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- Enhancing single and multi-component adsorption efficiency of pharmaceutical emerging contaminants using bio waste-derived carbon materials and geopolymersPublication . Silva, Ana P. F.; Baldo, Arthur P.; Silva, Adriano S.; Natal, Ana Paula S.; Bezerra, Ana J.B.; Tuesta, Jose L. Diaz de; Marin, Pricila; Peres, José A.; Gomes, HelderWater contamination with pharmaceuticals like acetaminophen (ACT), sulfamethoxazole (SMX), and phenolic compounds such as gallic acid (GA), have become a global concern. These contaminants are persistent environmental pollutants that threaten aquatic life and human health. Adsorption is recognized as an efficient and low-cost solution to tackle water pollution. In this study, the efficiency of three adsorbents—activated carbon (AC), geopolymer (GP), and carbon nanotubes (CNT) prepared from solid wastes for the removal of ACT, SMX, and GA by adsorption is assessed. AC, GP and CNT are synthesized from real wastes to address solid waste management needs. Physisorption confirmed AC superior BET surface area (527 m2 g 1), followed by CNTs (66 m2 g 1) and GPs (30 m2 g 1), allowing to achieve the highest adsorption capacity: 126.8 mg g 1 for ACT, 54.9 mg g 1 for SMX, and 151.5 mg g 1 for GA, with respective breakthrough times of 314, 66, and 68 min. Kinetic and isotherm adsorption models are fitted for all pair pollutant-adsorbent reaching 33 equations to accurately predict adsorption process, concluding that pseudo-second-order kinetic and Freundlich model best fit experimental data, demonstrating a strong adsorbent-adsorbate affinity. The findings suggest that these sustainable materials offer promising solutions for treating contaminated water.
- Simultaneous removal of o-and p-nitrophenol from contaminated water by wet peroxide oxidation using carbon-coated magnetic ferrite as catalystPublication . Dias, Arnaldo; Silva, Adriano S.; Silva, Ana P. F.; Roman, Fernanda; Díaz de Tuesta, Jose Luis; Oliveira, Jéssica; Ferrari, Ana M.; Lenzi, Giane G.; Gomes, Helder; Oliveira, JessícaGroundwater is the most common source of drinking water worldwide and is currently facing contamination problems with the discharge of pollutants into aquatic systems through different means, namely through municipal, industrial and agricultural activities. Contaminants, such as herbicides, pharmaceuticals, phenolic compounds and personal care products are not removed by conventional treatments from wastewater treatment plants, leading to their accumulation in the environment. In this regard, o-nitrophenol (o-NP) and p-nitrophenol (p-NP), commonly used as raw materials in chemical and pharmaceutical engineering, represent a severe risk to humans and aquatic life, leading to the necessity to properly treat wastewaters containing these contaminants before discharge into the aquatic environment. Catalytic wet peroxide oxidation (CWPO) showed promising results for removing nitrophenols from wastewater in previous works. In this technology, H2O2 is used as an oxidant, and its interaction with a suitable catalyst leads to the formation of hydroxyl radicals under determined conditions already established in literature (pH and temperature have a strong influence) [1]. Typical catalysts employed have a transition metal in its structure. Carbon-based catalysts also have activity in this technology, mostly ascribed to the electronic properties of the carbonaceous surface. Furthermore, carbon-coated metal oxide materials (hybrid) have also demonstrated potential applications in CWPO. Those structures combine carbon and metal activities with the advantage of protecting the metal core from leaching, increasing the efficiency and stability of the catalysts.
- Hybrid multi-core shell magnetic nanoparticles for wet peroxide oxidation of paracetamol: application in synthetic and real matricesPublication . Silva, Adriano S.; Roman, Fernanda; Dias, Arnaldo; Díaz de Tuesta, Jose Luis; Narcizo, Alexandre; Silva, Ana P. F.; Çaha, Ihsan; Deepak, Francis Leonard; Bañobre-López, Manuel; Ferrari, Ana M.; Gomes, HelderClean water availability is becoming a matter of global concern in the last decades. The responsible entities for wastewater treatment do not have the proper facilities to deal with a wide range of pollutants. Special attention should be given to emerging contaminants, whose presence in water bodies may cause adverse effects on the aquatic ecosystem and human health. Most studies in the literature do not consider the development of their solution in real matrices, which can hinder the applicability of the explored alternative in the real scenario. Therefore, in this work, we demonstrate the applicability of hybrid magnetic nanoparticles for removing paracetamol (PCM) from simulated and real matrices by catalytic wet peroxide oxidation (CWPO). To achieve carbon coating, the nanoparticles were prepared via the traditional route (resorcinol/formaldehyde, CoFe@CRF). A new methodology was also considered for synthesizing thin-layered carbon-coated magnetic nanoparticles (phloroglucinol/ glyoxalic acid, CoFe@CPG). TEM images revealed a multi-core shell structure formation, with an average carbon layer size of 7.8 ± 0.5 and 3.2 ± 0.3 nm for resorcinol/formaldehyde and phloroglucinol/ glyoxalic acid methodology, respectively. Screening the materials’ activity for PCM oxidation by CWPO revealed that the nanoparticle prepared by phloroglucinol/glyoxalic acid methodology has higher performance for the degradation of PCM, achieving 63.5% mineralization after 24 h of reaction, with similar results for more complex matrices. Iron leaching measured at the end of all reactions has proven that the carbon layer protects the core against leaching.
- Magnetic carbon nanotubes prepared from LDPE, HDPE and PPPublication . Sanches, Lucas Fenato; Silva, Adriano S.; Roman, Fernanda; Silva, Ana P. F.; Díaz de Tuesta, Jose Luis; Silva, Fernando Alves; Silva, Adrián; Faria, Joaquim; Gomes, HelderPlastics are among the most generated solid wastes, predominantly composed by polymers, as low-density polyethylene (LDPE), high-density polyethylene (HDPE), and polypropylene (PP).1 This work deals with the preparation of magnetic carbon nanotubes (CNTs) by catalytic chemical vapor deposition (CCVD) at 850 ºC, considering LDPE, HDPE and PP as carbon precursors representative of urban plastic solid waste in a perspective of circular economy.1 Magnetite supported in alumina nanoparticles previously synthesized by sol-gel were used as catalysts in the CCVD process. Afterward, each synthesized CNT was washed with 50% H2SO4 at 140 °C during 3 h to remove the remaining magnetite, following methods previously described.2 The successful removal of the magnetite particles was assessed measuring the ashes content of the CNTs, removals higher than 83% being achieved (ashes content of final CNT products ranging from 4.2 to 7.9%). The remaining catalyst was located inside the CNTs, conferring magnetic properties to the materials even after washing (Figure 1). BET specific surface areas of 94, 75, and 66 m2 g-1 were found for CNT_LDPE, CNT_HDPE and CNT_PP, respectively, and a slight increase of 1-5 m2 g-1 was observed after washing the materials with acid.
- 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).
- Production of catalysts for the valorization of plastic waste, and for the wet peroxide oxidation of paracetamolPublication . Silva, Ana P. F.; Gomes, Helder; Bineli, Aulus Roberto; Tuesta Triviño, José Luis Diaz deThe efficient treatment of waste plastics and pharmaceutical pollutants is of conspicuous environmental, social and economic benefits. Therefore, here it is approached the application of catalysts that can be efficient in mitigating both environmental problems. In this work, four different catalysts were prepared. Three of them were synthesized by co-precipitation of Ni, Al and Fe nitrates with different mass ratios (5%Ni:95%Al, 20%Ni:80%Al and 10%Ni10%Fe80%Al). The fourth catalyst was prepared by wet impregnation of nickel on alumina. Then fresh catalysts were characterized by Fourier Transformed Infrared Spectroscopy and X-ray diffraction to observe crystalline phases. Carbon structures were prepared from low-density polyethylene, used as representative compound of plastic solid waste by Chemical Vapor Deposition over 20% Ni/Al catalyst in a tubular furnace. Scanning Electron Microscopy analyses were performed, identifying the carbon nanostructures with size variation (1 μm to 4 μm). For paracetamol (PCM) removal Catalytic Wet Peroxide Oxidation was assessed with 20%Ni:80%Al, 10%Fe:10%Ni:80% and commercial Al2O3 catalysts. The conversion of paracetamol, hydrogen peroxide and Total Organic Carbon (TOC) were monitorized by High-Performance Liquid Chromatography, UV-Vis spectrophotometer and TOC analyzer, respectively. The iron-containing catalyst showed the highest catalytic activity in the CWPO of PCM satisfactory conversions (complete removal of PCM after 4 h of reaction time under the following operating conditions: Ccat = 2.5 g/L, CPCM,0 = 100 mg/L, pH0 = 3.5, and CH2O2 = 472.4 mg/L).
- Response surface method-driven design of experiments for the synthesis of fly ash-based geopolymers in the gallic acid optimized removal from wastewaterPublication . Silva, Ana P. F.; Natal, Ana Paula Silva; Baldo, Arthur Pietrobon; Silva, Adriano S.; Díaz de Tuesta, Jose Luis; Marin, Pricila; Peres, José A.; Gomes, HelderThe growing need for sustainable wastewater treatment solutions has led to exploring alternative materials to explore large-scale and reliable technologies. This study focuses on optimizing the synthesis of geopolymers based on fly ash using a Box-Behnken experimental design to enhance their adsorption efficiency for phenolic compounds, as gallic acid model pollutant which are widely found in wastewater leaching from landfills. Fifteen geopolymer samples were synthesized, characterized, and tested for adsorption performance. Various techniques were employed, including X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy. The optimization process highlighted the significance of the Si/Al mass ratio, NaOH molar concentration, and Na₂SiO₃/NaOH as variables in the geopolymers production. Geopolymer samples demonstrated significant adsorption capacities, with GP_2.0_10_2.5 achieving a maximum adsorption capacity of 75.8 mg g-1. Kinetic studies indicated that the pseudo-first-order model best described the adsorption process. At the same time, equilibrium data fitted well with both Langmuir and Freundlich isotherms, with GP_2.0_10_2.5 showing the best fit for the Langmuir model. These findings reveal the potential of geopolymers derived from fly ash as cost-effective adsorbents in wastewater treatment, promoting the reuse of industrial waste within the framework of a Circular Economy.
- Performance and modeling of Ni(II) adsorption from low concentrated wastewater on carbon microspheres prepared from tangerine peels by FeCl3-assisted hydrothermal carbonizationPublication . Díaz de Tuesta, Jose Luis; Roman, Fernanda; Marques, Vitor da Costa; Silva, Adriano S.; Silva, Ana P. F.; Bosco, Tatiane; Shinibekova, Assem A.; Aknur, Sadenova; Kalmakhanova, Marzhan; Massalimova, Bakytgul Kabykenovna; Arrobas, Margarida; Silva, Adrián; Gomes, HelderThe presence of heavy metals in the environment as a consequence of human activity is an issue that has caught the attention of researchers to find wastewater treatment solutions, such as adsorption. In this work, hydrochars and activated carbon microspheres are prepared from tangerine peels as carbon precursor and FeCl3 as activating and structure-directing agent in the hydrothermal carbonization, allowing to obtain hydrochar microspheres ranging from 50 to 3615 nm. In addition, a pyrochar was prepared by pyrolysis of the same precursor. The activated carbon shows the highest surface area (SBET up to 287 m2 g–1), but the basicity of the pyrochar (1.83 mmol g-1, SBET = 104 m2 g–1) was determinant in the adsorption of Ni, being considered the carbon-based material with the highest uptake capacity of Ni. Isotherm and kinetic adsorption of Ni on the most representative activated carbon microsphere, pyrochar and hydrochar microsphere are assessed by 10 and 7 models, respectively.
- Wet peroxide oxidation of paracetamol using carbon-coated spinel ferrite nanoparticles as catalystPublication . Gomes, Helder; Dias, Arnaldo; Silva, Adriano S.; Roman, Fernanda; Silva, Ana P. F.; Lima, Ana M.F.; Díaz de Tuesta, Jose LuisIn this study, carbon-based magnetic nanoparticles (MNPs) have been prepared by sucessive sol-gel method for core bare preparation and carbon coated through polymerization of phloroglucinol/glyoxylic acid, which are greener carbon precursors than the conventional method of resorcinol/formaldehyde (R/F), since formaldehyde is known to be a carcinogenic reagent. The bare core (CoFe2O4) and the carbon-coated MNPs (CoFe2O4@C) were tested as catalysts in the removal of paracetamol (PCM) from an aqueous solution by catalytic wet peroxide oxidation under optimum operational conditions, pH 3.5 and 80 °C. Values of paracetamol abatment between 33.0 and 100% were achieved after 6 h of reaction for the bare core and the carbon-based MNPs, respectively.
- Hybrid magnetic nanoparticles for wet peroxide oxidation of paracetamolPublication . Dias, Arnaldo; Silva, Adriano S.; Roman, Fernanda; Silva, Ana P. F.; Díaz de Tuesta, Jose Luis; Lima, Ana Maria; Gomes, HelderA performance de nanopartículas de ferrite de cobalto, ferrite de cobalto recoberta por carbono preparada por uma metodologia tradicional e ferrite de cobalto preparada por metodologia verde foi avaliada na remoção de paracetamol (PCM), escolhido como poluente modelo, por um processo de oxidação húmida com peróxido de hidrogénio (CWPO). O núcelo magnético foi sintetizado por sol-gel, e na metodologia tradicional de recobrimento de carbono foi considerado resorcinol/formaldeído como precursores de carbono, enquanto que na metodologia verde foi considerado phloroglucinol/ácido glioxílico. Todas as nanopartículas magnéticas (NPMs) apresentaram atividade na remoção de PCM por CWPO. Ambas as NPMs recobertas com carbono apresentaram resultados melhores que o núcleo não recoberto, devido à presença da camada de carbono à volta do núcleo, que também tem atividade pelas propriedades eletrónicas do recobrimento de carbono. O catalisador recoberto pela metodologia verde possui uma decomposição de peróxido de hidrogénio mais controlada. O teste de reutilização do catalisador mostrou a estabilidade do material, com perfis de concentração similares e uma remoção de PCM mais rápida que na primeira utilização