Enhancing interfacial charge transfer on novel 3D/1D multidimensional MoS2/TiO2 heterojunction toward efficient photoelectrocatalytic removal of levofloxacin

Magnetic-acoustic actuated spinous microrobot for enhanced degradation of organic pollutants

A growing interest in the development of efficient strategies for the removal of organic pollutants from polluted water is emerging. As such, artificial micro/nano machines performing excellent water purification tasks have recently attracted more research attention of scientists. Hereby a spinous Fe3O4@PPy microrobot is presented that towards an efficient organic pollutant removal by enhancing Fenton-like reaction. The microrobot is fabricated by wrapping polypyrrole (PPy) on a spiny magnetic template prepared from sunflowers pollen. Modulating the sound pressure and frequency of the ultrasonic field enables the Fe3O4@PPy microrobot to present multimode motion, such as violent eruption-like motion caused by local cavitation (ELM), march-like unific motion (MLM), and typhoon-like rotation toward the center gathered motion (TLM). This multimode motion achieves the sufficient locomotion of microrobots in three-dimensional space and effective contact with organic pollutants in polluted water. Furthermore, a 5.2-fold increase in the degradation rate of methylene blue has been realized using Fe3O4@PPy microrobots under low-concentration hydrogen peroxide conditions. Also, the magnetically controlled recovery of microrobots from water after the completion of the degradation task has been demonstrated. The magnetic-acoustic actuated spinous microrobot can be extrapolated to other catalytic microrobot, developing a new strategy for an easier implementation and recovery of microrobot in real applications of water purification.

Advancements in electrochemical technologies for the removal of fluoroquinolone antibiotics in wastewater: A review

In recent times, the need to make water safer and cleaner through the elimination of recalcitrant pharmaceutical residues has been the aim of many studies. Fluoroquinolone antibiotics such as ciprofloxacin, norfloxacin, enrofloxacin, and levofloxacin are among the commonly detected pharmaceuticals in wastewater. Since the presence of these pharmaceuticals in water bodies poses serious risks to living organisms, it is vital to adopt effective wastewater treatment techniques for their complete removal. Electrochemical technologies such as photoelectrocatalysis, electro-Fenton, electrocoagulation, and electrochemical oxidation have been established as techniques capable of the complete removal of organics including pharmaceuticals from wastewater. Hence, this review presents discussions on the recent progress (literature within 2018-2022) in the applications of common electrochemical processes for the degradation of fluoroquinolone antibiotics from wastewater. The fundamentals of these processes are highlighted while the results obtained using the processes are critically discussed. Furthermore, the inherent advantages and limitations of these processes in the mineralization of fluoroquinolone antibiotics are clearly emphasized. Additionally, appropriate recommendations are made toward improving electrochemical technologies for the complete removal of these pharmaceuticals with minimal energy consumption. Therefore, this review will serve as a bedrock for future researchers concerned with wastewater treatments to make informed decisions in the selection of suitable electrochemical techniques for the removal of pharmaceuticals from wastewater.

Data-Driven Materials Innovation and Applications

Owing to the rapid developments to improve the accuracy and efficiency of both experimental and computational investigative methodologies, the massive amounts of data generated have led the field of materials science into the fourth paradigm of data-driven scientific research. This transition requires the development of authoritative and up-to-date frameworks for data-driven approaches for material innovation. A critical discussion on the current advances in the data-driven discovery of materials with a focus on frameworks, machine-learning algorithms, material-specific databases, descriptors, and targeted applications in the field of inorganic materials is presented. Frameworks for rationalizing data-driven material innovation are described, and a critical review of essential subdisciplines is presented, including: i) advanced data-intensive strategies and machine-learning algorithms; ii) material databases and related tools and platforms for data generation and management; iii) commonly used molecular descriptors used in data-driven processes. Furthermore, an in-depth discussion on the broad applications of material innovation, such as energy conversion and storage, environmental decontamination, flexible electronics, optoelectronics, superconductors, metallic glasses, and magnetic materials, is provided. Finally, how these subdisciplines (with insights into the synergy of materials science, computational tools, and mathematics) support data-driven paradigms is outlined, and the opportunities and challenges in data-driven material innovation are highlighted.

A comprehensive review on recent advances toward sequestration of levofloxacin antibiotic from wastewater

Among various classes of antibiotics, fluoroquinolones, especially Levofloxacin, are being administered on a large scale for numerous purposes. Being highly stable to be completely metabolized, residual quantities of Levofloxacin get accumulated into the food chain proving a great global threat for aquatic as well as terrestrial ecosystems. Various removal techniques including both conventional and advanced methods have been reported for this purpose. This review is a novel attempt to make a critical analysis of the recent advances made exclusively toward the sequestration of Levofloxacin from wastewater through an extensive literature survey (2015-2021). Adsorption and advanced oxidation processes especially photocatalytic degradation are the most tested techniques in which assorted nanomaterials play a significant role. Several photocatalysts exhibited up to 100% degradation of LEV which makes photocatalytic degradation the best method among other tested methods. However, the degraded products need to be further monitored in terms of their toxicity. Biological degradation may prove to be the most environment-friendly with the least toxicity, unfortunately, not much research is reported in the field. With these key findings and knowledge gaps, authors suggest the scope of hybrid techniques, which have been experimented on other antibiotics. These can potentially minimize the disadvantages of the individual techniques concurrently improving the efficiency of LEV removal. Besides, techniques like column adsorption, membrane treatment, and ozonation, being least reported, reserve good perspectives for future research. With these implications, the review will certainly serve as a breakthrough for researchers working in this field to aid their future findings.

Effective stabilization of atomic hydrogen by Pd nanoparticles for rapid hexavalent chromium reduction and synchronous bisphenol A oxidation during the photoelectrocatalytic process

Atomic hydrogen (H*) plays a vital role in the synchronous redox of metallic ions and organic molecules. However, H* is extremely unstable as it is easily converted to hydrogen. Herein, we designed a novel strategy for the effective stabilization of H* to enhance its utility. The synthesized Pd nanoparticles grown on the defective MoS₂ (DMS) of TiO₂ nanowire arrays (TNA) (TNA/DMS/Pd) photocathode exhibited rapid Cr(VI) reduction (~95% in 10 min) and bisphenol A (BPA) oxidation (~97% in 30 min), with the kinetic constants almost 24- and 6-fold higher than those of the TNA photocathode, respectively. This superior performances could be attributed to: (i) the generated interface heterojunctions between TNA and DMS boosted the separation efficiencies of photogenerated electrons, thereby supplying abundant valance electrons to lower the overpotential to create a suitable microenvironment for H* generation; (ii) the stabilization of H* by Pd nanoparticles resulted in a significant increase in the yield of hydroxyl radical (•OH). This research provides a new strategy for the effective utilization of H* toward rapid reduction of heavy metals and synchronous oxidation of the refractory organics.

A critical review on the applications and potential risks of emerging MoS2 nanomaterials

Molybdenum disulfide (MoS₂) nanomaterials have been widely used in various fields such as energy store and transformation, environment protection, and biomedicine due to their unique physicochemical properties. Unfortunately, such large-scale production and use of MoS₂ nanomaterials would inevitably release into the environmental system and then potentially increase the risks of wildlife/ecosystem and human beings as well. In this review, we first introduce the physicochemichemical properties, synthetic methods and environmental behaviors of MoS₂ nanomaterials and their typical functionalized materials, then summarize their environmental and biomedical applications, next assess their potential health risks, covering in vivo and in vitro studies, along with the underlying toxicological mechanisms, and last point out some special phenomena about the balance between applications and potential risks. This review aims to provide guidance for harm predication induced by MoS₂ nanomaterials and to suggest prevention measures based on the recent research progress of MoS₂' applications and exerting toxicological data.

Enhanced Adsorption of Toxic and Biologically Active Levofloxacin Residuals from Wastewater Using Clay Nanotubes as a Novel Fixed Bed: Column Performance and Optimization

Kaolinite nanotube particles (KNTs) were synthesized by a chemical exfoliation and scrolling process in the existence of sonication waves. The KNT product was identified as a mesoporous material (12 nm in pore diameter) with high surface area (105 m²/g) and promising adsorption affinity for the levofloxacin antibiotic (LVOX) residuals in wastewater. The KNT particles were used as a fixed bed in the continuous adsorption column system for LVOX considering the essential variables. The investigation of the KNT fixed bed in a continuous column for 1800 min verified its suitability to reduce the LVOX content in 9 L of polluted solutions by 80.4%. This was recognized after using the KNT bed of 4 cm in height, a flow rate of 5 mL/min, a pH value of 8, a total flow interval of 1800 min, and an LVOX concentration of 10 mg/L. The regeneration study of the bed declared effective recyclability properties for the KNT particles in the LVOX adsorption column system. The dynamic properties of the KNT bed-based column system were explained based on Thomas, Adams-Bohart, and the Yoon-Nelson kinetic models. The LVOX adsorption reaction by KNTs follows Langmuir behavior with homogeneous and monolayer uptake form. The Gaussian energy (2.05 kJ/mol) and the thermodynamic parameters emphasized physical, spontaneous, and exothermic adsorption reactions for LVOX by KNTs.

Instantaneous oxidation of levofloxacin as toxic pharmaceutical residuals in water using clay nanotubes decorated by ZnO (ZnO/KNTs) as a novel photocatalyst under visible light source

Kaolinite nanotubes were synthesized by a simple scrolling process and decorated by ZnO nanoparticles as a novel nanocomposite (ZnO/KNTs). The synthetic ZnO/KNTs composite was characterized as an effective photocatalyst in the oxidation of levofloxacin pharmaceutical residuals in the water resources. The composite displays a surface area of 95.4 m²/g, average pore diameter of 5.8 nm, and bandgap energy of 2.12 eV. It is of high catalytic activity in the oxidation of levofloxacin in the presence of visible light source. The complete oxidation for 10 mg/L of levofloxacin was recognized after 55 min, 45 min, and 30 min with applying 30 mg, 40 mg, and 50 mg of ZnO/KNTs as catalyst dosage, respectively. Additionally, it achieved complete oxidation for 20 mg/L and 30 mg/L of levofloxacin after 45 min and 75 min, respectively using 50 mg as catalyst dosage. The degradation efficiency was confirmed by detecting the residual TOC after the treatment tests and the formed intermediate compounds were identified to suggest the degradation pathways. In addition to the oxidation pathway, the mechanism was evaluated based on the active trapping tests that proved the dominance of hydroxyl radicals as the essential active species. Finally, the ZnO/KNTs composite is of promising recyclability properties and achieved better results than several studied photocatalysts in literature.

Enhanced decontamination of levofloxacin as toxic pharmaceutical residuals from water using CaO/MgO nanorods as a promising adsorbent

Novel MgO/CaO nanocomposite (MgO/CaO NRs) was synthesized by the hydrothermal method using diatomite porous frustules as a substrate under the microwave irradiation. The composite appeared as well crystalline rod-like nanoparticles with 52.3 nm as average particle size and 112.8 m²/g as BET surface area. The synthetic MgO/CaO NRs were addressed as a novel adsorbent for promising removal of levofloxacin (LVX) as pharmaceutical residuals. The adsorption studies revealed effective uptake of levofloxacin by MgO/CaO NRs with theoretical q_max of 106.7 mg/g and the equilibrium time of 720 min considering the best pH value (pH 7). The equilibrium studies highly fitted with the Langmuir model of monolayer adsorption considering the values of Chi-squared (χ²) and determination coefficient. The estimated adsorption energy from Dubinin–Radushkevich (0.2 kJ/mol) signifies physisorption mechanisms that might be coulombic attractive forces considering the kinetic studies. The thermodynamic addressing for the reactions verified their spontaneous and exothermic nature within a temperature range from 303 to 333 K. Additionally, the prepared MgO/CaO NRs show significant recyclability properties to be used in realistic remediation process and its uptake capacity is higher than several studied adsorbents in literature.

Bimetallic PtCu nanoparticles supported on molybdenum disulfide-functionalized graphitic carbon nitride for the detection of carcinoembryonic antigen

A molybdenum disulfide based graphite phase carbon nitride (MoS₂/g-C₃N₄) which is supported by a platinum-copper nanoparticle (PtCu) Z-type catalyst was created in this study. The catalyst exploits optoelectronic synergistic effect with large surface area, good catalysis, and biocompatibility to amplify the signal. The electrode impedance of the synthesized MoS₂/g-C₃N₄-PtCu was reduced five times in visible light compared with dark conditions, thereby improving the detection of carcinoembryonic antigen (CEA). At a voltage of - 0.4 V, the immunoprobe constructed with this material is used for CEA detection. A linear relationship between 100 fg mL^-1 and 80 ng mL^-1 concentrations was achieved with a minimum detection limit of 33 fg mL^-1 (S/N = 3). The recovery rate was 103-104%, and the relative standard deviation was 2.9-3.8%. This implies that the sandwich immunosensors have good reproducibility, selectivity, and stability and can be used in various applications. Graphical Abstract.

Quantitative structure-property relationship of the photoelectrochemical oxidation of phenolic pollutants at modified nanoporous titanium oxide using supervised machine learning

Here we report on an advanced photoelectrochemical (PEC) oxidation of 22 phenolic pollutants based on modified nanoporous TiO2, which was directly grown on a titanium substrate electrochemically. Their degradation rate constants were experimentally determined and their physicochemical properties were computaionally calculated. The quantitative structure-property relationship (QSPR) was elucidated by employing multiple linear regression (MLR) method. A supervised machine learning approach was employed to build QSPR models. The high predictive abilities of the QSPR model were validated via leave-one-out (LOO) method and a strict regimen of statistical validation tests. The significant descriptors identified in the QSPR Model for the phenolic compounds were also assessed using a typical dye pollutant Rhodamine B, further confirming the high effectiveness and predictability of the optimized model. Our study has shown that the integrated effect of the structural, hydrophobic and topological properties along with electronic property should be considered in order to design an efficient PEC catalytic approach for environmental applications.

Highly boosted gas diffusion for enhanced electrocatalytic reduction of N2 to NH3 on 3D hollow Co-MoS2 nanostructures

Transition metal chalcogenide MoS₂ catalysts are highly selective for the electrochemical reduction of dinitrogen (N₂) to ammonia (NH₃) in aqueous electrolytes. However, due to the low solubility of N₂ in water, limited N₂ diffusion and mass transport have heavily restricted the yield and the faradaic efficiency (FE). Here, we have demonstrated a highly efficacious assembled gas diffusion cathode with hollow Co-MoS₂/N@C nanostructures to significantly improve the electrochemical reduction of N₂ to NH₃. Our results revealed that the synthesized Co-MoS₂ heterojunctions with abundant graphitic N groups exhibited a superb NH₃ yield of 129.93 μg h^-1 mg_cat^-1 and a high faradaic efficiency of 11.21% at -0.4 V vs. the reversible hydrogen electrode (RHE), as well as excellent selectivity and stability. The strategy described in this study offers new inspiration to design high-performance electrocatalyst assemblies for the sustainable environmental and energy applications.

Boosting interfacial charge transfer and electricity generation for levofloxacin elimination in a self-driven bio-driven photoelectrocatalytic system

Recently, molybdenum disulfide (MoS2) has stimulated significant research interest as a promising electrode candidate in solar cells and energy conservation fields. Unfortunately, the short lower electron/hole migration lifetimes and easy agglomeration hamper its wide practical applications to some extent. Herein, interface engineering coupled with a bio-assisted photoelectrochemical (PEC) strategy is presented to construct a 0D MoS2 quantum dot (QD)/1D TiO2 nanotube electrode for pollutant elimination. Aimed at accelerating charge transfer over the 0D/1D composite interface, three types of coupling PEC models were developed to optimize the catalytic performance. The single chamber microbial fuel cell (SCMFC)-PEC integrated system was found to be the best alternative for levofloxacin (LEV) elimination (0.029 min-1), and the sequential SCMFC-PEC further realized the whole system self-running independently. In addition, the interfacial electron migration and LEV degradation pathways were thoroughly investigated by LC/TOF/MS coupled with density functional theory (DFT) calculations to clearly elucidate the electron transfer paths, LEV-attacked sites and mineralization pathways in a joint sequential SCMFC-PEC system. As such, the constructed self-recycling system provides a new platform for bio-photo-electrochemical utilization, which could exhibit promising potential in environmental purification.

Sulfur vacancy-rich N-doped MoS2 nanoflowers for highly boosting electrocatalytic N2 fixation to NH3 under ambient conditions

Sulfur vacancy-rich N-doped MoS₂ nanoflowers act as highly effective electrochemical catalysts for efficient nitrogen reduction.