Aluminium Drinking Water Treatment Residuals and Their Toxic Impact on Human Health

Aluminium exerts undeniable human health effects, so its concentration should be controlled in water treatment plants. The article presents and discusses the results of studies on the influence of selected properties of aluminium coagulants on the concentration of aluminium remaining in the purified water. The coagulants used were classical hydrolysing aluminium salts: aluminium sulphate (VI) and sodium aluminate as well as pre-hydrolysed polyaluminium chlorides: Flokor 105B and PAX XL10 that had different the alkalinity coefficient r = [OH−]/[Al3+]. The Al species distribution in the coagulants samples were analysed by the Ferron complexation timed spectrophotometry. On the basis of their reaction rates with ferron reagent, the aluminium species were divided into three categories: monomeric (Ala), medium polymerised (Alb) and colloidal (Alc). The usefulness of the tested aluminium coagulants due to the concentration of residual aluminium and dissolved aluminium, which is easily assimilated by the human body, was increased according to the following series: sodium aluminate (Ala = 100%, Alb = 0) < aluminium sulphate (VI) (Ala = 91%, Alb = 9%) < PAX XL 10 (Ala = 6%, Alb = 28%, r = 2.10) < Flokor 105B (Ala = 3%, Alb = 54%, r = 2.55).

Ionic aluminium concentrations exceed thresholds for aquatic health in Nova Scotian rivers

Cationic aluminium species are toxic to terrestrial and aquatic life. Despite decades of acid emission reductions, accumulating evidence shows that freshwater acidification recovery is delayed in locations such as Nova Scotia, Canada. Further, spatial and temporal patterns of labile cationic forms of aluminium (Ali) remain poorly understood. Here we increase our understanding of Ali spatial and temporal patterns by measuring Ali concentrations in ten streams in acid-sensitive areas of Nova Scotia over a four-year time period. We observe widespread and frequent occurrences of Ali concentrations that exceed toxic thresholds (> 15 μg L−1). Ali patterns appear to be driven by known Ali drivers – pH, dissolved organic carbon, dissolved aluminium, and calcium – but the dominant driver and temporal patterns vary by catchment. Our results demonstrate that elevated Ali remains a threat to aquatic ecosystems. For example, our observed Ali concentrations are potentially harmful to the biologically, economically, and culturally significant Atlantic salmon (Salmo salar).

Pursuing the active species in an aluminium-based Lewis acid system for catalytic Diels–Alder cycloadditions

Detailed characterization of the catalytically active aluminium species supported by a bis(imino)aryl ligand has been reported.

The role of hydroxy aluminium sulfate minerals in controlling Al3+ concentration and speciation in acidic soils

A thermodynamic approach for the complex chemical equilibria investigation of two-phase systems containing hydroxy aluminium sulfate (HAS) minerals in soils has been developed. This approach utilizes thermodynamic relationships combined with original mass balance constraints, where the HAS mineral phases are explicitly expressed. The factors influencing the distribution and concentrations of various soluble aluminium species have been taken into account. The new type of diagrams, based on thermodynamic, graphical and computerized methods, which quantitatively describe the distribution of soluble and insoluble inorganic, and organic, monomeric and polymeric aluminium species in acidic soil solutions in a large range of pH values has been used. The thermodynamics of equilibria of different natural HAS in soils, the conditions under which solids involving common ions can coexist at equilibrium, the acid-base and mineral equilibria and complex formation have been examined. It has been proved that the presence of sulfate ion dramatically alters the HAS mineral solubility under acidic conditions. The obtained data regarding the factors influencing Al speciation, based on the constructed diagrams of heterogeneous chemical equilibria, are in good agreement with the current experimental and theoretical evidence. The proposed approach is intended to determine the dominant processes that are responsible for the Al3+ concentration levels and its speciation in acidic soils.

Zeolite Y: Synthesis, Modification, and Properties—A Case Revisited

Y zeolites dealuminated by steaming were introduced as fluid-cracking catalysts in the year 1970. Extensive research has been done to develop suitable dealumination techniques, to investigate crystal structure, and to characterize catalytic behaviour. However, the origin of the secondary pore system formed in the zeolite structure during dealumination process remained completely obscure over a period of four decades. Open questions concerned also the existence of extraframework siliceous admixture in addition to extraframework aluminium species which can dramatically change the catalytic properties of these zeolites. This paper gives a review on the synthesis of DAY materials and provides some answers to several open questions.