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Magnetic carbon xerogel composites with Fe3O4 nanoparticles (MNPs) prepared via co-precipitation can effectively remove arsenic (As(V) and As(III)) and fluoride ions from groundwater. The optimum conditions for the synthesis of these materials were studied, including the molar ratios of MNPs and catalyst. Carbonization and post-synthesis treatment with H2O2-induced surface modification were applied. SEM and Fe analysis revealed the presence of Fe in the materials. This study provides a promising new method for the removal of arsenic and fluoride from groundwater, with the feasibility of reusing adsorbent and magnetic separation, which could have a significant impact on public health. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Magnetic carbon xerogels were synthesized via direct sonication to load magnetite nanoparticles in sol–gel polycondensation onto resorcinol-formaldehyde gels. The resulting organic gels were carbonized and subjected to surface modification using H2O2 and characterized using scanning electron microscopy and energy-dispersive X-ray spectroscopy. The desorption capacity was optimized using response surface methodology, with the adsorbent dose identified as the most significant quantitative factor. The kinetic adsorption was well described using the Elovich and Power equations. The regeneration capacity was evaluated over four sequential adsorption–desorption cycles, demonstrating the possibility of reusing the adsorbent and reducing the environmental impact. [ABSTRACT FROM AUTHOR]

The reuse of a wastewater treatment system was investigated using intermittent media infiltration (IMI) to evaluate the fecal coliform (FC) removal efficiency with natural zeolite containing clinoptilolite from the state of San Luis Potosí, Mexico and its zinc-modified form (Zeo-Zn). The municipal wastewater, which was from Saltillo, Coahuila, Mexico, was treated for FC analysis for four months. The physicochemical properties of zeolite were analyzed, and their behavior as filter media for FC removal with an IMI system was studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and X-Ray fluorescence techniques (XRF). At the conditions under which natural zeolite was treated to functionalize its surface with a bactericide agent (Zn2+), there were no significant structural and chemical changes in the clinoptilolite contained in the natural zeolite. Thus, Zeo-Zn could be regenerated by treatment with a zinc salt after a long-term IMI process. The use of Zeo-Zn resulted in an average FC removal efficiency (2.99 ± 0.92 log) and FC reduction (99.44 ± 1.04%) that were significant better than those obtained with natural zeolite (approximately 47.44%). Zeo-Zn enhanced the removal of FC in the IMI system more than natural zeolite and thus complied with Mexican regulations for unrestricted reuse during the study period. The study showed that Mexican natural zeolite functionalized with zinc can be used as a disinfectant to achieve the antibacterial effect in an IMI system for wastewater treatment. [ABSTRACT FROM AUTHOR]