Seawater deaeration at very low steam flow rates in the stripping section

The model discussed in a previous work for the simulation of a deaerator to remove the oxygen from seawater in desalination plants has been improved. The conservative character of that model has been revised on the basis of the experimental industrial experience of FISIA Italimpianti S.p.A. In particular, the behaviour of the stripping section packing when very low, or null, steam flow rates are used has been investigated. An interesting interpretation of the stripping efficiencies has been used to demonstrate how the typical technical requirement of 0.02\u20130.03 ppm as maximum oxygen content in the outlet water stream can often be achieved also operating without steam feeding in the stripping section

Modelling of flash and stripping phenomena in deaerators for seawater desalination

In this paper deaeration efficiency is studied and discussed with regard to a seawater desalination plant under construction in Ruwais (United Arab Emirates) for ADNOC (Abu Dhabi National Oil Company). In particular, a modelling activity has been performed in order to optimise deareator design. Seawater flashing and stripping have been investigated, and a simulation code has been set up taking account of mass, energy and momentum balances together with phase equilibrium conditions. Parametric studies have been carried out analysing the effects of seawater and stripping steam flow rates, as well as those of temperature, pressure, packing height and other operating conditions or deaerator geometrical characteristics. Different models have been discussed interpreting flash and stripping phenomena; and in the light of the results obtained, here shown and discussed, new solutions have been proposed to reduce the costs of the deaerator installation and management

Hematite nanoparticles larger than 90 nm show no sign of toxicity in terms of lactate dehydrogenase release, nitric oxide generation, apoptosis and comet assay in murine alveolar macrophages and human lung epithelial cells

Three hematite samples were synthesized by precipitation from a FeCl3 solution under controlled pH and temperature conditions in different morphology and dimensions: (i) microsized (average diameter 1.2 μm); (ii) submicrosized (250 nm); and (iii) nanosized (90 nm). To gain insight into reactions potentially occurring in vivo at the particle-lung interface following dust inhalation, several physicochemical features relevant to pathogenicity were measured (free radical generation in cell-free tests, metal release, and antioxidant depletion), and cellular toxicity assays on human lung epithelial cells (A549) and murine alveolar macrophages (MH-S) were carried out (LDH release, apoptosis detection, DNA damage, and nitric oxide synthesis). The decrease in particles size, from 1.2 μm to 90 nm, only caused a slight increase in structural defects (disorder of the hematite phase and the presence of surface ferrous ions) without enhancing surface reactivity or cellular responses in the concentration range between 20 and 100 μg cm-

Nanotubes of imogolite do not activate macrophages and modestly perturb the barrier properties of airway epithelial cells in vitro

Since airways represent the first barrier for inhaled particles, the effects of nanomaterials on the cells of Lung Blood Barrier (LBB) should be investigated. Previous findings showed that MWCNT impair airway barrier function and are toxic to macrophage lines [1]. Here we investigate the effects of nanotubes of imogolite (INT), a hydrated alumino-silicate with the formula (OH)3Al2O3SiOH, previously proposed by some of us as a possible negative control for HARN [2]. INT - i.d. 1 nm, BET 394 m2 g-1, total and microporous volume of 0.27 and 0.11 cm3 g-1, respectively - were synthesized via sol-gel procedure and found organized into fibres at FESEM [3]. As in vitro models of LBB cells, we used two murine macrophage cell lines (Raw264.7 and MH-S) and the human airway epithelial cells Calu-3. Cell viability was assessed with resazurin. RT-PCR was used to study the expression of NOS2 and ARG1, markers of, respectively, macrophage classical or alternative activations, and concentration of nitrites in the culture medium was measured as an indicator of NO production.. Epithelial barrier integrity was evaluated from the trans-epithelial electrical resistance (TEER). At the same doses, INT caused much smaller effects than MWCNT on macrophage viability, while no significant damage was observed up to 40 g/cm2 of monolayer for exposure times up to 24h. The incubation of macrophages with INT at doses as high as 120 g/cm2 for 72h did not alter either NOS2 or ARG1 expression nor increased NO production. In Calu-3 monolayers exposed to INT (120 g/cm2 for 7d) only modest TEER changes were recorded (< 20%). As a whole, in spite of their fibrous nature, INT appear not markedly toxic for in vitro models of LBB cells and could represent a low-toxicity reference for in vitro toxicological studies on HARN, should further tests confirm their inertness. [1] Bianca Maria Rotoli et al., 2008. Non-functionalized multi-walled carbon nanotubes alter the paracellular permeability of human airway epithelial cells. Toxicol. Lett. 178:95-102. [2] Bice Fubini et al., 2010. Physico-chemical features of engineered nanoparticles relevant to their toxicity. Nanotoxicology, (DOI: 10.3109/17435390.2010.509519) [3] Ilaria Bottero et al. 2010. Synthesis and characterization of hybrid organic/inorganic nanotubes of the imogolite type and their behaviour towards methane adsorption. Phys. Chem. Chem. Phys. (DOI: 10.1039/C0CP00438C) (Supported by MIUR-PRIN Grant No. 2007498XRF

Hematite Nanoparticles Larger than 90 nm Show No Sign of Toxicity in Terms of Lactate Dehydrogenase Release, Nitric Oxide Generation, Apoptosis, and Comet Assay in Murine Alveolar Macrophages and Human Lung Epithelial Cells

Three hematite samples were synthesized by precipitation from a FeCl₃ solution under controlled pH and temperature conditions in different morphology and dimensions: (i) microsized (average diameter 1.2 μm); (ii) submicrosized (250 nm); and (iii) nanosized (90 nm). To gain insight into reactions potentially occurring <i>in vivo</i> at the particle–lung interface following dust inhalation, several physicochemical features relevant to pathogenicity were measured (free radical generation in cell-free tests, metal release, and antioxidant depletion), and cellular toxicity assays on human lung epithelial cells (A549) and murine alveolar macrophages (MH-S) were carried out (LDH release, apoptosis detection, DNA damage, and nitric oxide synthesis). The decrease in particles size, from 1.2 μm to 90 nm, only caused a slight increase in structural defects (disorder of the hematite phase and the presence of surface ferrous ions) without enhancing surface reactivity or cellular responses in the concentration range between 20 and 100 μg cm^–2