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The great part of municipal solid wastes is worldwide stored in sanitary landfills. The interaction of organic and inorganic wastes with rainwater produces in the landfill a leachate of extremely variable composition. It depends on several variables such as the type of wastes, the age of landfill, the pH, the redox potential, etc [1-2]. Four are the recognized categories of pollutants in landfill leachate: inorganic macrocomponents, dissolved organic matter (DOM), heavy metals and xenobiotic organic compounds [3]. In particular, heavy metals (arsenic, cadmium, copper, lead, mercury, etc.) are usually present at concentration of few ppb and up to some ppm. A variable but consistent fraction of DOM is constituted by humic and fulvic-like compounds, formed through a series of biological and chemical processes that involve DOM, especially during the methanogenic phase of wastes decomposition [3]. The great number of binding sites in humic like substances, mainly carboxylic and phenolic groups, are responsible of the high sequestering ability of leachate towards metal ions. As consequence, the speciation scheme of all the toxic metal ions contained in the landfill is strictly influenced by the amount and composition of DOM fraction in leachate. Due to the imperfections or the possible damages of landfill liners, the leachate can contaminate superficial and ground waters in proximity of the landfill causing serious environmental pollution and human health risks. In a previous study the presence and the amount of landfill leachate, also in trace, on some groundwater samples collected in proximity of Bellolampo landfill was evaluated [4]. The obtained results showed a leachate concentration of ~ 130 μg L-1. Landfill of Bellolampo is a solid waste sanitary landfill near Palermo (Sicily). The landfill has been created in 1960s and become a controlled dump site in 1980s. Previous ICP-OES measurements on Bellolampo leachate have been shown a Pb, Cd and Cu concentrations in the ranges 0.05 - 2.3, 0.02 - 0.12 and 0.02 - 0.6 mg L-1 respectively. The environmental and health risks related to the presence of toxic heavy metal ions in leachate depends on the species that metals form with the other components and at the conditions of the contaminated groundwater, with particular attention to the amount of free metal ions, the most dangerous among their possible species in aqueous solution. For this reason, the study of the sequestering ability of landfill leachate towards toxic metal ions is of fundamental importance to establish the environmental impact of leachate contamination. Here we present a potentiometric and voltammetric (Differential Pulse Anodic Stripping Voltammetry, DP-ASV) study on the acid-base properties and on the sequestering ability of leachate samples collected in Bellolampo landfill towards Cd(II), Pb(II) and Cu(II) ions. The voltammetric and potentiometric titrations were carried out in NaCl aqueous solution, at I = 0.1 mol L-1 in order to simulate the mean experimental conditions typical of groundwaters. The acid – base properties of the filtered leachate were compared to those of the soluble fraction of humic substances, with carboxylic and phenolic groups as main binding sites of the macromolecules. Two units namely leach1 and leach2 containing COOH and phenol OH groups, respectively were considered and the Diprotic Like model has been used to process the ISE-H+ potentiometric data [5]. The voltammetric titrations of toxic metal ions solutions with leachate (diluted or as it is) were carried out adjusting the pH of titrand solutions at 5. The results shown an appreciable sequestering ability of leachate towards the heavy metal ions considered and an estimation of the metal complexes stability has been done by calculating rough metal – leachate formation constants.

The Halloysite (Al2Si2O5(OH)4·2H2O) is an abundant and cheap clay and is considered one of the most promising nano structured and naturally occurring clay mineral. Large deposits of this material are present in France, Belgium, China, New Zealand and USA [1,2]. Among the spheroidal, tubular or platy morphologies, the tubular is the most common and abundant one. Typically, halloysite nanotubes (HNTs) are formed by 15 – 20 aluminosilicate layers, having a length of 1 ± 0.5 μm, and inner and outer diameters of 10 – 15 nm and 50 -70 nm, respectively [1]. In each layer, the SiOH and the AlOH groups are disposed on the external and the internal surfaces, respectively. As consequence, in each nanotube and in a large pH range, there is a charge separation between the inner and the outer surfaces. In particular, the inner surface is positively charged because of protonation of AlOH groups and the outer surface is negatively charged because of the gradual deprotonation of SiOH groups at pH higher than 2. This charge separation is one of the most important features for the HNTs versatility and is strictly dependent on the acid – base properties of their functional groups. In this work, the protonation / deprotonation of SiOH and AlOH groups of HNTs is evaluated by ISE-H+ potentiometric titrations of HNTs aqueous suspensions in different ionic media and ionic strengths (0.025 ≤ I / mol L-1 ≤ 0.750) and in a wide pH range (2 – 11), at T = 25°C.ISE-H+ potentiometric titration data have been processed by using the same models successfully used in a previous work for carboxylic and phenol groups of humic and fulvic substances [3]. Moreover, the change of superficial charge with the changing of pH was also evaluated by ζ potential measurements.Correlations between the ζ potential trend and the distribution of protonated and deprotonated species of HNTs were found.

Halloysite is one of the most interesting nano-structured clay materials. It is similar to kaolin but has a hollow tubular structure that can be attributable to particular crystallization conditions. Typically, halloysite nanotubes (HNTs) are formed by 15 – 20 aluminosilicate layers, has a length of 1 ± 0.5 μm and inner and outer diameters of 1 - 30 and 30 - 50 nm, respectively [1,2]. In each layer the SiOH and the AlOH groups are disposed on the external and the internal surfaces, respectively. The particular structure of HNTs makes this kind of material very useful for different purposes in several fields. Among the various applications, worth of mention are: i) their use as additive for devices in the capture tumor cells in blood; ii) nanoparticles for the entrapment and controlled release of active molecules; ii) additive agents in wound and personal care; iv) sorbents for water contaminants etc [1,2]. In all these applications, the knowledge of the acid-base properties of HNTs is of fundamental importance. The acid-base properties of HNTs have been studied by ISE-H+ potentiometric titrations in NaCl medium, in the range 0.025 ≤ I / mol L-1 ≤ 0.750 and at T = 25°C. Two functional groups indicated with HNT1 (SiOH) and HNT2 (AlOH) were considered in the analysis of the experimental data. Potentiometric data were processed with four different models previously used for the study of the acid - base properties of natural and synthetic polyelectrolytes: Högfeldt, Linear, modified Henderson-Hasselbalch and diprotic like models [3]. The results obtained with the four models for the protonation constants of HNT1 groups of HNTs were in good accordance, whilst the acid-base properties of HNT2 groups were well defined by one protonation constant calculated by processing the potentiometric titration data with the computer programs STACO and BSTAC.

In the last decade nanoparticles have assumed more and more importance because of their particular properties mainly due to the nanometer-scale dimensions that confer them a large surface/volume ratio. Among nanomaterials one of the most studied is the halloysite that, as well as the other natural clay minerals is safe for human and environmental friendly. Halloysite is abundant and cheap and is present in large deposits worldwide like those in New Zealand, France, Belgium and China [1,2]. It is similar to kaolin but has a hollow tubular structure that can be attributable to particular crystallization conditions. Typically, halloysite nanotubes (HNTs) are formed by 15 – 20 aluminosilicate layers, has a length of 1 ± 0.5 μm and inner and outer diameters of ~15 and 50 -70 nm, respectively [1,2]. In each layer the SiOH and the AlOH groups are disposed on the external and the internal surfaces, respectively. As consequence, the chemistry of the lumen and of the outer surface of HNTs is completely different. In particular, in each nanotube the inner surface is positively charged and the outer surface has an excess of negative charges in a wide pH range. The particular structure of HNTs makes this kind of clay mineral very useful for different purposes and several papers and reviews have been published on their different applications [1-3]. The behavior of HNTs in all these applications is strictly related to their acid-base properties that here have been studied by ISE-H+ potentiometric titrations in several interacting and non interacting ionic media, in the range 0.025 ≤ I mol L-1 ≤ 1.000, at T = 25°C. Two functional groups indicated with HNT1 (SiOH) and HNT2 (AlOH) were considered in the analysis of the experimental data. Potentiometric data related to the HNT1 groups were processed with four different models previously used for the study of the acid-base properties of natural and synthetic polyelectrolytes: Högfeldt, Linear, modified Henderson-Hasselbalch and diprotic like models [4]. The acid – base behavior of HNT2 groups were well defined by one protonation constant calculated by processing the potentiometric titration data with the computer programs STACO and BSTAC.

Background Peripheral blood (PB) hematopoietic progenitor cells (HPC) collected by apheresis are the first-choice source for allogeneic stem cell transplantation. The target HPC dose is usually considered to be 4 × 106 CD34+ cells/kg of the recipient, but higher doses are required in reduced-intensity conditioning and haploidentical transplants. Thus, prolonged stimulation and repeated collections or failure to reach HPC target may occur, increasing risks for donors and recipients. We carried out a retrospective multicenter study on healthy donors, to identify donor variables which may correlate with HPC mobilization. Study Design and Methods HPC allogeneic donations from sibling and unrelated donors performed in two centers from 1995 to 2012 were analyzed. We defined a mobilization cutoff of 50 × 10 6 CD34+ cells/L and tested somatic variables, blood counts, and granulocyte-colony-stimulating factor (G-CSF) dose and molecular form. Results A total of 360 donors were analyzed (male, 201; female, 159; sibling, 348; unrelated, 12; median [range] age, 44.8 [13-80] years). Median peak CD34+ in PB was 54.4 × 106/L (range, 5 × 106-299 × 106). By multivariate analysis, we identified the following variables to correlate with good mobilization: 1) male sex (p < 0.0005); 2) younger age (p = 0.007); 3) higher baseline (premobilization) white blood cell (WBC) count (p < 0.0005); 4) higher G-CSF dosage (p < 0.0005); and 5) use of lenograstim rather than filgrastim (p < 0.002). Conclusion In healthy donors it is possible to predict successful HPC mobilization by donor sex, age, WBC count, and G-CSF form and dose. Furthermore, based on these data, it may be possible, at least in parental setting, to modulate G-CSF dosage on the basis of donor characteristics.