Percorrer por autor "Lenzi, Giane G."
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- 17 α-Ethinylestradiol degradation in continuous process by photocatalysis using Ag/Nb2O5 immobilized in biopolymer as catalystPublication . Lenzi, Giane G.; Abreu, Eduardo; Fuziki, Maria Eduarda K.; Fidelis, Michel Zampieri; Brackmann, Rodrigo; Díaz de Tuesta, Jose Luis; Gomes, Helder; Santos, Onélia A.A. dosThis study describes the application of Ag/Nb2O5 catalysts, suspension and spheres alginate immobilized for the degradation of 17α-Ethinylestradiol (EE2). The techniques used to characterize the photocatalysts were as follows: X-ray diffraction (XRD), N2 adsorption–desorption analysis (BET), point charge zero charge (PZC), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Different catalyst calcination temperatures were studied by keeping the silver metal loading at 5%. Among the operational conditions analyzed were pH, catalyst concentration, the emitting source of radiation and the inlet flow rate (in continuous operation). The results of the experiments performed initially with the catalyst in suspension revealed that the highest catalytic activity in the degradation of EE2 was the 5%Ag/Nb2O5 catalyst calcined at 973 K, which removed 77.7% of the initial pollutant concentration in 120 min of reaction. The immobilization of the catalyst in alginate spheres resulted in a degradation reduction, being able to degrade 69.2% of the initial EE2 in a batch system. In the continuous system, the immobilized catalyst obtained a total degraded of 37.3%, with a flow rate of 10 L·h−1. Catalyst reuse was promising, even dropping the removal, degrading around 27% of the initial EE2 concentration in the third cycle of use.
- Acidic waste cooking oil valorization by biodiesel synthesis catalyzed by hydrogen sulfate 1-butyl-3-methylimidazoliumPublication . Baú, Ana; Lenzi, Giane G.; Ribeiro, António E.; Queiroz, Ana; Brito, PauloBiodiesel is a fuel that shows growing demand as a promising alternative to petroleum-derived fuels. It is produced by esterification or transesterification reactions from renewable raw materials such as animal fats and vegetable oils , where the presence of catalysts is used for an effective conversion. The basic catalysts are very sensitive to the presence of water and FFAs, promoting saponification reactions. On the other hand, the use of acid catalysts means reaction times up to 4000 times higher, higher alcohol/oil molar ratios and higher reaction temperatures. In this context, Ionic Liquids (ILs) used as catalysts, come as a viable alternative to overcome these problems in biodiesel production processes. Imidazolium-based ILs, have been extensively studied, mainly due to their specific characteristics such as, low pressure and ability for self-organization in different states. Hydrogen sulfate 1-butyl-3-methylimidazolium [BMIM]HSO4 has been showing promising results in this type of applications. Therefore, the objective of this work is to study the application of the [BMIM]HSO4 IL in the catalysis of esterification/transesterification reactions of triglycerides mixtures with high free fatty acid contents coming from waste cooking oils samples, with further characterization of the quality of the biodiesel produced. The present work includes also the assessment of the catalyst potential for recovery and recycling.
- Acidic waste cooking oil valorization by biodiesel synthesis catalyzed by hydrogen sulfate 1-butyl-3-methylimidazoliumPublication . Baú, Ana; Lenzi, Giane G.; Ribeiro, António E.; Queiroz, Ana; Brito, PauloBiodiesel is a fuel that shows growing demand as a promising alternative to petroleum-derived fuels. It is produced by esterification or transesterification reactions from renewable raw materials such as animal fats and vegetable oils , where the presence of catalysts is used for an effective conversion. The basic catalysts are very sensitive to the presence of water and FFAs, promoting saponification reactions. On the other hand, the use of acid catalysts means reaction times up to 4000 times higher, higher alcohol/oil molar ratios and higher reaction temperatures. In this context, Ionic Liquids (ILs) used as catalysts, come as a viable alternative to overcome these problems in biodiesel production processes. Imidazolium-based ILs, have been extensively studied, mainly due to their specific characteristics such as, low pressure and ability for self-organization in different states.
- Assisted hydrothermal carbonization of agroindustrial byproducts as effective step in the production of activated carbon catalysts for wet peroxide oxidation of micro-pollutantsPublication . Díaz de Tuesta, Jose Luis; Saviotti, Marcus Chamahum; Roman, Fernanda; Pantuzza, Gabriel F.; Sartori, Hiram J.F.; Shinibekova, Assem A.; Kalmakhanova, Marzhan; Massalimova, Bakytgul Kabykenovna; Pietrobelli, Juliana Martins Teixeira; Lenzi, Giane G.; Gomes, HelderThis work deals with the valorisation of bagasse of sugarcane – BC, bagasse of malt – BM and seed of chia – SC, through its transformation into pyrochars, hydrochars and activated carbons (ACs) by pyrolysis, hydrothermal carbonization (HTC) and sequential HTC and pyrolysis, respectively. The HTC process was carried out in the presence of H2O, FeCl3 and H2SO4 solutions. The materials resulting by HTC in the presence of FeCl3 revealed the highest burn-off, but the contents of carbon released into the liquid phase, measured as total organic carbon, and to the gaseous phase, determined by carbon balance, depend strongly on the carbon precursor. In this sense, BC generates more volatile organic compounds (up to 34% of the initial carbon content), followed by BM (< 15%) and SC (< 5%) in their HTC and pyrolysis (70%). The pyrochars, hydrochars and ACs prepared from BC also show the highest specific surface areas (SBET < 447 m2⋅g-1) when compared to the specific surface areas of the materials prepared from BM and SC. The carbon-based materials prepared with FeCl3 show the highest catalytic activity, but iron leaching into solution is observed. On the other hand, the materials prepared with H2SO4 show high activity, enabling its application in successive cycles and the complete degradation of caffeine in concentrations ranging from 1 to 100 mg⋅L-1, after 5–60 min of reaction.
- Biphasic oxidative denitrogenation with H2O2 of a simulated fuel using sustainable carbon nanotube catalystsPublication . Piccinin, Larissa; Roman, Fernanda; Freitas, Isabella Veronica; Díaz de Tuesta, Jose Luis; Silva, Adrián; Faria, Joaquim; Vieira, Admilson L.; Lenzi, Giane G.; Gomes, HelderThe presence of nitrogenated compounds in liquid fuels (e.g. quinoline (QN), azapyrene, pyrrole, indole or carbazole) is associated with a series of environmental and health issues [1], as upon their combustion, noxious NOx gases are formed. Typically, those heteroatoms are removed by hydrodenitrogenation (HDN), a process based on the application of H2 under high temperature and pressure [2]. However, due to the type of nitrogenated compounds found in crude oils, which consist mostly of cyclic structures containing two double bonds between N and C atoms, HDN fails to efficiently remove nitrogen without affecting the properties of the fuel [1]. Thus, alternatives to HDN have been sought, the removal of those nitrogenated compounds via oxidative processes being found as promising [1]. In oxidative denitrogenation (ODN), nitrogen-based compounds are oxidized towards more polar compounds, which can be further removed from the fuel with an extractant [3]. Furthermore, another contemporary issue is the production and accumulation of residues, especially plastic solid waste (PSW). PSW can be used as precursors for the synthesis of sustainable carbon nanotubes (CNTs), which could be further applied as catalysts in ODN. In this work, a nitrogen-rich fuel was simulated by dissolving QN (CQN-i-octane,0 = 1 g L-1) in 2,2,4-trimethylpentane (i-octane), and ODN was carried out using H2O2 as oxidant and CNTs (derived from a mixture of polymers simulating PSW) as catalysts, under a biphasic system (oxidation and extraction co-occurrence).
- Carbon nanofibers from plastic solid wastePublication . Lopes, Jéssica Paula Marim; Roman, Fernanda; Díaz de Tuesta, Jose Luis; Lenzi, Giane G.; Faria, Joaquim; Silva, Adrián; Gomes, HelderProduction of plastics reached 360 million tonnes in 2018, the EU production corresponding to 62 million tonnes (i.e. 17%), from which only 9.2 million tonnes were collected for recycling. Low- and high-density polyethylene (PE) and polypropylene (PP), commonly used for packaging purposes, represent 40% of EU production [1]. In 2018, landfilling of plastic solid waste still represented 18.5% of the collected material [1], so there is still a great fraction of plastic waste being sent to landfill, representing a strong concern, as this plastic waste does not easily decompose. On the other hand, plastic polymers are mostly composed by carbon, as both PE and PP have a carbon content of 85.6% [2]. In this context, those plastics containing PE or PP represent a good source to produce carbon-based materials. In this work, low-density PE was used as precursor for the synthesis of carbon nanofibers (CNFs) by Chemical Vapour Deposition (CVD) (800 °C, 1 h, under N2 flow), with the aim to evaluate the influence of different CVD catalysts based on Fe, Ni and Al, synthesized using coprecipitation or wet impregnation methods, on the valorisation of PE-containing plastic waste. Fig 1 displays the scanning electron micrographs (SEM) of the carbonaceous materials obtained using two different catalysts. As can be observed, filamentous carbons were obtained in both cases, attributed to the growth of CNFs. The CNFs were obtained with similar yields of carbonaceous material (37.6% with Ni+Fe@Al2O3-coprecipitation and 36.2% with Ni+Fe@Al2O3-wet impregnation). Catalyst Ni+Fe@Al2O3-coprecipitation (Fig 1(a)) led to the formation of entangled CNFs, with high density and diameters in the range 12 – 28 nm, with the catalysts metals visible at the tip of the fiber (brighter spots on the SEM image). On the other hand, the catalyst Ni+Fe@Al2O3- wet impregnation (Fig 1(b)) resulted in the growth of CNFs with higher apparent diameters, which indicates that the catalyst obtained via coprecipitation is more suitable for growing carbon nanostructures.
- Carbon nanomaterials from polyolefin waste: effective catalysts for quinoline degradation through catalytic wet peroxide oxidationPublication . Roman, Fernanda; Piccinin, Larissa; Silva, Adriano S.; Díaz de Tuesta, Jose Luis; Freitas, Isabella V. K.; Vieira, Admilson L.; Lenzi, Giane G.; Silva, Adrián; Faria, Joaquim; Gomes, HelderQuinoline (QN) is highly toxic and carcinogenic and has been detected in soil, groundwater, and biological tissues. Advanced oxidation processes (AOPs) have shown promise to address its degradation in wastewater treatment, with catalytic wet peroxide oxidation (CWPO) being highlighted due to its cost-effectiveness and mild operation. However, developing active and inexpensive catalysts is crucial for CWPO’s effectiveness. Another pressing issue is the accumulation of mixed, dirty plastic solid waste (PSW), particularly polyolefins used in packaging. Although recycling rates have increased, much plastic packaging remains in landfills. However, polyolefins can be converted into carbon-based nanostructured materials (CNMs), such as carbon nanotubes (CNTs), through chemical vapor deposition (CVD) using PSW as a carbon precursor. While many studies focus on CNT preparation, their application is often overlooked. In this context, this work proposes the preparation of CNMs, particularly CNTs, through CVD using a single-stage pyrolysis reactor. Polyolefins (LDPE, HDPE, and PP), both individually and in a mixture simulating PSW, were used as carbon sources. Given a sufficiently high temperature, the desired CNT architecture was successfully synthesized regardless of the starting polymer. These CNMs were then tested as catalysts for CWPO in simulated wastewater containing QN. The results showed a rapid degradation of QN (30–120 min) and high removals of total organic carbon (TOC) and aromatic compounds (75% and >90%, respectively), demonstrating the applicability of PSW-derived CNTs in the CWPO process for QN abatement.
- Carbon nanotubes synthesized from LDPE for application in wet peroxide oxidation of paracetamolPublication . Roman, Fernanda; Lopes, Jéssica Paula Marim; Díaz de Tuesta, Jose Luis; Lenzi, Giane G.; Silva, Adrián; Faria, Joaquim; Gomes, HelderCarbon nanotubes (CNTs) were produced by chemical vapor deposition (CVD) considering low-density polyethylene (LDPE) as a carbon source and as an alternative to upcycle plastic solid waste. The CNTs were synthesized over bimetallic catalysts (Ni and Fe) supported on Al2O3 and purified with H2SO4 to dissolve the metal particles from the material. Both original (CNT-O) and purified materials (CNT-P) were tested as catalysts in catalytic wet peroxide oxidation (CWPO) of paracetamol (PCM). Both catalysts promoted the complete conversion of PCM within 8 h of reaction and were able to mineralize 60% of the organic content of the effluent (measured as TOC) in 24 h. Catalyst CNT-O was able to completely decompose hydrogen peroxide (H2O2) within 24 h, whereas CNT-P was only able to decompose ~80%. Therefore, the efficiency of H2O2 consumption, measured as XTOC/XH2O2, was higher for catalyst CNT-P (0.75) than for CNT-O (0.61). Metal leaching, especially Ni, was observed during the CWPO run with CNT-O, while it is avoided when using CNT-P. Thus, purified CNTs have proved to be active in CWPO of PCM, allowing a more controlled decomposition of H2O2 and avoiding leaching of metal species.
- Catalytic wet peroxide oxidation of paracetamol using carbon nanotubes synthesized from low-density polyethylene as model plastic wastePublication . Roman, Fernanda; Lopes, Jéssica Paula Marim; Silva, Ana P. F.; Díaz de Tuesta, Jose Luis; Lenzi, Giane G.; Silva, Adrián; Gomes, HelderOne of the ongoing concerns related with wastewater treatment is the presence of micropollutants on water bodies, since they accumulate due to its recalcitrant behavior and its constant introduction in the system [1]. Catalytic Wet Peroxide Oxidation (CWPO) is a wastewater treatment technology based on the generation of powerful oxidants (hydroxyl radicals) from the decomposition of H2O2, providing that suitable solid catalysts are used, with promising results being reported in the removal of pharmaceuticals [2]. On the other hand, plastic waste is an actual concern in waste management, and alternatives to its post-use should be sought [3]. This study aims at the CWPO of paracetamol (PCM) as model micropollutant, using as catalysts carbon nanotubes (CNTs) synthesized from low-density polyethylene, as representative polymer found in municipal plastic solid waste streams. The CNTs were synthesized by chemical vapor deposition at 800 ºC, considering three catalyst based on Ni, Fe and Al prepared by coprecipitation and wet impregnation methods. The synthesized CNTs were further tested on the CWPO of PCM (100 mg L-1 of PCM, pH0 3.5, 474 mg L-1 H2O2, Ccatalyst = 2.5 g L-1 and 80 °C). All catalysts tested led to the complete conversion of both PCM and H2O2 after 24 h of reaction time (Figure 1(a,b)), with a contribution of 23-42% of adsorption according to pure adsorption tests performed at the same operating conditions (Figure 1(d)). The CNT synthesized on the catalyst prepared by the impregnation method shows a lower contribution of adsorption and led to a mineralization of 70% after 24 h of reaction time, with the highest efficiency of H2O2 consumption (determined as TOC conversion divided by H2O2 conversion).
- Degradation of emerging contaminants: effect of thermal treatment on nb2o5 as photocatalystPublication . Abreu, Eduardo; Fidelis, Michel Zampieri; Fuziki, Maria Eduarda Kounaris; Malikoski, R.M.; Mastsubara, M.C.; Imada, R.E.; Díaz de Tuesta, Jose Luis; Gomes, Helder; Anziliero, M.D.; Baldykowski, B.; Dias, Daniele Toniolo; Lenzi, Giane G.This study describes the use Nb2O5 catalysts – calcined at different temperatures (373–873 K) – in the photo-catalytic degradation reaction of four contaminants of emerging concern: acetylsalicylic acid (ASA), 17α-ethi-nylestradiol (EE2), ibuprofen (IBP) and paracetamol (PAR). The photocatalysts were characterized by different techniques – N2 adsorption/desorption, photoacoustic spectroscopy (PAS), Fourier Transform Infrared (FT-IR) and X-ray diffraction (XRD) – and applied in the photocatalytic degradation tests. Among the tested catalysts, non-calcined Nb2O5 showed the highest photocatalytic activity. The characterization results indicated that this catalyst presented an amorphous (non-crystalline) structure, low band gap and the highest surface area (SBET =182 m2 g-1). A design of experiments (DoE) methodology was applied in order to verify the effects of pH (4–10) and catalyst concentration (0.5–1.5 g L-1) in the four pollutants removal using the non-calcined Nb2O5. Ac-cording to the Experimental Design Analysis, a statistically significant linear effect with a negative coefficient was observed for pH in EE2, IBP and PAR photocatalytic degradation. Tests to verify the influence of the presence compounds together in the degradation reaction of each contaminant, suggested that the photocatalytic degradation of IBP occurs predominantly through the action of radicals O2•-, , with minor contribution from HO•.