Patrizia Primerano

Study of the pre-crystallization stage of hydrothermally treated amorphous aluminosilicates through the composition of the aqueous phase

A detailed study of the parameters and phases involved in the pre-crystallization of the hydrothermal conversion of coal fly ash to zeolites has been performed. The study has also been extended to pumice, a natural glassy aluminosilicate.Dissolution of the main components, their concentration ratio in the solution phase, the re-precipitation in the form of an amorphous gel from which evolves zeolite crystals, and the compositions, occurrence times and degrees of completeness of the gel and zeolite crystals have been found to be strongly interrelated and all influenced by the temperature and alkali–metal content of the treatment.In the case of coal fly ashes, the halt occurring in the conversion to zeolites some time after its beginning has been shown to be due to the mullitic phase located inside the ash particles and containing most of the total aluminium content of the ashes. In contrast to the external amorphous phase, this phase is insoluble at the experimental conditions suitable for the conversion treatment.

Possible alteration of monuments caused by particles emitted into the atmosphere carrying strong primary acidity

We discuss the effects of the presence in the atmosphere of acidic ashes originating from the burning of oil heavy fractions and of the damage they could cause to monuments if deposited onto them. After quantifying its load of potentially strong acidity, we studied the effect of this particulate coming into contact with samples of two of the most common types of calcareous materials used in the building of monuments in atmospheric conditions characterized by relative humidity values of between 0 and 94%. Visual examination of the surfaces of the calcareous materials revealed substantial alteration even after brief periods of exposure in atmospheres with relative humidity values above 40%. The transformation of calcium carbonate into bihydrate calcium sulphate and the release of coloured metal ions, both promoted by the humidity absorbed from the atmosphere, were evidenced by SEM images and confirmed by WDS probe investigation and XRD examination of the altered layers of material.

Diastereoselective multicomponent synthesis and anti-HSV-1 evaluation of dihydrofuran-fused derivatives

Enolizable 6-membered cyclic 1,3-dicarbonyls undergo an efficient and diastereoselective domino condensation/addition/heterocyclization reaction with arylaldehydes and phenacyl chloride, producing highly substituted dihydrofuran-fused derivatives. Ring size of the cyclic 1,3-dicarbonyls and the presence of at least one keto group are crucial to the reaction’s success. The new compounds were evaluated in vitro for antiviral activity against herpes simplex virus type-1 (HSV-1). Interestingly, some of them appeared able to interfere with HSV-1 replication, without detection of cytotoxic effects.

Sources of strong primary acidity in the atmosphere

Abstract The fly ashes produced by the burning of heavy oil have been identified in this study as carriers of strong primary acidity in the atmosphere in the form of sulphuric acidity and hydrolyzable metal ions. This is an acidity which is strong from the moment of its emission (strong primary acidity, SPA) and different from common sources of weak acidity (SO2 NO) which give rise to strong acidity only after some time in the atmosphere. The oil ash SPA is transmitted to water on impact resulting in highly acid pH values and high total acidity as well as significant concentrations of heavy metals. Here we present and discuss our results.

Formation of strong primary acidity in combustion particulate: causes and remedies

Abstract Having observed great variations in the strong primary acidity (SPA) content of the ash of fossil fuels with similar sulphur contents, we studied the chemical causes of the formation of SPA in ashes. The main factors behind these variations were found to be: (a) combustion conditions and the extent to which they favour or do not favour the formation of SO 3 (excess of oxygen, presence of suitable catalysts, etc.); (b) the amount of basic oxides present in the mineral fraction of the fuel in relation to the SO 3 produced; and (c) the basic strength of these oxides. The variable but, nevertheless, high SPA contents common only to oil ashes can be explained in the light of the modest values for factors (b) and (c) and the conditions favourable to factor (a) in this fuel. Remedies involve the in-flame addition of highly basic oxides in order to artificially increase factors (b) and (c).