Boron nitride ultrathin fibrous nanonets: one-step synthesis and applications for ultrafast adsorption for water treatment and selective filtration of nanoparticles

Recent progress on plant extract-mediated biosynthesis of ZnO-based nanocatalysts for environmental remediation: Challenges and future outlooks

The plant extract mediated green synthesis of nanomaterials has attracts enormous interest due to its cost-effectiveness, greener, and environmentally friendly. It is also considered as an alternative and facile method in which the phytochemicals can be used as a natural capping and reducing agents and helped to produce nanomaterials with high surface area, different sizes, and shapes. One of the materials fabricated using green methods is zinc oxide (ZnO) semiconductor due to its enormous applications in different field areas. In this review, an overview of recent progress on green synthesized ZnO-based catalysts and various modification methods for the purpose of enhancing the catalytic activity of ZnO and the corresponding structural-activity and interactions towards the removal of pollutants are highlighted. Particularly, the plant extract mediated ZnO-based photocatalysts application for the removal of pollutants via photocatalytic degradation, reduction reaction, and adsorption mechanism are demonstrated. Besides, the opportunities, challenges, and future outlooks of ZnO-based materials for environmental remediation with green and sustainable methods are also included. We believe that this review is a timely and comprehensive review on the recent progress related to plant extract mediated ZnO-based nanocatalysts synthesis and applications for environmental remediation.

Cytotoxic and photocatalytic studies of hexagonal boron nitride nanotubes: a potential candidate for wastewater and air treatment

Boron nitride (BN) nanomaterials are rapidly being investigated for potential applications in biomedical sciences due to their exceptional physico-chemical characteristics. However, their safe use demands a thorough understanding of their possible environmental and toxicological effects. The cytotoxicity of boron nitride nanotubes (BNNTs) was explored to see if they could be used in living cell imaging. It was observed that the cytotoxicity of BNNTs is higher in cancer cells (65 and 80%) than in normal cell lines (40 and 60%) for 24 h and 48 h respectively. The influence of multiple experimental parameters such as pH, time, amount of catalyst, and initial dye concentration on percentage degradation efficiency was also examined for both catalyst and dye. The degradation effectiveness decreases (92 to 25%) as the original concentration of dye increases (5-50 ppm) due to a decrease in the availability of adsorption sites. Similarly, the degradation efficiency improves up to 90% as the concentration of catalyst increases (0.01-0.05 g) due to an increase in the adsorption sites. The influence of pH was also investigated, the highest degradation efficiency for MO dye was observed at pH 4. Our results show that lower concentrations of BNNTs can be employed in biomedical applications. Dye degradation properties of BNNTs suggest that it can be a potential candidate as a wastewater and air treatment material.

High-Performance Boron Nitride Based Membranes for Water Purification

In recent years, nanotechnology-based approaches have resulted in the development of new alternative sustainable technologies for water purification. Two-dimensional (2D) nanomaterials are an emerging class of materials for nanofiltration membranes. In this work, we report the production, characterisation and testing of a promising nanofiltration membrane made from water-exfoliated boron nitride (BN) 2D nanosheets. The membranes have been tested for water purification and removal of typical water-soluble dyes such as methyl orange, methylene blue and Evans blue, with the water-exfoliated BN membranes achieving retention values close to 100%. In addition, we compared the performance of membranes made from water-exfoliated BN with those produced from BN using sonication-assisted liquid exfoliation in selected organic solvents such as 2-propanol and N-methyl-2-pyrrolidone. It was found that membranes from the water-exfoliated BN showed superior performance. We believe this research opens up a unique opportunity for the development of new high-performance environmentally friendly membranes for nanofiltration and new sustainable separation technologies.

Cross-linked sulfydryl-functionalized graphene oxide as ultra-high capacity adsorbent for high selectivity and ppb level removal of mercury from water under wide pH range

It is highly desirable but remains extremely challenging to develop a facile strategy to prepare adsorbent for dealing with heavy metal pollution in water. Here, we report a facile approach for preparing sulfydryl-functionalized graphene oxide (S-GO) by cross-linking method with an unprecedented adsorption capacity and ultrahigh selectivity for efficient Hg(II) removal. The adsorbents exhibit a prominent performance in capturing Hg(II) from wastewater with a record-high adsorption capacity of 3490 mg/g and rapid kinetics to reduce Hg(II) contaminants below the discharge standard of drinking water (2 ppb) within 60 min under a wide pH range even in the coexistent of other interfering metal ions. In addition, the adsorbents can be also easily recycled and reused multiple times with no apparent decline in removal efficiency. Considering the broad diversity, we developed also a magnetic Fe₃O₄/S-GO adsorbent by a simple chemical cross-linking reaction to achieve rapid separation of S-GO from their aqueous solution. In addition, the adsorbents were successfully applied in dealing with the practical industrial wastewater. The results indicate the potential of rationally designed sulfydryl-functionalized graphene oxide for high performance Hg(II) removal.

Hexabromocyclododecane alters malachite green and lead(II) adsorption behaviors onto polystyrene microplastics: Interaction mechanism and competitive effect

The role of microplastics (MPs) as a carrier of pollutants in water environment is an emerging issue; however, information regarding the underlying mechanisms for malachite green (MG) and Pb(II) adsorption onto hexabromocyclododecane (HBCD)-polystyrene (PS) composites MPs (HBCD-PS MPs) is still lacking. In this study, the adsorption behaviors and mechanisms of MG and Pb(II) onto PS and HBCD-PS MPs were investigated in batch adsorption experiments. The amounts of MG and Pb(II) adsorbed onto PS MPs were negligible while the presence of HBCD significantly enhanced the adsorption of MG and Pb(II) onto HBCD-PS MPs. The results of intra-particle and film diffusion model confirmed that the adsorption of MG and Pb(II) onto HBCD-PS MPs was dominated by intra-particle diffusion. The maximum adsorption amount (q_m) of Pb(II) and MG onto HBCD-PS MPs followed the sequence of Pb(II) (3.33 μmol g^-1) > MG (1.87 μmol g^-1). In binary systems, MG and Pb(II) showed competitive adsorption onto HBCD-PS MPs, and Pb(II) exhibited relatively higher affinity to be adsorbed onto HBCD-PS MPs. Solution pH and salinity played a crucial role in the adsorption process. XPS analysis suggested that the -Br participated in the adsorption process as an electron-withdrawing group. Overall, electrostatic interaction regulated the adsorption of MG and Pb(II) onto HBCD-PS MPs. Results from this study demonstrated that HBCD could enhance the role of MPs in the MG and Pb(II) migration by changing their adsorption behavior onto MPs.

Boron nitride-based materials for water purification: Progress and outlook

Analogous to the carbon family, boron nitride (BN)-based materials have gained considerable attention in recent times for applications in various fields. Owing to their extraordinary characteristics, i.e., high surface area, low density, superior thermal stability, mechanical strength, and conductivity, excellent corrosion, and oxidation resistance, the BN nanomaterials have been explored in water remediation. This article critically evaluates the latest development in applications of BN-based materials in water purification with focus on adsorption, synthesis of novel membranes and photocatalytic degradation of pollutants. The adsorption of various noxious pollutants, i.e., dyes, organic compounds, antibiotics, and heavy metals from aqueous medium BN-based materials are described in detail by illustrating the adsorption mechanism and regeneration potential. The major hurdles and opportunities related to the synthesis and water purification applications of BN-based materials are underscored. Finally, a roadmap is suggested for future research to assure the effective applications of BN-based materials in water purification. This review is beneficial in understanding the current status of these unique materials in water purification and accelerating the research focusing their future water remediation applications.

Hierarchical porous boron nitride with boron vacancies for improved adsorption performance to antibiotics

Designing atomically defective adsorbents with high specific surface area has emerged as a promising approach to improve sorption properties. Herein, hierarchical porous boron nitride nanosheets with boron vacancies (Bv-BNNSs) were in-situ synthesized via a one-step ZnCl₂-assisted strategy. Being benefitted from the dual-functional template of zinc salt, highly-active boron vacancies and abundant hierarchical pores were simultaneously generated in the Bv-BNNSs framework. By employing the boron vacancies engineering strategy, the morphological and electronic structures were controllably tuned. Meanwhile, the specific surface area was improved to as high as 1104 m²/g. Owning to the abundance of accessible surface active-sites, the sorption capacity to antibiotic tetracycline (TC) on Bv-BNNSs was boosted by 38% compared to the pristine boron nitride nanosheets (BNNSs). Detailed fitting results showed that TC sorption on Bv-BNNSs obeyed the pseudo-second order kinetic equation and the Freundlich isotherm model. The pi - pi interaction with a multi-layered stacking form was proposed as the dominated sorption mechanism. Furthermore, DFT calculations verified that the interaction energy between Bv-BNNSs and TC was enhanced. The high activity, excellent selectivity, and remarkable durability of the Bv-BNNSs nanomaterial suggest the great potential in practical wastewater treatment.

Fibrous Materials Based on Polymeric Salicyl Active Esters as Efficient Adsorbents for Selective Removal of Anionic Dye

To increase the performance efficiency and decrease the costs for organic dye wastewater purification, two fibrous adsorbents based on polymeric salicyl active esters were developed by means of a simple two-step approach. For the first time, salicyl-based active ester polymers were electrospun into fibrous membranes and subsequently postmodified with the desired functional groups under simple and mild reaction conditions. The morphology of the produced fibrous adsorbents was characterized by scanning electron microscopy (SEM), the surface properties were analyzed by nitrogen adsorption/desorption isotherms and contact angle measurements, and the completeness of the postmodification process was determined by Fourier transform infrared (FTIR) and elemental analyses. The adsorbents were further tested for their adsorption and selectivity performance of different organic dyes as well as for their recyclability. To explore the adsorption mechanism, four kinetic models and three isotherm models were used to analyze the adsorption data. The results indicated that the fibrous adsorbents showed an extremely high adsorption capacity for the anionic dye methyl blue. The fibrous adsorbents were also able to selectively adsorb anionic dyes from a mixture of anionic and cationic dyes, and they could be recycled at least 10 times. The simple and cost-efficient development process of these fibrous adsorbents and their excellent performance make them promising materials for further research and application in the area of water treatment.

A protein nanocomposite for ultra-fast, efficient and non-irritating skin decontamination of nerve agents

In recent assassinations reported in London and Malaysia, nerve agents were used to cause death, by skin poisoning. Skin decontamination is the ultimate and most important defense against nerve agent poisoning, because no effective antidote currently exists. However, almost no existing material can achieve effective and rapid decontamination without irritating the skin. This study links proteins that exhibit no decontamination ability with polymers to form a nanocomposite. This creates a nanospace on the surface of the protein that attracts and traps organic molecules, effectively adsorbing the nerve agent Soman within several seconds, without irritating the skin. Analysis of the different components of proteins and polymers reveals that the decontamination efficiency is considerably affected by the thickness of the coated polymer. Moreover, the thickness of the layer is predominantly determined by the size and species of the core and the crosslinking method. Further in vivo experiments on rats poisoned with Soman verify the efficiency and safety of the nanocomposite. These results could be used to design and synthesize more multi-functional and effective decontamination materials.

Nanoscale nickel metal organic framework decorated over graphene oxide and carbon nanotubes for water remediation

In this report, highly crystalline and well-dispersed nano-sized nickel metal organic framework (MOFs) was decorated over graphene oxide (GO) and carbon nanotubes (CNTs) platforms to form hybrid nanocomposites. These as-synthesized hybrid nanocomposites were synthesized through a one-pot green solvothermal method. The prepared nanocomposites were characterized by SEM, TEM, EDS, XRD, FT-IR, Raman and TGA techniques. XRD analysis revealed the crystalline structure of the hybrid nanocomposites. Morphological and elemental studies also verified successful decoration of nickel-benzene dicarboxylate (Ni-BDC) MOFs over GO and CNT platforms. Chemical analysis collected through IR, and thermal analysis collected through TGA technique, illustrated the presence of all the components in the hybrid nanomaterials. Methylene blue (MB) was used as a model organic pollutant to analyze the adsorption capacity of the prepared nanocomposites. According to the findings, a strong interaction exists between the MB molecule and the developed adsorbents at which due to the synergistic effect, the hybrid nanocomposites show several times higher adsorption capacity compared to that of parent materials. This improvement can be due to several reasons: high surface area of the MOFs in the composites resulting from the smaller size of MOFs, presence of the pores formed between the MOFs and the platforms and different morphological characteristic of Ni-BDC MOFs in hybrid nanocomposites, compared to bare Ni-BDC MOFs. Furthermore, the isotherm and kinetic studies revealed that the adsorption of MB onto the newly prepared adsorbents could best be explained by the Langmuir and Pseudo-second order kinetic models. A regeneration study demonstrated the highly stable nature of the hybrid nanocomposites.

From 2-D to 0-D Boron Nitride Materials, The Next Challenge

The discovery of graphene has paved the way for intense research into 2D materials which is expected to have a tremendous impact on our knowledge of material properties in small dimensions. Among other materials, boron nitride (BN) nanomaterials have shown remarkable features with the possibility of being used in a large variety of devices. Photonics, aerospace, and medicine are just some of the possible fields where BN has been successfully employed. Poor scalability represents, however, a primary limit of boron nitride. Techniques to limit the number of defects, obtaining large area sheets and the production of significant amounts of homogenous 2D materials are still at an early stage. In most cases, the synthesis process governs defect formation. It is of utmost importance, therefore, to achieve a deep understanding of the mechanism behind the creation of these defects. We reviewed some of the most recent studies on 2D and 0D boron nitride materials. Starting with the theoretical works which describe the correlations between structure and defects, we critically described the main BN synthesis routes and the properties of the final materials. The main results are summarized to present a general outlook on the current state of the art in this field.

Competitive removal of Pb2+ and malachite green from water by magnetic phosphate nanocomposites

The competitive removal of Pb²⁺ and malachite green (MG) from water by three magnetic phosphate nanocomposites (Fe₃O₄/Ba₃(PO₄)₂, Fe₃O₄/Sr₅(PO₄)₃(OH), and Fe₃O₄/Sr_5xBa_3x(PO₄)₃(OH), namely "FBP", "FSP", and "FSBP", respectively) was systematically investigated compared with Fe₃O₄ ("F") nanoparticle. Temperature and adsorbent dosage for competitive removal were optimized to be 20 °C and 0.05 g in 50 mL. The kinetic and isothermal adsorption results were fitted well with the pseudo-second-order model and Langmuir model, respectively. In the competitive removal process, FSP showed a high affinity to Pb²⁺ (202.8 mg/g) while FBP possessed high selectivity for MG (175.4 mg/g), and FSBP was effective at simultaneous removal of Pb²⁺ and MG, with a capacity of 143.7 and 90.9 mg/g, respectively. The magnetic contents in nanocomposites allow magnetic separation of materials from the water after treatment. We proposed that the simultaneous removal mechanism by FSBP was due to ion exchange between Pb²⁺ and Sr²⁺ in the lattice and then the formation of hydrogen bonds between PO₄^3- outside the material's surface and positively charged hydrogen in MG. This study indicates the potential of these phosphate nanocomposites to be used as effective materials for selective or simultaneous removal of Pb²⁺ and MG from water.

Porous boron nitride nanoribbons with large width as superior adsorbents for rapid removal of cadmium and copper ions from water

Porous boron nitride nanoribbons with large width and their possible mechanism for the removal of heavy metals.

Creation of Hollow Calcite Single Crystals with CQDs: Synthesis, Characterization, and Fast and Efficient Decontamination of Cd(II)

In this work, carbon quantum dots were first prepared through one-pot hydrothermal route of the propyl aldehyde and sodium hydroxide via an aldol condensation reaction, and a novel solid-phase extraction adsorbent of hollow calcite single crystals was prepared via the precipitation of metal nitrates by the CO₂ diffusion method in the presence of CQDs and further applied for excessive Cd(II) ions removal from water. The spectra and morphologies of the etched calcite were investigated by X-ray diffraction, Fourier transform infrared spectrometry, Scanning electron microscope, and Transmission electron microscopy. The results show that the CQDs etching technique successfully furnish a strategy for manufacturing interface defects onto the calcite crystal. Bath studies were done to evaluate the effects of the major parameters onto Cd(II) adsorption by the etched calcite, such as pH, contact time, and initial Cd(II) concentration. The Cd(II) adsorption onto the new adsorbent could reach a maximum adsorption amount of 66.68 mg/g at 120 min due to the abundant exterior adsorption sites on the adsorbent. The adsorption kinetics and adsorption isotherms of Cd(II) on the etched calcite were also investigated. The experimental datum showed that the adsorption kinetics and isotherms of Cd(II) on the etched calcite were well-fitted by the pseudo-second-order kinetic model and the Freundlich isotherm model respectively. The adsorption mechanisms could be primarily explained as the formation of Cd(OH)₂ and Ca_xCd_1-xCO₃ solid solution on the adsorbent surface with the help of X-ray photoelectron spectroscopy.

In Situ Liquid-Phase-Adsorption Measurement System Based on Fiber-Optic Sensing with the Aid of Membranes

At present, liquid phase adsorption (LPA) is still being quantitatively characterized in the way of manual sampling and off-line determination because of the complexity of the system comparing to gas adsorption. This paper describes a novel method for in situ, real-time measurement of LPA in general based on fiber-optic sensing (FOS) with the aid of membranes for the first time. A self-made measurement vessel was assembled from an adsorption bag, thermostatic devices with a stirrer, and a fiber-optic dipping probe. Also, macroporous adsorption resins (MARs) and rutin were chosen as model adsorbent and adsorbate to establish the FOS system. Here, in situ light absorption measurement was achieved by eliminating interference of adsorbent particles via encapsulating them with a membrane into the adsorption bag. In situ LPA measurement of rutin solution on MARs was obtained by detecting light absorption at 353 nm using dipping probe, in the broad concentration range from 0.3 to 60 mg/L with excellent linearity (R ² = 0.9996). In situ measurements of adsorption and desorption kinetics on five kinds of MARs with different polarities were systematically carried out, showing that the adsorption process obeyed the pseudo-second-model. As well as, the system was proved to be highly accurate and reproducible. More importantly, this method enabled to study the initial stage of the adsorption process, starting from the time of the first second, which is the most important part in the adsorption kinetics, and this is impossible for traditional sampling methods. The successful application of FOS to in situ measurement of LPA not only contributes to fast, automatic, and real-time monitoring of LPA process but also enriches the research connotation of adsorption.

Adsorption of estrone with few-layered boron nitride nanosheets: Kinetics, thermodynamics and mechanism

Boron nitride Nanosheets (BNNSs) was fabricated with a method of heating the mixture of boric acid and urea in N₂ atmosphere and used to remove estrone (E₁) from water. The obtained BNNSs exhibited a higher surface area of 896 m²/g, a large pore volume of 0.76 cm³/g, and only few layers (0.398 nm) with the boric acid and urea ratio of 1:80. The layer number of BNNSs decreased from 15 to 4 with the mole ratio of boric acid and urea decreasing from 1:20 to 1:80, which was identified by SEM, TEM, AFM and BET measurements. More importantly, BNNSs presented an outstanding adsorption performance for estrone with the adsorption capacity of 249.15 mg E₁/g BNNSs. The adsorption process could be best fitted by pseudo second-order kinetic model and the equilibrium data at different temperatures were well fitted by Langmuir isotherm model. The thermodynamics analysis revealed that E₁ adsorption on BNNSs was spontaneous (ΔG = -29.33 kJ mol^-1), enthalpy-retarded (ΔH = 29.75 kJ mol^-1), entropy-driven (ΔS = 198.26 J mol^-1 K^-1), and mostly chemical adsorption. The adsorption rates of E₁ in water were sharply enhanced with thinner BNNSs as absorbents and removal efficiency by BN-60 regenerated after 6 times was above 95%, it was shown that the surface areas, mesopores and remarkable structure played important roles in the adsorption process. The firmness of E₁ onto BNNSs and the stability of adsorption efficiency made BNNSs as a potential absorbent for efficient removal of E₁ from wastewater.

One-step template-free synthesis of 3D functionalized flower-like boron nitride nanosheets for NH3 and CO2 adsorption

3D functionalized flower-like boron nitride nanosheets (FBNNSs) were synthesized by a novel template-free method involving "cylinder compressing". Due to the high surface area (1114 m2 g-1), pore volume (0.7 cm3 g-1), hierarchical pore distributions, and abundant edge groups (-OH and -NH2), the 3D functionalized FBNNSs displayed excellent NH3 and CO2 adsorption up to 91 mg g-1 and 37.9 cc g-1 (74.4 mg g-1) at 1 bar, respectively. Moreover, the reusable performance of the material for gas adsorption was maintained for 10 cycles, indicating the stable structure of the FBNNSs. In addition, the adsorption mechanism was mainly explained by Lewis acid/base interactions, weak van der Waals interactions, and H-bonds. The combination of the enhanced adsorption capacity, excellent regenerability, and extraordinary chemical and thermal stability means that 3D FBNNSs possess huge potential for implementation in practical NH3 and CO2 capture.

Novel multifunctional cheese-like 3D carbon-BN as a highly efficient adsorbent for water purification

In this paper, a novel three dimensional carbon boron nitride (3D C-BN) was successfully prepared. The obtained material has porous cheese-like structure and pore size ranging from 2 nm to 100 nm. Attractively, the 3D C-BN, which combines the adsorption advantages of BN and carbon together, exhibits excellent adsorption properties for organic dyes, oils and heavy metal ions. The maximum removal capacities of 3D C-BN for methyl blue (MB) and congo red (CR) are 408 mg g⁻¹ and 307 mg g⁻¹, respectively. Furthermore, 3D C-BN can quickly and efficiently remove oils (salad oil, gasoline and pump oil) and heavy metal ions (Cr³⁺, Cd²⁺ and Ni²⁺) from waste water. The macro bulk 3D C-BN, which is more convenient to use than powdered materials, can be reused by burning or heating in air and still maintains high adsorption capacity. Significantly, these superior performances can find practical application in water purification.

Desulfurization of Model Oil by Selective Adsorption over Porous Boron Nitride Fibers with Tailored Microstructures

We report on the controllable synthesis of porous BN microfibers and explore their applications as adsorbent for removing dibenzothiophene (DBT) in model oil. The growth evolution of porous BN microfibers has been carefully investigated by correlating their structural characteristics with their synthesis conditions. The as-prepared BN microfibers exhibit very high adsorption capacity for DBT (86 mg S g⁻¹ according to the Langmuir isotherm model), showing excellent adsorptive desulfurization performance. The porous BN after adsorption can be regenerated by a simply heat treatment. After four times recycling, the regenerated adsorption capacity still remains more than 83% of that at the first adsorption. The superb oxidation resistance and chemical inertness, high sulfur adsorption capacity, as well as excellent regeneration performance render the developed porous BN microfibers to be a decent adsorbent for sulfur removal from fuels.

Superior Adsorption and Regenerable Dye Adsorbent Based on Flower-Like Molybdenum Disulfide Nanostructure

Herein we report superior dye-adsorption performance for flower-like nanostructure composed of two dimensional (2D) MoS₂ nanosheets by a facile hydrothermal method, more prominent adsorption of cationic dye compared with anodic dye indicates the dye adsorption performance strongly depends on surface charge of MoS₂ nanosheets. The adsorption mechanism of dye is analyzed, the kinetic data of dye adsorption fit well with the pseudo-second-order model, meanwhile adsorption capability at different equilibrium concentrations follows Langmuir model, indicating the favorability and feasibility of dye adsorption. The regenerable property for MoS₂ with full adsorption of dye molecules by using alkaline solution were demonstrated, showing the feasibility of reuse for the MoS₂, which is promising in its practical water treatment application.

Microwave-assisted rapid synthesis of graphene-analogue hexagonal boron nitride (h-BN) nanosheets and their application for the ultrafast and selective adsorption of cationic dyes from aqueous solutions

Graphene-analogue hexagonal boron nitride (h-BN) nanosheets are successfully synthesizedviaa facile and fast microwave-assisted method in 10 min and used as a novel adsorbent for the ultrafast removal of cationic organic dyes in aqueous solution.

Temperature Dependence of Wavelength Selectable Zero-Phonon Emission from Single Defects in Hexagonal Boron Nitride

We investigate the distribution and temperature-dependent optical properties of sharp, zero-phonon emission from defect-based single photon sources in multilayer hexagonal boron nitride (h-BN) flakes. We observe sharp emission lines from optically active defects distributed across an energy range that exceeds 500 meV. Spectrally resolved photon-correlation measurements verify single photon emission, even when multiple emission lines are simultaneously excited within the same h-BN flake. We also present a detailed study of the temperature-dependent line width, spectral energy shift, and intensity for two different zero-phonon lines centered at 575 and 682 nm, which reveals a nearly identical temperature dependence despite a large difference in transition energy. Our temperature-dependent results are well described by a lattice vibration model that considers piezoelectric coupling to in-plane phonons. Finally, polarization spectroscopy measurements suggest that whereas the 575 nm emission line is directly excited by 532 nm excitation, the 682 nm line is excited indirectly.

Microplasma Processed Ultrathin Boron Nitride Nanosheets for Polymer Nanocomposites with Enhanced Thermal Transport Performance

This Research Article reports on the enhancement of the thermal transport properties of nanocomposite materials containing hexagonal boron nitride in poly(vinyl alcohol) through room-temperature atmospheric pressure direct-current microplasma processing. Results show that the microplasma treatment leads to exfoliation of the hexagonal boron nitride in isopropyl alcohol, reducing the number of stacks from >30 to a few or single layers. The thermal diffusivity of the resulting nanocomposites reaches 8.5 mm(2) s(-1), 50 times greater than blank poly(vinyl alcohol) and twice that of nanocomposites containing nonplasma treated boron nitride nanosheets. From TEM analysis, we observe much less aggregation of the nanosheets after plasma processing along with indications of an amorphous carbon interfacial layer, which may contribute to stable dispersion of boron nitride nanosheets in the resulting plasma treated colloids.

Surfactant-free synthesis of octahedral ZnO/ZnFe2O4 heterostructure with ultrahigh and selective adsorption capacity of malachite green

A new octahedral ZnO/ZnFe₂O₄ heterostructure has been fabricated through a facile surfactant-free solvothermal method followed by thermal treatment. It exhibits a record-high adsorption capacity (up to 4983.0 mg·g⁻¹) of malachite green (MG), which is a potentially harmful dye in prevalence and should be removed from wastewater and other aqueous solutions before discharging into the environment. The octahedral ZnO/ZnFe₂O₄ heterostructure also demonstrates strong selective adsorption towards MG from two kinds of mixed solutions: MG/methyl orange (MO) and MG/rhodamine B (RhB) mixtures, indicating its promise in water treatment.

Synthesis of porous Al doped ZnO nanosheets with high adsorption and photodecolorizative activity and the key role of Al doping for methyl orange removal

Porous Al doped ZnO (AZO) nanosheets have been prepared as an efficient multifunctional water treatment material.

An amperometric glucose enzyme biosensor based on porous hexagonal boron nitride whiskers decorated with Pt nanoparticles

A novel amperometric electrode is fabricated using platinum nanoparticle (Pt NP) decorated porous hexagonal boron nitride (h-BN) whiskers.

Ultrafine porous boron nitride nanofibers synthesized via a freeze-drying and pyrolysis process and their adsorption properties

Ultrafine porous boron nitride nanofibers with high aspect ratios, high specific surface areas and large pore volumes has been synthesized in large quantity via a freeze-drying and post pyrolysis process.

Polyethyleneimine as a novel desorbent for anionic organic dyes on layered double hydroxide surface

Polyethyleneimine (PEI) is a positively charged polymer with hydrogen-bonding sites and hydrophobic chains. Therefore, it has been clearly established as an efficient adsorbent by means of these native properties in the literatures. However, there is apparently no good reason to disregard the use of PEI as a desired desorbent. Herein, using methyl orange as a model anionic dye, we investigated the desorption performances of PEI toward anionic dyes adsorbed on the surface of CO3-layered double hydroxides (LDHs) in a wide range of pH values. The experiment results showed that the positively charged PEI had very strong desorption capacity for anionic dyes at low pH values (<9.5) through electrostatic attraction between PEI and methyl orange because of the high degree of protonation of PEI. At high pH values (>9.5), PEI existed as neutral molecule, it could desorb methyl orange via hydrogen bonding between the amino groups of it and sulfonate group of methyl orange; simultaneously, the anion-exchange process occurred between abundant hydroxyl anions and anionic methyl orange. The adsorption capacity of the used LDH adsorbent was about 80% after five cycles of adsorption-desorption-regeneration, which was much higher than that conducted by 0.1M NaOH solution. These findings suggested that PEI could be regarded as a promising desorbent for enriching anionic dyes in wastewater and regenerating LDHs through surface adsorption-desorption cycles.

Free-standing membranes made of activated boron nitride for efficient water cleaning

Developing membranes with excellent mechanical strength and chemical stability is a practically important issue for efficient removal of pollutants from wastewater.

Biomaterials-based nanofiber scaffold: targeted and controlled carrier for cell and drug delivery

Nanofiber scaffold formulations (diameter less than 1000 nm) were successfully used to deliver the drug/cell/gene into the body organs through different routes for an effective treatment of various diseases. Various fabrication methods like drawing, template synthesis, fiber-mesh, phase separation, fiber-bonding, self-assembly, melt-blown, and electrospinning are successfully used for fabrication of nanofibers. These formulations are widely used in various fields such as tissue engineering, drug delivery, cosmetics, as filter media, protective clothing, wound dressing, homeostatic, sensor devices, etc. The present review gives a detailed account on the need of the nanofiber scaffold formulation development along with the biomaterials and techniques implemented for fabrication of the same against innumerable diseases. At present, there is a huge extent of research being performed worldwide on all aspects of biomolecules delivery. The unique characteristics of nanofibers such as higher loading efficiency, superior mechanical performance (stiffness and tensile strength), controlled release behavior, and excellent stability helps in the delivery of plasmid DNA, large protein drugs, genetic materials, and autologous stem-cell to the target site in the future.

Layered double hydroxide-carbon dot composite: high-performance adsorbent for removal of anionic organic dye

It would be of significance to design a green composite for efficient removal of contaminants. Herein, we fabricated a facile and environmentally friendly composite via direct assembly of surface passivated carbon dots with abundant oxygen-containing functional groups on the surface of the positively charged layered double hydroxide (LDH). The resulting LDH-carbon dot composites were characterized by X-ray diffraction (XRD), Fourier transformed infrared (FTIR) spectroscopy, high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), and N2 adsorption-desorption technique. The adsorption performances of the resulting LDH-carbon dot composites were evaluated for the removal of anionic methyl blue dye. Taking advantage of the combined benefits of LDH and carbon dots, the as-prepared composites exhibited high uptake capability of methyl blue (185 mg/g). The adsorption behavior of this new adsorbent fitted well with Langmuir isotherm and the pseudo-second-order kinetic model. The reasons for the excellent adsorption capacity of methyl blue on the surface of the LDH-carbon dot hybrid were further discussed. A probable mechanism was speculated to involve the cooperative contributions of hydrogen bonding between methyl blue and carbon dots and electrostatic attraction between methyl blue and LDH, in the adsorption process. This work is anticipated to open up new possibilities in fabricating LDH-carbon dot materials in dealing with anionic dye pollutants.

Polymer-Derived Boron Nitride: A Review on the Chemistry, Shaping and Ceramic Conversion of Borazine Derivatives

Boron nitride (BN) is a III-V compound which is the focus of important research since its discovery in the early 19th century. BN is electronic to carbon and thus, in the same way that carbon exists as graphite, BN exists in the hexagonal phase. The latter offers an unusual combination of properties that cannot be found in any other ceramics. However, these properties closely depend on the synthesis processes. This review states the recent developments in the preparation of BN through the chemistry, shaping and ceramic conversion of borazine derivatives. This concept denoted as Polymer-Derived Ceramics (PDCs) route allows tailoring the chemistry of precursors to elaborate complex BN shapes which cannot be obtained by conventional process. The effect of the chemistry of the molecular precursors, i.e., borazine and trichloroborazine, and their polymeric derivatives i.e., polyborazylene and poly[tri(methylamino)borazine], in which the specific functional groups and structural motifs determine the shaping potential by conventional liquid-phase process and plastic-forming techniques is discussed. Nanotubes, nano-fibers, coatings, monoliths and fiber-reinforced matrix composites are especially described. This leads to materials which are of significant engineering interest.