3D defective graphenes with subnanometric porosity obtained by soft-templating following zeolite procedures

Integrated Adsorption-Photocatalytic Decontamination of Oxytetracycline from Wastewater Using S-Doped TiO2/WS2/Calcium Alginate Beads

Integrated wastewater treatment processes are needed due to the inefficient removal of emerging pharmaceuticals by single methods. Herein, an adsorbent-photocatalyst integrated material was fabricated by coupling calcium alginate with sulfur-doped TiO2/tungsten disulfide (S-TiO2/WS2/alginate beads) for the removal of oxytetracycline (OTC) from aqueous solution by an integrated adsorption-photocatalysis process. The semiconductor S-TiO2/WS2 hybrid photocatalyst was synthesized with a hydrothermal method, while the integrated adsorbent-photocatalyst S-TiO2/WS2/alginate beads were synthesized by blending S-TiO2/WS2 with sodium alginate using calcium chloride as a precipitating agent. The physicochemical characteristics of S-TiO2/WS2/alginate beads were analyzed using X-ray diffraction , scanning electron microscopy, elemental mapping, X-ray photoelectron spectroscopy, and photoluminescence spectroscopy. The integrated adsorption-photocatalysis process showed enhanced removal from 92.5 to 72%, with a rise in the OTC concentration from 10 to 75 mg/L respectively. The results demonstrated that the adsorption of OTC onto S-TiO2/WS2/alginate beads followed the Elovich kinetic model and Redlich–Peterson isotherm models. The formations of H-bonds, cation bridge bonding, and n-π electron donor-acceptor forces were involved in the adsorption of OCT onto S-TiO2/WS2/alginate beads. In the integrated adsorption-photocatalysis, surface-adsorbed OTC molecules were readily decomposed by the photogenerated active radical species (h⁺, O2•−, and HO•). The persulfate addition to the OTC solution further increased the photocatalysis efficacy due to the formation of additional oxidizing species (SO4•⁻, SO4⁻). Moreover, S-TiO2/WS2/alginate beads showed favorable efficiency and sustainability in OTC removal, approaching 78.6% after five cycles. This integrated adsorption-photocatalysis process offered significant insight into improving efficiency and reusability in water treatment.

Biopolymeric Ni3S4/Ag2S/TiO2/Calcium Alginate Aerogel for the Decontamination of Pharmaceutical Drug and Microbial Pollutants from Wastewater

The ubiquitous presence of pharmaceutical drugs and microbes in the water is leading to the development of drug resistant microbes. Therefore, efficient materials that can remove or inactivate the drug and microbe contaminants are required. In this work, nickel sulfide/calcium alginate (Ni3S4/CA), silver sulfide/calcium alginate (Ag2S/CA), modified titanium dioxide/calcium alginate (TiO2/CA), and Ni3S4/Ag2S/TiO2/calcium alginate (Ni3S4/Ag2S/TiO2/CA) aerogels have been synthesized for the removal of the oxytetracycline (OTC) drug and microbial contaminants from real beverage industry wastewater. The results revealed that Ni3S4/Ag2S/TiO2/CA aerogel is highly efficient for OTC adsorption and inactivation of microbes compared to Ni3S4/CA, Ag2S/CA and TiO2/CA aerogels. The OTC adsorption depends greatly on the solution pH, and optimum OTC removal was observed at pH 6 in its zwitterionic (OTC±) form. The formation of H-bonding and n-π electron donor-acceptors is possible to a considerable extent due to the presence of the double bond benzene ring, oxygen and nitrogen, sulfur-containing functional groups on the OTC molecules, and the Ni3S4/Ag2S/TiO2/CA aerogel. Based on the statistical analysis, root-mean-square deviation (RMSD), chi square (χ2) values, and higher correlation coefficient (R2) values, the Redlich−Peterson isotherm model and Elovich kinetic model are most suited to modelling the OTC adsorption onto Ni3S4/Ag2S/TiO2/CA. The prepared aerogels’ excellent antimicrobial activity is observed in the dark and with solar light irradiation. The zone of inhibition analysis revealed that the antimicrobial activity of the aerogels is in the following order: Ni3S4/Ag2S/TiO2/CA > TiO2/CA > Ag2S/CA > Ni3S4/CA, respectively. Moreover, the antimicrobial results demonstrated that reactive oxygen species, electrons, and active radical species are responsible for growth inhibition and killing of the microbes. These results indicated that Ni3S4/Ag2S/TiO2/CA aerogel is highly efficient in decontaminating pollutants from wastewater.

Baldovi H, Dhakshinamoorthy A, Primo A, Garcia H. Tridimensional N, P-Codoped Carbon Sponges as Highly Selective Catalysts for Aerobic Oxidative Coupling of Benzylamine

Two tridimensional N-doped porous carbon sponges (3DC-X) have been prepared by using cetyltrimethylammonium chloride (CTAC) and cetyltrimethylammonium bromide (CTAB) as soft templates and alginate to replicate the liquid crystals formed by CTA+ in water. Alginate is a filmogenic polysaccharide of natural origin having the ability to form nanometric defectless films around objects. Subsequent pyrolysis at 900 °C under an Ar flow of the resulting CTA+-polysaccharide assemblies result in 3DC-1 and 3DC-2, with the N percentages of 0.48 and 0.36 wt % for the materials resulting from CTAC and CTAB, respectively. Another four 3DC materials were obtained via pyrolysis of the adduct of phytic acid and chitosan, rendering an amorphous, N and P-codoped carbon sample (3DC-3 to 3DC-6). The six 3DC samples exhibit a large area (>650 m2 × g-1) and porosity, as determined by Ar adsorption. The catalytic activity of these materials in promoting the aerobic oxidation of benzylamine increases with the specific surface area and doping, being the largest for 3DC-4, which is able to achieve 73% benzylamine conversion to N-benzylidene benzylamine in solventless conditions at 70 °C in 5 h. Quenching studies and hot filtration tests indicate that 3DC-4 acts as a heterogeneous catalyst rather than an initiator, triggering the formation of hydroperoxyl and hydroxyl radicals as the main reactive oxygen species involved in the aerobic oxidation.

Porous Graphitic Carbons Containing Nitrogen by Structuration of Chitosan with Pluronic P123

Using Pluronic P123 as a structure-directing agent and chitosan as a carbon precursor, different porous carbons with remarkable morphologies such as orthohedra or spheres with diametrically opposite holes are obtained. These particles of micrometric size are constituted by the stacking of thin sheets (60 nm) that become increasingly bent in the opposite sense, concave in the upper and convex in the bottom hemispheres, as the chitosan proportion increases. TEM images, after dispersion of the particles by sonication, show that besides micrometric graphene sheets, the material is constituted by nanometric onion-like carbons. The morphology and structure of these porous carbons can be explained based on the ability of Pluronic P123 to undergo self-assembly in aqueous solution due to its amphoteric nature and the filmogenic properties of chitosan to coat Pluronic P123 nanoobjects undergoing structuration and becoming transformed into nitrogen-doped graphitic carbons. XPS analysis reveals the presence of nitrogen in their composition. These porous carbons exhibit a significant CO2 adsorption capacity of above 3 mmol g-1 under 100 kPa at 273 K attributable to their large specific surface area, ultraporosity, and the presence of basic N sites. In addition, the presence of dopant elements in the graphitic carbons opening the gap is responsible for the photocatalytic activity for H2 generation in the presence of sacrificial electron donors, reaching a H2 production of 63 μmol g-1 in 24 h.