Browsing by Author "Bezerra, Ana J.B."
Now showing 1 - 3 of 3
Results Per Page
Sort Options
- 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.
- Polyolefin and Polystyrene‐Derived Carbon Nanotubes: Catalysts for Oxidative Desulfurization Under a Biphasic SystemPublication . Roman, Fernanda; Batista, Maria C.; Silva, Adriano S.; Bezerra, Ana J.B.; Tuesta, Jose L. de Diaz de; Mambrini, Raquel V.; Silva, Adrián; Faria, Joaquim L.; Gomes, HelderThe conversion of plastic solid waste into carbon nanotubes (CNTs) via chemical vapor deposition (CVD) and the effectiveness of these CNTs as catalysts for oxidative desulfurization (ODS) of a simulated fuel were investigated. The primary focus is on the use of CNTs synthesized from various polymer sources, including polyolefins and polystyrene (PS), to remove sulfur compounds using hydrogen peroxide (H 2 O2 ) as an oxidant. The surface modification of CNTs by using acids (H2 SO4 or HNO3 ), the influence of the carbon feedstock (polyolefins vs PS), the use of co-catalysts, and the effect of the extractant phase were all evaluated on the oxidative removal of dibenzothiophene from a simulated fuel. Results revealed that CNTs derived from polyolefins displayed higher desulfurization efficiency (up to 77% in 8 h), with nitric acid-treated CNTs showing the best performance under oil-water biphasic systems. Replacing water with acetonitrile and adding a co-catalyst (formic acid) resulted in a desulfurization of 91% in 2 h of reaction. Under certain conditions, C─S bond cleav-age was observed. This research contributes to the valorization of plastic solid waste and the reduction of atmospheric pollution, promoting circular economy practices and environmental sustainability.
- Synthesis of coated nanoparticles for the oxidative denitrogenation of fuelsPublication . Bezerra, Ana J.B.; Gomes, Hélder; Giona, Renata MelloThe presence of nitrogen compounds in fossil fuels leads to the formation of NOx during combustion, harmful pollutants that represent a significant challenge for the environment and health, making its removal very important. Hydrotreatment, currently the most common strategy for denitrogenation, requires severe operating conditions, which motivates the search for more sustainable alternatives. This study investigates oxidative denitrogenation (ODN) as a promising strategy, analyzing the oxidation of quinoline, a nitrogen-containing compound common in fossil fuels, using catalysts based cobalt ferrite and its variants coated with silica (CoFe2O4@SiO2) and carbon (CoFe2O4@C), applied in a biphasic system containing isooctane as the organic phase and hydrogen peroxide as the oxidant. Cobalt ferrite was synthesized using the sol-gel method, followed by silica and carbon coatings. Characterization techniques such as XRD, FTIR and contact angle measurements confirmed the successful synthesis of core-shell structures, with crystallite sizes in the 19-20 nm range. The coatings significantly modified the surface properties, reducing the hydrophobicity of the ferrite, with the contact angle reduced from 130° to 40° with silica. Quinoline adsorption tests revealed a low adsorption capacity of the materials, in line with the low surface area and low pore volume determined by N2 adsorption isotherms at 77 K (SBET = 9-10 m2/g). In the oxidation reactions, CoFe2O4@SiO2 showed the best catalytic performance removing 74% of quinoline in 8 hours, likely due to its hydrophilic surface, favorable to the generation of reactive oxygen species through the decomposition of H2O2 and consequent greater quinoline removal. GC-MS identified intermediate degradation products, including species suggesting the opening of pyridine rings, while TOC analysis confirmed significant quinoline mineralization. The study highlights the potential of oxidative denitrogenation systems, combined with coated catalysts, to effectively remove nitrogen impurities from liquid fuels, offering a promising alternative to conventional hydrotreatment.