Degradation Of Diclofenac Research Articles

Bifunctional S-scheme hybrid heterojunction comprising CdS nanorods and BiOIO3 nanosheets for efficient solar-induced antibiotic degradation and highly-selective CO2 reduction

The development of a bifunctional photocatalyst that can be utilized for both energy conversion and environmental remediation is of great practical significance. In addition, an S-scheme charge transfer process can assist a photocatalyst in efficiently separating photoexcited electrons and holes while maintaining the strong reducibility and oxidizability of the former and the latter, respectively. We developed a bifunctional S-scheme hybrid photocatalyst comprising CdS nanorods and BiOIO3 (BIO) nanosheets for efficient antibiotic degradation and cocatalyst- and sacrificial reagent-free CO2 reduction. The combination of visible-light-responsive one-dimensional (1D) CdS and UV-light-responsive 2D BIO resulted in a CdS/BIO hybrid photocatalyst with effective 1D/2D (line) interfacial contact and a broadened optical absorption range. Notably, the CdS/BIO hybrid exhibited exceptional diclofenac degradation and mineralization as well as outstanding CO2 reduction activity for CO production, with 95.4% CO selectivity over H2 production. The exceptional performance of the hybrid catalyst is primarily attributed to the accelerated photoexcited charge transfer caused by the 1D/2D line interfacial contact and the high charge separation and strong redox power of the separated charges, both of which stem from the effective S-scheme charge transfer process. In addition, photocorrosion of CdS was substantially mitigated, resulting in the high photocatalytic performance of the hybrid catalyst even after repeated test runs. This study provides insight into the rational design of bifunctional S-scheme hybrid photocatalysts for CO2 reduction and pollutant degradation.

Photocatalytic degradation of diclofenac using a novel double Z-scheme catalyst (O-g-C3N4/ZnO/TiO2@halloysite nanotubes): Degradation mechanism, identification of by-products and environmental implementation

It is challenging and expensive to synthesize multivariate composites with high photocatalytic efficiency and recyclability. Herein, a novel direct double Z-scheme O-g-C3N4/ZnO/TiO2@halloysite nanotubes (HNTs) photocatalyst was synthesized using a simple and low-cost method to degrade and mineralize diclofenac (DCF). During 50 min, O-g-C3N4/ZnO/TiO2@HNTs degraded DCF completely at pH 6.83, 10 mg/L DCF concentration, and 1.0 g/L catalyst, which was 1.66 and 2.4 times higher than ternary O-g-C3N4/ZnO/TiO2 and O-g-C3N4/HNTs/TiO2. Under the same conditions, 35.12 % of DCF was removed from urban wastewater. A negative effect of anions on the process was observed as follows: CO32− > HPO42− > Cl− > NO3−. Under the same conditions, 39.23 % of total organic carbon (TOC) was removed. Moreover, Mott-Schottky analysis and active species trapping experiments were performed to investigate the photodegradation mechanism systematically. It was observed that O2− played a minor part in the photodegradation process, while hole and OH were the more critical reactive species. Several intermediate compounds formed during the photocatalytic reaction were identified by LC-MS analysis. The results showed that a simple design and synthesis of multi-component complex catalysts presented a new insight into removing emerging pollutants from the aquatic environment and apprehending the enhanced photocatalytic mechanism.

Photocatalytic Degradation of Diclofenac by Nitrogen-Doped Carbon Quantum Dot-Graphitic Carbon Nitride (CNQD)

In this study nitrogen-doped carbon quantum dots/graphitic carbon nitride nanosheet (CNQD) composites with different contents of nitrogen-doped carbon quantum dots (NCQDs; 2, 4, 6, and 8 wt%) were synthesized. The morphological, physicochemical, and photoelectrochemical properties were investigated using complementary methods such as scanning electron microscopy (SEM), powder X-ray diffraction (pXRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), UV/Vis spectroscopy in diffuse reflectance (DRS), photoluminescence (PL), nitrogen physisorption (BET), photocurrent response, and electrochemical impedance spectroscopy (EIS). The photocatalytic activity of the synthesized materials was assessed during diclofenac (DCF) degradation in an aqueous solution under visible light irradiation. As a result, improved photocatalytic efficiency in DCF degradation was observed for all the CNQD composites compared with bulk graphitic carbon nitride (bCN) and nanosheet g-C3N4 (CNS). The fastest DCF degradation was observed for the 6 wt% NCQD on the surface of CNS (CNQD-6), which removed 62% of DCF in 3 h, with an associated k value of 5.41 × 10−3 min−1. The performance test results confirmed the contribution of NCQDs to enhancing photocatalytic activity, leading to an improvement factor of 1.24 over bCN. The morphology of the CNS and the synergistic interaction between NCQDs and CNS were essential elements for enhancing photocatalytic activity. The photoelectrochemical data and photoluminescence analyses showed the efficient migration of photoexcited electrons from NCQDs to the CNS. The reduced charge recombination rates in CNQD photocatalysts might be due to the synergistic interaction between NCQDs and CNS and the unique up-conversion photoluminescence properties of NCQDs. Further investigations revealed that the photogenerated superoxide radicals (•O2−) predominated in the degradation of DCF, and this photocatalyst had good reusability and toxicity reduction abilities. This work provides insight into the effects of NCQDs on the CNS surface to enhance its potential to remove emerging organic pollutants from water and wastewater.

Photo-Fenton process applied for the treatment of industrial wastewaters containing diclofenac: optimization with low iron ions concentrations and without pH control

Diclofenac (DCF) can cause several adverse effects in the environment and it should be removed from industrial pharmaceutical wastewaters. Advanced oxidation processes (AOPs) are promising methods for the DCF degradation. But, in many cases, AOPs require acidic pH. However, at this condition, DCF precipitates, which may hinder its oxidation. Thus, in this work, some AOP were studied for the DCF degradation, especially the photo-Fenton process, applying the experimental design technique (Doehlert matrix), operating without and with pH control (between 6.5 and 7.0). As independent variables, the initial ferrous ion concentration ([Fe2+]) and the molar addition rate of H2O2 (FH2O2) were evaluated. Empirical models were proposed and optimized conditions were determined without ([Fe2+] = 0.27 mmol L−1 and FH2O2 = 1.64 mmol min−1) and with pH control ([Fe2+] = 1.0 mmol L−1 and FH2O2 = 1.64 mmol L−1), with the following predicted mineralization percentages: 93% and 68%, respectively. So, photo-Fenton process without pH control presented the best performances. Furthermore, at this condition, iron concentration respects the limit value established by the Brazilian environmental legislation. That is, in this condition, additional processes, in order to remove iron ions, would not be necessary, that is very interesting for applications on an industrial scale.

Fenton-like degradation of diclofenac in water using iron-impregnated mussel shell biochar (Fe@MSBC)

Emerging pollutants such as diclofenac (DFC) are a cause of concern worldwide due to their persistence in the environment. Advanced oxidation processes (AOPs), such as Fenton-like processes, are among the emerging technologies for wastewater treatment due to their capability to completely degrade even recalcitrant pollutants. However, previously-investigated catalysts are expensive. Here, we report the performance of the synthesized iron-impregnated biochar derived from mussel shells (Fe@MSBC) as a catalyst for DFC degradation in water using sodium percarbonate (SPC) as an oxidant. SEM, EDX, FTIR, DSC, and TGA confirmed the successful synthesis of Fe@MSBC. A Box-Behnken design of experiments was used to investigate the effects of Fe@MSBC catalyst loading, initial DFC concentration, and SPC concentration on the removal of DFC. Here, we found that a reduced cubic model can adequately model these effects. Lower Fe@MSBC catalyst loadings, higher initial DFC concentrations, and SPC concentrations near 1.5 mmol L-1 SPC yielded higher DFC degradation. Maximum DFC removal can be achieved at 15.1831 mg L-1 Fe@MSBC catalyst loading, 60 mg L-1 initial DFC concentration, and 1.5228 mmol L-1 SPC concentration. 98.2872 % ± 0.0278 % DFC can be degraded under these conditions. These results show the exceptional degradation efficiency of Fe@MSBC in degrading DFC. These findings could help our search for novel materials to degrade emerging pollutants in wastewater, leading to a safer wastewater effluent to be released into the environment.

Modified Nanocellulose-Based Adsorbent from Sago Waste for Diclofenac Removal

A nanocellulose-based adsorbent was successfully synthesized via a hydrothermal process. It was characterized by X-ray diffraction, Fourier Transform Infrared Spectroscopy, Field Emission Electron Microscopy and Brunauer–Emmett–Teller surface area analysis. Photocatalysis has the best potential to replace the conventional wastewater treatment technology through the photodegradation of organic contaminants. This study focuses on the preparation of a photocatalytic adsorbent of nanocellulose prepared from sago waste for the removal of diclofenac from industrial wastewater. Its photocatalytic activity was evaluated through the degradation of diclofenac (100 mg/L) under ultraviolet (UV) light. The effect of different loadings of TiO2 and kinetics on the photocatalytic activity was investigated. To study its removal, the experiments were carried out under UV light with different contact times ranging from 30 to 120 min at room temperature. The maximum removal percentage was found to be 57.5% for 200 µL of TiO2, and this increased up to 82.4% for 800 µL of TiO2. The maximum removal capacity was found to be 13.3 mg/g. The kinetics was well fitted with “pseudo-first order model” (PSO). Kinetic analysis using the PSO model at 100 ppm of diclofenac sodium gave a value of equilibrium adsorption capacity, qe of 13.52 mg/g. The adsorption kinetics gave a value of calculated equilibrium adsorption capacity, qe of 13.52 mg/g using different non-linear regression plots. It obeyed a pseudo-first-order reaction with the lowest AICc, RSME values of 0.56 and 0.53 and the highest correlation coefficient, R2, of 0.99. Three kinetics models were fitted for the current adsorption kinetics data, and their suitability was inferred as the following: pseudo-first-order > pseudo-second-order > Langmuir–Hinshelwood.

Activation of peroxymonosulfate by Co2SnO4/Co3O4/SnO2 material for the effective degradation of diclofenac

Activation of peroxymonosulfate by Co2SnO4/Co3O4/SnO2 material for the effective degradation of diclofenac

Bifunctional catalytic degradation of diclofenac over Cu–Pd co-modified sponge iron-based trimetal: Parameter optimization

Currently, the pharmaceutical and personal care products (PPCPs) have posed great challenge to advanced oxidation techniques (AOTs). In this study, we decorated sponge iron (s-Fe0) with Cu and Pd (s-Fe0-Cu-Pd) and further optimized the synthesis parameters with a response surface method (RSM) to rapidly degrade diclofenac sodium (DCF). Under the RSM-optimized conditions of Fe: Cu: Pd = 100: 4.23: 0.10, initial solution pH of 5.13, and input dosage of 38.8 g/L, 99% removal of DCF could be obtained after 60 min of reaction. Moreover, the morphological structure of trimetal was characterized with high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), X-ray diffraction (XRD), X-ray photoelectron spectra (XPS). Electron spin resonance (ESR) signals have also been applied to capture reactive hydrogen atoms (H*), superoxygen anions, hydroxyl radicals, and single state oxygen (1O2). Furthermore, the variations of DCF and its selective degradation products over a series of s-Fe0-based bi(tri)metals have been compared. Additionally, the degradation mechanism of DCF has also been explored. To our best knowledge, this is the first report revealing the selective dechlorination of DCF with low toxicity over Pd–Cu co-doped s-Fe0 trimetal.

Dual defect sites of nitrogen vacancy and cyano group synergistically boost the activation of oxygen molecules for efficient photocatalytic decontamination

Solar-driven photodegradation of pharmaceutical and personal care products (PPCPs) is an attractive strategy for environmental remediation but faces poor activity mainly due to the unsatisfied generation rate of active radicals. Herein, we design and synthesize a hierarchical C3N4 tubes containing dual defect sites of nitrogen vacancy and cyano group (Nv/Cy-tCN) via an alkali-assisted strategy. Density functional theory calculations demonstrate that modification of dual defect sites boost the activation of molecular oxygen through the polarization of O-O bonds. Furthermore, the ability to separate carriers and absorb light can be enhanced by the creation of an electron-rich structure in Nv/Cy-tCN. Consequently, the Nv/Cy-tCN shows excellent photo-degradation performance for eleven types of PPCPs, affording a 100% removal rate toward diclofenac within 7 min of natural sunlight irradiation. The Nv/Cy-tCN system exhibited enhanced diclofenac degradation kinetics with a reaction rate constant of 0.055 min−1, which was 12.8 times higher than that of pristine carbon nitride (0.0043 min−1). Importantly, the impacts on real wastewater and the degradation of trace contaminants further support that this photocatalytic system could be effectively used to remediate PPCPs pollution in environmental waterways.

Maximization of the photocatalytic degradation of diclofenac using polymeric g-C3N4 by tuning the precursor and the synthetic protocol

A green-oriented synthesis of highly photoactive nano-scaled graphitic carbon nitride (g-C3N4) is presented with water to be utilized as a critical reagent in order to tune desired physicochemical properties, and so, to elevate the photocatalytic activity. The materials’ optimization strategy involved the use of three precursors (melamine, urea or thiourea) and different thermal polycondensation (pyrolysis) durations. The synthesized materials were characterized by SEM, XRD, XPS, N2 sorption, FT-IR, and UV–vis DRS. Their photocatalytic activity against a non-steroidal anti-inflammatory pharmaceutical compound, diclofenac, was evaluated under ultraviolent irradiation, also investigating the influence of pH, photocatalyst dosage/mass and concentration of H2O2. The results revealed that the precursor, pyrolysis time and use of water effect significantly the physicochemical features and the photocatalytic activity. Urea-derived samples showed the highest specific surface areas and smallest crystalline domains, as well as the highest photocatalytic efficiency. The involved mechanisms were examined by exploring the optical properties, the role of the photo-generated radicals and the reactive oxygen species, as well as LC-MS analysis. The Orbitrap high-resolution mass-spectrometry analysis revealed the formation of 26 transformation products governed by different processes such as hydroxylation and further oxidation to keto derivatives and ring opening, decarboxylation/hydroxylation with further oxidation, dichlorination, and lactam formation.

Synthesis of CuS/NiS heterostructural photocatalyst and its performance in the degradation of metronidazole and diclofenac drugs: optimization of operating conditions

In this research, nanoparticles of copper sulfide (CuS), nickel sulfide (NiS), and CuS/NiS were synthesized and characterized by XRD, DRS, BET, EDS, FE–SEM, FT-IR, BET/BJH, and PZC. The photocatalytic efficiency of the synthesized nanoparticles on the degradation of diclofenac and metronidazole was measured and compared via UV–Vis spectroscopy. In addition, the effective parameters on the degradation process including pH, diclofenac and metronidazole concentrations (mg/L), CuS/NiS photocatalyst mass (g), and irradiation time (min) were investigated using the response surface methodology (RSM) with Box–Behnken design (BBD). Based on the results, diclofenac had a higher removal efficiency than metronidazole. Under optimal conditions with 0.2 g of CuS/NiS photocatalyst, with concentrations of 131.115 mg/L of diclofenac and 150 mg/L of metronidazole at pH 10 for 120 min, they had efficiencies of 68.45% and 23.31%, respectively.

Diclofenac Biodegradation by Microorganisms and with Immobilised Systems—A Review

Diclofenac is one of the most popular non-steroidal anti-inflammatory drugs. Due to its over-the-counter availability and high consumption along with municipal and hospital wastewater, it enters the sewage treatment plant, where it is not completely degraded. This results in the appearance of diclofenac in the effluents from the treatment plant, and with them, it enters the surface waters. Due to its structure, it is characterised by its high resistance to degradation in the environment. At the same time, it shows documented acute and chronic toxicity to non-target organisms. For this reason, it is necessary to look for cheap solutions that enhance the degradation of diclofenac. The paper discusses both the pathways of microbiological degradation of this drug described so far, as well as modern systems of biocatalyst immobilisation, with a particular emphasis on laccases involved in the biotransformation of diclofenac.

Enhancing the removal of the diclofenac contaminant and accelerating the desalinization of seawater by using a biodegradable fibrous support functionalized with Sr2.7Ln0.3Fe1.4Co0.6O7-δ (Ln = La or Nd) perovskites

A biodegradable fibrous support (oak-gall, OG) was functionalized with graphene (G) and Sr2.7Ln0.3Fe1.4Co0.6O7-δ perovskite (named SLFCO and SNFCO when Ln = La and Nd, respectively) to remove the diclofenac (DCF) contaminant from the drinking water by photocatalysis. The photocatalytic experiments revealed that the SNFCO and SLFCO powders produced DCF degradation of 100 % and 94 %, respectively, after 150 min under UV–vis irradiation. This means that making a perovskite with Nd dopant instead of La is more effective to induce the DCF degradation. Later, a composite made of OG + G was evaluated, but only a DCF degradation of 50 % was produced. Subsequently, a floatable composite made with SNFCO particles (OG + G + SNFCO) was tested and produced a complete degradation for DCF after 150 min of UV–vis irradiation, thus, adding the perovskite produced higher DCF degradation. Additionally, scavenger experiments were carried out and confirmed the formation of oxidizing agents such as ∙OH and ∙O2−, which mainly attacked the DCF molecules. Raman, absorbance, and X-ray photoelectron spectroscopy (XPS) measurements demonstrated the presence of oxygen vacancy defects in the biodegradable photocatalytic composites. Such vacancies acted as electron trapping centers, which enhanced the DCF degradation. The OG + G + SNFCO composite was also tested for the evaporation of seawater under natural solar light and produced a maximum evaporation-rate and evaporation-efficiency of 1.67 kg/m2∙h and 95 %, respectively. Adding the OG + G + SNFCO composite to the seawater accelerated its desalination ≈2 times. In fact, the Fourier-transform-infrared (FTIR) technique demonstrated the no presence of NaCl in the condensed water recovered after desalination. Hence, the results of this research indicate that a biodegradable composite functionalized with G + SNFCO is useful for the elimination of pharmaceutical drugs from the water and for seawater desalination.

Effect of lignocellulosic biomass composition on the performance of biochar for the activation of peroxymonosulfate to degrade diclofenac

In this study, poplar flour (PF) and walnut shell flour (WSF) with different proportions of lignocellulosic composition were selected as representative plant-based biomass precursors to prepare biochars (PB and WSB) for the activation of peroxymonosulfate (PMS). The structure of biochars and the removal performance of diclofenac (DCF) were examined in detail. Generally, the PB derived from PF that contained higher ratio of cellulose outperformed the WSB derived from WSF that contained higher ratio of lignin in the adsorption and degradation of DCF due to the more graphitized and aromatic structure of PB than that of WSB. Moreover, the adsorption and catalytic performance of two kinds of biochars were improved with the increase of pyrolysis temperature. The superior porosity property, abundant oxygen containing functional groups and good electrical conductivity of PB1000 led to the stronger capability than that of WSB1000. Nonradical oxidation mechanism including the singlet oxygen (1O2) and electron transfer was found to contribute to DCF degradation. Moreover, the PB1000 also demonstrated stronger adaptability to complex water environment than WSB1000. The findings of this work may provide enlightenment in the selection of lignocellulosic bio-wastes to prepare biochar for the degradation of organic pollutants.

Impacts of autochthonous particulate organic matter on redox-conditions and elimination of trace organic chemicals in managed aquifer recharge

Autochthonous carbon fixation by algae and subsequent deposition of particulate organic matter can have significant effects on redox conditions and elimination of trace organic chemicals (TOrCs) in managed aquifer recharge (MAR). This study investigated the impacts of different algae loadings (0–160 g/m2) and infiltration rates (0.06–0.37 m/d) on overall oxygen consumption and elimination of selected TOrCs (diclofenac, formylaminoantipyrine, gabapentin, and sulfamethoxazole) in adapted laboratory sand columns. An infiltration rate of 0.37 m/d in conjunction with an algae load of 80 g/m2 (dry weight) sustained oxic conditions in the sand bed and did not affect the degradation of TOrCs. Thus, the availability of easily degradable organic carbon from algae did not influence the removal of TOrCs at an influent concentration of 1 µg/L. In contrast, a lower infiltration rate of 0.20 m/d in combination with a higher algae loading of 160 g/m2 caused anoxic conditions for 30 days and significantly impeded the degradation of formylaminoantipyrine, gabapentin, sulfamethoxazole, and diclofenac. Especially the elimination of gabapentin did not fully recover within 130 days after pulsed algae deposition. Hence, measures like micro-sieving or nutrient control are required at bank filtration or soil aquifer treatment sites with low infiltration rates.

Electrochemically assisted photocatalytic degradation of contaminants of emerging concern in simulated wastewater using WO3 – Elucidation of mechanisms

In this work, the performance of a photoelectrochemical cell to degrade a mixture of contaminants of emerging concern (CECs) in distilled water and simulated wastewater effluents (SWWE) was assessed. The CECs mixture included trimethoprim (TMP), diclofenac (DFC), sulfamethoxazole (SMX) and carbamazepine (CBZ) (100 μg·L−1 each). WO3 nanoplate-like structures synthesized on fluorine tin oxide coated glass (FTO) were used as the photoanode with Pt or carbon gas diffusion electrodes (GDE) as the counter electrode. The most efficient degradation of the CECs was obtained with the WO3-GDE combination. Significant degradation of the CECs was observed under visible only radiation. Even under visible radiation, reasonable rate constants 5.67·10-3, 5.35·10-3, 2.9·10-3 and 4.35·10-3 min−1 were obtained for TMP, SMX, CBZ and DFC degradation. The degradation mechanism at the cathode and the photoanode was elucidated using a two-compartment cell, which allowed the identification of reactive species generated at each electrode. Photogenerated holes were the main responsible for CEC degradation in SWWE. With the carbon GDE, a high Faradaic efficiency (55 %) for H2O2 production was observed.

Fabrication of multiphase MoSe2 modified BiOCl nanosheets for efficient piezo-photoelectric hydrogen evolution and antibiotic degradation.

Efficient spatial charge separation plays a crucial role in improving the photocatalytic performance. Therefore, 1T/2H MoSe2/BiOCl (1T/2H MS/BOC) and 2H MoSe2/BiOCl (2H MS/BOC) piezo-photocatalysts are synthesized. By combining piezoelectric catalysis and photocatalysis, a highly active piezo-photocatalytic process is realized. The optimal 1T/2H MS/BOC piezo-photocatalyst displays superior diclofenac (DCF) degradation and hydrogen (H2) evolution activity under the combined action of ultrasound and light. In particular, the DCF degradation kinetic constant (k) of optimal 0.5% 1T/2H MS/BOC under the synergistic effect of ultrasound and light is 0.057 min-1, which is 8.1 and 6.3 times higher than those of BiOCl (0.007 min-1) and 0.5% 2H MS/BOC (0.009 min-1). Moreover, the H2 evolution rate of 0.5% 1T/2H MS/BOC is 122.5 μmol g-1 h-1, which is also higher than those of BiOCl (45.8 μmol g-1 h-1) and 2H MS/BOC (49.5 μmol g-1 h-1). The dramatic improvement in the DCF degradation and H2 evolution piezo-photocatalytic performance of 1T/2H MS/BOC catalysts is ascribed to the built-in polarization electric field and abundance of active sites of 1T/2H MS/BOC as well as the advantageous band structure between BiOCl and 1T/2H MoSe2. Additionally, three probable degradation pathways of DCF were put forward from the results of liquid chromatography-mass spectrometry (LCMS) and density functional theory (DFT) calculations. This study provides the design strategy of high efficiency piezo-photocatalysts in environmental purification and energy-generation fields based on phase and band structure engineering.

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

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

Ultraviolet Light (UV)-Induced Photocatalytic Degradation of Diclofenac Using Naturally Derived TiO2@rGO Composite

Ultraviolet Light (UV)-Induced Photocatalytic Degradation of Diclofenac Using Naturally Derived TiO2@rGO Composite

Degradation of diclofenac and 4-chlorobenzoic acid in aqueous solution by cold atmospheric plasma source

In this study, cold atmospheric plasma (CAP) was explored as a novel advanced oxidation process (AOP) for water decontamination. Samples with high concentration aqueous solutions of Diclofenac sodium (DCF) and 4-Chlorobenzoic acid (pCBA) were treated by plasma systems. Atmospheric pressure plasma jets (APPJs) with a 1 pin-electrode and multi-needle electrodes (3 pins) configurations were used. The plasma generated using argon as working gas was touching a stationary liquid surface in the case of pin electrode-APPJ while for multi-needle electrodes-APPJ the liquid sample was flowing during treatment. In both configurations, a commercial RF power supply was used for plasma ignition. Measurement of electrical signals enabled precise determination of power delivered from the plasma to the sample. The optical emission spectroscopy (OES) of plasma confirmed the appearance of excited reactive species in the plasma, such as hydroxyl radicals and atomic oxygen which are considered to be key reactive species in AOPs for the degradation of organic pollutants. Treatments were conducted with two different volumes (5 mL and 250 mL) of contaminated water samples. The data acquired allowed calculation of degradation efficiency and energy yield for both plasma sources. When treated with pin-APPJ, almost complete degradation of 5 mL DCF occurred in 1 min with the initial concentration of 25 mg/L and 50 mg/L, whereas 5 mL pCBA almost degraded in 10 min at the initial concentration of 25 mg/L and 40 mg/L. The treatment results with multi-needle electrodes system confirmed that DCF almost completely degraded in 30 min and pCBA degraded about 24 % in 50 min. The maximum calculated energy yield for 50 % removal was 6465 mg/kWh after treatment of 250 mL of DCF aqueous solution utilizing the plasma recirculation technique. The measurements also provided an insight to the kinetics of DCF and pCBA degradation. Degradation products and pathways for DCF were determined using LC-MS measurements.