Removal of caffeine and diclofenac on activated carbon in fixed bed column

The occurrence of emerging contaminants in wastewaters, and their behaviour during wastewater treatment and production of drinking water are key issues in the re-use of water resources. The objective of this study was the adsorption of caffeine and diclofenac from aqueous solutions on fixed beds of granular activated carbon. Several operation conditions on the shape of breakthrough curves were investigated. Adsorption equilibrium is reached after 3 days for caffeine and after 14 days for diclofenac. In caffeine, breakthrough times, corresponding to C/C₀ = 0.02 were found to be 19.1, 47.6 and 48.5 h for the columns operating with bed weights of 0.6, 0.8 and 1.0 g, respectively. Saturation times (corresponding to C/C₀ = 0.95) were found to be 91.8, 114.3 and 121.0 h, respectively. The activated carbon is not an efficient adsorbent for diclofenac.     

Preparation and Characterization of Spray-Dried Polymeric Nanocapsules

Recently, much interest has been generated by colloidal drug delivery systems such as nanocapsules because of the possibilities for controlled release, increased drug efficacy, and reduced toxicity after parenteral administration. Nanocapsules of poly-ε-caprolactone and Eudragit S90® were prepared. However, these systems present physicochemical instability. To dry these nanocapsule suspensions with the view of obtaining a solid form, the spray-drying process was used. Spray-dried powders of nanocapsules of poly-ε-caprolactone and Eudragit S90® were prepared by atomization in a Büchi 190 Mini-spray dryer using colloidal silicon dioxide as a technological carrier. The morphological analysis of the surface at the powders showed that nanocapsules remain intact, and no change in particle size was detected after the spray-drying process. These results suggest that this method can be an interesting alternative to dry nanocapsule suspensions.     

Degradation of diclofenac in water by heterogeneous catalytic oxidation with H2O2

Diclofenac and other anti-inflammatory drugs have been detected not only in effluents of sewage treatment plants, hospitals and nursing homes but also in rivers and lakes. The heterogeneous catalytic oxidation was investigated for degradation of diclofenac. The kinetic of the degradation of the drug and of the formation of mineralization products with various heterogeneous catalysts has been studied. From the nature of the intermediate products a reaction path via hydroxylation, dehalogenation and cleavage of the NH-bridge between the aromatic rings is proposed. Subsequent oxidative ring opening and stepwise degradation lead to carboxylic acids.     

Sweet Potato Starch Microparticles as Controlled Drug Release Carriers: Preparation and In Vitro Drug Release

The aim of this study was to investigate the in vitro drug release behavior of sweet potato starch (SPS) microparticles intended for controlled drug delivery applications. Diclofenac sodium (DS) was used as a model drug candidate in the present study. SPS microparticles were prepared using a spray-drying technique by varying the polymer concentration and drug loading. The mean particles size of drug-loaded spray-dried SPS microparticles was between 10.3 and 13.1 µm. The mean particle size increased slightly with increase in the concentration of SPS. The mean particle size of spray-dried SPS microparticles increased from 10.3 to 13.1 µm when the concentration of SPS increased from 2 to 4% w/v. Under the current spray-drying conditions, the percentage yield of spray-dried SPS microparticles did not vary much among the various formulations and it was between 65.2 and 70.1%. The encapsulation efficiencies of SPS microparticles formulations was between 95.1–98.2%, suggesting good encapsulating ability of the SPS polymer by spary drying. Drug release from all the formulations of spray-dried SPS microparticles was controlled over period of 6 h. The cumulative amount of drug release from the spray-dried SPS microparticles decreased with an increase in the concentration of SPS, while it increases as the drug loading is increased. Release of the drug from spray-dried SPS microparticles followed Fick's law of diffusion since a good correlation coefficient (R²) was observed with the Higuchi plots (R² = 0.9928 to 0.9979).     

Advanced oxidation of the pharmaceutical drug diclofenac with UV/H2O2 and ozone

Diclofenac, a widely used anti-inflammatory drug, has been found in many Sewage Treatment Plant effluents, rivers and lake waters, and has been reported to exhibit adverse effects on fish. Advanced oxidation processes, ozonation and H2O2/UV were investigated for its degradation in water. The kinetic of the degradation reaction and the nature of the intermediate products were still poorly defined. Under the conditions adopted in the present study, both ozonation and H2O2/UV systems proved to be effective in inducing diclofenac degradation, ensuring a complete conversion of the chlorine into chloride ions and degrees of mineralization of 32% for ozonation and 39% for H2O2/UV after a 90 min treatment. The reactions were found to follow similar, but not identical, reaction pathways leading to hydroxylated intermediates (e.g. 2-[(2,6-dichlorophenyl)amino]-5-hydroxyphenylacetic acid) and C-N cleavage products (notably 2,5-dihydroxyphenylacetic acid) through competitive routes. Subsequent oxidative ring cleavage leads to carboxylic acid fragments via classic degradation pathways. In the pH range 5.0-6.0 kinetic constants (1.76 x 10(4)-1.84 x 10(4) M(-1) s(-1)) were estimated for diclofenac ozonation.     

Diclofenac sodium: oxidative degradation in solution and solid state

The formation of two oxidative degradates of diclofenac in solution and the solid state was demonstrated.     

Photocatalytic degradation of non-steroidal anti-inflammatory drugs with TiO2 and simulated solar irradiation

The aim of this work is to evaluate and compare the degradation achieved for three non-steroidal anti-inflammatory drugs (NSAIDs) by heterogeneous TiO2 photocatalytic means in aqueous solution at laboratory scale. The selected pharmaceutical compounds were diclofenac (DCF), naproxen (NPX) and ibuprofen (IBP). These compounds were used in their sodium salt chemical form. Previous experiments (adsorption, photolysis and thermodegradation) were developed to evaluate non-catalytic degradation for each NSAID. Photocatalytic experiments were carried out in a Xe-lamp reactor in order to study the influences of different operational conditions (catalyst load, temperature and dissolved oxygen concentration). These results showed that the optimum amount of TiO2, to achieve maximum degradation, of IBP was 1g/L. In contrast, the maximum degradation for DCF or NPX was observed at a TiO2 loading of 0.1g/L. Temperature had a significant effect only for NPX degradation, achieving almost 99% phototransformation. No significant differences were observed for DCF and IBP at 20, 30 and 40 degrees C. Dissolved oxygen concentration was an important parameter to increase the degradation for NPX and IBP. However, it was observed that its rate of mineralization did not increase. Intermediate metabolites were detected in all cases. Hydroxyl metabolites were the most important residual compounds after the photocatalytic treatment of IBP. The inhibition percentage of bioluminescence from Vibro fischeri--as a toxicity parameter--increased during the irradiation time due to the residual concentration of the hydroxyl metabolites generated. However, after 120 min, in experiments with 40 mg/L of dissolved oxygen, a decrease of the % inhibition was observed. Only photocatalytic treatment of IBP drives to a satisfactory biodegradability index BOD5/COD (between 0.16 and 0.42) and, only in this case, a post-biological treatment could be suggested.     

Immobilized copper ions on MWCNTS-Chitosan thin film: Enhanced amperometric sensor for electrochemical determination of diclofenac sodium in aqueous solution

A simple and effective electrochemical sensor was designed by the drop cast method for the detection of Diclofenac Sodium (DS), a widely used painkiller, by combining the significant catalytic property of multi-walled carbon nanotubes (MWCNTs), excellent adsorption capacity and film forming ability of Chitosan and synergistic catalytic effect of Chitosan-copper complex. The characteristics of newly proposed composite (MWCNTs/CTS-Cu/GCE) were investigated by different techniques like Fourier Transform Infrared Spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM) and Energy dispersive X-ray analysis (EDX). The electrochemical performance of the newly modified composite was studied by using Cyclic voltammetry (CV), Electrochemical impedance spectroscopy (EIS), Square wave voltammetry (SWV). Under the optimum conditions, the anodic peak current for Diclofenac sodium (DS) was linear and the range is between 0.3 and 200 μmol L^?1 with the detection limit of 0.021 μmol L^?1 at pH 4.0. Finally, this modified composite exhibit good selectivity, sensitivity and stability for the detection of Diclofenac sodium (DS) from the pharmaceutical dosage form and real samples.     

Effects of ozone pre-treatment on diclofenac: Intermediates, biodegradability and toxicity assessment

Diclofenac (DCF), a common analgesic, anti-arthritic and anti-rheumatic drug, is one of the most frequently detected compounds in water. This study deals with the degradation of diclofenac in aqueous solution by ozonation. Biodegradability (BOD₅/COD ratio and Zahn-Wellens test), acute ecotoxicity and inhibition of activated sludge activity were determined in ozonated and non-ozonated samples. Liquid chromatography coupled with time-of-flight mass spectrometry (LC/TOF-MS) was used to identify the intermediates formed in 1 h of ozonation. Eighteen intermediates were identified by these techniques and a tentative degradation pathway for DCF ozonation is proposed.Experimental results show that ozone is efficient at removing DCF: > 99% removal (starting from an initial concentration of 0.68 mmol L^− 1) was achieved after 30 min of ozonation (corresponding to an absorbed ozone dose of 0.22 g L^− 1, which is 4.58 mmol L^− 1). However, only 24% of the substrate was mineralized after 1 h of ozonation. The biodegradability, respiration inhibition in activated sludge and acute toxicity tests demonstrate that ozonation promotes a more biocompatible effluent of waters containing DCF.     

Comparison of the removal of hydrophobic trace organic contaminants by forward osmosis and reverse osmosis

We compared the rejection behaviours of three hydrophobic trace organic contaminants, bisphenol A, triclosan and diclofenac, in forward osmosis (FO) and reverse osmosis (RO). Using erythritol, xylose and glucose as inert reference organic solutes and the membrane pore transport model, the mean effective pore size of a commercial cellulose-based FO membrane was estimated to be 0.74 nm. When NaCl was used as the draw solute, at the same water permeate flux of 5.4 L/m² h (or 1.5 μm/s), the adsorption of all three compounds to the membrane in the FO mode was consistently lower than that in the RO mode. Rejection of bisphenol A and diclofenac were higher in the FO mode compared to that in the RO mode. Because the molecular width of triclosan was larger than the estimated mean effective membrane pore size, triclosan was completely rejected by the membrane and negligent difference between the FO and RO modes could be observed. The difference in the separation behaviour of these hydrophobic trace organics in the FO (using NaCl the draw solute) and RO modes could be explained by the phenomenon of retarded forward diffusion of solutes. The reverse salt flux of NaCl hinders the pore diffusion and subsequent adsorption of the trace organic compounds within the membrane. The retarded forward diffusion effect was not observed when MgSO₄ and glucose were used as the draw solutes. The reverse flux of both MgSO₄ and glucose was negligible and thus both adsorption and rejection of BPA in the FO mode were identical to those in the RO mode.