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Mechanochemistry, a technique concerning with milling contaminated samples for prolonged times, induces massive degradation of pollutants by grinding them in ball mills with different soil components or additives. In the present study, laboratory experiments were conducted to evaluate the effect of aging on the mechanochemical efficiency of the Mn-oxide birnessite in degrading pentachlorophenol (PCP). A comparative study on an aged birnessite (KBiA), used after 3 years from synthesis, and a fresh birnessite (KBiF), employed immediately after synthesis, was carried out. The differences between the two birnessites, evidenced by spectroscopic and diffractometric techniques, are mainly relative to reduction of the Mn(IV) centered at the MnO6 octahedra layers from the birnessite structure, which represent the most reactive sites for PCP degradation. The long term air drying at room temperature, by favouring reduction of Mn( IV) to Mn(III), produces an inorganic substrate that offers paucity of the less reactive sites for PCP degradation, thus reducing the oxidative potential of the KBiA. Accordingly, the more reactive fresh birnessite was employed in the experiment with a polluted soil. Adding a small amount of KBiF to soil only induces a light increase in PCP removal, probably due to the mechanically induced PCP adsorption and transformation onto clay minerals present in the soil. Besides, adding a higher dose of birnessite causes a stronger degradation of PCP.

A multi-methodical characterization of a sauconite (Zn-bearing trioctahedral smectite) specimen from the Skorpion ore deposit (Namibia) was performed by combining X‑ray powder diffraction (XRPD), cation exchange capacity (CEC) analysis, differential thermal analysis (DTA), thermo‑ gravimetry (TG), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM‑HRTEM‑AEM). The X‑ray diffraction pattern exhibits the typical features of turbostratic stacking disorder with symmetrical basal 00l reflections and long‑tailed hk bands, as confirmed by TEM observations. Besides sauconite, the sample contains minor amounts of kaolinite, dioctahedral smectite, and quartz. CEC analysis provides a total of Ca (~69%), Mg (~26%), Na (~4%), and K (0.7%) exchangeable cations. Therefore, Zn is located exclusively within the octahedral site of sauconite. TG analysis of the sample yields a total mass loss of about 17%. Three endothermic peaks can be observed in the DTA curve, associated with dehydration and dehydroxylation of the material. An exothermic peak at 820 °C is also present as a consequence of decomposition and recrystallization. The infrared spectrum shows the typical ZnOH stretching signature at 3648 cm, whereas, in the OH/HO stretching region two bands at 3585 and 3440 cm can be attributed to stretching vibrations of the inner hydration sphere of the interlayer cations and to absorbed HO stretching vibration, respectively. Diagnostic bands of kaolinite impurity at ~3698 and 3620 cm are also found, whereas 2:1 dioctahedral layer silicates may contribute to the 3585 and 3620 cm bands. Finally, using the one-layer supercell approach implemented in the BGMN software, a satisfactory XRPD profile fitting model for the Skorpion sauconite was obtained. These findings have implications not only for economic geology/recovery of critical metals but also, more generally, in the field of environmental sciences., The XRPD laboratory at the Dipartimento di Scienze della Terra and Geoambientali, University of Bari “Aldo Moro”, was funded by Potenziamento Strutturale PONa3_00369 “Laboratorio per lo Sviluppo Integrato delle Scienze e delle TEcnologie dei Materiali Avanzati e per dispositivi innovativi (SISTEMA)”. The XRPD facility at the DiSTAR, University “Federico II” Napoli, is acknowledged. The authors acknowledge Annett Steudel and Katja Emmerich for CEC measurement at the Competence Center for Material Moisture, University of Karlshrue, Germany. GB and NM thank Maria Boni, invaluable scientific guide who promoted the study of the economic geology of worldwide nonsulfide ore deposits, and G. Arfè who firstly characterized the Skorpion samples and for continuous help and fruitful discussions. This work was partly supported by DiSTAR fund 2017 (University of Naples Federico II, Italy) granted to G. Balassone, as well as by the research projects PGC2018-094573-B-100 from the Spanish Government and the Research Group RNM-179 of the Junta de Andalucía granted to F. Nieto. Two anonymous referees are thanked for insightful comments that helped to improve the quality of the manuscript.

The first diiodo palladium complex with nucleophilic benzothiazole carbenes as ligands has been synthesized and characterized. The complex, which is extraordinarily stable towards heat, oxygen, and moisture, has been found to show good catalytic activity in the Heck coupling reaction.