RESUMO

Research on innovative approaches to the valorisation of glycerol as a subproduct of biodiesel production has acquired an increasing demand in the development of a circular economy around energy generation, especially, in the line of improvement of the heterogeneous metallic catalysts used. In this regard, carbon xerogels have gained importance due to their stability and modifiability, while transition metals such as copper stand out as a cost-effective alternative, resulting in a technology where surface engineering plays a crucial role in achieving competitive catalytic activity. Building upon this, current research evaluates doped xerogels (Si, N, or GO) as supports of Cu and catalysts by themselves for glycerol oxidation. Benefits from the incorporation of oxygenated functional groups (OFG) were also evaluated. Results showed a consistently higher selectivity towards lactic acid (LA) across all catalysts and competitive catalytic conversion. In this performance, dopants played a crucial role in surface acid-base characteristics, while oxygenated functional groups (OFG) influenced copper adsorption, dispersion, and reducibility. Notably, the Cu/CXN-f catalyst demonstrated the highest LA yield by combining the effect of N as a doping species, with the presence of OFG and the formation of appropriated metallic Cu domains. This research underscores the potential of carbon xerogels in the tailored catalyst design, contributing to sustainable chemical production through their customizable textural and chemical properties.

Assuntos

Carbono , Cobre , Géis , Glicerol , Oxigênio , Glicerol/química , Carbono/química , Oxigênio/química , Cobre/química , Géis/química , Catálise , Propriedades de Superfície , Oxirredução , Biocombustíveis

RESUMO

Inorganic arsenic in drinking water from groundwater sources is one of the potential causes of arsenic-contaminated environments, and it is highly toxic to human health even at low concentrations. The purpose of this study was to develop a magnetic adsorbent capable of removing arsenic from water. Fe3O4-monolithic resorcinol-formaldehyde carbon xerogels are a type of porous material that forms when resorcinol and formaldehyde (RF) react to form a polymer network, which is then cross-linked with magnetite. Sonication-assisted direct and indirect methods were investigated for loading Fe3O4 and achieving optimal mixing and dispersion of Fe3O4 in the RF solution. Variations of the molar ratios of the catalyst (R/C = 50, 100, 150, and 200), water (R/W = 0.04 and 0.05), and Fe3O4 (M/R = 0.01, 0.03, 0.05, 0.1, 0.15, and 0.2), and thermal treatment were applied to evaluate their textural properties and adsorption capacities. Magnetic carbon xerogel monoliths (MXRF600) using indirect sonication were pyrolyzed at 600 °C for 6 h with a nitrogen gas flow in the tube furnace. Nanoporous carbon xerogels with a high surface area (292 m2/g) and magnetic properties were obtained. The maximum monolayer adsorption capacity of As(III) and As(V) was 694.3 µg/g and 1720.3 µg/g, respectively. The incorporation of magnetite in the xerogel structure was physical, without participation in the polycondensation reaction, as confirmed by XRD, FTIR, and SEM analysis. Therefore, Fe3O4-monolithic resorcinol-formaldehyde carbon xerogels were developed as a potential adsorbent for the effective removal of arsenic with low and high ranges of As(III) and As(V) concentrations from groundwater.