Daniele Montanaro

Sequential extraction analysis provides decision-making tools for the use of contaminated sediments

To construct a new tourist harbour in Marina di Ragusa (Sicily), the dredging of 300,000 m3 of marine sediment is required. To evaluate potential disposal options, a detailed physico-chemical characterisation of this material is needed. A very cost-effective solution is represented by the re-use of the dredged material for beach nourishment. To this aim, compliance with environmental standards and a strong homogeneity between the receiving beach and the source sediments must be proved. Analytical determinations for the main parameters show an arsenic content exceeding the Italian quality standard (12 mg·kg−1). In order to evaluate arsenic mobility and availability, and therefore the actual release into the environment, a three-step sequential extraction procedure was applied to a limited number of samples. The results obtained seem to exclude the risk, showing that arsenic is almost totally bound to the resistant fraction and thus does not represent an impediment to the beneficial re-use of sediment.

A feasibility study of hydrogen peroxide electrogeneration in seawater for environmental remediation

The electrogeneration of hydrogen peroxide in seawater by oxygen reduction on a gas diffusion cathode was investigated considering the feasibility of this process in an undivided reactor. The possible co-presence of different oxidants and the possibility of their synergistic action was evaluated. The loss of hydrogen peroxide due to direct anodic oxidation and to reaction with anodically electrogenerated species was evidenced. To optimize the production efficiencies of both active chlorine and hydrogen peroxide, the influence of electrode materials and current density was studied. An investigation of the possible analytical interferences was also provided.

Manganese-containing mixed oxide electrodes as anode materials for degradation of model organic pollutants

Mixed oxide thin film electrodes have been prepared by thermal decomposition from alcoholic solution on Pt substrate. In particular, three different anodes have been obtained by co-deposition of Ru (Ruthenium) and Mn (Manganese) oxides, Ru, Mn and Cu (Copper) oxides and co-deposition of Ru, Mn and Co (Cobalt) oxides. The electrochemical behaviour of the prepared electrodes was evaluated by potentiodynamic polarization curves and cyclic voltammetry tests. We also tested and compared their oxidizing ability in the degradation of aqueous solutions containing methyl orange as model compound and small amount of chloride. Galvanostatic experiments were conducted in a membrane-free reactor. The treatment extent was assessed by detection of color and TOC decay. The electrogeneration of active chlorine, chlorate and perchlorate was also monitored. The preliminary results show that ternary oxides coated electrodes exhibit enhanced electrocatalytic activity without producing undesired chlorinated by-products.