Papers by Author: Anca Duta

Abstract: The paper presents the results on accelerated corrosion/erosion tests, of Thickness Insensitive Spectrally Selective paints, based on alumina matrix infiltrated with inorganic oxide pigments used in the solar-thermal energy conversion. The mechanism of the corrosion/erosion process is presented and discussed based on the polarization Tafel curves obtained in NaCl 3.5% solution. Optical properties (solar absorptance and thermal emittance) were measured before and after the corrosion tests and the results were correlated with the sample’s morphologies and the corrosion parameters. The influence of the antireflection layer on the corrosion resistance and spectral selectivity is also discussed.

Abstract: The paper presents the results obtained when using two ketonic Mannich bases (BM1 and BM2) as corrosion inhibitors in saline (standard sea water-3.5% NaCl) for different types of steel, with various alloying elements. The corrosion experiments were performed by potentiodynamic polarization studies. Based on the polarization curves, the corrosion current density and rate were calculated. The inhibitors efficiencies were evalued and the protection mechanisms were discussed.

Abstract: Nitrite removal from municipal wastewater is mandatory considering the treated wastewater reuse. Removal on an anion exchanger leads to simple wastewater treatment installations, easy to handle, to exploit and to maintain. This study reports on the performance of anion exchange resin on removing nitrite from synthetic solutions. Equilibrium data could be well fitted using the Langmuir model, confirming ion exchange without any parallel mechanisms. Kinetic study of the process is evaluated using the shrinking core model and the dominant rate mechanism is estimate.

Abstract: The paper presents the results obtained when using Mannich bases (and derivatives) as corrosion inhibitors in saline environment, for different types of steels, with various alloying elements. The Mannich basis (ketonic combinations with naphtenic and nitrogen containing rings) were synthesized as such (polar) and as chlorhydrates (ionic) and used in corrosion experiments, in concentrations varying from 0….1300 ppm. The corrosion experiments were performed by potentiodynamic polarization studies. Based on the polarization curves, the corrosion current density and rate were calculated. The inhibitor efficiency was evaluated and based on these values the protection mechanisms was discussed.

Abstract: In a wastewater resulted from the dyes finishing industry there are amounts of dyes (very common Methyl Orange) and heavy metals resulted mainly from the organo-metallic dyes. Heavy metals (Cd2+ and Cu2+) advanced removal is usually proposed via adsorption and the use of modified fly ash as adsorbent represents a sustainable solution. The paper presents the results obtained in investigating the effect of methyl orange adsorbed onto the fly ash with modified surface, on the removal efficiency of cadmium and copper ionic species, considering the final application: a single step treatment process applied for wastewaters containing both heavy metals and dyes. The adsorption mechanisms are discussed based on the kinetic results and on the Langmuir model.

Abstract: Advanced wastewater treatment requires highly efficient substrates, able to insure in a single step process the water discharge requirements. The paper the results obtained in the simultaneous removal of heavy metals and dyes, using a composite powder of fly ash and activated carbon. The results show that adding a small amount of activated carbon in a powder mixture with modified fly ash is highly effective in removing cadmium from wastewaters also containing dyes (methylen blue or methyl orange). Chemisorption is the likely mechanism governing this process.

Abstract: The structural and surface properties of thin, metal oxides films can be tailored by including various additives in the precursors’ systm. The paper presents a comparative approach concerning the properties of WO3 thin layers obtained via spray pyrolysis deposition (SPD) using hydrophilic and hydrophobic polymers as additives. The influence of the thin films composition and morphology is reported, considering their applications of photocatalyst in the advanced treatment of waters resulted in the dye finishing industry, containing methylen blue and methyl orange.

Abstract: The photocatalytic activity of the titanium dioxide thin film has been investigated towards the degradation of methyl orange in aqueous solutions. Porous TiO2 thin films were deposited on glass substrate by doctor blade technique. The thickness of the film prepared by doctor blade was also evaluated from de UV spectrum and the average value corresponds to 5 μm. The photocatalytic efficiency was evaluated as the percentage of pollutant bleaching, after 6h of UV illumination. The influence of the operational parameters (dye concentration, pH) on the degradation rate of the dye on TiO2 was examined. The catalytic activity of the films towards photodegradation of methyl orange pollutant was examined and their photocatalytic efficiency was calculated.