Browsing by Author "Guliyeva, Rima"
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- Adsorption of Sudan IV from oily wastewater by using modified activated carbon materialsPublication . Díaz de Tuesta, Jose Luis; Guliyeva, Rima; Martin-Martinez, Maria; Silva, Adrián; Faria, Joaquim; Gomes, HelderA commercial activated carbon (AC: Norit ROX 0.8, D = 0.8 mm) was modified by chemical and thermal processes, following the procedures described elsewhere [1]. The materials were tested as adsorbents for the removal of a lipophilic pollutant, Sudan IV (S-IV), using a biphasic medium (water/cyclohexane) in order to simulate contaminated petroleum mixtures with water [2]. The AC was modified in successive steps considering: (1) grinding and sieving (< 250 μm) and (2) treatment with nitric acid, followed by hydrotreatment with urea and thermal treatment at 800 ºC under inert atmosphere, resulting in the adsorbents PAC and PACNAUT, respectively. Adsorption experiments were performed in a 500 mL batch glass reactor, using 2.5 g of adsorbent per litre of organic phase, 2.5 g/LOP. Fig.1A shows results with different particle size (ps), initial S-IV concentration (CS-IV,0) and AC modifications. As expected, it can be observed that adsorption is faster when ps is smaller. However, the powdered activated carbon (PAC) is not able to adsorb all S-IV in high initial concentration (500 mg/L). This target was achieved with PACNAUT (adsorption of S-IV was 90 % at 1 h and 2.5 g/LOP of adsorbent, higher than the removal observed by other authors [2] at the same time and 4 g/LOP of material). The adsorption kinetics was fitted by a pseudo-second-order model to the data obtained with 500 mg/L of CS-IV,0 (Fig. 1B). PACNAUT has higher adsorption capacity (qe) and rate constant (kS).
- Amphiphilic catalysts for the treatment of oily wastewatersPublication . Guliyeva, Rima; Gomes, Helder; Martinez, Maria MartinThe main objective of this study was to obtain an effective catalyst for removal of diazo dye - Sudan IV by Catalytic Wet Peroxide Oxidation (CWPO). For this purpose liquid phase treatment was used to increase the basicity of activated carbon surface favoring the adsorption of organic pollutants. Modified activated carbon catalysts were used in different types of experiments: 1) decomposition of H2O2 in aquatic media, 2) decomposition of H2O2 in organic media, 3) adsorption of Sudan IV, 4) Sudan IV removal by CWPO. As the result of all of these experiments the most effective catalyst was obtained and discussed. It was not observed removal of Sudan IV from biphasic system by CWPO. The obtained results in some cases show a slight increase in concentration of Sudan IV, which may be ascribed to experimental errors. Different factors could be the reason of those errors. For example, the high volatility properties of organic media used in experiments should be taken into account during experiments. Under settled reaction temperature the decrease of cyclohexane volume during experiment could give rise in Sudan IV concentration. The initial concentration of model diazo dye also should be reviewed more detailed for CWPO experiments. Despite of these experimental errors the behavior of our catalysts in different media was observed.