The effect of synthesis method on the structure, and magnetic and photocatalytic properties of hematite (α-Fe2O3) nanoparticles

Samples of hematite (α-Fe2O3) nanoparticles have been synthesized through the co-precipitation route in cetyltrimethylammoniumbromide (Hem_PR), via a citric acid sol-gel method (Hem_SG) and a modified sol-gel method inTween20 (Hem_TW), and each were annealed at three different temperatures (400, 500 and 600 °C). The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission and high-resolution electron microscopy (TEM and HRTEM), Mössbauer spectroscopy and by means of a vibrating sample magnetometer (VSM). In addition, the photocatalytic behaviour of each sample was tested on the degradation of rhodamine B (RhB) in solution. All the characterization techniques showed the formation of phases of pure hematite nanoparticles with improved crystallinity after higher temperature annealing. However, the nanoparticles synthesized in Tween 20 showed the smallest particle size and highest BET surface area, saturation magnetization and photocatalytic activity. Of particular note was the ability of Tween 20 to control the growth of the particles so that grain sizes well below 10 nm were obtained. Thus, Tween 20, when used as a surfactant in the sol-gel route, can serve to improve the physical properties of synthesized hematite nanoparticles.Keywords: Hematite, nanoparticles, Mössbauer spectroscopy, magnetic properties, Tween 20, photocatalysi

Self-organization with traveling waves: A case for a convective torus

A traveling wave of BaSO4 in the chlorite-thiourea reaction has shown concentric precipitation patterns upon being triggered by the autocatalyst HOCl. The precipitation patterns show circular rings of alternate null and full precipitation regions. This self-organization appears to be the result of the formation of a convective torus. The formation of the convective torus can be described as a Benard-Marangoni instability with lateral heating

Redetermination of chlorido(2,2′:6′,2′′-terpyridine-κ3 N,N′,N′′)gold(I) dichloride trihydrate at 173 K

The redetermined structure of the title compound, [AuCl(C15H11N3)]Cl2·3H2O, at 173 (2) K is reported. The structure displays O—H⋯Cl and O—H⋯O hydrogen bonding. The distance of one of the chloride ions from the gold(I) atom [5.047 (1) Å] differs from that determined previously

Alkylphenols and alkylphenol ethoxylates in dust from homes, offices and computer laboratories: Implication for personal exposure via inadvertent dust ingestion

In the present study, the levels of alkylphenols (APs) and alkylphenol ethoxylates (APEs) in indoor dust of three different microenvironments were measured and daily intake via dust ingestion estimated. Alkylphenols and alkylphenol ethoxylates were extracted with the aid of sonication and analyzed by gas chromatography mass spectrometry after heptafluorobutyric anhydride derivatization. The concentration values of these pollutants ranged from 1918–10 935 ng g−1; 343–12 438 ng g−1 and 1122–15 324 ng g−1 in dust samples from homes, computer laboratories and offices, respectively. In all the microenvironment studied, di-NPE and mono-NPE were the most abundant isomers suggesting widespread use of NPE-based consumer products in the studied microenvironments. The daily exposure dose (DED) was estimated using min, mean and max concentrations of APs and APEs detected in respected microenvironments. The worst case scenario for the exposure of APEs was highest for toddlers at 146 ng kg−1 bw day−1 followed by teenagers at 11.3 ng kg−1 bw day−1 and adults at daily exposure of 8.53 ng kg−1 bw day−1. Though the daily exposure doses are low, there is a cause for concern as these surfactants are not regulated in many developing countries and their use may be increasing. Keywords: Alkylphenols, Alkylphenol ethoxylates, Concentrations, Indoor dust, Exposure assessmen

Vanadium removal and floc characteristics of tannin biocoagulants and iron sulphate in the treatment of mine effluent

Abstract This study compared the performance of tannin (quebracho and spruce) and iron sulphate (FS) coagulants for the removal of vanadium from effluent derived from an abandoned vanadium mine. The efficacy of the materials was studied at the natural pH of the mine effluent (7.4), and at adjusted pH levels of 4 and 9. The quebracho tannin coagulant (QT) recorded impressive turbidity and vanadium removals of above 88% over a wide pH range. However, the spruce tannin coagulant (ST) was not as effective at pH 9 (39%) although it showed an improved vanadium removal of 46% and 70% at pH 7.4 and 4, respectively. This was attributed to the lower charge density of ST than that of QT, and to a loss of cationic properties at pH 9. FS performed better in terms of vanadium removal (pH 4: 86%, pH 7: 98%, pH 9: 100%) with lower coagulant doses, although effective turbidity removal required precise pH control. QT produced the largest flocs and the highest floc regrowth at pH 4 and 7. Under alkaline conditions, tannin coagulants exhibit no regrowth, which implies that a careful flocculation and floc separation step is needed. The natural organic matter fractionation results revealed that FS effectively removed hydrophilic carbon (76%) in a pH-controlled mine effluent better than tannin coagulants (QT: 12% and ST: 22%) from the pH 4 effluent; however, ST removed hydrophobic carbon entirely. All coagulants adequately removed humic substances, with FS being the most efficient (88%), followed by ST (53%) and QT (47%). X-ray photoelectron spectroscopy (XPS) analysis of jar test residues showed that some of the vanadium removed existed in the V(IV) oxidation state

Città per tutti

Dal 2003, Anno Europeo delle Persone Disabili, l’inclusione delle persone con disabilità in tutti gli aspetti della vita civile, è diventata una priorità degli Stati membri. Si tratta infatti di tener conto dei bisogni di tutti nella progettazione architettonica e urbana, riuscendo ad individuare soluzioni in grado di privilegiare utenze con necessità diverse quali quella motoria, visiva, uditiva, psichica, mentale e/o cognitiva. L'accessibilità dello spazio pubblico nella città è la prima chiave verso un abitare autonomo.Since 2003, the European Year of Disabled Persons, the inclusion of persons with disabilities in all aspects of personal and civic life has become a priority for the member states. Accessibility needs to be taken into account when planning architectural and urban projects. Access to public space is the first key to indipendent living