Carbamazepine (CBZ), an anticonvulsant drug, is one of the most recalcitrant pharmaceuticals detected in wastewater. For the photocatalytic degradation of CBZ, visible light assisted heterogeneous ...Fenton-like hybrid composites were synthesized via a co-precipitation method by anchoring magnetite (Fe3O4) with reduced graphene oxide (rGO). The rGO loading not only reduced the aggregation of Fe3O4 nanoparticles, but also increased the adsorption capacity of the hybrid composites. The mass ratio of rGO in the composites substantially affected CBZ photocatalytic degradation and a 10 wt% rGO loading (rGF10) provided nearly complete CBZ degradation within 3 h. Moreover, the addition of rGO reduced the charge recombination of the bare Fe3O4 nanoparticles and provided more accessible reactive sites, enhancing the degradation capacity. The visible light excited Fe3O4 nanoparticles yielded reactive species such as hydroxyl radicals (·OH), holes (h+), and superoxide radicals (O2·−) during the photodegradation process that were evaluated by using specific scavengers during the degradation experiment. The hybrid catalyst was effective under wide pH ranges (from 3 to 9) and showed faster degradation rates in the acidic condition. The composites were magnetically separable, easily regenerated, and exhibited considerably high photocatalytic activity up to five cycles.
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•A Fenton-like composite was synthesized by co-precipitation method.•The composite photochemically degraded CBZ molecule under solar light.•Certain amount of rGO loading in magnetite increased the photodegradation capacity.•A 10 wt% rGO loading was optimum to get highest degradation capacity.•The composite was reusable and the TOC removal was high after the reaction.
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•A simple hydrothermal process is used for the fabrication of Ti3C2Tx (MXene) nanosheets.•Ti3C2Tx MXene-based heterojunction (001-T/MX) can be used as a photocatalyst.•Carbamazepine ...(CBZ) degradation under direct sunlight and ultraviolet light is studied.•T/MX photocatalyst degrades 98.67% CBZ under UV light irradiation.
A simple hydrothermal treatment process was used for the fabrication of a Ti3C2Tx (MXene) nanosheet-based hybrid photocatalyst. The chemical composition of the MXene and its derivatives (nanosize {0 0 1} facets of TiO2 in Ti3C2Tx (001-T/MX)), as well as the structural properties and morphology of the as-prepared photocatalyst, were well characterised. The heterostructure of the as-prepared photocatalyst was obtained by controlled oxidation action via the Schottky junction formed between TiO2-MXene interfaces. The adsorption/photocatalytic degradation abilities of the pristine MXene and the as-synthesised 001-T/MX nanocomposite for carbamazepine (CBZ) were investigated. The determined Kapp value of CBZ under ultraviolet light was 0.0304 min−1, higher than that under natural solar light, and the degradation capacity was strongly controlled under acidic conditions (pH 3.0–5.0). During the photocatalytic degradation, OH and O2 attacked the CBZ molecule; detailed degradation pathways were proposed accordingly. The novel heterojunction 001-T/MX exhibited excellent applicability for CBZ decomposition.
Two-dimensional Ti3C2Tx MXene nanosheets intercalated with sodium ions (SI-Ti3C2Tx) was synthesized by a facile batch fabrication method and applied for Ciprofloxacin (CPX) removal in the adsorption ...and electrochemical regeneration process. The successful synthesis and properties of the synthesized nanosheets were evaluated with X-ray diffraction (XRD), FE-scanning electron microscopy (SEM), FE-transmission electron spectroscopy, Zeta-potential analyses, and X-ray photoelectron spectroscopy. After intercalation, the surface terminations and the spacing between the layers of SI-Ti3C2Tx MXene were increased which enhanced the adsorption capacity of nanosheets in terms of fast kinetics and higher removal rates. As a result, 10 mg L−1 CPX was reduced to approximately 1 mg L−1 in just 15–20 min, which is an extraordinary kinetic behavior in CPX adsorption. Elovich kinetic model and the Redlich-Peterson isotherm model fitted the experimental data with the highest correlation coefficient. SI-Ti3C2Tx could be completely regenerated through an electrochemical regeneration approach within 5 min. Even after the subsequent adsorption and regeneration cycles, the removal rate enhanced up to ~99.7%. After the electrochemical treatment, the results of XRD and SEM indicated the stability of the material. Results obtained herein suggest that this type of nanoadsorbent will be useful in practical water treatment applications.
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•Sodium intercalated Ti3C2Tx (SI-Ti3C2Tx) MXene nanosheets were fabricated using a simple batch reaction method.•The SI-Ti3C2Tx MXene provided better CPX adsorption performance than pristine Ti3C2Tx MXene.•An increase in spacing between layers and higher surface terminations collectively enhanced the adsorption capacity.•The electrochemical technique along with complete regeneration improved the adsorption capacity.•SI-Ti3C2Tx was found to be stable for five regeneration cycles.
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•A novel PGP hydrogel was synthesized by a facile synthesis route.•Hydrogel with a rGO-to-P25 mass ratio of 1:0.5 showed higher photocatalytic activity.•Radical scavenger experiments ...revealed hydroxyl radical as the main oxidative species.•PGP composite showed high reusability up to five cycles.•RSM was employed to determine the optimal conditions for enhanced MB removal.
An environment-friendly hydrogel was synthesized by entrapping Degussa P25 on the surface of a reduced graphene oxide (rGO)-polyacrylamide (PAM) matrix.The PAM content of the P25-rGO-PAM (PGP) hydrogel considerably influenced the adsorption and photocatalytic degradation of methylene blue (MB), and the optimal PAM content was 10% (w/v). Furthermore, rGO not only enhanced the adsorption capacity of the hydrogel by increasing the surface area but also increased the photodegradation efficiency synergistically by separating electron-hole pairs. The reaction kinetic constant for MB degradation by the hydrogel was 0.0276 min−1, which was three and five times the reaction kinetic constants of P25-PAM and rGO-PAM hydrogels, respectively. The synthesized PGP showed high stability and its MB degradation efficiency was considerably high up to five consecutive cycles under UV-irradiation. The eco-friendly nature of the hydrogel was evaluated on the basis of bacterial inactivation, and the treated water was found to be safe for use. Three key operating parameters (initial MB concentration, temperature, and pH) were optimized for maximizing MB removal using a response surface methodology. The complete MB removal efficiency was obtained for the optimal conditions of pH 9.4, a temperature of 31.2 °C, and an initial MB concentration of 5.2 mg/L.
Advanced engineering of naturally occurring materials opens new doors in nanoscience and nanotechnology for the separation and/or removal of environmental hazards. Here, a series of nanocomposites ...containing kaolinite and chitosan varying in the range of 20 to 80% (w/w) kaolinite were used for the adsorptive removal of a reactive textile dye, Remazol Red, from an aqueous solution. Batch experiments were carried out to investigate the effects of pH, contact time, and initial dye concentration on the adsorption capacity. Nanocomposites containing 80% kaolinite (w/w) and 20% chitosan (w/w), i.e., NK80C20, showed an equilibrium adsorption capacity of 371.8 mg/g at pH 2.5, which was 5.2 times higher than that of commercial activated charcoal. Moreover, NK80C20 was regenerated instantly up to 99.9% at pH 10. Therefore, NK80C20 can be effectively utilized as a potential adsorbent for the separation of Remazol Red and homologous azo dyes from industrial effluents. We expect that the findings from this study will play a vital role in environmental research leading to advanced applications in water purification.
Fabrication of MX-SA4:20 spheres through MXene-Alginate networking and their application in Hg2+ uptake.
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•Ti3C2Tx nanosheets were synthesized using a low-toxicity etching agent ...(NH4F).•Core-shell of MX-SA4:20 spheres was capable of very effectively removing heavy metals.•MX-SA4:20 spheres exhibited exceptional Hg2+ adsorption capacity of 932.84 mg g−1.•MX-SA4:20 performed excellently in extreme acidic conditions.
Two-dimensional (2-D) titanium carbide MXene core (Ti3C2Tx) shell aerogel spheres (MX-SA) for mercuric ion removal were designed and fabricated with varying concentrations of Ti3C2Tx MXene and sodium alginate (SA) using a facile method. Owing to their unique inside structures, high porosities, large specific surface areas, oxygenated functional groups of MXene nanosheets, and available active binding sites, the synthesized microspheres constitute a unique adsorbent for heavy metals removal in water. The MX-SA4:20 spheres exhibit an exceptional adsorption capacity of 932.84 mg/g for Hg2+, which is among the highest value reported for adsorbents. The adsorbent exhibits high single- and multi-component removal efficiencies, with 100% efficiency for Hg2+ and >90% efficiency for five heavy metal ions. The synthesized materials are highly efficient for Hg2+ removal under extreme pH conditions (0.5–1.0 M HNO3) and have additional excellent reproducible properties. The micro-size and spherical shape of MX-SA4:20 also allow it to be used in column-packed devices.
A highly efficient anode is very crucial for an improved microbial fuel cell (MFC) performance. In this study, a binder-free manganese cobalt oxide (MnCo2O4@CF) anode was synthesized using a ...conventional carbon felt (CF) by a facile hydrothermal method. A large electrochemically active and rough electrode surface area of MnCo2O4@CF anode improved the substrate fluxes and microbial adhesion/growth. Furthermore, the electrochemical tests on the synthesized anode confirmed the superior bioelectrochemical activity, reduced ion transfer resistance, and excellent capacitance. This resulted in an improved power density (945 mW/m2), which was 3.8 times higher than that of CF anode. The variable valence state, high stability and biocompatibility of MnCo2O4@CF resulted in continuous current density performance for five MFC cycles. High-throughput biofilm analysis revealed the enrichment of electricity producing phylum of Proteobacteria and Bacteroidetes (∼90.0%), which signified that the modified MnCo2O4 anode accelerated the enrichment of electro-active microbes.
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•A binderless and stable MnCo2O4@CF anode was fabricated using a facile hydrothermal method.•The synthesized anode generated 3.8 times higher power density than the uncoated electrode.•The improved current density was observed for all five MFC cycles.•Biofilm was enriched with electro-active microorganisms of Proteobacteria and Bacteroidetes.
Fe-based amorphous alloys have been found to be very efficient in the degradation of water pollutants due to their unique atomic arrangements with long-range disordered structure. In this work, ...Fe–B–C–Ti amorphous ribbons were successfully synthesized and showed high catalytic efficiency in the degradation of methylene blue (MB) under simulated sunlight and across a wide pH range. The catalytic efficiency was evaluated under different conditions to optimize the degradation performance. The amorphous ribbon Fe75B10C10Ti5 was found to exhibit the highest photocatalytic activity as explained by its optical and photoelectrochemical properties. It can degrade MB completely with low Fe-leaching and significant recyclability at pH close to a neutral range (pH 5). The degradation mechanisms can be explained in terms of photocatalytic activity along with the galvanic cell effect which contributed to the efficient MB degradation. This work provides a comprehensive idea for the synthesis of amorphous alloys by optimizing their elemental composition and also explains the catalytic activity of partially crystallized regions on the ribbon surface. The significant corrosion resistance and the quick degradation of MB in a wide pH range in a recyclable manner by these easily separable and highly efficient catalysts indicate great potential for their practical application.
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•FeBCTi ribbons with high catalytic efficiency for the degradation were synthesized.•High efficiency was attributed to the heterogeneous structures and photocatalysis.•Amorphous ribbon Fe75B10C10Ti5 gave 100% MB degradation within 4 min at pH 3.•Ti addition enhanced the corrosion resistance and the light harvesting property.
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•A novel MXene-coated CF cathode was fabricated using a facile dip-and-dry method.•The MXene@CF biocathode exhibited excellent microbial electrosynthesis performance.•A 2.9-fold ...increase in average current density was observed using the modified cathode.•The MXene@CF biocathode produced a more continuous and electroactive biofilm.
Microbial electrosynthesis (MES) is a promising bioelectrochemical technology for the simultaneous consumption of carbon dioxide/bicarbonate and generation of useful chemical products. However, low current densities and a narrow product range with an inadequate production rate are bottlenecks in current MES technologies. In response to this, cathode modification has been suggested as a strategy to improve MES performance. Titanium carbide (Ti3C2TX MXene), a recently discovered 2D material, has a multilayered structure, high surface area, and excellent conductivity, which are prerequisites for an excellent cathode material. In this study, a novel MXene-coated carbon felt electrode (MXene@CF) was fabricated and investigated for use in MES. The modified cathode material exhibited excellent current generation and volatile fatty acid production. The availability of more active sites and sufficient space for microbial growth enhanced the mass transfer between the microbes and the substrate, resulting in a 1.6-, 1.1-, and 1.7-fold increase in the concentration of acetic, butyric, and propionic acid, respectively, compared to uncoated carbon felt. Scanning electron microscopy, electrochemical, and microbial community analyses revealed that the MXene-coated cathode promoted the formation and enrichment of biofilm. Thus, these results demonstrate that MXene@CF is a promising cathode material for MES.
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•Sodium alginate helped to synthesize a robust graphene-TiO2 aerogel.•Graphene-TiO2/sodium alginate aerogel efficiently degraded microcystin-LR.•Synthesized aerogel was highly ...recyclable without producing any secondary pollution.•In microcystin-LR degradation pathway, significant role of OH radicals was found.
In this study, sustainable graphene oxide-TiO2/sodium alginate and reduced graphene oxide-TiO2/sodium alginate aerogels were synthesized and the potential of these aerogels was investigated for microcystin-LR degradation in aqueous solution. Along with the role of alginate in the synthesis of aerogels, effects of different concentrations of photocatalyst, photolysis, pH, and combination of TiO2 (anatase)/Degussa P25 with graphene were investigated in lieu of microcystin-LR photodegradation.The complete degradation of microcystin-LR was attained in case of reduced graphene oxide-TiO2/sodium alginate aerogel—not in graphene oxide-TiO2/sodium alginate aerogel case—by the synergistic effect of adsorption and photodegradation. The recyclability study of reduced graphene oxide-TiO2/sodium alginate aerogel demonstrated high stability and photoactivity and the degradation efficiency was not much hampered during six consecutive cycles of degradation reaction. The possible fragmentation pathways were also proposed based on identified intermediate products. High adsorption and degradation synergy and ease of separation/recycling of reduced graphene oxide-TiO2/sodium alginate aerogel can make it a suitable option for removing microcystin-LR from water systems.
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