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Occurrence of micropollutants in surface water and removal by catalytic wet peroxide oxidation enhanced filtration using polymeric membranes loaded with carbon nanotubes
Publication . Silva, Adriano S.; Zadra Filho, Paulo Cesar; Ferreira, Ana Paula; Roman, Fernanda; Baldo, Arthur Pietrobon; Rauhauser, Madeleine; Díaz de Tuesta, Jose Luis; Pereira, Ana I.; Silva, Adrián; Pietrobelli, Juliana Martins Teixeira; Kalmakhanova, Marzhan; Snow, Daniel D.; Gomes, Helder
Monitoring campaigns of contaminants of emerging concern (CECs) in surface waters is of utmost importance in
evaluating the anthropogenic impact on riparian ecosystems. Beyond identifying pollutants and threats, treatment
solutions are also needed to mitigate the adverse effects caused by polluted water discharged into the
environment. For years, grab samples have been used to assess water quality, but the results can be misleading
since contaminants are not always found due to the low and highly variable concentrations at which they are
present in these matrices. Even in such small concentrations, the contaminants can be harmful to aquatic life.
Therefore, for about three months, passive samplers were used to monitor the presence of pharmaceuticals in
river water up- and downstream the discharge of a wastewater treatment plant (WWTP). Passive samplers were
extracted, analyzed and the results were used to identify possible pollution composition and potential sources.
Our campaign enabled the identification and quantification of 28 contaminants and showed that 27 increased in
amount after WWTP discharge entered the river. The statistical analysis revealed the correlation between the
pollutants, showed the oscillation in their amounts, and enabled the identification of specific pollutant groups
that deserve attention for treatment, such as antibiotics and antidepressants. Moreover, an innovative catalytic
wet peroxide oxidation (CWPO) intensified filtration process was investigated as a possible water treatment
solution, using composite polymeric membranes loaded with carbon nanotubes (CNTs). Sulfamethoxazole (SMX)
was selected as a model pollutant, and 85–90 % removals were achieved in continuous flow mode during 8 h
(equivalent to 2255–2315 mg m-2 h-1).
Response surface method-driven design of experiments for the synthesis of fly ash-based geopolymers in the gallic acid optimized removal from wastewater
Publication . 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, Helder
The 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.
Carbon-Coated Magnetic Catalysts for Enhanced Degradation of Nitrophenols: Stability and Efficiency in Catalytic Wet Peroxide Oxidation
Publication . Baldo, Arthur P.; Bezerra, Ana J.B.; Silva, Adriano S.; Silva, Ana P. F.; Roman, Fernanda; Çaha, Ihsan; Bañobre-López, Manuel; Deepak, Francis Leonard; Gomes, Helder
Nitrophenols are persistent organic pollutants that pose serious environmental and health risks due to their toxic and lipophilic nature. Their persistence arises from strong aromatic stability and resistance to biodegradation, while their lipophilicity facilitates bioaccumulation, exacerbating ecological and human health concerns. To address this challenge, this study focuses on the synthesis and characterization of two different types of hybrid multi-core magnetic catalysts: (i) cobalt ferrite (Co-Fe2O4), which exhibits ferrimagnetic properties, and (ii) magnetite (Fe3O4), which demonstrates close superparamagnetic behavior and is coated with a novel and less hazardous phloroglucinol–glyoxal-derived resin. This approach aims to enhance catalytic efficiency while reducing the environmental impact, offering a sustainable solution for the degradation of nitrophenols in aqueous matrices. Transmission electron microscopy (TEM) images revealed the formation of a multi-core shell structure, with carbon layer sizes of 6.6 ± 0.7 nm for cobalt ferrite and 4.2 ± 0.2 nm for magnetite. The catalysts were designed to enhance the stability and performance in catalytic wet peroxide oxidation (CWPO) processes using sol–gel and solution combustion synthesis methods, respectively. In experiments of single-component degradation, the carbon-coated cobalt ferrite (CoFe@C) catalyst achieved 90% removal of 2-nitrophenol (2-NP) and 96% of 4-nitrophenol (4-NP), while carbon-coated magnetite (Fe3O4@C) demonstrated similar efficiency, with 86% removal of 2-NP and 94% of 4-NP. In the multi-component system, CoFe@C exhibited the highest catalytic activity, reaching 96% removal of 2-NP, 99% of 4-NP, and 91% decomposition of H2O2. No leaching of iron was detected in the coated catalysts, whereas the uncoated materials exhibited similar and significant leaching (CoFe: 5.66 mg/L, Fe3O4: 12 mg/L) in the single- and multi-component system. This study underscores the potential of hybrid magnetic catalysts for sustainable environmental remediation, demonstrating a dual-function mechanism that enhances catalytic activity and structural stability.
Enhancing single and multi-component adsorption efficiency of pharmaceutical emerging contaminants using bio waste-derived carbon materials and geopolymers
Publication . 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, Helder
Water 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.
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Fundação para a Ciência e a Tecnologia
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Funding Award Number
PRT/BD/153090/2021