# Production of Porous Ceramic Materials from Spent Fluorescent Lamps
## 2 Materials and Methods
### Analytical Methods  
All samples underwent mineralogical analysis by means of a Bruker D8 Advance diffractometer (XRD, Bruker AXS, Karlsruhe, Germany), equipped with a Cu anode. The scans were performed at 40 kV and 40 mA in the 2\(\upmu\) range of 10-70\({}^{\circ}\). Semi-automatic phase identification was performed by using the Matchf(r) (Crystal Impact GbR, Bonn, Germany) and High Score Plus 4\({}^{\oplus}\) (Malvern Panalytical Ltd., Spectris, Egham, UK) program package, supported by crystallographic data from the PDF-2 (ICDD-International Centre for Diffraction Data, Newtown Square, PA, USA), ICSD (FIZ Karlsruhe, Germany) and COD (Crystallographic Open Database) [19] databases. Fourier-transform infrared spectroscopy (FTIR, PerkinElmer spectrum 100, Waltham, MA, USA) was performed in the absorbance mode on solid samples included in KBr pellets of 1 cm diameter and 1-2 mm thickness. The powder mixtures used for pellets (in the weight proportion sample:KBr = 1:10) were homogenized by grinding in an agate mortar and pressed at 80 MPa for 5 min. For each sample, 32 scans were recorded with a resolution of 4 cm\({}^{-1}\) in the 4000-400 cm\({}^{-1}\) range. Morphological and microchemical analyses were performed using a variable pressure/environmental instrument (FEI Quanta 200 ESEM, Eindhoven, The Netherlands), equipped with backscattered electron (BSE) and energy dispersive X-ray detectors (EDX-EDAX Element-C2B). The micro-analyses were performed at low vacuum mode and a blow-up of 150\(\times\) for solid powders and of 800\(\times\) for both green and sintered samples, choosing different areas to ensure a standard deviation lower than 5%. The XAF correction has been applied to consider the contribution in the analyses of atomic number, fluorescence, and adsorption, which are typical of all the elements. The geometric density (\(\rho_{\rm geom}\)) of foamed (fired) samples were evaluated by considering the mass-to-volume ratio of cubic samples (10 mm \(\times\) 10 mm \(\times\) 10 mm) cut from the bigger specimens. The apparent (\(\rho_{\rm app}\)) and the true density (\(\rho_{\rm t}\)) were measured by using a helium pycnometer (Micromerities AccuPyc 1330, Norcross, GA, USA), using bulk or finely crushed samples, respectively. The three density values were used to compute the amounts of open and closed porosity. The compressive strength (\(\sigma_{\rm c}\)) of foams was measured on small blocks (10 mm \(\times\) 10 mm \(\times\) 10 mm) at room temperature, employing a Galdabini Quasar 25 UTM material testing machine (Galdabini S.p.a., Cardano al Campo, Italy) operated with a cross-head speed of 1 mm/min. Each data point represents the average value of at least 7-8 individual tests. Finally, leaching tests were carried out following the standard UNI EN 12457-2:2002 [20]. In particular, the foamed samples were grinded to a dimension lower than 2 mm and mixed with Milli-Q water in an L/S ratio of 10 L/kg. The suspensions were kept under mechanical stirring at ambient temperature (20 \(\pm\) 2 \({}^{\circ}\)C) for 24 h and then filtered at 0.45 \(\upmu\)m with a PTFE syringe filter. Portions of liquid leachates were used to measure the pH and the content of chloride, sulphate, and nitrate by means of ionic chromatography. The analyses were performed in triplicate using a DIONEX ion-chromatograph (Thermo Fisher Scientific Inc., Waltham, MA, USA). The device was equipped with a 250 \(\times\) 4 mm AS4A-SC column coupled to a 50 \(\times\) 4 mm AG4A-SC pre-column, a DIONEX ASRS ULTRA II suppressor (regenerated with 25 mM sulfuric acid), and a conductivity detector C (XS sensor, conductivity cell C = 1 cm\({}^{-1}\), PCS0+DHS\({}^{\otimes}\)). The operative conditions were: T\({}_{\text{work}}\) = T\({}_{\text{ambient}}\), flow rate = 1.2 mL/min; the eluent was a mixture of sodium carbonate/bicarbonate = 4.5/1.5 mM in ultrapure water.