Degradation Of Naproxen Research Articles

Visible-light-driven BNQD/BiVO4 material with enhanced photocatalytic activities for naproxen degradation and kinetic insights

The recombination of photogenerated electrons and holes represents a formidable constraint on the efficacy of semiconductors, which comprises a pivotal determinant of their performance in photocatalysis.

Photocatalytic degradation of naproxen using single-doped TiO2/FTO and co-doped TiO2-VO2/FTO thin films synthesized by sonochemistry

Abstract Single-doped TiO2/FTO and co-doped TiO2-VO2/FTO thin films were prepared by sonochemistry and spray pyrolysis deposition on FTO substrates. The co-deposition of TiO2-VO2 on FTO significantly changed the morphological, structural, optical, and photocatalytical properties compared to the single-deposition. X-ray diffraction and HRTEM results showed polycrystalline film structures composed of SnO2-tetragonal from FTO, anatase-TiO2, rutile-TiO2, and monoclinic-VO2 phases. The co-deposition technique increases the particle size distribution by approximately two times compared to simple deposition. The single-doped TiO2/FTO thin film had a 15% higher bandgap than the co-doped TiO2-VO2/FTO thin film, and the electrical resistivity calculated from the van der Pauw method was 55.3 MΩ sq−1 for the TiO2-VO2/FTO co-doped thin film, 2.7 times lower than that obtained for the TiO2/FTO thin film. Single-doped TiO2/FTO and co-doped TiO2-VO2/FTO thin films presented pseudo-first-order reactions at pH 6.5, with kinetic constants of 0.026 and 0.015 min−1, respectively. This behavior is related to the production of inactive or less active aggregates by the addition of vanadium during the co-doping process, which led to lattice contraction, which encouraged the formation of the rutile phase rather than the anatase phase. However, the co-doped thin film can modify the metal-insulator transition compared to the single-doped TiO2/FTO thin film. Furthermore, co-deposition decreased the bandgap value by 16% compared to single-deposition thin film. In this sense, co-doped TiO2-VO2/FTO thin films inhibited the recombination of photogenerated carriers and the formation of reactive oxygen species involved in the photocatalytic degradation of naproxen.

Non-toxic fluorine-doped TiO2 nanocrystals from TiOF2 for facet-dependent naproxen degradation

In the present study, the photocatalytic degradation of naproxen (NPX), which is a nonsteroidal anti-inflammatory drug (NSAID), frequently detected in drinking water, was investigated. The F-doped TiO2 with defined morphology was successfully obtained from TiOF2 and applied for photocatalytic degradation under UV–vis and visible light. All samples were characterised by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, zeta potential, diffuse reflectance spectroscopy, and Brunauer–Emmett–Teller surface area analyses. The effect of morphology on the photocatalytic activity of the F-TiO2 nanostructures with exposed {1 0 1}, {0 0 1} and {1 0 0} facets was studied. Octahedral F-TiO2 particles with exposed {1 0 1} facets revealed the highest photocatalytic activity, and degraded 100% of the initial NPX concentration after 40 min of the photodegradation process under simulated solar light (UV–vis). Moreover, this sample exhibited the highest TOC removal and NPX degradation under visible light (>420 nm). Based on HPLC-MS analysis, it was assumed that {0 0 1} facets present in fluorinated decahedral nanostructures promote the formation of a dimer, which further hinders the mineralisation rate. Therefore, decahedral nanostructures exposing {1 0 1} and {0 0 1} facets revealed lower photocatalytic activity than octahedral F-TiO2 particles with exposed {1 0 1} facets, which is also consistent with DFT studies. Finally, toxicity assessment of post-process suspensions using Microtox bioassay confirmed that fluorine-doped octahedral anatase particles are non-toxic, although fluorine ions were the reactants of the synthesis from TiOF2. Overall results showed the possibility of application of highly efficient and environmentally safe fluorine-doped anatase photocatalysts in improved degradation of naproxen.

Enhanced photocatalytic degradation of naproxen in aqueous matrices using reduced graphene oxide (rGO) decorated binary BSO/g-C3N4 heterojunction nanocomposites

Reduced graphene oxide-bismuth silicate-graphitic carbon nitride (rGO/BSO/g-C3N4) heterostructured nanocomposites was synthesised by wet-impregnation method. The morphology, microscopic, structural composition and optical properties of the nanocomposites were characterised, before and after modification of the materials with different amounts of rGO, using XRD, FTIR, TEM, HR-TEM, UV-Vis DSR, PL and BET analysis. The rGO/BSO/g-C3N4 nanocomposites are of high crystallinity. TEM images revealed the presence of wrinkled aggregates of rGO on layers of BSO and g-C3N4 sheets. A band gap energy of 2.34 eV was achieved in compositing, which results in increase in the composites absorption capacity and reduced photoluminescence emission. The reduced PL emission suggests decreased recombination of the photon-induced electron-hole pair, due to the decoration of rGO on the surface of the BSO/g-C3N4 composites. The rGO decoration of binary BSO/g-C3N4 composites improved the photocatalytic efficiency of the heterostructured rGO/BSO/g-C3N4 materials, with the 0.3wt% rGO/BSO/g-C3N4 nanocomposite achieving 97.70 and 77.52%, 90 min visible light irradiative degradation efficiency for naproxen in simulated and real wastewater samples, respectively. This efficiency is ascribed to excellent electron-hole separation, and good charge transfer occasioned by rGO decoration of BSO/g-C3N4. Photogenerated holes (h+) and .O2¯ radicals were noted as the main active species involved in naproxen degradation.

Cu0 incorporated cobalt/nitrogen doped carbonaceous frameworks derived from ZIF-67 (Cu@Co[sbnd]N[sbnd]C) as PMS activator for efficient degradation of naproxen: Direct electron transfer and 1O2 dominated nonradical mechanisms

In this study, zero valent copper (Cu0) was incorporated into ZIF-67 to construct Cu0 and cobalt/nitrogen doped carbonaceous frameworks x-Cu@CoNCy. The obtained Cu@CoNC was employed to activate PMS to degrade naproxen (NPX) in aqueous phase. Influencing factors on NPX degradation were investigated, including mole ratio of Cu/Co, pyrolysis temperature, pH, catalyst dosage, PMS concentration, and coexisting inorganic anions. In the presence of 0.5 mM PMS and 25 mg/L 1:3-Cu@CoNC900, complete degradation of NPX (50 μM) could be achieved in 20 min within a wide pH range of 3 to 10. The superior catalytic activity of Cu@CoNC900 for PMS activation was related to the increased surface –OH groups, accelerated electron transfer rate induced by Cu0 with strong conductivity, formed surface PMS complexes with high oxidation activity, and synergistic effect between Cu and Co. EPR analysis, radical scavenging and probe tests excluded the participation of SO4− and OH in NPX degradation. Nonradical pathways of electron transfer from NPX to PMS and 1O2 oxidation contributed to the excellent degradation. The 1:3-Cu@CoNC900 demonstrated a decent degradation performance even after five consecutive recycles with low cobalt and copper ions leaching due to the encapsulation of Co and Cu on N-doped porous carbon. Further, the intermediates of NPX degradation were identified, and three possible degradation pathways were proposed. Overall, this work provides a feasible strategy to improve the stability and catalytic activity of ZIF-67 by the incorporation of Cu0.

Sulfate radical-based advanced oxidation process (SR-AOP) on titania supported mesoporous dendritic silica (TiO2/MDS) for the degradation of carbamazepine and other water pollutants

Sulfate radical-based advanced oxidation processes (SR-AOPs) coupled with photocatalysis provide a viable solution for complete degradation of micropollutants pollutants, These micropollutants pose a significant threat to humans and aquatic organisms. In this study, TiO2 supported on mesoporous dendritic silica (TiO2/MDS) was prepared via ultrasonic assisted impregnation method for degradation of carbamazepine and other micropollutants in the presence of persulfate. FT-IR, XRD, BET, FE-SEM/EDS, TEM, PL, UV–Vis DRS, XPS, and electrochemical techniques were employed for characterization. The TiO2/MDS system exhibits an efficient PS activation activity and outstanding CBZ degradation efficiency compared to MDS and TiO2 system. The results also show that CBZ solution could be completely degraded with 1.0 mM PS and 0.5 g/L photocatalyst. The high activity and stability were a result of reduced electron-hole recombination, effective charge separation and transfer, and a longer electron lifetime observed in TiO2/MDS, among others. The MDS as the support also improved the adsorption and proximity of reactants to the TiO2 activity sites in the system. Additionally, the TiO2/MDS/PS/UV system was tested for degradation of amoxicillin, sulfamethoxazole, naproxen, and bisphenol A. Quenching experiments demonstrated that OH•, SO4•-, h+ and O2•- contributed to the overall degradation efficiency. The results undoubtedly illustrate that the TiO2/MDS/persulfate system is an effective system with potential applicability for water treatment.

New insights into the degradation of micro-pollutants in the hydroxylamine enhanced Fe(II)/peracetic acid process: Contribution of reactive species and effects of pH

The hydroxylamine-enhanced Fe(II)/peracetic acid (PAA) process is a promising advanced oxidation process (AOP) with the generation of reactive species (RS) including RO•, •OH and Fe(IV). Nevertheless, it is still challenging to identify which RS is the major intermediate oxidant, and the reasons why the optimal condition is pH 4.5 rather than 3.0 are also unclear. Herein, the generation of RS and their contribution to the degradation of three micro-pollutants were explored. The quenching experiments and pseudo first-order kinetic model demonstrated that RO• rather than the other two RS were predominant. Then the overall generation and evolution pathways of RS were depicted. The elevation of pH (3.0–4.5) would accelerate the Fe(II)/Fe(III) redox cycle through the enhanced reduction of Fe(III) by hydroxylamine and induce the conversion of Fe(IV) to RO•, which benefited naproxen degradation. While the adverse Fe(III) precipitation would dominate the reduced degradation performance with the solution pH higher than 4.5. The elevation of PAA and Fe(II) dosages sped up the PAA activation, while excess hydroxylamine could consume the formed RS and exhibited an inhibitory effect. This study helps further understand the role of HA and differentiate the contribution of RS in the emerging PAA-based AOPs.

Comparative study of naproxen degradation via integrated UV/O3/PMS process: Degradation products, reaction pathways, and toxicity assessment

Comparative study of naproxen degradation via integrated UV/O3/PMS process: Degradation products, reaction pathways, and toxicity assessment

Insights into CQDs-doped perylene diimide photocatalysts for the degradation of naproxen

Advanced efficacious catalytic technologies have the capacity to enhance the degradation of emerging anthropogenic contaminants. Herein, the supramolecular nanofibers, namely carbon quantum dots doped perylene diimide (PDI/CQDs), was prepared via a one-step acidification polymerization method. The results showed that the rate constants of naproxen (NPX) were of 3.50 times in contrast to pristine PDI. When the doping amount of CQDs on PDI was 2%, the half-life of NPX was only 0.66 min in the PDI/CQDs photocatalytic system. The main active substances in the photocatalytic degradation of NPX were h+, O2•−, 1O2, H2O2 and •OH. Degradation mainly occurred through four paths, including the decarboxylation reaction, classical Ipso-substitution reaction, electron-dominated reaction, and intramolecular dehydration reaction paths. The obvious inhibitory effects of HA, Cl−, NO2– and HCO3– was observed, where a lower pH value was beneficial for the degradation of NPX. An overall mechanism was proposed through Density Functional Theory calculations of high-efficiency electron-hole separation of PDI/CQDs. To improve the nanomaterial applicability, PDI/CQDs cellulose acetate membrane was synthesized and used under different water conditions, which further revealed the stability and efficient of this membrane. Ultimately, the aggregate results provided basic supportive data for the remediation of contaminants in water and wastewater.

Electrochemical oxidation of Naproxen in aqueous matrices: Elucidating the intermediates’ eco-toxicity, by assessing its degradation pathways via experimental and density functional theory (DFT) approaches

The removal of the non-steroidal anti-inflammatory drug (NSAID) Naproxen (NAX) in water by hydroxyl radicals (•OH) was performed by electrochemical advanced oxidation processes either with Pt or BDD anodes and a 3D carbon felt cathode. The degradation of NAX by (•OH vs electrolysis time) was well fitted to a pseudo-first-order reaction rate kinetic. The detected reaction intermediates (aromatic compounds and carboxylic acids) were experimentally monitored during the process via LC, while density functional theory (DFT) was applied to uncover undetected intermediates, some for the first time in literature. The formation of toxic intermediates with higher toxicity than NAX were identified, such as IMS4b (6-Methoxy-1-[1-(6-methoxynaphthalen-2-yl) ethyl] naphthalen-2-ol), catechol, and glycolic acid. Based on these data, a detailed oxidation pathway of NAX by •OH was proposed. The evolution of solution toxicity indicated that the formed toxic intermediates were subsequently removed during the TOC removal process. Finally, almost complete mineralization of NAX was achieved in simulated urine or wastewater by the electro-Fenton treatment, with an optimized dose of iron as catalyst, showing the EAOPs’ potential to efficiently remove NAX even from challenging matrices. In extension, the strategies developed can be applied to the treatment of other NSAIDs.

Photocatalytic activity of ZrO2/TiO2/Fe3O4 ternary nanocomposite for the degradation of naproxen: characterization and optimization using response surface methodology

In this study, ZrO2, TiO2, and Fe3O4 components were synthesized by co-precipitation, sol–gel, and co-precipitation methods, respectively. In addition, solid-state dispersion method was used for synthesizing of ZrO2/TiO2/Fe3O4 ternary nanocomposite. The ZrO2/TiO2/Fe3O4 nanocomposite was characterized by different techniques including XRD, EDX, SEM, BET, FTIR, XPS, EELS, and Photoluminescence (PL). The FTIR analysis of ZrO2/TiO2/Fe3O4 photocatalyst showed strong peaks in the range of 450 to 700 cm−1, which represent stretching vibrations of Zr–O, Ti–O, and Fe–O. The results of FTIR and XRD, XPS analyses and PL spectra confirmed that the solid-state dispersion method produced ZrO2/TiO2/Fe3O4 nanocomposites. The EELS analysis confirmed the pure samples of Fe3O4, TiO2 and ZrO2. The EDAX analysis showed that the Zr:Ti:Fe atomic ratio was 0.42:2.08:1.00. The specific surface area, pores volume and average pores size of the photocatalyst were obtained 280 m2/g, 0.92 cm3/g, and 42 nm respectively. Furthermore, the performance of ZrO2/TiO2/Fe3O4 nanocomposite was evaluated for naproxen removal using the response surface method (RSM). The four parameters such as NPX concentration, time, pH and catalyst concentration was investigated. The point of zero charge of the photocatalyst was 6. The maximum and minimum degradation of naproxen using photocatalyst were 100% (under conditions: NPX concentration = 10 mg/L, time = 90 min, pH = 3 and catalyst concentration = 0.5 g/L) and 66.10% respectively. The stability experiment revealed that the ternary nanocatalyst demonstrates a relatively higher photocatalytic activity after 7 recycles.

Enhancement on the degradation of naproxen in Cu0 activated peroxymonosulfate system by complexing reagents

In recent years, there has been growing interest in the mechanism (radical or nonradical) of persulfate activation processes. In this study, the enhancement of naproxen (NPX) degradation in a Cu0/peroxymonosulfate (PMS) system by complexing reagents was investigated. Surprisingly, neocuproine (NCP) alters the nature of reactive species in the Cu0/PMS system. A high-valent copper species, Cu(III)-NCP, was found to dominate NPX degradation rather than radicals under acid conditions for the first time. Moreover, systematically designed experiments revealed that the Cu(III)-NCP complex was a strong selective oxidant that reacted with organics through a single electron transfer pathway. Meanwhile, the degradation efficiency of NPX was highly dependent on the solution pH and dosage of Cu0 and NCP, but was irrelevant to the concentration of NPX. Additionally, the enhancement of NCP on other copper based PMS activation systems (i.e., Cu2+/HA/PMS and Cu0/HA/PMS systems) was investigated. Considering that the released copper can be removed by a simple precipitation method to meet the effluent standards, the new complex-enhanced Cu0/PMS system provided a new method to enhance the degradation efficiencies of pollutants by a copper-catalyzed Fenton-like system.

Hydrogen generation from photocatalytic treatment of wastewater containing pharmaceuticals and personal care products by Oxygen-doped crystalline carbon nitride

Degrading organic pollutants while generating hydrogen from water splitting is an ideal application of photocatalysis. Herein, we presented an efficient photocatalyst, oxygen-doped crystalline carbon nitride, to power the degradation of various kinds of pharmaceuticals and personal care products and the simultaneous hydrogen production. The highest efficiency was achieved in treating the simulated wastewater containing naproxen (NPX), with the H2 evolution rate of 819.1 µmol/g/h and the NPX degradation efficiency of 92 % upon visible light irradiation. Experimental and computational results suggested that the doped oxygen atoms thermodynamically favored the generation of hydroxyl peroxide for pollutant degradation and lowered the energy barrier of H2O reduction to produce hydrogen fuel. Most importantly, the catalysts functioned well in the natural aquatic environment including sea water, sewage water, river water, and well water. This study provides fundamental insights into photocatalytic water treatment with simultaneous hydrogen production, indicating an energy-recovering approach for wastewater treatment.

TiO2-La2O3 as Photocatalysts in the Degradation of Naproxen

The indiscriminate use of naproxen as an anti-inflammatory has been the leading cause of pollution in sewage effluents. Conversely, titanium dioxide is one of the most promising photocatalyst for the degradation of pollutants. Ti-La mixed oxides containing 0, 1, 3, 5, and 10 wt.% of lanthanum were synthetized by sol-gel and tested as photocatalysts in the degradation of naproxen (NPX). The materials were further characterized by X-ray diffraction (XRD), nitrogen physisorption (BET), scanning electron microscopy (SEM), UV-Vis and Fourier-transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The XRD patterns resembled that of anatase titania. The Eg values, determined from the UV-Vis spectra, vary from 2.07 to 3.2 eV corresponded to pure titania. The photocatalytic activity of these materials showed a degradation of naproxen from 93.6 to 99.8 wt.% after 4 h under UV irradiation.

A novel NH2-MIL-88B(Fe)-modified ceramic membrane for the integration of electro-Fenton and filtration processes: A case study on naproxen degradation

• Novel NH 2 -MIL-88B(Fe)-decorated ceramic membrane for combined filtration-EF at mild pH. • Almost total degradation of naproxen in Na 2 SO 4 after 90 min at 50 mA and 2 mL min −1 . • Mechanism for heterogeneous EF with catalytic ceramic membrane (EFCCM) treatment. • Identification of 7 primary oxidation byproducts and EFCCM viability in urban wastewater. • Low iron release (<1 mg L −1 at pH ≥ 5) ensured a good CM reusability for at least 5 cycles. Process intensification based on innovative coupling between membrane microfiltration and catalytic oxidation technologies has become a promising strategy for water treatment. Here, a surface-nucleated metal–organic framework (MOF) was grown in situ to obtain an NH 2 -MIL-88B(Fe)-functionalized catalytic ceramic membrane (NH 2 -MIL-88B(Fe)@CM), whose ability to remove naproxen from water matrices via the so-called electro-Fenton with catalytic ceramic membrane (EFCCM) process was systematically investigated. The physicochemical properties of the NH 2 -MIL-88B(Fe) and membranes were characterized by XRD, FTIR, XPS and SEM, revealing the formation of a well-defined NH 2 -MIL-88B(Fe) layer on the porous CM with a thickness of around 13.5 µm, which provides a large amount of active sites for H 2 O 2 activation to generate hydroxyl radical ( OH). The EFCCM treatment of naproxen in Na 2 SO 4 solution under recirculation batch mode yielded almost complete drug removal in 90 min at 50 mA, whereas the stability and catalyst loss tests gave evidence of good membrane reusability for 5 cycles. The treatment of naproxen in urban wastewater confronted severe membrane fouling, but this was effectively mitigated by combining hot water backwash with EF self-cleaning. Finally, the naproxen degradation routes involving 7 byproducts are proposed. This is an effective approach to the fabrication of CCM, which could be used for wastewater treatment in continuous mode as suggested by the minimal NPX content at the membrane outlet.

Peroxymonosulfate activation by magnetic NiCo layered double hydroxides for naproxen degradation

It is desirable to prepare efficient catalysts to activate peroxymonosulfate (PMS) for catalytic degradation of organic pollutants in water. This study reported on the preparation of a promising PMS activator, magnetic NiCo layered double hydroxides (Fe3O4 @NiCo LDHs) for naproxen (NPX) degradation in aqueous solution in the presence of PMS. Fe3O4 @NiCo LDHs were prepared by simple hydrothermal method. The structure characterization showed that the layered structure of the material was obvious, and there was no obvious agglomeration phenomenon. Magnetic nanoparticles Fe3O4 were loaded on the surface of Fe3O4 @NiCo LDHs to provide magnetism, which facilitated subsequent separation and recovery. The catalytic tests were carried out in a thermostatic oscillator (20 ℃, 180 rpm) and the results indicated that Fe3O4 @NiCo LDHs exhibited excellent catalytic performances for NPX in which 83.9% of NPX was removed within 20 min. Notably, Fe3O4 @NiCo LDHs maintained good reusability and stability with removal efficiency of 78.1% even after five cycles. In addition, the potential applications of Fe3O4 @NiCo LDHs for the degradation of NPX in actual water samples (the tap water and Yellow River water) were also investigated.

New insight into the regulation mechanism of visible light in naproxen degradation via activation of peroxymonosulfate by MOF derived BiFeO3

BiFeO3 (BFO) nanocage prepared by metal-organic-framework derivatization (MOF-d) was adopted as activator to first investigate the effect mechanism of visible-light on naproxen-degradation via peroxymonosulfate (PMS) activation. MOF-d BFO expressed more excellent PMS activation ability than hydrothermal-synthetic BFO, due to highly ordered mesopores. A 3.0 times higher pseudo-first-order degradation rate constant was achieved after visible-light introduced. The quenching experiments indicated that the contribution of ROS in naproxen degradation followed the order of SO4•->1O2 ≈ •OH in MOF-d BFO/PMS/dark system, while changed into h+>1O2 > >O2•-≈SO4•-> •OH after visible-light introduced. EPR tests first revealed that visible-light promoted 1O2 yield (non-radical pathway) but suppressed •OH and SO4•- generation (free-radical pathways). N2-purging experiments further proved that 1O2 primarily originates from the reaction between h+ and PMS, equivalently to that between O2 and e--h+ in MOF-d BFO/PMS/vis system. Under visible-light, PMS activation via Fe (III) might be hindered by e- filling on Fe 3d orbital and anion PMS preferred to approach h+ rather than e-, resulting in the decrease of •OH and SO4•- yields. Moreover, PMS faces competition from adsorbed-O2 and oxygen-vacancies for e- capture. The degradation-pathways for naproxen in dark and under visible light were both proposed in MOF-d BFO/PMS system.

Degradation of Naproxen by UV-irradiation in the presence of nitrate: Efficiency, mechanism, products, and toxicity change

• Nitrate photolysis facilitated the photo-degradation of naproxen. • HO • and reactive nitrogen species played important roles in naproxen degradation. • Water matrix influenced the degradation efficiency of naproxen differently. • Naproxen was degraded mainly via ring-opening, hydroxylation, and nitration steps. • Increasing cytotoxicity was observed and the corresponding mechanism was proposed. Nitrate photolysis can produce reactive species that may affect the fate of coexisting micropollutants in the aquatic environment. In this study, the photo-degradation of naproxen (NPX) in the presence of nitrate was investigated. The observed pseudo-first-order rate constant ( k obs ) increased linearly with the nitrate dosage increasing from 1 mM to 10 mM. According to the EPR analysis and the quenching experiments, hydroxyl radicals (HO • ) and reactive nitrogen species (RNS, mainly NO 2 • ) were found to play major roles in NPX degradation at pH 7.0 with the contribution rates of 34.3% and 40.7%, respectively. The k obs decreased with increasing pH due to the lower contribution of HO • and RNS. Moreover, water matrix components impacted the kinetics of NPX decomposition differently. Natural organic matter (NOM) had an inhibitory effect on the degradation of NPX, while bicarbonate and chloride ions slightly promoted the degradation. Furthermore, the degradation products in the system were identified by UPLC Q-TOF-MS analysis, and the transformation of NPX was shown to be mainly side-chain cleavage, hydroxylation, ring-opening, and nitration, indicating the role of HO • as well as RNS. According to the cytotoxicity assay and the toxicity of identified products predicted by ECOSAR program, the formation of several toxic products with aldehyde and nitro groups led to the increased toxicity during NPX degradation. Our study provides insights into the transformation mechanisms and the toxicity evolution of NPX in the photolysis system.

Multi-elemental doped g-C3N4 with enhanced visible light photocatalytic Activity: Insight into naproxen Degradation, Kinetics, effect of Electrolytes, and mechanism

• Multi elemental doped g-C 3 N 4 was prepared by a solid-state method. • 92.9% degradation of naproxen was achieved under visible light irradiation. • Doping increased the Urbach energy of g-C 3 N 4 . • Mechanism for the degradation of naproxen was proposed. The complexity and heterogeneous existence of water pollutants ensures that development of possible large-scale water remediation technologies encompasses mimicking real water compositions. Naproxen (NPX) photocatalytic degradation in the presence of brilliant black and different electrolytes was tested, under visible light irradiation, with rare earth metals (Ce, Er, Gd, and Sm) doped graphic carbon nitride (CN) prepared via one pot solid state method. The materials were characterized with FESEM, TEM, XRD, PL, XPS, BET, UV–vis DRS, TGA, FTIR, and electrochemical techniques. Doping increased the Urbach energy compared to pristine graphitic carbon nitride due to observed shift in absorption towards the visible range of the electromagnetic spectrum, and there was proposed interaction of dopants and CN which decreased photoexcited electrons and holes recombination. The highest degradation efficiency of 92.9% was obtained at 1% loading of Ce, Er, Gd, and Sm metals in CN (1RECN) under visible light irradiation which was ascribed to Z-scheme formation, enhanced visible light absorption and superoxide anion radical’s involvement as the major species based on radical trapping experiments. The 1RECN photocatalyst demonstrated remarkable stability with a 3.4 % efficiency reduction after six photocatalytic degradation cycles. The effective and efficient separation and migration of photoexcited electron-hole pairs resulted in their high photodegradation activity compared to other synthesized composites and pristine CN. The fabricated composites provided an interesting perspective for a highly stable multi-elemental doped CN photocatalysts that could be employed for large scale remediation of different classes of organic pollutants.

Degradation of API pollutants using hydrodynamic cavitation and process intensification

Degradation of Naproxen, a common nonsteroidal anti-inflammatory drug as a model compound, has been reported using hydrodynamic cavitation (HC) and process intensification. Two types of cavitating devices, vortex diode that employs vortex flow and a conventional linear flow based device, orifice have been investigated for their effectiveness in degradation. Process intensification was carried out by employing simple aeration and also by addition of oxidising agent, hydrogen peroxide (H2O2). Vortex diode required significantly lower pressure drop (1.5 bar) compared to the orifice (5 bar). A high extent of degradation, 67%, was possible using the process intensification; representing a very high enhancement, to an extent of more than 200%, by combining HC+H2O2. The degradation of naproxen progresses via intermediates formation and intermediates also eventually get gradually degraded. The kinetics of degradation was evaluated using per pass degradation model and for the different approaches, confirming higher per-pass degradation in the vortex diode and for the process intensification. The cavitational yield in HC+H2O2+aeration using vortex diode (23.4 × 10−5 mg/J) was ∼ 5 times greater than that for orifice (4.5 × 10−5 mg/J). The present study clearly highlights utility of process intensification approach for the degradation of active pharmaceutical ingredients (API) pollutants for increased efficacy.