Amphiphilic carbon-based materials for one-pot desulfurization and denitrogenation of liquid fuels

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Publications

Magnetic carbon nanotubes obtained from plastic as catalysts for wet peroxide oxidation of paracetamol

Publication . Sanches, Lucas Fenato; Silva, Adriano S.; Roman, Fernanda; Díaz de Tuesta, Jose Luis; Silva, Fernando Alves; Silva, Adrián; Gomes, Helder

Magnetic carbon nanotubes (MCNTs) were prepared by catalytic chemical vapour deposition (CCVD) and tested as catalysts for catalytic wet peroxide oxidation (CWPO) of paracetamol (PCM). For the synthesis of the MCNTs, low-density polypropylene (LDPE) and high-density polypropylene (HDPE) were used as model carbon precursors present in urban plastic solid waste (Aboul-Enein, 2018). The catalyst employed in CCVD was magnetite supported on alumina prepared by a sol-gel process. The CWPO runs were conducted with the stoichiometric concentration of H2O2 needed for the full mineralization of 100 ppm of PCM, at 80 °C and initial pH 3.5, following experimental methods described elsewhere (Silva, 2019). The catalyst prepared from LDPE, LDPE_MCNTW, was able to completely degrade the pollutant within 6 h of reaction, while HDPE_MCNTW took 8 h to achieve the same removal. Iron measurement in the final reaction solutions showed the absence of possible additional pollution coming from iron leaching of the catalysts.

2021Conference object

Open access

Carbon nanomaterials from polyolefin waste: effective catalysts for quinoline degradation through catalytic wet peroxide oxidation

Publication . 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, Helder

Quinoline (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.

2023Journal article

Open access

Comprehensive characterization and development of multi-core shell superparamagnetic nanoparticles for controlled delivery of drugs and their kinetic release modelling

Publication . Moretto, Simone; Silva, Adriano S.; Díaz de Tuesta, Jose Luis; Roman, Fernanda; Cortesi, Rita; Bertão, Ana Raquel; Bañobre-López, Manuel; Pedrosa, Marta; Silva, Adrián; Gomes, Helder

The nanoparticles designed for application in cancer treatment should have biocompatibility, colloidal stability and triggered release at tumor sites. Magnetic nanoparticles arise as an interesting option to be used as drug nanocarriers, considering the possibility of driving nanoparticles to the correct delivery site and exploring different triggers to achieve such accomplishment. In this study, nickel ferrite nanoparticles are explored as a magnetic core for drug delivery systems, using doxorubicin and omeprazole as model drugs. The developed nickel ferrite presents a strong superparamagnetic behavior and high purity, as demonstrated by magnetometry and TGA results. The carbon-coating procedure and functionalization allowed the nanoparticle to achieve the desired characteristics for biomedical applications (i.e. stability in water, biocompatibility, and size). According to TEM results, the final carbon-coated magnetic nanoparticles have an average size of 25.09 ± 0.58 nm and multi-core shell architecture, which is suitable for biomedical applications as drug nanocarriers. In addition, DLS demonstrated that functionalized nanoparticles are monodisperse, with a hydrodynamic diameter of 167 ± 59 nm, which fits the recommended range (100–200 nm) to benefit from enhanced permeability and retention effect. Drug loading tests with doxorubicin and omeprazole revealed the versatility of the designed nanoparticles, able to load 97% of doxorubicin and 51% of omeprazole. The pH-triggered release was also confirmed for both pharmacological compounds, showing a higher cumulative drug under acidic conditions (simulating a tumor microenvironment). Finally, the kinetic analysis applied to the study of the release mechanism of both medicines showed that non-linear models fit with higher accuracy the experimental data.

2023Journal article

Open access

Oxidative denitrogenation of a simulated fuel under a biphasic green system

Publication . Roman, Fernanda; Piccinin, Larissa; Freitas, Isabella Veronica; Díaz de Tuesta, Jose Luis; Silva, Adrián; Faria, Joaquim; Vieira, Admilson L.; Lenzi, Giane G.; Gomes, Helder

Este trabalho trata da desnitrificação catalítica de um combustível simulado (quinolina (QN) em 2,2,4-trimetilpentano) por oxidação com peróxido de hidrogénio em meio bifásico. Como catalisadores, foram utilizados três materiais: (i) ferro suportado em alumina (Fe/Al2O3) obtido por sol-gel, (ii) nanotubos de carbono (CNT) produzidos através da deposição química em fase de vapor de propileno (PP) sobre o catalisador anterior (Fe/Al2O3), e (iii) os CNT fornecidos pela Sigma Aldrich. A contribuição da adsorção e da extração foi avaliada, sendo ambas consideradas desprezáveis ou pouco efetivas para a remoção da QN. O desempenho de cada material foi analisado em testes de reação de 4 h, a 80 °C, através da monitorização da degradação de H2O2 e da concentração de QN em meio oleoso e aquoso. Como resultados, todos os materiais utilizados atenderam ao objetivo proposto, sendo 100% da QN removida da fase oleosa nos ensaios de oxidação bifásica. Em resumo, todos os catalisadores produzidos foram eficientes no processo proposto e são comparáveis ao desempenho obtido pelo CNT comercial

2022Conference object

Open access

Selective denitrification of lipophilic pollutants from oily wastewater by peroxidation using Janus-structured amphiphilic carbon nanotubes as catalysts

Publication . Sanches, Flávia Kim; Roman, Fernanda; Silva, Adriano S.; Díaz de Tuesta, Jose Luis; Marin, Pricila; Machado, Bruno; Serp, Philippe; Silva, Adrián; Gomes, Helder

Carbon nanotubes (CNTs) were tested as catalysts in the selective denitrification of 4-nitrophenol (4-NP) from oily wastewater by catalytic wet peroxide oxidation (CWPO). The CNTs were prepared by chemical vapor deposition, feeding sequentially ethylene (E) and/or acetonitrile (A) during different times until 20 min, resulting in samples E20, A20 and E10A10, the number denoting the time feeding of each precursor and the order of appearance of the letter indicating the order of each precursor. The synthesized CNTs were tested in the CWPO of 4-NP in aqueous solutions and in simulated oily wastewater (2,2,4-trimethylpentane and water) at 80 ºC, initial pH 3.5, C4-NP = 1 g L-1, CH2O2 = 3.56 g/L and Ccatalyst = 2.5 g L-1. The catalyst A20 promoted a faster decomposition of H2O2 and a lower degradation of 4-NP in the aqueous system, whereas the catalyst E20 displayed the opposite trend, since E20 was able to remove 99% of the pollutant and A20 only 69% after 8 h of reaction. E10A10 in biphasic L-L media presented the highest conversion of 4-NP after 24 h in the oily phase (51%), followed by A20 (38%) and then E20 (25%). This tendency may be ascribed to the formation of Pickering emulsions by E10A10. The amphiphilic carachteristic of this material ensures a closer contact between the liquid phases, allowing higher mass transfer.

2021Conference object

Open access