Optimization of iron-ZIF-8 catalysts for degradation of tartrazine in water by Fenton-like reaction.

Optimization of iron zeolitic imidazole framework-8 (FeZIF-8) nanoparticles, as heterogeneous catalysts, were synthesized and evaluated by the Fenton-like reaction for to degrade tartrazine (Tar) in aqueous environment. To achieve this, ZIF-8 nanoparticles were modified with different iron species (Fe2+ or Fe3O4), and subsequently assessed through the Fenton-like oxidation. The effect of different parameters such as the concentration of hydrogen peroxide, the mass of catalyst and the contact time of reaction on the degradation of Tar by Fenton-like oxidation was studied by using the Box-Behnken design (BBD). The BBD model indicated that the optimum catalytic conditions for Fenton-like reaction with an initial pollutant concentration of 30 ppm at pH 3.0 were T = 40 °C and 12 mM of H2O2, 2 g/L of catalyst and 4 h of reaction. The maximum Tar conversion value achieved with the best catalyst, Fe1ZIF-8, was 66.5% with high mineralization (in terms of decrease of total organic carbon - TOC), 44.2%. To assess phytotoxicity, the germination success of corn kernels was used as an indicator in the laboratory. The results show that the catalytic oxidation by Fenton-like reaction using heterogeneous iron ZIF-8 catalysts is a viable alternative for treating contaminated effluents with organic pollutants and highlighted the importance of the validation of the optimized experimental conditions by mathematical models.

The Use of 3D Optical Coherence Tomography to Analyze the Architecture of Cyanobacterial Biofilms Formed on a Carbon Nanotube Composite.

The development of environmentally friendly antifouling strategies for marine applications is of paramount importance, and the fabrication of innovative nanocomposite coatings is a promising approach. Moreover, since Optical Coherence Tomography (OCT) is a powerful imaging technique in biofilm science, the improvement of its analytical power is required to better evaluate the biofilm structure under different scenarios. In this study, the effect of carbon nanotube (CNT)-modified surfaces in cyanobacterial biofilm development was assessed over a long-term assay under controlled hydrodynamic conditions. Their impact on the cyanobacterial biofilm architecture was evaluated by novel parameters obtained from three-dimensional (3D) OCT analysis, such as the contour coefficient, total biofilm volume, biovolume, volume of non-connected pores, and the average size of non-connected pores. The results showed that CNTs incorporated into a commercially used epoxy resin (CNT composite) had a higher antifouling effect at the biofilm maturation stage compared to pristine epoxy resin. Along with a delay in biofilm development, a decrease in biofilm wet weight, thickness, and biovolume was also achieved with the CNT composite compared to epoxy resin and glass (control surfaces). Additionally, biofilms developed on the CNT composite were smoother and presented a lower porosity and a strictly packed structure when compared with those formed on the control surfaces. The novel biofilm parameters obtained from 3D OCT imaging are extremely important when evaluating the biofilm architecture and behavior under different scenarios beyond marine applications.

Performance of Graphene/Polydimethylsiloxane Surfaces against S. aureus and P. aeruginosa Single- and Dual-Species Biofilms.

The increasing incidence of implant-associated infections has prompted the development of effective strategies to prevent biofilm formation on these devices. In this work, pristine graphene nanoplatelet/polydimethylsiloxane (GNP/PDMS) surfaces containing different GNP loadings (1, 2, 3, 4, and 5 wt%) were produced and evaluated on their ability to mitigate biofilm development. After GNP loading optimization, the most promising surface was tested against single- and dual-species biofilms of Staphylococcus aureus and Pseudomonas aeruginosa. The antibiofilm activity of GNP/PDMS surfaces was determined by the quantification of total, viable, culturable, and viable but nonculturable (VBNC) cells, as well as by confocal laser scanning microscopy (CLSM). Results showed that 5 wt% GNP loading reduced the number of total (57%), viable (69%), culturable (55%), and VBNC cells (85%) of S. aureus biofilms compared to PDMS. A decrease of 25% in total cells and about 52% in viable, culturable, and VBNC cells was observed for P. aeruginosa biofilms. Dual-species biofilms demonstrated higher resistance to the antimicrobial activity of GNP surfaces, with lower biofilm cell reductions (of up to 29% when compared to single-species biofilms). Still, the effectiveness of these surfaces in suppressing single- and dual-species biofilm formation was confirmed by CLSM analysis, where a decrease in biofilm biovolume (83% for S. aureus biofilms and 42% for P. aeruginosa and dual-species biofilms) and thickness (on average 72%) was obtained. Overall, these results showed that pristine GNPs dispersed into the PDMS matrix were able to inhibit biofilm growth, being a starting point for the fabrication of novel surface coatings based on functionalized GNP/PDMS composites.

Carbon Nanotube/Poly(dimethylsiloxane) Composite Materials to Reduce Bacterial Adhesion.

Different studies have shown that the incorporation of carbon nanotubes (CNTs) into poly(dimethylsiloxane) (PDMS) enables the production of composite materials with enhanced properties, which can find important applications in the biomedical field. In the present work, CNT/PDMS composite materials have been prepared to evaluate the effects of pristine and chemically functionalized CNT incorporation into PDMS on the composite's thermal, electrical, and surface properties on bacterial adhesion in dynamic conditions. Initial bacterial adhesion was studied using a parallel-plate flow chamber assay performed in conditions prevailing in urinary tract devices (catheters and stents) using Escherichia coli as a model organism and PDMS as a control due to its relevance in these applications. The results indicated that the introduction of the CNTs in the PDMS matrix yielded, in general, less bacterial adhesion than the PDMS alone and that the reduction could be dependent on the surface chemistry of CNTs, with less adhesion obtained on the composites with pristine rather than functionalized CNTs. It was also shown CNT pre-treatment and incorporation by different methods affected the electrical properties of the composites when compared to PDMS. Composites enabling a 60% reduction in cell adhesion were obtained by CNT treatment by ball-milling, whereas an increase in electrical conductivity of seven orders of magnitude was obtained after solvent-mediated incorporation. The results suggest even at low CNT loading values (1%), these treatments may be beneficial for the production of CNT composites with application in biomedical devices for the urinary tract and for other applications where electrical conductance is required.

Distribution of micropollutants in estuarine and sea water along the Portuguese coast.

This work provides the first spatial distribution report of micropollutants (MPs) in the entire Portuguese coast, comprising the ocean shore (sea water, SW) and whenever possible the nearest river discharging on it (estuarine water, EW). This surface water monitoring programme aimed to assess the spatial distribution of 37 MPs with a wide chemical nature, including some substances prioritized by the European Union Directive 39/2013/EU and contaminants of emerging concern targeted in the Watch List of Decisions 495/2015/EU and 840/2018/EU. The risk quotients were estimated in each sampling point for the detected MPs. High concentrations of diclofenac, tramadol and carbamazepine were determined, the latter with medium to high risk for algae. Some pharmaceuticals and perfluorooctanesulfonic acid (PFOS) were broadly distributed, maybe due to the direct discharge into the sea. Atrazine and alachlor were found in the majority of the samples, with alachlor levels often considered as medium to high risk.

Catalytic and Photocatalytic Nitrate Reduction Over Pd-Cu Loaded Over Hybrid Materials of Multi-Walled Carbon Nanotubes and TiO2.

TiO2 and carbon nanotube-TiO2 hybrid materials synthesized by sol-gel and loaded with 1%Pd-1%Cu (%wt.) were tested in the catalytic and photocatalytic reduction of nitrate in water in the presence of CO2 (buffer) and H2 (reducing agent). Characterization of the catalysts was performed by UV-Vis and fluorescence spectroscopy, X-ray diffraction, temperature programed reduction, N2 adsorption, and electron microscopy. The presence of light produced a positive effect in the kinetics of nitrate removal. Higher selectivity toward nitrogen formation was observed under dark condition, while the photo-activated reactions showed higher selectivity for the production of ammonium. The hybrid catalyst containing 20 %wt. of carbon nanotubes shows the best compromise between activity and selectivity. A mechanism for the photocatalytic abatement of nitrate in water in the presence of the hybrid materials was proposed, based in the action of carbon nanotubes as light harvesters, dispersing media for TiO2 particles and as charge carrier facilitators.

Eco-friendly LC-MS/MS method for analysis of multi-class micropollutants in tap, fountain, and well water from northern Portugal.

Organic micropollutants present in drinking water (DW) may cause adverse effects for public health, and so reliable analytical methods are required to detect these pollutants at trace levels in DW. This work describes the first green analytical methodology for multi-class determination of 21 pollutants in DW: seven pesticides, an industrial compound, 12 pharmaceuticals, and a metabolite (some included in Directive 2013/39/EU or Decision 2015/495/EU). A solid-phase extraction procedure followed by ultra-high-performance liquid chromatography coupled to tandem mass spectrometry (offline SPE-UHPLC-MS/MS) method was optimized using eco-friendly solvents, achieving detection limits below 0.20 ng L-1. The validated analytical method was successfully applied to DW samples from different sources (tap, fountain, and well waters) from different locations in the north of Portugal, as well as before and after bench-scale UV and ozonation experiments in spiked tap water samples. Thirteen compounds were detected, many of them not regulated yet, in the following order of frequency: diclofenac > norfluoxetine > atrazine > simazine > warfarin > metoprolol > alachlor > chlorfenvinphos > trimethoprim > clarithromycin ≈ carbamazepine ≈ PFOS > citalopram. Hazard quotients were also estimated for the quantified substances and suggested no adverse effects to humans. Graphical Abstract Occurrence and removal of multi-class micropollutants in drinking water, analyzed by an eco-friendly LC-MS/MS method.

Occurrence and removal of organic micropollutants: An overview of the watch list of EU Decision 2015/495.

Although there are no legal discharge limits for micropollutants into the environment, some regulations have been published in the last few years. Recently, a watch list of substances for European Union-wide monitoring was reported in the Decision 2015/495/EU of 20 March 2015. Besides the substances previously recommended to be included by the Directive 39/2013/EU, namely two pharmaceuticals (diclofenac and the synthetic hormone 17-alpha-ethinylestradiol (EE2)) and a natural hormone (17-beta-estradiol (E2)), the first watch list of 10 substances/groups of substances also refers three macrolide antibiotics (azithromycin, clarithromycin and erythromycin), other natural hormone (estrone (E1)), some pesticides (methiocarb, oxadiazon, imidacloprid, thiacloprid, thiamethoxam, clothianidin, acetamiprid and triallate), a UV filter (2-ethylhexyl-4-methoxycinnamate) and an antioxidant (2,6-di-tert-butyl-4-methylphenol) commonly used as food additive. Since little is known about the removal of most of the substances included in the Decision 2015/495/EU, particularly regarding realistic concentrations in aqueous environmental samples, this review aims to: (i) overview the European policy in the water field; (ii) briefly describe the most commonly used conventional and advanced treatment processes to remove micropollutants; (iii) summarize the relevant data published in the last decade, regarding occurrence and removal in aqueous matrices of the 10 substances/groups of substances that were recently included in the first watch list for European Union monitoring (Decision 2015/495/EU); and (iv) highlight the lack of reports concerning some substances of the watch list, the study of un-spiked aquatic matrices and the assessment of transformation by-products.

Effect of different carbon materials as electron shuttles in the anaerobic biotransformation of nitroanilines.

Aromatic amines resulted from azo dyes biotransformation under anaerobic conditions are generally recalcitrant to further anaerobic degradation. The catalytic effect of carbon materials (CM) on the reduction of azo dyes is known and has been confirmed in this work by increasing threefold the biological reduction rate of Mordant Yellow 1 (MY1). The resulting m-nitroaniline (m-NoA) was further degraded to m-phenylenediamine (m-Phe) only in the presence of CM. The use of CM to degraded anaerobically aromatic amines resulted from azo dye reduction was never reported before. In the sequence, we studied the effect of different CM on the bioreduction of o-, m-, and p-NoA. Three microporous activated carbons with different surface chemistry, original (AC0 ), chemical oxidized with HNO3 (ACHNO3 ), and thermal treated (ACH2 ), and three mesoporous carbons, xerogels (CXA and CXB) and nanotubes (CNT) were assessed. In the absence of CM, NoA were only partially reduced to the corresponding Phe, whereas in the presence of CM, more than 90% was converted to the corresponding Phe. ACH2 and AC0 were the best electron shuttles, increasing the rates up to eightfold. In 24 h, the biological treatment of NoA and MY1 with AC0 , decreased up to 88% the toxicity towards a methanogenic consortium, as compared to the non-treated solutions. Biotechnol. Bioeng. 2016;113: 1194-1202. © 2015 Wiley Periodicals, Inc.

Environmental friendly method for urban wastewater monitoring of micropollutants defined in the Directive 2013/39/EU and Decision 2015/495/EU.

The fate and removal of organic micropollutants in the environment is a demanding issue evidenced by the recent European policy. This work presents an analytical method for the trace quantification of 37 micropollutants including Priority Substances (Directive 2013/39/EU), substances of the recent watch list (Decision 2015/495/EU) and contaminants of emerging concern: pesticides, multi-class pharmaceuticals and a metabolite, estrogens and one industrial compound. The analytical method was based on solid phase extraction (SPE) followed by ultra-high performance liquid chromatography with tandem mass spectrometry (UHPLC-MS/MS), using eco-friendly solvents (ethanol and ultrapure water) both in the SPE and UHPLC, according to green analytical chemistry principles. Briefly, Oasis(®) HLB cartridges were used to preconcentrate 100mL of water samples and the reconstituted extracts were analyzed with a Kinetex™ column under reversed mode, the linear ranges extended to 200ngL(-1) (R(2)>0.99) for all the analytes. The method detection limits were between 0.04 and 2.26ngL(-1) and the method quantification limits were between 0.13 and 6.85ngL(-1). The identity of the compounds was confirmed using two MS/MS transitions and its ion ratios, according to Decision 2002/657/EC. The validated method was applied to wastewater treatment plant samples, assessing the concentration of micropollutants after secondary biological and tertiary UV treatments. Lab-scale photolysis and ozonation experiments were also performed with the secondary effluents, with ozonation showing the best performance for the removal of most of the determined micropollutants.

Adsorption of dyes by ACs prepared from waste tyre reinforcing fibre. Effect of texture, surface chemistry and pH.

This paper compares the importance of the texture and surface chemistry of waste tyre activated carbons in the adsorption of commercial dyes. The adsorption of two commercial dyes, Basic Astrazon Yellow 7GLL and Reactive Rifafix Red 3BN on activated carbons made up of reinforcing fibres from tyre waste and low-rank bituminous coal was studied. The surface chemistry of activated carbons was modified by means of HCl-HNO3 treatment in order to increase the number of functional groups. Moreover, the influence of the pH on the process was also studied, this factor being of great importance due to the amphoteric characteristics of activated carbons. The activated carbons made with reinforcing fibre and coal had the highest SBET, but the reinforcing fibre activated carbon samples had the highest mesopore volume. The texture of the activated carbons was not modified upon acid oxidation treatment, unlike their surface chemistry which underwent considerable modification. The activated carbons made with a mixture of reinforcing fibre and coal experienced the largest degree of oxidation, and so had more acid surface groups. The adsorption of reactive dye was governed by the mesoporous volume, whilst surface chemistry played only a secondary role. However, the surface chemistry of the activated carbons and dispersive interactions played a key role in the adsorption of the basic dye. The adsorption of the reactive dye was more favored in a solution of pH 2, whereas the basic dye was adsorbed more easily in a solution of pH 12.

Lanthano phosphomolybdate-decorated silica nanoparticles: novel hybrid materials with photochromic properties.

Novel photochromic hybrid nanomaterials were prepared through the immobilization of the lacunary Keggin-type phosphomolybdate (TBA4H3[PMo11O39]·xH2O, denoted as PMo11) and sandwich-type lanthano phosphomolybdates (K11[Ln(III)(PMo11O39)2]·xH2O, denoted as Ln(PMo11)2, where Ln(III) = Sm, Eu, Gd, Tb and Dy) onto positively-charged functionalized silica nanoparticles. The functionalized silica nanoparticles were prepared by a one-step co-condensation route between tetraethyl orthosilicate and dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride, presenting an average particle size of 95 ± 26 nm, a spherical morphology and a pore diameter of 13.7 nm. All characterization techniques proved the successful immobilization of the phosphomolybdates. The photochromic properties of the resulting hybrid nanomaterials in the solid state were evaluated by UV-Vis spectroscopy and colorimetry. All materials revealed promising photochromic properties under UV irradiation (λ = 254 nm). The lacunary phosphomolybdate anchored onto the silica nanoparticles, C18-SiO2@PMo11, showed the best photoswitching properties, with the color changing from green to dark-blue (ΔE* = 26.8). Among the Ln(PMo11)2-based hybrid nanomaterials, those containing higher Mo loadings--Eu(III)- and Tb(III)-based samples--presented more significant color changes from green to dark-blue (ΔE* = 18.8-18.9). These results revealed that the optical properties of the as-prepared hybrid nanomaterials did not depend directly on the type of Ln(III) cation, but only on the amount of Mo, which was the target element responsible for the photochromic behavior.

An overview on the advanced oxidation processes applied for the treatment of water pollutants defined in the recently launched Directive 2013/39/EU.

Environmental pollution is a recognized issue of major concern since a wide range of contaminants has been found in aquatic environment at ngL(-1) to µgL(-1) levels. In the year 2000, a strategy was defined to identify the priority substances concerning aquatic ecosystems, followed by the definition of environmental quality standards (EQS) in 2008. Recently it was launched the Directive 2013/39/EU that updates the water framework policy highlighting the need to develop new water treatment technologies to deal with such problem. This review summarizes the data published in the last decade regarding the application of advanced oxidation processes (AOPs) to treat priority compounds and certain other pollutants defined in this Directive, excluding the inorganic species (cadmium, lead, mercury, nickel and their derivatives). The Directive 2013/39/EU includes several pesticides (aldrin, dichlorodiphenyltrichloroethane, dicofol, dieldrin, endrin, endosulfan, isodrin, heptachlor, lindane, pentachlorophenol, chlorpyrifos, chlorfenvinphos, dichlorvos, atrazine, simazine, terbutryn, diuron, isoproturon, trifluralin, cypermethrin, alachlor), solvents (dichloromethane, dichloroethane, trichloromethane and carbon tetrachloride), perfluorooctane sulfonic acid and its derivatives (PFOS), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), nonylphenol and octylphenol, as well as the three compounds included in the recommendation for the first watch list of substances (diclofenac, 17-alpha-ethinylestradiol (EE2) and 17-beta-estradiol (E2)). Some particular pesticides (aclonifen, bifenox, cybutryne, quinoxyfen), organotin compounds (tributyltin), dioxins and dioxin-like compounds, brominated diphenylethers, hexabromocyclododecanes and di(2-ethylhexyl)phthalate are also defined in this Directive, but studies dealing with AOPs are missing. AOPs are recognized tools to destroy recalcitrant compounds or, at least, to transform them into biodegradable species. Diuron (a phenylurea herbicide) and atrazine (from the triazine chemical class) are the most studied pesticides from Directive 2013/39/EU. Fenton-based processes are the most frequently applied to treat priority compounds in water and their efficiency typically increases with the operating temperature as well as under UV or solar light. Heterogeneous photocatalysis is the second most used treatment to destroy pollutants defined in the Directive. Ozone alone promotes the partial oxidation of pollutants, and an increase in the effluent biodegradability, but complete mineralization of pollutants is difficult. To overcome this drawback, ozonation has been combined with heterogeneous catalysts, addition of H2O2, other AOPs (such as photocatalysis) or membrane technologies.

Potentiation of 5-fluorouracil encapsulated in zeolites as drug delivery systems for in vitro models of colorectal carcinoma.

The studies of potentiation of 5-fluorouracil (5-FU), a traditional drug used in the treatment of several cancers, including colorectal (CRC), were carried out with zeolites Faujasite in the sodium form, with different particle sizes (NaY, 700nm and nanoNaY, 150nm) and Linde type L in the potassium form (LTL) with a particle size of 80nm. 5-FU was loaded into zeolites by liquid-phase adsorption. Characterization by spectroscopic techniques (FTIR, (1)H NMR and (13)C and (27)Al solid-state MAS NMR), chemical analysis, thermal analysis (TGA), nitrogen adsorption isotherms and scanning electron microscopy (SEM), demonstrated the successful loading of 5-FU into the zeolite hosts. In vitro drug release studies (PBS buffer pH 7.4, 37°C) revealed the release of 80-90% of 5-FU in the first 10min. To ascertain the drug release kinetics, the release profiles were fitted to zero-order, first-order, Higuchi, Hixson-Crowell, Korsmeyer-Peppas and Weibull kinetic models. The in vitro dissolution from the drug delivery systems (DDS) was explained by the Weibull model. The DDS efficacy was evaluated using two human colorectal carcinoma cell lines, HCT-15 and RKO. Unloaded zeolites presented no toxicity to both cancer cells, while all DDS allowed an important potentiation of the 5-FU effect on the cell viability. Immunofluorescence studies provided evidence for zeolite-cell internalization.

Pore tuned activated carbons as supports for an enantioselective molecular catalyst.

The Jacobsen catalyst was immobilized onto four activated carbons with different average pore sizes, achieved by a gasification process followed by molecular oxygen oxidation. The influence of the textural properties of the activated carbon in the immobilization process and in the catalytic performance of the Mn(III) heterogeneous catalysts was investigated in detail. Three different catalytic systems were studied: styrene epoxidation using m-chloroperoxybenzoic acid; 6-CN-2,2-diMeChromene epoxidation using NaOCl and iodosylbenzene (PhIO) as oxidants. The catalysts tested were active and enantioselective in the three systems studied. Selectivity towards the desired epoxide only decreases in the case of the material with smaller pores, remaining identical to that of the homogeneous phase in all the other materials. The enantiomeric excess values (%ee) for alkene epoxidation increase with the pore size of the heterogeneous catalysts, and these values are even higher than the homogeneous counterparts in the styrene epoxidation reaction. Total Mn(III) loadings increase with the pore size, as well as their distribution within the carbon porous matrix. Characterization of the activated carbons bearing the immobilized manganese(III) complexes by TPD and XPS point to reaction between carbon surface phenolate groups and the manganese(III) complexes through axial coordination of the metal centers to these groups.