Removal of the emerging contaminant bisphenol A by an ureasil–PEO hybrid membrane: experimental study and molecular dynamic simulation

This work reports the use of a cross-linked ureasil–PEO hybrid matrix (designated PEO800) as an efficient adsorbent to retain the emerging contaminant bisphenol A (BPA) from an aqueous medium. The in-deep experimental and theoretical results provide information about the interactions between PEO800 and BPA. The in situ UV-vis spectroscopy data and the pseudo-first order, pseudo-second order, Elovich, and Morris–Webber intraparticle diffusion models allowed us to propose a three-step mechanism for the adsorption of BPA onto PEO800. The results indicate that the pseudo-first-order kinetic model effectively describes the adsorption of BPA onto PEO800. Differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy confirmed the interaction of PEO800 with BPA, showing an alteration in the chemical environment of the polymer ether oxygen atoms present in the hybrid matrix. The molecular dynamic simulation provides further evidence that the BPA molecules interact preferentially with PEO. The amount of desorbed BPA depended on the pH and solvent used in the assays. This work provides new opportunities for using the hydrophilic ureasil–PEO matrix which has demonstrated its abilities in being a fast and easy alternative to successfully removing organic contaminants from aqueous mediums and therefore having potential applications in water remediation.

Graphical abstract

     

Organochlorine concentrations in franciscana dolphins, Pontoporia blainvillei, from Brazilian waters

Blubber samples were collected from ten franciscana dolphins either incidentally captured in fishing operations or stranded on São Paulo (SP) and Paraná (PR) states littoral, Southeastern and Southern Brazilian coast, respectively. Determination of PCB, DDT and HCB concentrations were performed by capillary gas chromatograph coupled to electron capture detector (ECD). ΣDDT, ΣPCB and HCB concentrations ranged from 264 ng g⁻¹ to 5811 ng g⁻¹ lipid, from 909 ng g⁻¹ to 5849 ng g⁻¹ lipid and from 10 ng g⁻¹ to 61 ng g⁻¹ lipid, respectively. Regarding DDTs, the distribution of the mean percentages decreased in the following order: p,p′-DDE > p,p′-DDD > p,p′-DDT. The ΣDDT/ΣPCB ratio varied between 0.27 and 0.42 in Northern and Central SP coast, while in Southern SP and PR coast the values were 1.6 and 1.9, respectively. Dissimilarities in ΣDDT/ΣPCB ratios point to different sources of organochlorine compounds to franciscana dolphins in the study area. Considering the endocrine disruptive action of organochlorine compounds, the concentrations found in franciscana dolphins from Brazilian waters may represent an additional obstacle to the conservation of this endangered cetacean species.     

Persistent organic pollutants (POPs) in populations of the clam Chione californiensis in coastal lagoons of the Gulf of California

This study examines the potential public health risk due to the massive use of organochlorine pesticides (OCs) in agriculture in the Gulf of California. Specimens of the clam Chione californiensis were collected from three coastal lagoons (Yavaros, Altata and Reforma). Sites were classified as polluted/nonpolluted based on the presence/absence of OCs as an indicator of the persistence of these pollutants; in polluted sites, the time elapsed since pesticide application (past or recent) was estimated. Screening values (SV) for protecting human health as per the U.S. Environmental Protection Agency (EPA) were used for risk assessment. OCs detected were ranked according to frequency of occurrence as follows: γ-chlordane (75%) > endrin (54%) > aldrin (48%) > heptachlor, and dichlorodiphenyl-trichloroethane (DDE) (37%) > β-heptachlor epoxide (30%) > lindane (α-BHC, δ-BHC) and endosulphan I (≤ 6%). Specifically, OCs detected at the highest concentration were heptachlor in Yavaros (0.0168 µgg^?1) and Altata (0.0046 µgg^?1), and aldrin in Reforma (0.0019 µgg^?1). β-Heptachlor epoxide in Altata and Reforma was the only OC with a concentration exceeding the EPA Screening Value. From our results and based on the monthly consumption limit set forth by EPA, the maximum safe consumption of clams to avoid a carcinogenic risk derived from β-heptachlor epoxide in the fishing villages of Yavaros and Altata is 4 servings per month (1 serving = 0.227 kg) by a 70-kg person. These findings suggest that concentrations of OCs and their isomers in C. californiensis populations reflect environmental persistence as well as recent inputs of OCs into coastal lagoons in the Gulf of California.     

Effect of clomazone herbicide on biochemical and histological aspects of silver catfish (Rhamdia quelen) and recovery pattern

The effects of the herbicide, clomazone, on acetylcholinesterase (AChE), catalase and TBARS formation in teleost fish (Rhamdia quelen) were studied. The fish were exposed to 0.5 or 1.0 mg L⁻¹ of clomazone for 12, 24, 48, 96 and 192 h. After 192 h of exposure period, fish were transferred to clean water and kept in the same for 192 h to study the recovery response. Same parameters as that of exposure period were assayed after 96 and 192 h of recovery period. Specific AChE activity was reduced in the brain and muscle after treatments, reaching a maximum inhibition of 47% in the brain and 45% in the muscle after 12 h of exposure. Fish exposed to clomazone increased TBARS production in the liver for all exposure periods. The brain presented elevated TBARS levels after 12, 24 and 48 h, but after 96 and 192 h, these levels decreased. The decrease of TBARS levels persisted in brain tissue after 96 h of recovery and returned to the control value after 192 h in clean water. Catalase activity was reduced for all periods of exposure. Histological analysis showed vacuolation in the liver after herbicide exposure. Some of the alterations observed were completely restored after recovery period.     

Characterization of Atrazine-Loaded Biodegradable Poly(Hydroxybutyrate-Co-Hydroxyvalerate) Microspheres

Polyhydroxybutyrate-co-hydroxyvalerate microspheres (PHBV-MS) were prepared as a delivery system for the herbicide atrazine (ATZ). Characterization of the system included investigation of in vitro release properties and genotoxicity. ATZ − PHBV-MS particle diameters showed a size distribution range of 1–13 μm. Differential scanning calorimetry analyses indicated that ATZ was associated with the PHBV microparticles. The release profiles showed a different release behavior for the pure herbicide in solution, as compared with that containing ATZ-loaded PHBV-MS. Korsmeyer–Peppas model analyses showed that atrazine release from the microparticles occurred by a combination of diffusion through the matrix and partial diffusion through water-filled pores of the PHBV microparticles. A Lactuca sativa test result showed that the genotoxicity of ATZ-loaded PHBV-MP was decreased in relation to ATZ alone. The results demonstrate a viable biodegradable herbicide release system using atrazine for agrochemical purposes.     

Equilibrium disorders in workers exposed to mixed solvents

Background. Organic solvents cause diseases of the vestibular system. However, little is known regarding the correlation between vestibular damage and exposure to organic solvents below threshold limit values. The best measure by which to evaluate vestibular disorders is static and dynamic posturography. Objective. The aim of this study was to evaluate equilibrium disorders via static and dynamic posturography in workers without clear symptoms and exposed to low doses of mixed solvents. Methods. 200 subjects were selected. Using an Otometrics device (Madsen, Denmark), all subjects endured static and dynamic posturography testing with both eyes-open and eyes-closed conditions. Results were compared with a control group of unexposed individuals. Result. Based on the obtained data, the following results can be drawn: (a) subjects exposed to mixtures of solvents show highly significant differences regarding all static and dynamic posturography parameters in comparison to the control group; (b) posturography testing has proven to be a valid means by which to detect subliminal equilibrium disorders in subjects exposed to solvents. Conclusion. We can confirm that refinery workers exposed to mixtures of solvents can present subliminal equilibrium disorders. Early diagnosis of the latter is made possible by static and dynamic posturography.     

Diffuse source apportionment of the Po river eutrophying load to the Adriatic sea: assessment of Lombardy contribution to Po river nutrient load apportionment by means of an integrated modelling approach

The source apportionment of the annual nutrient load carried by the Po river to the Adriatic sea has been studied.

An integrated modelling approach was applied to the Lombardy plain area, which covers about 34% of the Po river watershed area and accounts for about 50% of the point sources’ loads carried by the river. To extract all the information available from direct instream measurements, two different modelling tools were alternatively used. The source apportionment was investigated considering both dry and wet weather scenarios. In order to quantify the apportionment in dry-weather conditions, the Lombardy portion of the Po river basin was modelled by using the US-EPA QUAL2E model. Such a simulation allowed to assess a significant contribution (about 50% of the total dry-weather load) of a not rain-driven diffuse pollution component (i.e. groundwater, springs, lake emissaries). Moreover, to estimate the rain-driven surface runoff contribution to the instream total load, the Lombardy plain area was also modelled by means of the US-DA SWAT model. SWAT results indicate a runoff contribution to the Po river instream total load of about 10 000 t N yr⁻¹ and 1300 t P yr⁻¹ (i.e. approximately the 10–20% of the total annual Lombardy nutrient load). At the event scale (i.e. the single rainstorm event) the runoff contribution may rise up to 30–80% of the total instream load. Finally, the total annual nitrogen load at the Po basin closure was estimated for the period 1985–2001. Out of a total annual load of 140 000 t N yr⁻¹, Lombardy accounts for 43% (point plus diffuse sources). The rain-driven diffuse sources constitute the 20% of the overall total load, the point sources account for 40%, whereas the remaining 40% is mainly constituted by “dry-weather diffuse sources” (i.e. groundwater, springs, lake emissaries).     

Laminar jet modelling for hazardous area classification

A previous article dealt with turbulent jet flow modelling with the aim at developing a method for estimating the size of explosive clouds following a high Reynolds number release, within hazardous area classification scheme. The results have demonstrated that the standard EN 60079-10 (2009) largely overestimates the real size of clouds resulting from a piping or a vessel leak. On the other hand, laminar jets are possible also at moderately high Reynolds numbers; furthermore, a reduced momentum, typical of laminar jets, is often assumed in QRA studies, as a conservative assumption, due to the expected lower air entrainment and to the corresponding larger size of the flammable cloud volume. These considerations have suggested the suitability to extend the previous analysis also to laminar regime, taking into account the effect of density and viscosity differences between air and flammable gas.     

Out with the garbage: the parasitic strategy of the mantisfly Plega hagenella mass-infesting colonies of the eusocial bee Melipona subnitida in northeastern Brazil

Between April and June of 2012 mantisflies (Plega hagenella) were found to be extensively parasitizing the nests of two groups of managed colonzies of eusocial stingless bees (Melipona subnitida) in the semi-arid region of northeastern Brazil. The mantisfly larvae developed inside closed brood cells of the bee comb, where each mantispid larva fed on the bee larva or pupa present in a single brood cell. Mature mantispid larvae pupated inside silken cocoons spun in place within their hosts' brood cells then emerged as pharate adults inside the bee colony. Pharate adults were never attacked and killed by host colony workers. Instead, colony workers picked up the pharates and removed them from the nest unharmed, treating them similar to the way that the general refuse is removed from the nest. Adult mantispids subsequently eclosed from their pupal exuviae outside the nest. Manipulative experiments showed that post-eclosion adult mantispids placed back within active bee colonies were quickly attacked and killed. These observations demonstrate that pharate and post-eclosion adults of P. hagenella are perceived differently by colony workers and that delayed adult eclosion is an important functional element in the parasitic life strategy of P. hagenella, allowing adults to escape without injury from the bee colonies they parasitize.     

Photomineralization of n-alkanoic acids in aqueous solution by photocatalytic membranes. Influence of trialkyl vanadates as catalytic promoters of immobilized titanium dioxide

The Ti0₂-mediated photomineralization of 8–1000 ppm of methanoic acid, of 6–100 ppm of ethanoic acid, of 6–180 ppm of propanoic acid, and of 6–90 ppm of n-decanoic acid in aqueous solutions was studied at 296± 2 K or 308 ± 2 K, with low and high pressure mercury arc lamps (radiant power in the absorption range 8 and 145 W respectively), using PHOTOPERM® CPP/313 membranes containing immobilized 30±3 wt.% Ti0₂, and, in parallel runs, 7 wt.% of a synergic mixture of tri(t-butyl)- and tri-(i-propyl) vanadate(V) as photocatalytic promoter. Stoichiometric H₂0₂ was used or, in some of the runs, 0₃, at saturation, as oxygen suppliers. Disappearance of total organic carbon (TOC) was followed as a function of time. To fit kinetic curves up to complete photomineralization, a kinetic model was employed, already used successfully in previous studies, which considers appearance and disappearance of all intermediates, as if they were represented by a hypothetical single molecule, mediating all of them. The photocatalytic activity of trialkyl vanadates was evaluated from quantum yields at “infinite” concentration, with respect to the maximum allowable efficiencies. When using O₃, a dark catalysis effect clearly appeared towards intermediate species produced during the photocatalysed degradation.