Study of the performances of innovative materials for the treatment of contaminated water

In this thesis were evaluated the performances of various type of “zeolite like” adsorbents used for wastewater treatment in P&T or PRB installations. This was made up by characterizing the equilibrium behavior, through the construction of isotherms and how they behave in a flow system through the study and evaluation of breakthrough curve. In particular, we take into account water contaminated by emulsified and dissolved oil, high concentrations of organic contaminants (> 100 ppm), inorganic ions, cations as Cd2+, Pb2+, Mn2+ and anions of As. This is a typical situation of produced water or groundwater underlying refineries, depots and petrol stations. It will also evaluate the effect of the presence of salts in solution, because the sites are often located in coastal areas where there are often significant phenomena of saline intrusion. To solve such complex situations of contamination, it was imagined an intervention strategy based on the coupling in series of different adsorption processes, agents selectively on different fractions of contaminants and based on the use of different adsorbent materials. In particular it has been suggested to use: - amorphous mesoporous materials (MSA) for the removal of dispersed and emulsified oil. Mesoporous materials with appropriate open channels have been found effective in removing dissolved and emulsified oil, the result made evident by GC and GC-MS treated real water. We observe the disappearance/reduction of the peaks relating to trimethylbenzenes, naphthalenes and the hydrocarbon fraction to C-33. For these materials can thus hypothesize a plant types used in P & T. Mesoporous materials were used also for the removal of high concentrations of organic contaminants. For this materials we hypothesize an use in the In Well Air Stripping. application, because the inability of these materials to work in the aqueous phase and the good performance in the vapor phase. - titanium silicate materials known from the literature, such as cation exchangers: from the three considered materials, ETS-4 resulting the most promising and not affected to the presence in solution of a salt concentration (NaNO3). - amorphous mesoporous materials functionalized with organic chelating agents for the removal of anions and cations simultaneously. MCM-41, SBA-15 and silica were functionalized with amine pendants for the removal of cations and thiol pendants for removing anions. The MCM-41 material was more promising in the removal of cations, SBA-15 in the removal of arsenic. The obtained results allow to affirm that both type of materials used for the inorganic contamination removal could be used in systems like P & T and PRB. At this point it is necessary to have some consideration about the costs of used materials. For a right evaluation of the total costs it must be keep care all the process from the installation to the end of the reclamation. Immediately, it turn out to have a comparison with the activated carbon that today is the prince of the adsorbent material in P&T and PRB installation, it is clear that for zeolitici materials the unitary cost is bigger. First of all it must be considered that the materials considered in this work are synthesized on a laboratory scale, while it is not possible a direct relation with materials usually produced and used on industrial scale. Besides, as in all the process, the bigger is the required quantity, to small will be the price. Otherwise it need to consider that zeolite like materials compared to activated carbons have some advantages that diminish the total cost of the process. Firstly, the services of the activated carbon are influenced by the presence in water of humic acids and saline concentrations, differently zeolite like materials are not influenced. Zeolite may be regenerated because they have high thermal and mechanical stability, contrary to activated carbon that must be disposed after the use. At the end, but not for importance, zeolite and related materials are selective for the contaminants differently to the activated carbon.