In situ growth of hollow Cu 2 O spheres using anionic vesicles as soft templates

Dextran mediated MnFe2O4/ZnS magnetic fluorescence nanocomposites for controlled self-heating properties

Dextran mediated MnFe2O4/ZnS opto-magnetic nanocomposites with different concentrations of ZnS were competently synthesized adopting the co-precipitation method. The structural, morphological, magnetic, and optical properties of the nanocomposites were exhaustively characterized by XRD, HRTEM, FTIR, VSM techniques, and PL spectroscopy. XRD spectra demonstrate the existence of the cubic spinel phase of MnFe2O4 and the cubic zinc blend phase of ZnS in the nanocomposites. HRTEM images show the average crystallite size ranges of 15-21 nm for MnFe2O4 and 14-45 nm for ZnS. Investigation of the FTIR spectra reveals the incorporation of ZnS nanoparticles on the surface of MnFe2O4 nanoparticles by dint of biocompatible surfactant dextran. The nanocomposites exhibit both magnetic and photoluminescence properties. Photoluminescence analysis confirmed the redshift of the emission peaks owing to the trap states in the ZnS nanocrystals. The room temperature VSM analysis shows that the saturation magnetization and coercivity of MnFe2O4 nanoparticles initially increase then decrease with the increasing concentration of ZnS in the nanocomposite. The induction heating analysis shows that the presence of dextran enhances the self heating properties of the MnFe2O4/ZnS nanocomposites which can also be controlled by tailoring the concentration of the ZnS nanoparticles. These suggest that MnFe2O4/Dex/ZnS is a decent candidate for hyperthermia applications.

Vesicle formation of single-chain amphiphilic 4-dodecylbenzene sulfonic acid in water and micelle-to-vesicle transition induced by wet-dry cycles

Simple single-chain amphiphiles (SCAs) can form vesicular structures in their single-component aqueous solutions, which has attracted great attention, but the understanding of their aggregation behavior is still limited. In this work, the aggregation behavior of 4-dodecylbenzene sulfonic acid (DBSA), a typical simple SCA, in water was investigated. The structure and properties of the aggregates formed were determined. In particular, the effect of wet-dry cycles on the structures of aggregates was examined. The mechanisms of aggregate formation and structural transition were discussed. It was found that the increase of DBSA concentration can drive the occurrence of a micelle-to-vesicle transition, showing a critical micelle concentration and critical vesicle concentration of ∼0.53 and 2.14 mM, respectively. The vesicles formed coexist with micelles in solution, with a unilamellar structure and ∼80 nm size, and exhibit size-selective permeability. In addition, the vesicles show remarkable stability upon long-term storage, exposure to high temperature, and freeze-thaw cycles. The H-bonding interaction between DBSA species and the interdigitated structure of alkyl chains in bilayers play a key role in the formation and stability of DBSA vesicles. Interestingly, it was found that the wet-dry cycle can induce a micelle-to-vesicle transition and an obvious increase in the size of the original vesicles, accompanied by the formation of some multilamellar vesicles. This work provides a better understanding of the aggregation behavior of simple SCAs in their single-component aqueous solutions.

Prediction of organic pollutant removal using Corynebacterium glutamicum fermentation waste

The disposal of bio-waste (e.g., Corynebacterium glutamicum) produced by the fermentation industry is a serious problem and has a negative impact on economic returns. Some fermentation waste can be recycled as livestock feed, but much cannot be used. Therefore, other recycling methods must be developed to increase its applications, for example, as an environmentally friendly adsorbent for the removal or recovery of chemicals. To broaden its application as an adsorbent, we carried out comprehensive experimental and theoretical analysis. From the experiments, adsorption affinity values between C. glutamicum and micropollutants were measured, and, based on the experimental values, we developed a predictive model. The experimental results reveal that the degree of adsorption is dependent on the structural properties of the micropollutants. In particular, the adsorbent has remarkable adsorption ability toward cations, whereas anionic and neutral compounds interact weakly with the adsorbent. In addition, we found that adsorption is affected by the sodium chloride concentration. Briefly, an increase in salt concentration increases the adsorption of anions, whereas the opposite behavior is observed for cations. In contrast, the adsorption of neutral compounds was not affected by the presence of salt. The modeling studies revealed that a linear free energy relationship model can be used to predict the adsorption affinity. Based on the developed model, we found that hydrogen-bond basicity, anionic coulombic interactions, and molecular volume are the main contributing factors to the adsorption model. However, to achieve the best predictability (a coefficient of determination (R²) of 0.902), additional parameters, such as the dipolarity/polarizability and dispersive interaction, should be included. This indicates that adsorption is a product of complex interactions.

Bimetallic metal-organic frameworks anchored corncob-derived porous carbon photocatalysts for synergistic degradation of organic pollutants

Metal-organic frameworks (MOFs) are promising for photocatalysis owing to their excellent structure and performance. Unfortunately, poor stability in both aqueous solutions and high temperatures and lack of adsorption centers during reactions limit their practical applications. Herein, a bimetallic MOF anchored corncob calcined derived activated carbon (CCAC) was successfully prepared by a one-step solvothermal method. Benefiting from unique structures and synergetic effect, the porous carbon provided a high specific surface area for stable MOF support and served as an organic pollutant buffer-reservoir, which was advantageous for efficient photocatalytic degradation of organic pollutants. The optimized MOF/CCAC-5 samples possessed excellent visible light degradation rate, i.e., 100% for Rh B, more than 96% for six mixed dyes, and 98% for tetracycline. This prominent photocatalytic activity was caused by active species, including photoelectrons (e^-), photo-holes (h⁺) and superoxide free radicals (•O^2-). The transient photocurrent response and electrochemical impedance tests showed that MOF/CCAC-5 exhibited a relatively high charge separation and low carrier recombination rate. Cyclic and simulation experiments indicated high reusability, stability and universality of the composite photocatalysts. These exciting results provide new pathways for the fabrication of MOFs anchored porous carbon materials.

Immobilization interaction between xenobiotic and Bjerkandera adusta for the biodegradation of atrazine

The aim of the present work is to evaluate the ability of 'fungi' for the biodegradation of recalcitrant xenobiotic compound, 'Atrazine' in batch liquid cultures. Different parameters like pH (2.0-8.0) temperature (16-32 °C), biomass (1-5 g), and concentration (25-100 ppm) were optimized for the efficient degradation of atrazine. The decomposition behavior of atrazine is analyzed with the help of Fourier Transform Infrared (FTIR) spectroscopy. Herein, we have reported that the Bjerkandera adusta possess high removal efficiency of the xenobiotic compound (atrazine) up to 92%. The fungal strain investigated could prove to be a valuable active pesticide degrading micro-organism, with high detoxification values. These results are useful for improved understanding and prediction of the behavior and fate of B. adusta in the bio-purification of wastewater contaminated with xenobiotics. Thus providing a new and green approach for the remediation of toxicants without altering the environmental components.

Vitamin D3 Loaded Niosomes and Transfersomes Produced by Ethanol Injection Method: Identification of the Critical Preparation Step for Size Control

Vesicular nanocarriers have an important role in drug delivery and dietary supplements. Size control and optimization of encapsulation efficiency (EE) should be optimized for those applications. In this work, we report on the identification of the crucial step (injection, evaporation, or sonication) innanovesicles (transfersomes and niosomes) preparation by theethanol injection method (EI). The identification of each production step on the final vesicle size was analyzed in order to optimize further scale-up process. Results indicated that the final size of transfersomeswas clearly influenced by the sonication step while the final size of niosomes was mainly governed by the injection step. Measurements of final surface tension of the different vesicular systems prepared indicate a linear positive tendency with the vesicle size formed. This relation could help to better understand the process and design a vesicular size prediction model for EI. Vitamin D3 (VitD3) was encapsulated in the systems formulated with encapsulation efficiencies larger than 90%. Interaction between the encapsulated compound and the membrane layer components is crucial for vesicle stability. This work has an impact on the scaling-up production of vesicles for further food science applications.

Efficient and stable catalysis of hollow Cu9S5 nanospheres in the Fenton-like degradation of organic dyes

The development of new heterogeneous catalysts with stable catalytic activity in a wide pH range to prevent polluting precipitation plays a vital role in large-scale wastewater treatment. Here, a facile anion exchange strategy was designed to fabricate hollow Cu₉S₅ nanospheres by using Cu₂O nanospheres as hard-templates. The structural and compositional transformation from Cu₂O nanospheres to hollow Cu₉S₅ nanospheres were investigated via X-ray diffraction, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The Fenton-like degradation of organic dyes was used to evaluate the catalytic performance of the obtained Cu-containing catalysts. Results reveal that the hollow Cu₉S₅ nanospheres have the best catalytic activity among five kinds of Cu-containing catalysts. Hollow Cu₉S₅ nanospheres can effectively accelerate the decomposition of H₂O₂ into hydroxyl radicals and superoxide radical, which have been proven to be mainly oxidative species in the Fenton-like degradation of organic pollutants. Hollow Cu₉S₅ nanospheres have a wide pH application range of 5.0-9.0, and their extremely stable activity can be maintained in at least 15 catalytic cycles with a Cu²⁺ ion leaching rate of less than 1.0 %. The outstanding catalytic performance of the Cu₉S₅ catalyst is expected to enhance the practical applications of copper sulfide catalysts in Fenton-like wastewater treatment.

An integrated electrocoagulation - Electrocatalysis water treatment process using stainless steel cathodes coated with ultrathin TiO2 nanofilms

Anodic electrocoagulation processes can remove broad varieties of pollutants in industrial wastewater. However, some stubborn contaminants may still remain in effluents after the treatment and cause environmental issues. To further improve the efficiency of pollutant removal, we have coupled electrocatalysis with electrocoagulation and applied an atomic layer deposition (ALD) enabled TiO₂ ultrathin overcoating at a nanometer scale on a stainless steel cathode. The electrocatalytic overcoating increased the elimination efficiency of organics and microorganisms, likely due to the electro-generation of adequate reactive oxygen species (ROS). The thickness of TiO₂ nanofilm was controlled by the number of ALD cycles, and it was found that nanofilms processed with 50-100 cycles led to the maximum benefit of pollutant removal. By using the novel electrocoagulation-electrocatalysis cell to treat synthetic wastewater, a remarkable removal of 99.92% of E. Coli, 92.1% of suspended solids, 98.3% of heavy metal ions, and 88.8% of methylene blue was observed. This hybrid electrochemical treatment process may have the potential to treat wastewater at a larger scale.

Microwave Hydrothermally Synthesized Metal-Organic Framework-5 Derived C-doped ZnO with Enhanced Photocatalytic Degradation of Rhodamine B

C-doped ZnO particles have been successfully prepared by the calcination using microwave hydrothermally prepared metal-organic framework-5 (MOF-5) as the precursor. MOF-5 was turned into C-doped ZnO through calcination at 500 °C, and its cubic shape was well-maintained. X-ray photoelectron spectroscopic studies confirmed the C-doping in the ZnO. The as-prepared C-doped ZnO demonstrated a Rhodamine B (RhB) degradation efficiency of 98% in 2 h under an solar-simulated light irradiation, much higher than that of C-doped ZnO derived from MOF-5 synthesized by the ordinary hydrothermal method. The trapping experiment revealed that the crucial factors in the RhB removal were photogenerated h⁺ and •O₂^-.

A Molecularly Imprinted Fluorescence Sensor Based on the ZnO Quantum Dot Core-Shell Structure for High Selectivity and Photolysis Function of Methylene Blue

ZnO quantum dots and CuFe2O4 nanoparticles were synthesized by chemical precipitation. The ZCF composite was created by the solvothermal method. A new molecularly imprinted fluorescence sensor (ZCF@MB-MIP) with unique optical properties and specific MB recognition was successfully generated. ZCF@MB-MIPs were characterized by Fourier-transform infrared spectroscopy, transmission electron microscopy, and X-ray diffraction and were applied for the selective detection of methylene blue (MB). The optimal working time of ZCF@MB-MIPs was 15 min, and the optimal working concentration was 37 mg·L-1. The fluorescence intensity was linearly quenched within the 0-100 μmol·L-1 MB range, and the detection limit was 1.27 μmol·L-1. The imprinting factor of the sensor (IF, K MB-MIPs/N-MIPs) was 5.30. At the same time, a real-time monitoring system was established for the photodegradation process of MB, which had the effect of reflecting the degradation degree of MB at any given time. Hence, ZCF@MB-MIPs are a promising candidate for use in MB monitoring, and they also provides a new strategy for constructing a multifunctional fluorescence sensor with a high selectivity and photolysis function.

Bioinspired design of underwater superoleophobic Poly(N-isopropylacrylamide)/ polyacrylonitrile/TiO2 nanofibrous membranes for highly efficient oil/water separation and photocatalysis

Inspired by fish scales, this study prepares a thermo-responsive underwater oleophobic PNIPAM/PAN/TiO₂ nanofibrous membranes by traditional electrospinning technique using poly-N-isopropylacrylamide (PNIPAM) and polyacrylonitrile (PAN). Thermal properties, mechanical properties, surface chemical composition, wettability, photocatalysis, and oil/water separation of PNIPAM/PAN/TiO₂ membrane are explored compared to pure PNIPAM membrane. Result reveals that PAN/TiO₂ compounds make PNIPAM membrane with a smaller fiber diameter of 141 nm and high tensile stress of 7.4 MPa, and also decompose 98% of rhodamine B after UV light radiation. This bioinspired design structure endows the membrane with superhydrophilicity with a low water contact angle, and underwater superoleophobicity with a high oil contact angle of 157° (petroleum ether) and 151° (dichloromethane). This membrane can efficiency separate oil/water mixture with a high separation efficiency. Moreover, the resultant PNIPAM/PAN/TiO₂ membrane has the bionic fish scale structure, and has wettability respond at lower critical solution temperature making the water flux decreased from 10013 ± 367 L m^-2·h^-1 to 7713 ± 324 L m^-2·h^-1, and thus has a potential to be used in purification of reclaimed water and separation of oil from water.

Green synthesis of CuO- and Cu2O-NPs in assistance with high-gravity: The flowering of nanobiotechnology

This study, for the first time, reports the synthesis of CuO- and Cu2O nanoparticles (NPs) using the Salvia hispanica extract by a high-gravity technique. The original green synthesis procedure led to the formation of nanoparticles with promising catalytic and biological properties. The synthesized nanoparticles were fully characterized and their catalytic activity was evaluated through a typical Azide-Alkyne Cycloaddition (AAC) reaction. The potential antibacterial activity against gram positive (S. aureus) and gram negative (E. coli) bacteria were investigated. It was shown that the antibacterial properties were independent of the NP morphology as well as of the texture of the synthesis media. As a result, the presently synthesized nanoparticles showed very good photocatalytic and catalytic activities in comparison with the literature. From a biological perspective, they showed lower cytotoxicity in comparison with the literature, and also showed higher antioxidant and antibacterial activities. Thus, these present green CuO and Cu2O nanoparticles deserve further attention to improve numerous medical applications.

Low optical dosage heating-reduced viscosity for fast and large-scale cleanup of spilled crude oil by reduced graphene oxide melamine nanocomposite adsorbents

Heating under low solar radiation intensity is demonstrated to facilitate the cleaning of crude oil by the hydrophobic nanocomposite adsorbents of reduced graphene oxide (RGO) melamine sponge (MS@RGO) foams. The heat generated by the irradiation reduces the viscosity of the crude oil, and consequently increases the oil-diffusion coefficient of the pores of the MS@RGO foams and speeds up the oil-sorption rate. Even under a solar radiation intensity as low as 2 kW m^-2, the temperature of crude oil rapidly rises to 68 °C or higher within 10 min. It only takes 29 s to completely absorb 6 g of crude oil at 60 °C by three tiny pieces of MS@RGO foam. This work makes better use of the excellent photothermal conversion characteristics of crude oil, and its photothermal conversion mechanism under simulated solar radiation is also discussed. This methodology can be adopted to clean up viscous crude oil or extract other chemicals effectively at a large scale, and provides a complete solution for the cleanup of crude oil in the sea or on the beach for actual engineering applications.

A study on the mechanism of oxidized quinoline removal from acid solutions based on persulfate-iron systems

Quinoline (Qu) and its derivatives have been widely regarded as hazardous pollutants in the world because of their acute toxicity to humans and animals, and potential carcinogenic risks. In this study, a novel sulfate radical system co-activated by ferrous and ZVI was developed to remove Qu from acidic solutions. The optimal ratio of ferrous and ZVI in the system and the mechanism of Qu removal from acidic solutions are also explored. The ZVI can initiate activation using hydrogen ions, which are released from the reaction of Fe2+, organics and PS in acidic solutions. This may dramatically improve the overall removal efficiency of Qu. The results indicated that the initial removal rate of Qu increases from 85.8% to 92.9%. The cleavage pathway of Qu is speculated by Frontier molecular orbital (FMO) theory and verified by GC/MS analysis.

Optimizing nanocarbon shell in zero-valent iron nanoparticles for improved electron utilization in Cr(VI) reduction

A core-shell structured zero-valent iron@carbon (ZVI@C) nanocompoiste was designed to improve the electron utilization of ZVI in the Cr(VI) reduction. The porosity of carbon layer in ZVI@C was optimized for improving the efficiency of electron utilization of ZVI in the Cr(VI) reduction process. The porous structure of carbon layer was controllably synthesized by adjusting the carbon source and the ratio of C/Fe in the precursor. The glucose was suggested as the optimal carbon source, and a high specific surface area (37.067 m²/g) was reached for the prepared ZVI@C when the ratio of C/Fe was controlled at 20. These ZVI@C performed well on Cr(VI) reduction, e.g. a complete reduction of Cr(VI) (2 mg/L) to Cr(III) within 10 min. The removal capacity (800 mg/g) exceeded previously recorded ZVI based adsorbents. The pH and initial Cr(VI) concentration were demonstrated as the key factors for the efficient electron utilization of ZVI. Furthermore, the efficiency of electron utilization of the ZVI increased up to 80% when the concentration of Cr(VI) was 2000 mg/L and the pH was controlled at 3, which was much higher than 8% of the naked ZVI.

Colorimetric determination of amaranth followed enrichment and separation using buoyant adsorbents

A buoyant solid-phase extraction adsorbent was prepared by sodium alginate-coated hollow glass microspheres (HGMs) modified with 3-aminopropyltrimethoxysilane (3-APTS) for the separation and enrichment of anionic dye amaranth. After adsorbing amaranth, these low-density adsorbents can float on the surface of the solution, so the separation between adsorbents and substrates can be carried out by flotation. Quantitative determination of amaranth after separation and enrichment can be achieved by combining spectrophotometry. Under the optimum conditions, the linear range and detection limit for amaranth detection were 0.02 mg L−1–2.0 mg L−1 and 0.0021 mg L−1, respectively. The proposed method was applied to the determination of amaranth in different beverages, and the results were in good agreement with those by high-performance liquid chromatography (HPLC). The recoveries of amaranth in different beverages were between 97.93 and 105.91%. The floating adsorbent can be used as a conventional sample preparation method for the detection of low concentration analytes in complex samples.

Advances in Template Prepared Nano-Oxides and their Applications: Polluted Water Treatment, Energy, Sensing and Biomedical Drug Delivery

The nano-oxide materials with special structures prepared by template methods have a good dispersion, regular structures and high specific surface areas. Therefore, in some areas, improved properties are observed than conventional bulk oxide materials. For example, in the treatment of dye wastewater, the treatment efficiency of adsorbents and catalytic materials prepared by template method was about 30 % or even higher than that of conventional samples. This review mainly focuses on the progress of inorganic, organic and biological templates in the preparation of micro- and nano- oxide materials with special morphologies, and the roles of the prepared materials as adsorbents and photocatalysts in dye wastewater treatment. The characteristics and advantages of inorganic, organic and biological template are also summarized. In addition, the applications of template method prepared oxides in the field of sensors, drug carrier, energy materials and other fields are briefly discussed with detailed examples.

One-step co-precipitation synthesis of novel BiOCl/CeO2composites with enhanced photodegradation of rhodamine B

BiOCl/CeO₂composites were synthesized by a facile one-step co-precipitation method and showed good photodegradation activity of rhodamine B (RhB).

Magnetic nanocellulose-magnetite aerogel for easy oil adsorption

HYPOTHESIS

Cellulose aerogels are a new category of high-efficiency adsorbents for treating oil spills and water pollution. However, the hydrophilic properties and recyclability of aerogels after adsorption hamper developments and applications. Combining both hydrophobic and magnetic properties are expected to improve their adsorption capacity and functionality.

EXPERIMENTS

In this study, the effect of oleic acid (OA) and nanomagnetite on the preparation of magnetic nanocellulose aerogels (called as NCA/OA/Fe₃O₄) by a mechanical mixing combined with freeze-drying method have been investigated.

FINDINGS

It has been found that the optimal condition for fabricating this NCA/OA/Fe₃O₄ aerogel is 0.4 wt% nanocellulose, 3 mg mL^-1 OA and 0.5 wt% Fe₃O₄ in the aqueous solution. This aerogel has a very low density of 9.2 mg cm^-3 and demonstrates a high adsorption capacity of 68.06 g g^-1 for cyclohexane. In addition, this aerogel adsorbent demonstrates an excellent magnetic responsivity and can be easily recycled by a permanent magnet after adsorption. As a consequence, this hydrophobic magnetic NCA/OA/Fe₃O₄ aerogel is promising not only for easy oil and organic solvent adsorption but also potentially for other magnetic related applications.

Carbon nitride nanoplatelet photocatalysts heterostructured with B-doped carbon nanodots for enhanced photodegradation of organic pollutants

Decorating electron-accepting materials on carbon nitride (C₃N₄) is a promising strategy to construct heterostructure catalysts for improved photocatalytic abilities. In this study, B-doped carbon-dots (B-C-dots) decorated C₃N₄ (C₃N₄/B-C-dots) catalysts were fabricated through the surface deposition. The benefits from integration of B-C-dots and C₃N₄ are four folds: (i) increasing surface area; (ii) improving visible light absorption; (iii) promoting the transfer of photoinduced carriers; and (iv) reducing the recombination of photoinduced carriers. The optimum photocatalytic activity of B-C-dots/C₃N₄ for Rhodamine B (Rh B) (or tetracycline hydrochloride (TC)) degradation was about 7.21 (6.56) and 4.80 (4.35) times higher than that of C₃N₄ and C-dots/C₃N₄, respectively, exhibiting both remarkable stability and repeatability. Moreover, enhanced photocatalytic activity of C₃N₄/B-C-dots could also be attributed to the type-II heterojunction formed between C₃N₄ and B-C-dots caused by B doping.

Effect of hydroxyapatite concentration and size on morpho-mechanical properties of PLA-based randomly oriented and aligned electrospun nanofibrous mats

The growing demand for nanofibrous biocomposites able to provide peculiar properties requires systematic investigations of processing-structure-property relationships. Understanding the morpho-mechanical properties of an electrospun scaffold as a function of the filler features and mat microstructure can aid in designing these systems. In this work, the reinforcing effect of micrometric and nanometric hydroxyapatite particles in polylactic acid-based electrospun scaffold presenting random and aligned fibers orientation, was evaluated. The particles incorporation was investigated trough Fourier transform infrared spectroscopy in attenuated total reflectance. The morphology of the nanofibers was analyzed through scanning electron microscopy and it was correlated with the viscosity of polymeric solutions studied by rheological measurements. Scaffolds were mechanical characterized with tensile tests in order to find a correlation between the preparation method and the strength of the mats. The influence of hydroxyapatite particles on the crystallinity of the composites was investigated by differential scanning calorimetry. Finally, cell culture assays with pre-osteoblatic cells were conducted on a selected composite scaffold in order to compare the cell proliferation and morphology with that of polylactic acid scaffolds. Based on the results, we can prove that polylactic acid/hydroxyapatite composites can be one of the biomaterials with the greatest potential for bone tissue regeneration.

Reversibly switching water droplets wettability on hierarchical structured Cu2S mesh for efficient oil/water separation

Surfaces with reversible wettability have broad applications but remain challenging since the switching process is usually energy intensive and complex. In this paper, a pyramid shaped Cu2S film with hierarchical micro/nanostructures is formed on a commercial copper mesh. This film is formed by a spontaneous redox sulfuration reaction and results in a roughened surface, which enables reversible wetting transition between superhydrophilicity to superhydrophobicity. This switching occurs by simple processes such as alternately storing in air or using an ethanol solution treatment and yields cyclic wettability switching for many cycles. This convenient wetting transition behavior, as well as strong stability and efficient oil/water separation with efficiency exceeding 98%, renders it as a potentially useful mesh material for switchable surfaces.