the beads can easily be regenerated by ethanol and reused within seven cycles.

Experimental investigation of competitive co-adsorption of naproxen and diclofenac from water by an aluminum-based metal-organic framework

Commercially available Aluminum-benzenedicarboxylate (Basolite A100, MIL-53 (Al)), Metal-Organic Framework was successfully used for the adsorption and co-adsorption of Naproxen (NAP) and Diclofenac (DCF) from aqueous solutions. The adsorption experiments were carried out using single-component NAP/DCF and their binary aqueous solutions. The experimental results demonstrated the remarkable removal efficiency of the MOF (>96% for NAP and >99% for DCF). Besides, the competitive adsorption of the drugs from binary solutions showed higher selectivity toward DCF. The hydrogen bonding and π-π stacking were investigated to gain insight into the adsorption mechanism. The pH effect experiments in the range of 2 to 8 showed that as pH increased, the adsorption capacity of both drugs decreased. The fitting of the adsorption isotherm and kinetic models confirms that both contaminants conform to the Langmuir model and pseudo-second-order (PSO) models with high regression coefficient ( R 2 > 0.99). The PSO rate constant values for NAP were 0.0056 (single-component) and 0.0024 g·mg −1 ·min −1 (binary), while for DCF these values were 0.0037 (single-component) and 0.0014 g·mg −1 ·min −1 (binary). According to the isotherm model, the calculated maximum removal capacities ( q m ) values were found equal to 297 and 422 mg/g for NAP and DCF, respectively. The suitability of MIL-53(Al) for adsorption of naproxen and diclofenac in mineral water was also investigated. Finally, MIL-53(Al) was confirmed to be a promising adsorbent candidate thanks to its highly efficient removal of NAP and DCF in both single and binary solutions and then can be deployed in water treatment. • MIL-53(Al) showed great potential for water purification from pharmaceuticals. • MIL-53(Al) had better selectivity for DCF compared to NAP. • Adsorption mechanism was determined to be due to hydrogen bonding and π-π stacking. • The experimental data fitted best the Langmuir isotherm and PSO kinetic models. • The maximum adsorption capacities' values were found equal to 297 and 422 mg/g for NAP and DCF, respectively.

Bio-extract assisted in-situ green synthesis of Ag-RGO nanocomposite film for enhanced naproxen removal

The present study reports in-situ green synthesis of Ag-RGO nanocomposite film using turnip leaves-extract as a reducing as well as a capping agent and its application as a highly efficient naproxen adsorbent from a contaminated aqueous solution. The nanocomposite was characterized employing XRD, Raman and FT-IR spectroscopy, FETEM and FESEM microscopy, EDS spectroscopy. The pseudo-second-order and Elovich kinetic model furnished the best correlation of the experimental data, specifying the adsorption as the rate-limiting step for naproxen (NPX) removal by Ag-RGO composite film. The Freundlich and Dubinin-Radushkevich (D-R) isotherms represented the experimental adsorption data satisfactorily, suggesting a multilayered chemical adsorption process on the heterogeneous adsorbent surfaces. The process parameters were optimized to get the maximum adsorption capacity, which was obtained as 229.25 mg g−1 (92.62%). The parametric effects of pHs and NPX concentrations were tested within a range of 2.50–8.50 and 25–100 mg dm−3, respectively, for the contact time of 0.33–3 min at a constant temperature (298 K) and adsorbent dose (20.2 mg). The feasibility of the regeneration of the materials after adsorption is based on the experimental results. The experimentally optimized process parameters were validated using response surface methodology (RSM).

Naproxen Removal Capacity Enhancement by Transforming the Activated Carbon into a Blended Composite Material

The naproxen adsorption capacity enhancement of activated carbon prepared from the Indian gooseberry seed-shells by manufacturing a composite blended with the surface-modified graphite powder and silver nanoparticles was studied in the present context. The composite of the nano-sized materials was prepared in dimethylformamide solution and characterized by employing XRD, Raman, EDS and FT-IR spectroscopy, FETEM, and FESEM microscopy. The pseudo-first-order, pseudo-second-order, and Elovich models were applied to test the removal kinetics. Preliminary results were also fitted to the Langmuir, Freundlich, Temkin, and Dubinine-Radushkevich (D-R) adsorption isotherm models to determine the specific parameters of each model. The effects of the initial pH of the solution, naproxen concentration, and contact time on the process were optimized. The maximum adsorption capacity was obtained as 154.98 mg g−1 (61.99%) with an increment of 25.31% by the addition of surface-modified graphite powder and silver nanoparticles at the optimized experimental conditions.

Distribution, Removal, and Risk Assessment of Pharmaceuticals and Their Metabolites in Five Sewage Plants.

The extensive use of pharmaceuticals and personal care products (PPCPs) leads to a continuous increase of their presence in urban wastewater. These pollutants are discharged into natural waters and pose a threat to human health and the ecological environment. This study focused on five sewage treatment plants in three cities of China’s Yangtze River Delta as research sites to study the distribution and degradation of drugs and their conversion products in wastewater. The concentration of target compounds in the water ranged from 0 to 510.8 ng/L, and both positive and negative removal rates occurred during the treatment. Acetaminophen (ACE) and ibuprofen (IPF) can be completely removed in the biological treatment stage. The addition of flocculants and sand filtration has a positive effect on the removal of naproxen (NPX) and bezafibrate (BZB). Ultraviolet disinfection is beneficial for the removal of antipyrine (ATP) and diclofenac (DCF). A small amount of PPCPs were found in the sludge and particulate matter, which had little effect on removal. Finally, the risk quotients were used to evaluate the harmfulness of the PPCPs detected in the effluent to the ecological environment, and the results showed that there was little hazard.

Role of Design and Operational Factors in the Removal of Pharmaceuticals by Constructed Wetlands

This study evaluates the role of design, operational, and physicochemical parameters of constructed wetlands (CWs) in the removal of pharmaceuticals (PhCs). The correlation analysis demonstrates that the performance of CWs is governed by several design and operational factors (area, depth, hydraulic loading rate, organic loading rate, and hydraulic retention time), and physicochemical parameters (dissolved oxygen, temperature, and pH); the removal efficiency of about 50% of the examined PhCs showed a significant correlation with two or more factors. Plants contributed significantly in the removal of some of the PhCs by direct uptake and by enhancing the process of aerobic biodegradation. The use of substrate material of high adsorption capacity, rich in organic matter, and with high surface area enhanced the removal of PhCs by adsorption/sorption processes, which are the major removal mechanisms of some PhCs (codeine, clarithromycin, erythromycin, ofloxacin, oxytetracycline, carbamazepine, and atenolol) in CWs. Although the removal of almost all of the studied PhCs showed seasonal differences, statistical significance was established in the removal of naproxen, salicylic acid, caffeine, and sulfadiazine. The effective PhCs removal requires the integrated design of CWs ensuring the occurrence of biodegradation along with other processes, as well as enabling optimal values of design and operational factors, and physicochemical parameters.

Visible-light-driven photocatalytic degradation of naproxen by Bi-modified titanate nanobulks: Synthesis, degradation pathway and mechanism

Naproxen (NPX) as one of the typical pharmaceuticals and personal care products (PPCPs) has been constantly detected in aquatic environment recently which has potentially hazard to the human health and ecosystem. However, the practical applicability of photocatalysts in degradation of NPX is still restricted by challenges that most nanomaterials need to be stimulated by ultraviolet light and their limited photocatalytic activity under visible light. Therefore, we synthesized bismuth titanate nanobulks (Bi-TNB) through the two-step method of hydrothermal-calcining. The crystal structure, morphology, UV–vis diffuse reflectance spectra and surface adsorption performance of the as-prepared were investigated by XRD, SEM, UV–vis and BET. Several parameters which might influence the degradation efficiency were studied including initial NPX concentration, catalyst dosage, solution pH and concentration of anions, cations and humus. The results indicated that more than 99.9% of NPX (0.25 mg/L) was removed by Bi-TNB (0.5 g/L) at pH = 7. Reactive species scavenging experiments indicated that h+ and O2·− were the dominant active species involved the degradation of NPX. In photodegradation process, NPX was firstly decarboxylated and then further photocatalytic oxidized to form carboxylic acids of lower molecular weights and would be finally transformed into CO2 and H2O. PPCPs coexistence experiment showed that acetaminophen would hinder the removal of NPX by Bi-TNB. Both the reaction in different water matrices and degradation under the condition of sunlight indicated that Bi-TNB could be applied in degradation of NPX in environmental water systems. This study provides a new strategy for enhancing material photocatalytic performance to be used in practical applications.

Biological removal of pharmaceuticals by Navicula sp. and biotransformation of bezafibrate

Pharmaceutically active compounds are of great concern due to their detection frequency in the environment and the unexpected risks. In this study, the simultaneous removal of mixed pharmaceuticals by microalgae was explored using a typical freshwater diatom Navicula sp. Results showed that Navicula sp. could efficiently remove atenolol, carbamazepine, ibuprofen and naproxen with the efficiencies of >90% after 21 d of exposure. As compared to the removal efficiencies of each pharmaceutical in the individual pharmaceutical treatments, the degradation of sulfamethoxazole, bezafibrate, and naproxen was improved in the mixed treatment, whereas the removal efficiencies of carbamazepine and atenolol decreased. Additionally, the presence of hydrophobic pharmaceuticals (i.e., ibuprofen and naproxen) accelerated the degradation of carbamazepine and sulfamethoxazole and inhibited the removal of atenolol in the mixture with the combination of six pharmaceuticals, while the addition of other pharmaceuticals show no significant effect on the removal of ibuprofen and naproxen. The bioaccumulation of pharmaceuticals in Navicula sp. increased as their log KOW values decreased. Four bezafibrate metabolites were identified and the degradation pathways of bezafibrate in diatom were proposed. It is the first report on the metabolism of BEZ in diatom, and further studies on the environmental risk of the metabolites should be investigated.