Heterogeneous photocatalytic degradation over titanium dioxide of touene in gas phase and diphenhydramine in liquid phase

Màster d'Enginyeria Ambiental, Facultat de Química, Universitat de Barcelona, Curs: 2015-2016, Tutors: Pilar Marco Buj, Bernardí Bayarri FerrerScientific studies on photocatalysis started about two and a half decades ago. Titanium dioxide (TiO2), which is one of the most basic materials in our daily life, has emerged as an excellent photocatalyst material for environmental purification. In this study, current progress in the area of TiO2 photocatalysis, mainly photocatalytic air and water purification are discussed together with some fundamental aspects. In the air purification line it was set-up an installation for descontamination of toluene in gas phase. It was explained the experimental method to carry out different experiments and the experiments performed. Moreover, it was created a new chromatographic method to analyze toluene in GC-2010. Best results showed 97% of recovery with 0.5 L/min of toluene during 10 minutes and it desorbed with Vortex during 10 minutes without photocatalytic reaction. But after some deficiencies were found in the installation and in this work it were proposed some enhancement options to study different variables involved in photocatalytic process in gas phase (photolysis, adsorption, total flow rate, radiation and concentration of pollutant). In the water purification line the degradation of diphenhydramine hydrochloride (DPH) by TiO2 photocatalysis was studied under different radiation sources: UVC (λ=254 nm), black blue lamps (BLB, λ=365 nm), simulated solar radiation (SB, Solarbox) and CPCs, at pilot plant scale with sunlight. Photolysis shows an important role in the DPH abatement under UVC radiation (31.5% of DPH conversion) but mineralization was not observed. Different TiO2 concentrations (0.05, 0.1 and 0.4 g/L) were used in SB device and the best results were obtained for 0.4 g/L: 35.7% of DPH conversion and 9.8% of TOC removal, after 60 min of irradiation. The UV-Vis/H2O2/TiO2 process represents an improvement with respect to the photocatalytic process (without H2O2). Thus, at 60 min with 150 mg/L of H2O2, 62.6% of DPH conversion (kinetic constant 15.05 ·10-3 h-1) in SB was achieved instead of 35.7% obtained without H2O2. Concerning the energy consumption in the useful wavelength range, SB and BLB reactors displayed the best ratios (mg DPH removed/kJ): 0.10 and 0.12, respectively, with 0.4 g/L of TiO2. Finally, reaction intermediates were identified and DPH photo-degradation pathway was proposed. Keywords: air purification, water purification, toluene, diphenhydramine hydrochloride, titanium dioxide, UVC, BLB, SB, CPC

Mixtures of chelating agents to enhance photo-Fenton process at natural pH: Influence of wastewater matrix on micropollutant removal and bacterial inactivation

Three organic fertilizers (EDTA (Ethylenedinitrilotetraacetic acid), EDDS (Ethylenediamine-N, N′-disuccinic acid) and DTPA (Diethylene triamine pentaacetic acid)) were tested as Fe-complexes in photo-Fenton process at natural pH for micropollutants (MPs) abatement and simultaneous E.coli inactivation. Less stable Fe-complexes show high iron precipitation, stopping MPs degradation. On the contrary, stable Fe-complexes imply low kinetic rates for MPs removal. To solve these inconveniences, three mixtures of organic fertilizers were also tested, trying to improve the kinetic rates of micropollutants oxidation and overcome iron precipitation. Three different pollutants (propranolol (PROP), acetamiprid (ACMP) and sulfamethoxazole (SMX)) were used as the target compounds. As the iron release is, in part, linked to the hardness of water, two water matrices from two different secondary wastewaters (Membrane Bioreactor (MBR) and Conventional Activated Sludge (CAS)) were tested. The best performance in micropollutant degradation and E.coli inactivation was achieved with the combination of EDDS + EDTA, accomplishing a good equilibrium between iron precipitation and rate of MPs removal. For instance, total removal of propranolol was achieved at 45 min in MBR, while it was only 85.7% in CAS, being an improvement of the process comparing with that obtained using single organic fertilizers. At the end of the treatment, 2.1 log-inactivation for E.coli was reached in CAS. The differences observed between both wastewaters were related to CAS' higher DOC, turbidity, and hardness. Finally, from the physicochemical characterization conducted, including Biochemical Oxygen Demand at 5 days and phytotoxicity, it is possible to highlight the suitability of these treated effluents for its reuse in irrigation, as long as in CAS matrix the final values of E. coli are within the legal limit

Green approach for micropollutants removal: Study of constructed wetlands as pretreatment of solar photo-Fenton catalyzed by organic fertilizers

This study proposes a combination of vertical-flow constructed wetlands and solar photo-Fenton catalyzed by Fe-EDTA/DTPA as a greener approach to enhance micropollutant removal from simulated polluted water. In this research, two planted microcosms, one featuring Cyperus haspan and the other Phragmites australis, were examined for their effectiveness in eliminating 5 different micropollutants over varying retention times (2, 4, 7, and 14 days). The goal was to identify the most suitable conditions for an integrated treatment approach. The findings revealed that in all cases the hybrid system provided better removals than the individual treatments, above all for the more recalcitrant compounds. Notably, the combined use of C. haspan and 2 days retention time in the CW, followed by photo-Fenton applying 5 mg L−1 of iron, 50 mg L−1 of H2O2 and 20 min of irradiation achieved total removal of the micropollutants. In contrast, using only the photo-Fenton process, it needed 60 min to remove just 60% of acetamiprid, which is the most resilient of the studied substances. Constructed wetlands, however, required a longer period of contact, up to 14 days, to completely eliminate this pharmaceutical. Ultimately, this hybrid system offers a practical and adaptable solution to meet regulatory limits, tailored to the intended use or destination of the effluent. It combines cost-effectiveness, environmental friendliness, and sustainability

VI Jornada de Joves Investigadors de l’IdRA

La VI Jornada de Joves Investigadors de l'Institut de Recerca de l'Aigua (IdRA) es planteja, un cop més, com una oportunitat científica per a les noves veus expertes en estudis de l'aigua que formen part de la Universitat de Barcelona. La finalitat principal de la jornada és el foment de les relacions científiques entre investigadors en l’àmbit de l’aigua de qualsevol branca del coneixement, que promogui sinèrgies i col·laboracions entre disciplines i permeti l’adquisició, ja des de les primeres etapes de la carrera científica, d’una perspectiva holística i transdisciplinària dels estudis relacionats. Amb aquesta idea en ment, es proposa una jornada a la que els joves investigadors puguin disseminar la seva recerca sobre l’aigua mitjançant presentacions orals curtes o de tipus pòster, seguides de breus discussions al voltant dels treballs presentats.L’edició d’enguany està formada per sis blocs temàtics: mitigació de la contaminació, qualitat de l’aigua, meteorologia i climatologia, tecnologia de l’aigua, aigua i societat i microbiologia i bioremediació. Hi participen un total de 10 departaments universitaris i 16 grups de recerca, i tots ells amb investigadors i investigadores que presenten propostes innovadores i d’alt nivell científic. A més, aquesta VI edició inclou novetats importants. D’una banda, s’ha aconseguit arribar a un total de trenta-set ponents: rècord històric de participació respecte a les edicions anteriors. D’altra banda, s’ha incorporat la modalitat de presentació en format pòster per tal de fomentar la síntesi i la divulgació dels treballs presentats. En total, aquest any comptem amb 26 presentacions orals tipus flash talks i 9 pòsters. Finalment, ens agradaria també mencionar el fet d’obrir la VI Jornada a estudiants d’altres entitats per tal de fomentar el diàleg, compartir i descobrir altres reptes científics que és desenvolupen en altres centres i Universitats. En aquesta edició, podem comptar amb la participació de joves veus investigadores de la Universitat Autònoma de Barcelona i de la Fundació BCN Formació Professional..

Photocatalytic degradation of sulfamethoxazole using TiO2 in simulated seawater: evidence for direct formation of reactive halogen species and halogenated by-products

Combined sewer overflows (CSO), generated during the wet weather flow from the combination of the inflow and stormwater runoff in sewer system, result in an overflow of untreated wastewater from sewer system, which might ultimately contain different micropollutants (MPs). In this study, a coagulation-flocculation-sedimentation (CFS) pretreated CSO spiked with MPs was treated by catalytic ozonation using carbon, iron and peroxide based catalysts. The catalysts were characterized and their activity on MPs removal was studied at two different ozone (O3) doses (5 and 10 mg L‒1). The effect of the treatment on the spiked CSO effluent was also assessed from the acute toxicity of the effluent using Microtox®, Yeast and Macrophage cell-line toxicity assay tests. All the carbon-based catalysts showed large surface area, which was strongly influenced by the activation technique in the preparation of the catalyst. The CFS treatment strongly reduced the turbidity (≥ 60%) but had marginal effect on the UV254, dissolved organic carbon (DOC) and pH. Sludge Based Carbon (SBC) showed strong adsorption capacity (≥ 60% removal efficiency) for all MPs studied compared to other carbon and iron-based catalysts. Ozonation alone was effective for the degradation of easily oxidizable MPs (sulfamethoxazole, mecoprop, and 2,4-dichlorophenoxyl acetic acid), achieving more than 80% degradation efficiency at 10 mg L‒1 of ozone, but not effective for atrazine (≤ 60% degradation efficiency) at similar O3 dose. Catalytic ozonation (at 10 mg L‒1 O3 dose) improved the degradation of the MPs at low catalyst dosage but higher dosage strongly inhibited their degradation. In all cases, the effluents showed negligible acute toxicity, indicating the suitability of the process for the treatment of CSO

Treatment of Diphenhydramine with diferent AOPs including photo-Fenton at circumneutral pH.

The degradation of diphenhydramine hydrochloride (DPH), via UV-vis/H2O2, Fenton, photo-Fenton and photocatalysis processes, was studied under different radiation sources. In addition, the Fenton and photo-Fenton processes at acid pH and circumneutral pH have been compared. The importance of the source of irradiation, UV-C (λ = 254 nm), black blue lamps (BLB, λ = 365 nm) and simulated solar radiation (SB, SolarBox), was investigated at lab-scale. Moreover, compound parabolic collectors (CPC), at pilot plant scale with sunlight, have been also applied in photocatalytic treatments. Photo-Fenton process employing black blue lamps gave the best DPH abatement (100% of DPH conversion at 10 min for acid pH and 20 min for circumneutral pH), using the highest Fe2+ (5 mg/L) and H2O2 (150 mg/L) concentrations at 50 mg/L of initial DPH concentration. Using Fenton, 100% of DPH conversion was reached at 30 min for both pHs tested. In the case of UV-C/H2O2, 100% of DPH elimination was achieved in 20 min using 150 mg/L of H2O2. In the photocatalytic process, using 0.4 g TiO2/L, after 60 min of irradiation, only 35.7% and 8.7% of DPH conversion have been obtained in SB and CPC, respectively. The DPH degradation in the photocatalytic process was greatly enhanced adding H2O2. In all the cases, increasing the H2O2 dose enhances the reaction rate due to higher OH[rad] production. However, not significant mineralization was obtained. The highest DPH mineralization was 36.8% and 38.5% of TOC reduction with photo-Fenton in BLB lamps using 150 mg/L of H2O2 and 2.5 mg/L of Fe2+, for acid pH and circumneutral pH, respectively. The major reaction intermediates these processes were identified by ionization/mass spectrometry and a DPH photo-degradation structures was proposed

Catalytic ozonation by metal ions for municipal wastewater disinfection and simulataneous micropollutants removal

This work evaluated the effects of Fe2+, Co2+ and Al3+ in municipal wastewater disinfection through E.coli and Pseudomonas spp inactivation along with cellular adenosine triphosphate (ATP) depletion. Simultaneously, the effect of catalytic ozonation of secondary effluent on the removal of selected micropollutants with different ozone kinetics (acetamiprid, dichlorvos and atrazine) was evaluated. E.coli and Pseudomonas spp inactivation increased almost 20% with 1 mgL-1 Fe2+, Co2+, Al3+ and 40% with 10 mgL-1 Fe2+ compared with single ozonation. The bacteria reactivation after the treatments showed that Fe2+ was the most effective metal ion on inhibiting regrowth. The cellular ATP followed the same trend as the indicators microorganisms inactivation, with significant reduction of ATP over the treatment compared to single ozonation. Finally, the HO¿ exposure per consumed ozone ratio was applied for single ozonation, Fe2+/O3, Co2+/O3 and Al3+/O3 processes to evaluate and compare the contribution of radical pathway on micropollutants abatement

Removal of neonicotinoid insecticide clothianidin from water by ozone-based oxidation: Kinetics and transformation products

In this paper, reaction kinetics, degradation mechanisms and associated toxicity have been assessed in detail concerning the abatement of neonicotinoid insecticide clothianidin (CLO) by ozone-based oxidation in water. The second-order rate constants for the reaction of CLO with molecular ozone (O3) and hydroxyl radical (radical dotOH) were determined by the direct and competition kinetics (with UV/H2O2 system as the radical source) methods, respectively, and estimated to be 103 M−1 s−1 and 3.7·109 M−1 s−1. This suggested a (potential) higher contribution of the indirect mechanism rather than the direct degradative pathway in the CLO ozonation process. Additionally, CLO oxidation was studied through an O3 and O3/H2O2 system for three complex real water matrices with distinct characteristics. DOC content was found to be the main parameter responsible for making difficult the achievement of high CLO degradations, whereas carbonate alkalinity did not exert a great impact on the process efficiency. Results indicated that typical ozone doses (up to 1 mg O3/mg DOC) were not enough for the complete removal of this micropollutant, ranging only from 50 to 80%. The study concerning the transformation products (TPs), performed by means of high-resolution mass spectrometry, allowed to suggest potential degradation routes based on the five major CLO-TPs identified. It was inferred that radical dotOH was involved in the formation of all TPs, whereas O3 was only involved in the formation of two of them. A preliminary toxicity assessment concerning CLO and its TPs during ozonation was conducted at three different trophic levels via the ECOSAR software. Results showed that none of the compounds was classified as very toxic for aquatic organisms, and all TPs exhibited minor toxicity than the parent compound. Changes in molecular structure, such as chlorothiazole ring breakdown, could be the main reason for this considerable decrease in toxicity. Overall, the present study demonstrates that ozonation can be considered a suitable technology alternative for CLO (and associated toxicity) abatement from aqueous matrices

VII Jornada de Joves Investigadors de l’IdRA

L'aigua, element fonamental de la vida, esdevé la protagonista de la recerca científica multidisciplinària. En un món on la crisi hídrica amenaça amb desafiar la sostenibilitat de la societat i el benestar humà, l'exploració i comprensió d'aquest recurs són fonamentals. Per contribuir en aquesta exploració i comprensió, ens plau presentar la Jornada de Joves Investigadors de l'Institut de Recerca de l'Aigua (IdRA) de la Universitat de Barcelona, un espai dedicat a la convergència de joves compromesos amb l'estudi de forma transversal d'aquest element essencial. Aquesta jornada, que celebra la seva setena edició, reuneix investigadors emergents de diverses disciplines, incloent-hi hidrologia, geologia, mineralogia, enginyeria, química, microbiologia, biotecnologia, remediació, física i humanitats, amb un interès comú: comprendre i abordar els desafiaments relacionats amb l'aigua en un món canviant. En un context marcat per la sequera que hem experimentat en els últims mesos, aquesta jornada adquireix una rellevància encara major. L'escassetat d'aigua ens ha recordat la importància de la recerca científica per fer front als impactes dels fenòmens climàtics extrems en la nostra societat i medi ambient. És en moments com aquests quan la innovació, la multidisciplinarietat i la col·laboració científica es tornen imperatives.Durant aquesta jornada, els joves investigadors tindran l'oportunitat de compartir la seva recerca, idees i solucions en el camp de la ciència de l'aigua. Presentacions orals, pòsters i debats científics seran el medi per promoure l'intercanvi de coneixements i la generació de noves perspectives. La Jornada de Joves Investigadors de l'IdRA representa un pas endavant en el nostre compromís col·lectiu amb la comprensió i protecció d'un dels recursos més preuats del nostre planeta. L'organització d'aquest esdeveniment reflexa també la iniciativa i destresa dels membres més joves de l'IdRA, que reconeixen la importància de la divulgació com un pilar essencial en el procés de la recerca. El Document 008 de l'IdRA recull els resums de les presentacions orals i pòsters realitzats durant la jornada i es troba disponible al Dipòsit Digital de la UB

Improving ferrate disinfection and decontamination performance at neutral pH by activating peroxymonosulfate under solar light

In this work, the effect of solar light as a 'reducing agent' in Fe(VI)/PMS process for disinfection and decontamination of water was investigated. Single, double and triple-factor disinfection processes were systematically studied against Escherichia coli and validated on sulfamethoxazole. The experiments performed with PMS or Fe(VI) in dark conditions only achieved 1-log reduction in 2 h, while no significant enhancement was found in the Fe(VI)/PMS system. The introduction of solar light in either PMS or Fe(VI) process enhanced the E. coli inactivation since complete inactivation (6-log) was reached at 90 min. However, the best improvement was done with the triple-factor disinfection process (Fe(VI)/PMS/solar light) which presented 6-log reduction at only 40 min. In the case of sulfamethoxazole, more than 70% removal was achieved under the Fe(VI)/PMS/solar light system, while only about 20% was observed with single and double-factor processes. Our study revealed the light spectrum distribution effects, the iron implications, while a main role for 〖HO〗^¿ and the participation of 〖SO〗_4^(¿-) was found, without overlooking the direct effects of solar light and PMS itself, as well as the possible involvement of other transient species. Overall, the efficacy of the Fe(VI)/PMS/solar light process against a series of microorganisms combined with the effectiveness at near-neutral pH, suggest its suitability for further assessment in disinfection and/or decontamination of water