Photocatalytic degradation of chlorophenols using Ru(bpy) 3 2+ /S2O 8 2−

Advanced oxidation processes, such as photocatalysed oxidation, provide an important route for degradation of wastes. In this study, the lowest excited state (³MLCT) of Ru(bpy)₃²⁺ is used to break down chlorophenol pollutant molecules to harmless products. This has the advantage of using visible light and a short-lived catalytically active species. Photolysis of deaerated aqueous solutions of a variety of mono- and poly-substituted chlorophenols has been followed in the presence of Ru(bpy)₃²⁺/S₂O₈²⁻ with near visible light (λ > 350 nm) by UV/visible absorption spectroscopy, luminescence, potentiometry, NMR and HPLC techniques. Upon irradiation, a decrease is observed in the chlorophenol concentration, accompanied by the formation of Cl⁻, H⁺ and SO₄²⁻ ions as the main inorganic products. Benzoquinone, phenol, dihydroxybenzenes and chlorinated compounds were the dominant organic products. As the ruthenium(II) complex is regenerated in the reaction, the scheme corresponds to an overall catalytic process. The kinetics of the rapid chlorophenol photodechlorination has been studied, and are described quite well by pseudo-first order behaviour. Further studies on this were made by following Cl⁻ release with respect to the initial Ru(bpy)₃²⁺ and S₂O₈²⁻ concentrations. A comparison is presented of the photodechlorination reactivity of the mono and polychlorophenols studied at acidic and alkaline pH.     

Sorption of pentachlorophenol on pine bark

The minimization of pentachlorophenol (PCP) transport in the environment driven by industrial wastewater discharges can be accomplished by sorption in natural, available and low cost by-products like pine bark. Taking into account that PCP is a chemical which behaviour is highly dominated by the surrounding features, this work intended to evaluate the sorption kinetics and equilibrium parameters according to the pH and temperature as well as the pine bark particle size. The PCP uptake by pine bark showed to be faster in the initial phase followed by a slower process, being 24 h the suitably time to reach the sorption equilibrium in the range of pH studied. The neutral PCP species showed to have higher binding capacity to pine bark than the anionic PCP, which was reflected in a decrease in the distribution coefficient (Kd) of the linear sorption isotherm with the increase of solution pH from 2 to 7. On the other hand, between 10 degrees C and 35 degrees C, the temperature does not seem to play a significant role in the PCP sorption by pine bark, while the sorbent size is a key parameter to enhance the overall process.     

Influence of air pollution on the incidence of respiratory tract neoplasm

To evaluate the possible influence of air pollutants on the incidence of respiratory tract neoplasm we studied 12 S?o Paulo City districts where air pollution is observed. We collected data on pollutants from 1981-1990 and correlated it with the incidence of larynx and lung neoplasms in 1997. Ozone was the pollutant that best correlated with the incidence of neoplasm. The correlation coefficients were 0.7234 (p=0.277) and 0.9929 (p=0.007) for lung and larynx cancer, respectively. There may be a relationship between air pollution and the incidence of respiratory tract neoplasm. This study, however, does not allow us to conclude that there is a causal relationship.     

Remote sensing for mapping algal blooms in freshwater lakes: a review

Environmental Science and Pollution Research - A large number of freshwater lakes around the world show recurring harmful algal blooms, particularly cyanobacterial blooms, that affect public health...     

Biological impacts of ocean acidification: a postgraduate perspective on research priorities

Research into the effects of ocean acidification (OA) on marine organisms has greatly increased during the past decade, as realization of the potential dramatic impacts has grown. Studies have revealed the multifarious responses of organisms to OA conditions, indicating a high level of intra- and interspecific variation in species’ ability to accommodate these alterations. If we are to provide policy makers with sound, scientific input regarding the expected consequences of OA, we need a broader understanding of these predicted changes. As a group of 20 multi-disciplinary postgraduate students from around the globe, with a study focus on OA, we are a strong representation of ‘next generation’ scientists in this field. In this unique cumulative paper, we review knowledge gaps in terms of assessing the biological impacts of OA, outlining directions for future research.     

Molecular insight into the population structure of common and spotted dolphins inhabiting the pelagic waters of the Northeast Atlantic

Several cetacean species exhibit fine-scale population structure despite their high dispersal capacities and the apparent continuity of the marine environment. In dolphins, most studies have focused on coastal areas and continental margins, and they revealed differentiated populations within relatively small geographic areas, sometimes in conjunction with a specialisation for different habitats (ecotypes). We analysed the population genetic structure of short-beaked common dolphins (Delphinus delphis) and Atlantic spotted dolphins (Stenella frontalis) in the Azores and Madeira, the two most isolated archipelagos of the North Atlantic. The archipelago of the Azores is divided into three groups of islands and stands 900 km away from Madeira. It is not known whether individuals migrate between groups of islands and archipelagos, nor whether distinct ecotypes are present. These questions were investigated by genetic analyses of 343 biopsy samples collected on free-ranging dolphins. The analyses consisted in sequencing part of the mitochondrial hyper-variable region, screening up to 14 microsatellite loci, and molecular sexing. Results did not unravel any population structure at the scale of the study area. Lack of differentiation matches expectations for spotted dolphins, which are transient in both archipelagos, but not for common dolphins, which are present year-round in the Azores and potentially resident. Absence of genetic structure over hundreds and even thousands of kilometres implies the existence of gene flow over much larger distances than usually documented in small delphinids, which could be achieved through individual movements. This finding indicates that population structure in oceanic habitat differs from that observed in coastal habitat.     

Bio-based Films and Coatings: Sustainable Polysaccharide Packaging Alternatives for the Food Industry

Journal of Polymers and the Environment - Polymers used as raw materials for synthetic packaging, i.e., those obtained from petroleum-derived sources, are resistant to degradation. Because of this,...     

Synthesis and application of graphene oxide as a nanoadsorbent to remove Cd (II) and Pb (II) from water: adsorption equilibrium,kinetics, and regeneration

Environmental Science and Pollution Research - In this work, graphene oxide (GO) was synthesized by the modified Hummers method. The nanomaterial was characterized by FTIR and Raman spectroscopy,...     

Evaluation of boron removal from water by hydrotalcite-like compounds

Layered double hydroxides (LDHs) or hydrotalcite (HT)-like compounds with different kinds of metal ions (Mg-Al and Mg-Fe) in the brucite-like sheets were prepared and their adsorption properties were studied in the boron removal from aqueous solution under laboratory conditions. The hydrotalcites were synthesized by the coprecipitation method and were characterized by chemical analyses, X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR) and specific surface area measurements (BET). The affinity of these materials with a mixture of B(OH)(3) and B(OH)(4)(-) was studied as a function of contact time, initial pH of the solutions, HT quantity and B concentration (adsorption isotherms). It was found that 120 min is enough time for the equilibrium state to be reached in boron adsorption. Boron removal was independent of the initial pH of the solutions because of the high buffering capacity of the LDHs. On the other hand, the adsorption capacity increases with increasing the adsorbent quantity. The adsorption isotherms, described by the Langmuir model, are of L-type, suggesting that B(OH)(4)(-) is adsorbed preferentially on HT-like materials. Besides, Mg-Al hydrotalcites showed higher adsorption capacity than Mg-Fe. We proposed that in Mg-Al hydrotalcites, the boron removal occurs by both adsorption on external surface and ion exchange, whereas for Mg-Fe it occurs only by surface adsorption. After treatment of a solution containing 5.2 mgBl(-1) with Mg-Al hydrotalcites the final boron concentration reached the recommended limit by WHO for drinking water (0.5 mgl(-1)).