P. Pozzi

Crystallization of some anorthite-diopside glass precursors

Anorthite and diopside have been obtained from complete devitrification of glasses belonging to the quaternary system MgO-CaO-Al2O3-SiO2. Microstructure, the natural trend of the nucleation mechanism and kinetic studies on the crystallization phenomenon have been investigated by means of optical and electron microscopies, thermal and thermomechanical techniques and X-ray powder diffractometry. All the glasses investigated show a complete crystallization starting from a simple surface nucleation process. The activation energy for the crystallization process proved to be higher than that for viscous flow, leading to an important aspect modification in the sample during ceramization. Thermal stability and physical properties of both glass and glass-ceramic materials have been tested, suggesting the possible use of these materials in industrial application.

Facile characterization of polymer fractions from waste electrical and electronic equipment (WEEE) for mechanical recycling

In view of the environmental problem involved in the management of WEEE, and then in the recycling of post-consumer plastic of WEEE there is a pressing need for rapid measurement technologies for simple identification of the various commercial plastic materials and of the several contaminants, to improve the recycling of such wastes. This research is focused on the characterization and recycling of two types of plastics, namely plastic from personal computer (grey plastic) and plastic from television (black plastic). Various analytical techniques were used to monitor the compositions of WEEE. Initially, the chemical structure of each plastic material was identified by Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). Polymeric contaminants of these plastics, in particular brominated flame retardants (BFRs) were detected in grey plastics only using different techniques. These techniques are useful for a rapid, correct and economics identification of a large volumes of WEEE plastics.

Monomeric and oligomeric phosphates as deflocculants of concentrated aqueous clay suspensions

Abstract The deflocculating ability of some phosphates, with different P2O5/Na2O molar ratios, towards very concentrated aqueous suspensions (62.5 wt.%) of three clays (named Castellamonte, Samone and Debbia), widely used in the factories of Sassuolo (Italy), has been investigated by means of rheological measurements in the absence and the presence of calcium (II) ions (0–6·10−3 mol dm−3). All slips present a non-Newtonian, thixotropic behaviour. Oligomeric phosphates are very efficient deflocculants for clay suspensions, acting by an essentially electrostatic stabilization mechanism. Furthermore their strong complexing capabilities toward calcium (II) ions make them very appropriate deflocculants for industrial aqueous clay suspensions.

An efficient and fast analytical procedure for the bromine determination in waste electrical and electronic equipment plastics

In this study, X-ray fluorescence (XRF) spectroscopy was used, in combination with micro-Raman spectroscopy, for a fast determination of bromine concentration and then of brominated flame retardants (BFRs) compounds in waste electrical and electronic equipments. Different samples from different recycling industries were characterized to evaluate the sorting performances of treatment companies. This investigation must be considered of prime research interest since the impact of BFRs on the environment and their potential risk on human health is an actual concern. Indeed, the new European Restriction of Hazardous Substances Directive (RoHS 2011/65/EU) demands that plastics with BFRs concentration above 0.1%, being potential health hazards, are identified and eliminated from the recycling process. Our results show the capability and the potential of Raman spectroscopy, together with XRF analysis, as effective tools for the rapid detection of BFRs in plastic materials. In particular, the use of these two techniques in combination can be considered as a promising method suitable for quality control applications in the recycling industry. GRAPHICAL ABSTRACT

INFLUENCE OF IONIC ENVIRONMENT AND pH ON THE ELECTROKINETIC PROPERTIES OF BALL CLAYS

Three ball clays (SP from England, TSMA from France and UK from the Ukraine) were characterized for their dry and wet colloidal properties. On the basis of X-ray diffraction and chemical analyses the clays were classified as kaolinite-rich clay, smectitic kaolinite-rich clay and illitic kaolinite-rich clay. The ζ (zeta) potential at the clay-water interface as a function of pH, in three different electrolytes, was investigated using an electroacoustic technique. Starting from measurements of dynamic mobility, the calculated ζ potential was found to be almost constant as a function of pH for the TSMA and UK clays, while it increased from −20 to −60 for the SP clay, when potassium nitrate was used as an electrolyte. The behavior of the three clays in calcium and magnesium nitrate was slightly different: SP showed a smaller increase in ζ potential, while a small deviation from the constant behavior of the UK clay was found. The results are explained in terms of the surrounding-ion atmosphere in light of the chemical-physical properties measured. Our results may well be of use to those involved in ceramic processing.

The recycling of ceramic sludges in the production process: An option for ceramic tile factories to reach zero pollution

Abstract The paper considers a way of minimizing the pollution due to ceramic sludges, by rationalizing the addition of waste waters and sludges in tile production processes. The analytical and rheological results, obtained on the body slips used for “white gres”; tile production in waste or purified waters, demonstrate that the addition of dried sludges up to 5 % wt (in place of the <2% wt amount till now used) makes the slip completely compatible with industrial requirements. This paper evidences the possibility of direct use of waste waters, containing sludges, in the wet grinding process, making purification treatments of waters unnecessary and greatly reducing the economical engagement.