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Herein, we report for the first time the use of ternary oxide nanoheterostructure photocatalysts derived from (Nby, Ti1-y)2CTx MXene in the treatment of water. Three different compositions of binary MXenes, viz., (Ti0.75Nb0.25)2CTx, (Ti0.5Nb0.5)2CTx, and (Ti0.25Nb0.75)2CTx (with Tx = OH, F, and Cl), were used as single-source precursor to produce TiNbOx-3:1, TiNbOx-1:1, and TiNbOx-1:3 by controlled-atmosphere thermal oxidation. Phase identification and Le Bail refinements confirmed the presence of a mixture of rutile TiO2 and monoclinic Ti2Nb10O29. Morphological investigations through scanning and transmission electron microscopies revealed the retention of layered nanostructures from the MXene precursors and the fusion of TiO2 and Ti2Nb10O29 nanoparticles in forming nanosheets. Among the three oxide nanoheterostructures, TiNbOx-3:1 exhibited the best photocatalytic performance by the removal of 83% of sulfamethoxazole (SMX) after 2 h of reaction. Such a result is explained by a complex influence of structural, morphological, and electronic properties since TiNbOx-3:1 consisted of small-sized crystallites (40-70 nm) and possessed a higher surface area. The suggested electronic band structure is a type-II heterojunction, where the recombination of electrons and holes is minimized during photocatalytic reactions. The photocatalytic degradation of SMX was promoted by the attack of •OH, as evidenced by the detection of 2.2 μM •OH, using coumarin as a probe. This study highlights the potential application of MXene-derived oxide nanoheterostructures in wastewater treatment. [ABSTRACT FROM AUTHOR]

MXene is an innovative multilayered material that has been prepared by an acid-salt (HCl + NH4F) etching route and tested for the removal of 133Ba and 137Cs in radioactive conditions for the first time. MXene has exhibited high uptake capacity of about 154.9 and 121.5 mg g−1 for 133Ba and 137Cs, respectively, in 0.01 mol L−1 solution and using 5 g L−1 of adsorbent at natural pH. [ABSTRACT FROM AUTHOR]

Nanoparticles of zinc oxide (ZnO) combined with a Jania rubens (JR) biosorbent have been embedded in a sodium alginate (SA)–polyvinyl alcohol (PVA) matrix. This hybrid biosorbent was characterized by FTIR, and the presence of functional groups involved in the adsorption of Pb2+ was revealed. SEM/EDX analyses have shown that the hybrid biosorbent exhibited porous microstructures which are decorated with ZnO nanoparticles (hydrodynamic size of 68 ± 2 nm). The removal of Pb2+ from aqueous medium was thoroughly investigated. The adsorption capacity has been measured at qe = 39.1 mg g−1 at pH = 5 and T = 303 K with the concentration of biosorbent and Pb2+ at 2.0 g L−1 and 100 mg L−1, respectively. The Freundlich and Langmuir isotherms have been used to model the adsorption process, from which the maximum adsorption capacity (qm) of the hybrid biosorbent was calculated to be 111 mg g−1. The adsorption kinetics are represented by a pseudo-second order model. In addition, the hybrid biosordent was regenerated and reused for four cycles for the removal of Pb2+. [ABSTRACT FROM AUTHOR]

The preparation of anodic TiO2 nanotube layers has been performed using electrochemical anodization of Ti foil for 4 h at different voltages (from 0 V to 80 V). In addition, a TiO2 thin layer has been also prepared using the sol–gel method. All the photocatalysts have been characterized by XRD, SEM, and DRS to investigate the crystalline phase composition, the surface morphology, and the optical properties, respectively. The performance of the photocatalyst has been assessed in versatile photocatalytic reactions including the reduction of N2O gas and the oxidation of aqueous sulfamethoxazole. Due to their high specific surface area and excellent charge carriers transport, anodic TiO2 nanotube layers have exhibited the highest N2O conversion rate (up to 10% after 22 h) and the highest degradation extent of sulfamethoxazole (about 65% after 4 h) under UVA light. The degradation mechanism of sulfamethoxazole has been investigated by analyzing its transformation products by LC-MS and the predominant role of hydroxyl radicals has been confirmed. Finally, the efficiency of the anodic TiO2 nanotube layer has been tested in real wastewater reaching up to 45% of sulfamethoxazole degradation after 4 h. [ABSTRACT FROM AUTHOR]