DCF Concentration Research Articles

Response surface methodology-based optimisation of adsorption of diclofenac and treatment of pharmaceutical effluent using combined coagulation-adsorption onto nFe2O3 decorated water chestnut shells biochar.

This work involved the preparation of pristine and iron nanoparticle-loaded biochar from a water chestnut shell to remove diclofenac sodium (DCF) containing effluent of pharmaceutical origin. To create suitable forecasting equations for the modelling of the DCF adsorption onto the adsorbent, response surface methodology (RSM) was used. The parameters, e.g. pH, adsorbent mass, DCF concentration and contact time, were used for the modeling of adsorption. The RSM model predicts that for 98.0% DCF removal, the ideal conditions are pH 6, an adsorbent dose of 0.5 g L-1, and a contact time of 60 min with an initial adsorbate concentration of 25 mg L-1 at 303 K. The maximum capacity deduced from the Langmuir model was 75.9 mg g-1 for pristine water chestnut shell biochar (pWCBC) and 122.3 mg g-1 for magnetically modified nano-Fe2O3 biochar (mWCBC). Under equilibrium conditions, the Langmuir model was the best-suited model compared to the Temkin and Freundlich models. The adsorption data in this investigation efficiently fitted the pseudo-second-order model, emphasizing that chemisorption or ion exchange processes may be involved in the process. The WCBC demonstrated recyclability after 10 cycles of repeated adsorption and desorption of DCF. A combined coagulation adsorption process removed COD, NH3-N, NO3-, PO43-, and DCF by 92.50%, 86.41%, 77.57%, 84.54%, and 97.25%, respectively. This study therefore shows that coagulation followed by adsorption onto biochar can be a cost-effective substitute for conventional pharmaceutical wastewater treatment.

Adsorptive removal of diclofenac sodium from aqueous solution by highly efficient metal organic framework (UiO-66)/multi-walled carbon nanotube composite.

In the current study, synthesis and use of a novel adsorbent (composite in nature) are presented for treatment of one of the most commonly found pharmaceutical compound, viz, diclofenac sodium (DCF) in waste water. Synthesis of the composite adsorbent was done by hydrothermal method metal organic framework (MOF) based on Zr metal and multi-walled carbon nanotube (MWCNT). The composite adsorbent is termed as UiO-66/MWCNT. The confirmation of successful synthesis of the adsorbent is done with the help of sophisticated characterization techniques like FTIR, XRD, zeta potential analyser, and SEM. The synthesized composite adsorbent is found to have good adsorption capacity for DCF. The experiments related to the process of adsorption were done in batch mode and the significance of various operating parameters affecting the specific uptake of DCF. Maximum adsorption is observed at 3 pH (acidic condition) when the initial concentration of DCF and adsorbent dose was 30 mg/L and 100 mg/L, respectively. The Langmuir isotherm model best describes the process of adsorption with a maximum adsorption capacity of 256.41 mg/g. Experimental results obtained through the studies conducted related to the kinetics displayed that the process followed pseudo-second order model, and intraparticle studies suggested that diffusion through pores controls the rate. Thermodynamic studies suggest that the adsorption of DCF on UiO-66/MWCNT was completely spontaneous with ΔH = -22.089 kJ/mol. The possible mechanism for the adsorptive removal of DCF through UiO-66/MWCNT as found from this study is electrostatic interaction.

Design strategy of self-assembled BC@MIL-100(Fe) composite membrane for the efficient removal of diclofenac sodium from water.

Pharmaceuticals and personal care products (PPCPs) as typical emerging pollutant have attracted extensive attention due to the risks to human health and environment. As a kind of harmful PPCPs, diclofenac sodium (DCF) has been frequently detected in water environment, which needs to be removed effectively. Herein, we successfully fabricated network structure composite membranes consisting of one-dimensional (1D) well-defined core-shell bacterial cellulose (BC)@MIL-100 (Fe) nanofibers by a simple but effective step-by-step strategy. The BC@MIL-100(Fe) composite membrane has three-dimensional network utilizing bacterial cellulose nanofiber as template, which was observed as the MIL-100(Fe) grew on the nanofiber uniformly and obvious core-shell structure. Impressively, the BC@MIL-100(Fe) not only possessed favorable architecture but also behaved good properties to adsorb DCF from water. As we expected, the as-obtained BC@MIL-100(Fe) composite membrane exhibited convenient recycling, high chemical stability, and short equilibrium time (30min) with high adsorption capacity (296mgg-1). Strikingly, in low DCF concentration solution, BC@MIL-100(Fe) composite showed high adsorption efficiency in periodic test, which can still reach 70% after five successive adsorptions without desorption. The results demonstrated that the adsorption mechanism may involve π-π interaction, H-bond interaction, and electrostatic interaction. This work proposes the new finding to understand the removing of DCF from water environment.

Effective adsorption of diclofenac sodium from aqueous solution using cationic surfactant modified Cuminum cyminum agri-waste: kinetic, equilibrium, and thermodynamic studies

The occurrence of pharmaceutical pollutants in aqueous media has increased where significant research is being conducted to eliminate these toxic compounds. In the present study, Tetradecyltrimethylammonium bromide (TTAB) modified Cuminum cyminum agri-waste (CCW) was prepared to investigate the removal of diclofenac sodium (DCF) from aqueous solution in the batch process for the first time. Physical and chemical characterizations of as-prepared adsorbent were conducted using field emission scanning electron microscopy, Fourier-transform infrared spectroscopy, N2 adsorption-desorption, and point of zero charge analysis. Besides, the effect of the main parameters that affect the adsorption process, i.e., adsorbent dosage (0.25–6 g/L), contact time (0–300 min), initial DCF concentration (10–500 mg/L), and pH of the solution, were investigated. Furthermore, the resulted data were analyzed using various kinetic and isotherm models. The Pseudo-second-order model with R 2 = 0.9981 showed the highest agreement with kinetic behavior. Also, the maximum adsorption capacity of DCF is 93.65 mg/g, according to the Langmuir isotherm. In acidic media, the adsorption capacity reached the highest value (44.69 mg/g). As a result, this study revealed that the agri-waste material could be modified and, as a low-cost adsorbent, have promising adsorption potential to remove pharmaceutical contaminants from the aqueous solution.

Highly efficient visible light photocatalysis of Nix Zn1-x Fe2O4 (x= 0, 0.3, 0.7) nanoparticles: Diclofenac degradation mechanism and eco-toxicity.

Pharmaceuticals and personal care products occupy a predominant position with respect to both utility and release into the ecosystem, thereby contributing to environmental pollution at alarming rates. Of the several methods identified to minimize the concentration of PPCPs, nanomaterial based photocatalysis seems to be a potential alternative for it being highly economical and eco-friendly. In this study, we synthesized Nickel zinc ferrite (Ni-ZF) [Nix Zn1-x Fe2O4 (x=0, 0.3, 0.7)] nanoparticles with an average diameter of ∼400nm by a co-precipitation method towards diclofenac degradation. The composite showed greater degrees of crystallinity devoid of any impurities. Nearly complete DCF degradation (∼99%) was achieved after 50min reaction time with the nanoparticles at pH 7 for an initial DCF concentration of 50mg/L. The degradation process followed a pseudo first-order rate law with the rate constant of 0.1657min- 1. Microbial toxicity and phytotoxicity studies demonstrated negligible toxicity imposed by the contaminated water treated with the prepared composite, suggesting it as a promising photocatalyst benefitting in all aspects.

Pencil graphite synergistic improvement of zero-valent iron composite for the removal of diclofenac sodium in aqueous solutions: Kinetics and comparative study

Pencil graphite (PG) was used as a carrier material to increase the stability, dispersity, and removal capacity of zero-valent iron (Fe0) in an aqueous solution. Freshly synthesized composite adsorbent from Fe0 and pencil graphite (Fe0-PG) was established. The morphology of Fe0 and Fe0-PG was characterized using FTIR, SEM, TEM, XRD, and BET techniques. The adsorption mechanism and potential removal of Diclofenac sodium (DCF) onto the surface of Fe0 and Fe0-PG composite in an aqueous solution were investigated in terms of pH, contact time, initial DCF concentration, adsorption dose, and temperature. The adsorption data fit better the pseudo-second-order kinetic and Langmuir isotherm model via both adsorbents (R2 > 0.992). The experimental results indicated that the maximum adsorption capacity qmax of DCF via Fe0-PG, obtained from Langmuir isotherm was 48.1 mg.L−1, and it is an extraordinary value in comparison with that of Fe0 (23.1 mg.L−1). The maximum removal efficiency was achieved at pH = 6 for both adsorbents (Fe0: 51% and Fe0-PG: 92%). The calculated value of the activation energy Ea for adsorption of DCF via Fe0-PG composite is 112 kJ.mol−1, which signifies the chemisorption nature of the adsorption mechanism. The data suggest that the process for both sorbates is endothermic and spontaneous in nature at high temperatures. Higher environmental temperature is more favorable for uptake of DCF onto the Fe0-PG surface. PG was found to be a promising synergistic material, and Fe0-PG shows enhancement for DCF removal in aqueous solutions compared with the bare Fe0 NPs.

Adsorption of Diclofenac Sodium Using Low-Cost Activated Carbon in a Fixed-Bed Column

In recent years, the presence of pharmaceutical contaminants, such as diclofenac sodium (DCF) in water bodies and their potential influence on aquatic organisms gained much attention. As a result of high demand and usage by consumers, in addition to incomplete removal during wastewater treatment, pharmaceutical contaminants will end up on water surfaces. To mitigate this problem, the elimination of DCF by employing activated carbon derived from Dillenia Indica peels was evaluated. The adsorption of DCF was performed in a continuous process. The findings showed that the adsorption of DCF was favorable at a lower flow rate, greater bed height, and initial DCF concentration, with the highest removal percentage of 44.93%. To assess the characteristics of the breakthrough curve of DCF, the adsorption data were used to match three distinct adsorption models, namely, Boharts and Adam, Yoon-Nelson, and Thomas. The breakthrough results were well-fitted with these models, as the values of R2 for all models and parameters were higher than 0.88. Thus, it was concluded that the activated carbon from Dillenia Indica can effectively remove DCF from an aqueous solution.

Degradation of diclofenac via sequential reduction-oxidation by Ru/Fe modified biocathode dual-chamber bioelectrochemical system: Performance, pathways and degradation mechanisms

A sequential reduction-oxidation for DCF degradation was proposed by alternating anaerobic/aerobic conditions at Ru/Fe-biocathode in a dual-chamber bioelectrochemical system (BES). Results showed that Ru/Fe-electrode was successfully fabricated by in-situ electro-deposition, which was rough and uniformly distributed with Ru0 and Fe0 particles. The morphologic changing and biocompatibility were favorable to increase the surface area and enhance microbial adhesion on Ru/Fe-electrode. At an applied voltage of 0.6 V, the potential and impedance of Ru/Fe-biocathode were −0.80 V and 26 Ω, respectively, lower than that of carbon-felt-biocathode. It led to a higher DCF degradation efficiency of 93.2% under anaerobic conditions, which was superior to that of 88.0% under aerobic conditions. Using NaHCO3 as carbon source, DCF removal efficiency increased with increasing applied voltage, but decreased with increasing initial DCF concentration. Thirteen intermediates were measured, and two degradation pathways were proposed, among which sequential reduction-oxidation of DCF was the main pathway, dechlorination intermediates were first generated by [H] attacked under anaerobic conditions, further oxidized by microbes and OH attacked under aerobic conditions, achieving 69.6% of mineralization. After 4 d of reaction, microcystis aeruginosa growth inhibition rate decreased from 22.9 to 8.0%, signifying a significant reduction in biotoxicity. Bacteria (e.g. Nitrobacter, Nitrosomonas, Pseudofulvimonas, Aquamicrobium, Sulfurvermis, Lentimicrobiaceae, Anaerobineaceae, Bacteroidales, Hydrogenedensaceae, Dethiosulfatibacter and Azoarcus) for DCF degradation were enriched in Ru/Fe-biocathode. Microbes in Ru/Fe-biocathode had established defense mechanisms to acclimate to the unfriendly environment, while Ru/Fe-biocathode possessed higher nitrification and denitrification activities than carbon-felt-biocathode, and Ru/Fe-biocathode might be of aerobic and anaerobic biodegradation activities. DCF could be mineralized by the synergistic reaction between Ru/Fe and bacteria under sequential anaerobic/aerobic conditions.

Layer-by-layer coated silicone-based soft contact lens hydrogel for diclofenac sustained release

Introduction Soft contact lenses (SCLs) constitute a promising vehicle for ocular drug delivery due to their biocompatibility, prolonged contact with the eye and general acceptance. Soaking in the drug solution is the simplest method to load the drug into the SCLs. However, it usually does not ensure a controlled drug release, compatible with the therapeutic needs. Thus, additional approaches, such as the application of coatings on the SCLs that constitute a barrier to the drug release, have been tried to achieve that purpose [1]. The main goal of this work is to investigate the possibility of using a layer-by-layer (LbL) coating strategy, with alginate, chitosan and hyaluronic acid (ALG/CHI/HA) to get a controlled release of diclofenac from silicon based hydrogels. Materials and methods A lab-made silicon-based hydrogel intended for SCLs was loaded by soaking with the anti-inflammatory (diclofenac, DCF) and coated layer-by-layer (LbL) by immersion in solutions of alginate, chitosan and hyaluronic acid. Material properties such as transmittance, wettability, ionic permeability and swelling were studied. Drug release experiments were carried out under sink conditions (3 mL NaCl aqueous solution 130 mM, 36 °C, 180 rpm stirring). The coating stability and lysozyme-coating interaction was evaluated by quartz crystal microbalance with dissipation (QCM-D). A mathematical model was applied to predict the in vivo efficacy of the coated lenses. Chorioallantoic membrane (HET-CAM) tests were carried out to predict potential ocular irritation. Results The coating did not impair the studied physico-chemical properties, relevant for the application of the material in SCLs. HET-CAM tests did not suggest any potential for ocular irritation of both uncoated and coated samples. QCM-D data revealed the stability of the deposited layers and no adsorption of the protein. DCF release kinetics was controlled by the presence of the coating. The DCF concentration profile in the tear fluid estimated from the mathematical model predicts values above the half maximal inhibitory concentrations (IC50) for cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) during more than 2 weeks, for the coated hydrogels, while for the uncoated such levels are only expected in the first day of release. Discussion and conclusions ALG/CHI/HA LBL coated silicon hydrogels present adequate properties to be used in DCF releasing SCLs. They reveal an antifouling behaviour against lysozyme, one of the most abundant protein in lacrimal fluid. In vitro studies suggest that such system has potential to be used in the production of efficient therapeutic SCLs.

Enhanced photocatalytic performance of visible light driven TiO2/g-C3N4 for degradation of diclofenac in aqueous solution

Emerging contaminants such as diclofenac is frequently detected in wastewater treatment plants as they are not specifically designed for the removal of pharmaceutical effluents, which results in poor removal efficiency. Even though photocatalyst has emerged as an excellent alternative, most of the reported photocatalyst portrays fast recombination rate of electron–hole pair and has slow electron mobility. In order to overcome these shortcomings, in the present work, visible light-driven TiO 2/g-C3N4 photocatalyst was synthesized for the photodegradation of diclofenac in aqueous solution. The morphological and optical properties of the photocatalyst were analysed. The photodegradation efficiency was highly improved even at low g-C3N4 loading, indicating the Z-scheme photocatalyst, successfully overcame the electron–hole pair’s fast recombination rate. The photodegradation efficiency was represented as a function of all independent variables, using a second-order quadratic model. Response surface methodology (RSM) was used to optimize the degradation process. A maximum degradation efficiency (93.49%) was achieved at the optimum conditions (irradiation time = 90 min, initial solution pH = 5, initial DCF concentration = 5 ppm and g-C3N4 loading = 0.3g/g TiO 2). The as developed photocatalyst is found to be highly stable as it showed a satisfactory recyclability. The process followed a pseudo-first-order reaction. Photodegradation of diclofenac also resulted in ten intermediates as identified using LCMS analysis.

Decorating graphene oxide with zeolitic imidazolate framework (ZIF-8) and pseudo-boehmite offers ultra-high adsorption capacity of diclofenac in hospital effluents

This study reports on an easy and scalable synthesis method of a novel magnetic nanocomposite (GO/ZIF-8/γ-AlOOH) based on graphene oxide (GO) nanosheets decorated with zeolitic imidazolate framework-8 (ZIF-8), pseudo-boehmite (γ-AlOOH), and iron oxide (Fe3O4) nanoparticles by combining solvothermal and solid-state dispersion (SSD) methods. The nanocomposite was successfully applied to remove of diclofenac sodium (DCF) – a widely used pharmaceutical – from water. Response Surface Methodology (RSM) was used to optimize the adsorption process and assess the interactions among the influencing factors on DCF removal efficiency; including contact time, adsorbent dosage, initial pH, solution temperature, and DCF concentration. Adsorption isotherm results showed a good fitting with the Langmuir isotherm model with an exceptional adsorption capacity value of 2594 mg g−1 at 30 °C, which was highly superior to the previously reported adsorbents. In addition, kinetic and thermodynamic investigations further illustrated that the adsorption process was fast (equilibrium time = 50 min) and endothermic. The regeneration of GO/ZIF-8/γ-AlOOH nanocomposite using acetic acid solution (10% v/v) after a simple magnetic separation was confirmed in five consecutive cycles, which eliminate the usage of organic solvents. The nanocomposite has also shown a superior performance in treating a simulated hospital effluent that contained various pharmaceuticals as well as other organic, and inorganic constituents.

Characterization, optimization and kinetic study of diclofenac degradation by novel bacterial strains and their synthetic consortia

Diclofenac (2-(2-(2, 6-dichlorophenylamino) phenyl) acetic acid, DCF) is an emerging pollutant under the sub-class of pharmaceutical and personal care products (PPCPs). This study focused on the degradation of DCF with isolated microbial strains. The bacterial strains are considered a cost effective and eco-friendly approach for the degradation of such harmful compounds from the environment. Therefore, the experiments were started with isolation of the DCF degrading strains by the enrichment culture method. Finally, four bacterial strains; Enterococcus lactis strain DSD-1 (MN744331), Bacillus paranthracis strain DYD-1 (MN744332), Citrobacter portucalensis strain PPD-2 (MN744333) and Enterococcus faecium strain DKD-1 (MN744334) were isolated from wastewater samples. These strains degrade DCF and use it as the sole carbon and energy source. Optimized physical parameters such as temperature (32.65 °C), pH (6.36), agitation speed (82.93 rpm), and DCF concentration (40.53 mg/L) were reported through Design Expert® software. The microbial consortium experiments suggested that equal volume of all the strains was very effective. This common microbial consortium degraded almost 90% of DCF in 20 days. This was due to the synergistic activities of the strains. We have reported five intermediate metabolites (DF-1, DF-2, DF-3, DF-4, and DF-5) through the GC-MS. These further used to predict the metabolic pathway of DCF degradation.

Diclofenac-induced cytotoxicity in cultured carp leukocytes.

Diclofenac is a drug commonly used in human and veterinary medicine for the treatment of diseases associated with inflammation and pain. Medicinal products enter waste and surface waters on an everyday basis and contaminate the aquatic environment. Fish are therefore permanently exposed to these chemicals dissolved in their aquatic environment. To simulate variable environmental conditions, the aim of our study was to examine adverse effects of diclofenac under different temperatures of cell incubation (18, 21, 24, 27 and 30 °C). Cyto-toxic and -static effects of diclofenac in concentrations of 0.001 mcg/ml, 0.01 microg/ml, 0.1 mcg/ml, 1 mcg/ml, 10 mcg/ml and 100 mcg/ml for the carp (Cyprinuscarpio) cultured leukocytes were quantified using detection of lactate dehydrogenase released from damaged cells. Overall DCF cytotoxicity was relatively low and its impact was pronounced at higher temperature and DCF concentration. Cells growth inhibition is changing more rapidly but it is high mainly at the highest concentration from low temperature. DNA fragmentation was not detected in tested leukocyte cell line. CYP450 increased diclofenac cytotoxicity only at the highest concentration but at incubation temperatures 18 and 27 °C. Leukocyte viability is essential for immune functions and any change can lead to reduction of resistance against pathogens, mainly in cold year seasons, when the immune system is naturally suppressed.

Efficient degradation of diclofenac by LaFeO3-Catalyzed peroxymonosulfate oxidation---kinetics and toxicity assessment

Diclofenac was frequently found in various waters, indicating conventional wastewater treatment methods ineffective in its removal. In this study, LaFeO3 (LFO) was synthesized and its catalytic activity of LFO as the activator of different oxidants such as persulfate (PS), hydrogen peroxide and peroxylmonosulfate (PMS) was evaluated in terms of DCF degradation. The influence of calcination temperature was examined on the catalytic activity of LFO. The effects of various parameters including pH levels, PMS concentration, LFO dose and initial DCF concentration were investigated on DCF degradation rate. The marginal effects of PMS concentration and LFO dose were compared. Langmuir-Hinshelwood (LH) model was used to quantitatively describe DCF degradation reaction in LFO/PMS system. The two constants, k (Limiting reaction rate at maximum coverage) and K (Equilibrium adsorption constant), were determined on the basis of LH model. The performance of LFO/PMS process was also estimated in the presence of various inorganic anions. The potential toxicity of LFO and PMS were evaluated using phytoplankton and the toxicity evolution during DCF degradation was also investigated using luminescent bacteria. This contribution provides a basic study regarding the potential application of heterogeneous PMS activation by perovskite LFO for both DCF removal and toxicity elimination.

Diclofenac affects early embryo development in the marine bivalve Mytilus galloprovincialis

Diclofenac-DCF, one of the most widely prescribed non-steroidal anti-inflammatory drug, is globally detected in environmental compartments. Due to its occurrence in freshwater and potential impact on aquatic organisms, it has been added to the watch list of chemicals in the EU Water Directive; consequently, research on the impact of DCF in model aquatic organisms has great regulatory implications towards ecosystem health. DCF is also detected in coastal waters at concentrations from ng/L to 1 μg/L, as well as in marine organisms, such as the mussel Mytilus. Increasing evidence indicates that environmental concentrations of DCF have multiple impacts in adult mussels. Moreover, in M. galloprovincialis, DCF has been shown to affect early embryo development.The developmental effects of DCF in mussels were further investigated. DFC (1 and 10 μg/L) was added at different times post-fertilization (30 min and 24 hpf) and the effects were compared in the 48 hpf embryotoxicity assay. Shell mineralization and morphology were investigated by polarized light microscopy, X-Ray Spectrometry-XRD and Scanning Electron Microscopy-SEM. Transcriptional profiles of 12 selected genes physiologically regulated across early embryo development were assessed at 24 and 48 hpf.DCF induced shell malformations, irrespectively of concentration and time of exposure. DCF phenotypes were characterized by convex hinges, undulated edges, fractured shells. However, no changes in biomineralization were observed. DCF affected gene transcription at both times pf, in particular at 1 μg/L. The most affected genes were those involved in early shell formation (CS, CA, EP) and biotransformation (ABCB, GST). The results confirm that Mytilus early development represents a significant target for environmental concentrations of DCF. These data underline how the standard embryotoxicity assay, in combination with a structural and transcriptomic approach, represents a powerful tool for evaluating the early impact of pharmaceuticals on mussel embryos, and identification of the possible underlying mechanisms of action.

Mycoremediation of diclofenac using Mucor hiemalis

ABSTRACTDiclofenac (DCF) is a pharmaceutical drug widely found in the aquatic environment, where it represents a persistent, anthropogenic hazard to all biota. Owing to the reported inefficiency of water treatment strategies to remove pharmaceuticals, the present study aimed to investigate the ability of the aquatic fungus Mucor hiemalis to take up and accumulate DCF. Cultures of M. hiemalis were exposed to varying concentrations of DCF (10, 25 and 50 µg/L) over a period of 144 h. In the presence of M. hiemalis, DCF concentrations in the media decreased by 95% within 24 h. This early removal was most likely due to extracellular metabolism of DCF, as low proportions of the pharmaceutical were found in the mycelium of the fungus, thereby excluding bioaccumulation as the main mode of removal. However, adsorption of DCF onto the surface of the M. hiemalis pellets cannot be excluded. Our study provides the first report of DCF remediation using M. hiemalis and is the first successful step towards a feasible and inexpensive bioremediation technique for DCF.

REMOVAL OF DICLOFENAC FROM SECONDARY WASTEWATER EFFLUENTS BY FENTON BASED PROCESSES

This study considers the removal of diclofenac (an important representative of pharmaceuticals and personal care products -PPCPs) from the secondary effluents of Iasi municipal wastewater treatment plant by means of different advanced oxidation processes (homogeneous Fenton, photo-Fenton and photolysis), carried out in a laboratory scale reaction system. The influence of three qualitative or quantitative factors (Fe3+ concentration, the absence/presence of UV-A radiation and H2O2) was studied in 4 h oxidation tests, at both acidic and neutral pH conditions. A 23 full factorial plan was designed to check the influence of the main parameters affecting the process. The removal efficiencies of several process variants were determined by measuring the DCF concentration in the influent and effluent, by gas chromatography - mass spectrometry analysis. Total organic carbon, specific UV absorption at 254 nm and the hydrogen peroxide concentration were determined for each experiment. At acidic pH, the main effects plots showed that both use UV-A radiation and H2O2 addition improve the DCF removal efficiency, Fe concentration having a much smaller effect. DCF removal efficiencies of up to 98% were obtained depending on the operational conditions. At neutral pH, UV-A radiation is the most important factor that contributes to the removal of DCF and the interaction plots demonstrated this fact. The Pareto chart shows that all factors, with the exception of Fe concentration and H2O2 interactions, are influential. DCF removal efficiencies of up to 70% were obtained depending on the operational conditions.

Solar degradation of diclofenac using Eosin-Y-activated TiO2: cost estimation, process optimization and parameter interaction study

ABSTRACTDiclofenac (DCF), a widely used non-steroidal anti-inflammatory drug, is a commonly detected substance that readily accumulates in tissues of aquatic fish and poses a threat to wildlife and freshwater quality. Advanced Oxidation Processes have been employed as an alternative due to the inadequacy of conventional treatment methods of trace contaminants. This study utilized an innovative method of solar-activation of TiO2 using Eosin-Y dye for the degradation of DCF. Furthermore, the study incorporated a central composite design (CCD) to optimize the dye concentration and estimated the cost for the present process. Optimized parameters for light intensity (750 mW/cm2), Eosin-Y dye concentration (2 mg/L), TiO2 loading (37.5 mg/cm2) and DCF concentration (25 mg/L) were determined through a CCD. The optimized parameters convey a DCF degradation rate of 40% and 49% for 2 ppm (low range) and 4 ppm (high range) dye concentrations, respectively, for a 5-minute reaction time. Cost estimation for the materials used was for the current process was also performed. It was determined that the additional cost of using 4 ppm instead of 2 ppm to achieve only 10% more DCF degradation is not warranted and would require additional treatment to remove subsequently formed halogenated compounds.

Uso de fotorreatores UV para a remoção de diclofenaco, bezafibrato e etinilestradiol de esgoto tratado em sistema UASB-FBP

RESUMO Este trabalho avaliou a remoção de diclofenaco (DCF), bezafibrato (BZF) e etinilestradiol (EE2) de efluentes de sistema UASB-FBP (reator anaeróbio de manta de lodo seguido de filtro biológico percolador) em fotorreatores UV de lâmpadas imersas (FRI) e emersas (FRE). Os resultados mostram que baixa eficiência de remoção de tais compostos foi obtida em ambos fotorreatores quando se utilizou baixo tempo de contato (~10 min) e baixa concentração inicial de fármacos (0,5 µg.L-1 para EE2, e 21 µg.L-1 para DCF e BZF). O aumento da concentração inicial de DCF (para 20 mg.L-1) e do tempo de contato (para 20 min) resultaram em aumento da eficiência de remoção (de 31 para 83% no FRI e de 36 para 86% no FRE), indicando que compostos dissolvidos presentes no efluente biológico afetaram adversamente a remoção de fármacos nos fotorreatores devido a competição pela radiação UV incidente.

On the effect of serum on the transport of reactive oxygen species across phospholipid membranes.

The transport of plasma generated reactive oxygen species (ROS) across a simple phospholipid membrane mimic of a (real) cell was investigated. Experiments were performed in cell culture media (Dulbecco's modified Eagle's medium, DMEM), with and without 10% serum. A (broad spectrum) ROS reporter dye, 2,7-dichlorodihydrofluorescein (DCFH), was used to detect the generation of ROS by a helium (He) plasma jet in DMEM using free DCFH and with DCFH encapsulated inside phospholipid membrane vesicles dispersed in DMEM. The authors focus on the concentration and on the relative rates (arbitrary units) for oxidation of DCFH [or the appearance of the oxidized product 2,7-dichlorofluorescein (DCF)] both in solution and within vesicles. In the first 1 h following plasma exposure, the concentration of free DCF in DMEM was ~15× greater in the presence of serum (cf. to the serum-free DMEM control). The DCF in vesicles was ~2× greater in DMEM containing serum compared to the serum-free DMEM control. These data show that serum enhances plasma ROS generation in DMEM. As expected, the role of the phospholipid membrane was to reduce the rate of oxidation of the encapsulated DCFH (with and without serum). And the efficiency of ROS transport into vesicles was lower in DMEM containing serum (at 4% efficiency) when compared to serum-free DMEM (at 32% efficiency). After 1 h, the rate of DCFH oxidation was found to have significantly reduced. Based upon a synthesis of these data with results from the open literature, the authors speculate on how the components of biological fluid and cellular membranes might affect the kinetics of consumption of plasma generated ROS.