Examinando por Autor "Pariente, Maria Isabel"

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Application of a Fenton process for the pretreatment of an iron-containing oily sludge: A sustainable management for refinery wastes
(Elsevier, 2021-12-03) Jerez, Sara; Ventura, Maria; Molina, Raul; Martínez, Fernando; Pariente, Maria Isabel; Melero, Juan Antonio
The feasibility of a Fenton-type process for the pretreatment of an oily refinery sludge has been explored taking advantage of the iron contained in the own sludge. This process reduces the content of total petroleum hydro-carbons (TPHs) accompanied by an increase in the total organic carbon concentration in the liquid phase. The effect of the temperature and the hydrogen peroxide loading was thoroughly studied in this work being the oxidant concentration the most critical parameter. Under 60 ◦C and 90 g/L of initial hydrogen peroxide concentration, the Total Organic Carbon (TOC) of the liquid phase was increased up values of 1336 mg/L and with a remarkable contribution of acetic acid as final oxidized compound (396 mgC/L). Additionally, nitrogen and phosphorous compounds were also dissolved in the aqueous phase achieving values of 250 mg/L and 7 mg/L for total Kjeldahl nitrogen and total phosphorous, respectively. Respirometry assays of the aqueous phase after the Fenton pretreatment have evidenced an increase of biodegradability up to 49% which makes this phase suitable for further biological processing in the refinery scheme. The reduction of the content of TPHs (61%) of the oily sludge, has also improved the settleability of the treated effluent (reducing the capillary suction time (CST) in ca. 88%).
Fe-N doped carbon materials from oily sludge as electrocatalysts for alkaline oxygen reduction reaction
(Elsevier, 2024-03-01) Jerez, Sara; Pedersen, Angus; Ventura, Maria; Mazzoli, Lorenzo; Pariente, Maria Isabel; Titirici, Magdalena; Melero, Juan Antonio; Barrio, Jesús
Alkaline oxygen reduction reaction (ORR) presents an important role for energy conversion technologies and requires the development of an efficient electrocatalyst. Pt-based catalysts provide suitable activity; however, Pt production accessibility and high costs create hurdles to their commercial implementation. Fe coordinated within N-doped carbon materials (Fe–N–C) are a promising alternative due to their high ORR catalytic activity, although the currently commercially available Fe–N–C materials rely on harsh synthetic protocols which can lead to increased environmental impacts. In this work we target this issue by taking advantage of an oily sludge waste currently generated in refineries to synthesize Fe–N–C materials, thus, avoiding the environmental impact caused by the management of this waste. The solid particles within oily sludge, which present a high concentration of C and Fe, were combined by different nitrogen sources and pyrolyzed at high temperatures. The prepared materials present a hierarchical pore structure with surface areas up to 547 m2 g−1. X-ray photoelectron spectroscopy analysis found that the impregnation of N using phenanthroline promotes the formation of pyridinic-N structures, which enhances the ORR performance compared to melamine doping. Additional doping of Fe with phenanthroline results in an ORR mass activity of 1.23 ± 0.04 A gFeNC at 0.9 VRHE, iR-free in a rotating disc electrode (0.1 M KOH). This catalyst also shows a lower relative loss in activity at 0.9 VRHE after 8000 cycles in O2-saturated conditions compared to a commercial FeNC catalyst, PMF D14401, (−63.5 vs −69 %, respectively), demonstrating promise as a cheap and simple route to Fe–N–C catalysts for alkaline ORR.
Thermal hydrolysis of solid fraction reduces waste disposal and provides a substrate for anaerobic photobiological treatment of refinery wastewater
(Royal Society of Chemistry, 2023-02-15) Jerez, Sara; San Martín, Javier; Ventura, Maria; Pariente, Maria Isabel; Segura, Yolanda; Puyol, Daniel; Molina, Raúl; Melero, Juan Antonio; Martinez, Fernando
Oil refineries generate vast amounts of refinery wastewater (RWW) and oily sludge (OS). Conventional treatments typically manage these effluents separately, and resource recovery potential is not considered. The thermal hydrolysis (TH) of oily sludge at different temperatures from 175 to 200 °C and several hydrolysis times from 30 to 90 minutes has been assessed. The TH reduced the solid fraction of the oily sludge by up to 50% and released substrates in the liquid stream with up to 14 g L−1 of soluble chemical oxygen demand (SCOD) and 592 mg L−1 of NH4+-N. Additionally, the hydrolyzed fraction was assessed as a substrate for the biological treatment of the refinery wastewater. An anaerobic photobiological system based on purple phototrophic bacteria (PPB) was considered to evaluate the co-treatment of both effluents. Batch experiments showed a 10- to 30-fold enhancement of the biomass yield, using both the RWW and the hydrolyzed fraction of the oily sludge. The less energetic TH conditions in terms of temperature and operation time produced the most biodegradable hydrolyzed stream with biomass yields close to those obtained for the control under optimal growth conditions. These results demonstrate the feasibility of the proposed integrated strategy to reduce the solid fraction of the oily sludge by the TH process and to release soluble substrates for a novel anaerobic photobiological treatment along with the RWW.