Facile synthesis of 3D flower-like Pt nanostructures on polypyrrole nanowire matrix for enhanced methanol oxidation

Here we report the simple and rapid synthesis of three-dimension Pt flower-like nanostructures (PtNFs) on a polypyrrole nanowires (PPyNWs) matrix. Both PtNFs and PPyNWs are prepared by an electrochemical approach without using any seed, template or surfactant. The morphology and chemical composition of the resulting PtNF/PPyNWs hybrids are characterized by scanning electron microscopy and by X-ray photoelectron spectroscopy, respectively. Taking methanol oxidation as a model catalysis reaction, the electrocatalytic performance of the as-prepared PtNF/PPyNWs system has been evaluated by cyclic voltammetry and chronoamperometry, evidencing that these 3D materials exhibit excellent electrocatalytic activity and high level of poisoning tolerance to the carbonaceous oxidative intermediates. Such electrocatalytic performances can be ascribed to the combined effect of the flower-like structure promoting the exposure of more sites and the polymer nanowires matrix endorsing high dispersion of PtNF on a high electrochemically active surface area, besides the removal of sub-products from electrocatalytic sites.

Platinum nanoflowers on polymer nanowires exhibit catalytic properties ascribed to the effect of high surface area flower-like structures and polymer 3D structure.     

Facile synthesis of flower-like hierarchical N-doped Nb2O5/C nanostructures with efficient photocatalytic activity under visible light

Significant endeavors have been devoted in the past few years to establish efficient visible light-activated photocatalysts. Herein, we successfully synthesized a flower-like hierarchical nitrogen-doped and carbon-sensitized Nb₂O₅ (NBO) nanostructure (denoted N-NBO/C). The as-prepared N-NBO/C possessed a specific surface area of 260.37 m² g⁻¹ and single wire diameter of less than 10 nm. The effect of reaction parameters such as hydrothermal reaction time, temperature and concentration of hexamethylenetetramine (Hmta) on the morphology of NBO was systematically investigated to elucidate the growth mechanism. The carbon on the surface and the nitrogen in the framework of NBO are beneficial for light harvesting, visible light absorption, formation of oxygen vacancies, and electron–hole separation. The photocatalytic performance of the as-fabricated N-NBO/C nanostructures was estimated via the photodegradation of 30 mg L⁻¹ RhB, where greater than 98% of RhB was decomposed within 30 min upon visible-light radiation. Hence, the obtained N-NBO/C nanostructure exhibits much higher photocatalytic activity for the decomposition of RhB upon visible light irradiation than that of pure niobium oxide (NBO), nitrogen-doped titanium oxide (N-TIO), and nitrogen-doped niobium oxide (N-NBO). This work supplies a versatile route for the synthesis of nitrogen-doped and carbon-sensitized metal-oxide nanostructures for possible utilization in solar energy transformation and environmental remediation.

Flower-like hierarchical N-doped Nb₂O₅/C nanostructures with efficient visible light-driven photocatalytic activity synthesized via a facile hexamethylenetetramine-assisted hydrothermal route.     

Facile synthesis and characterization of magnesium and manganese mixed oxides for the efficient removal of tartrazine dye from aqueous media

Nanomaterials are the most effective class of substances for use as adsorbents in wastewater treatment. Hence, the current study involves the facile and low-cost synthesis of MgMn₂O₄/Mn₂O₃ and MgMn₂O₄/Mn₂O₃/Mg₆MnO₈ as novel nanostructures from mixed solutions of Mg(ii) and Mn(ii) ions using the Pechini sol–gel method. After that, the remaining powder was calcined at 500, 700, and 900 °C for 3 h; the products were designated as G500, G700, and G900, respectively. The G500 sample consists of MgMn₂O₄ and Mn₂O₃, while the G700 and G900 samples consist of MgMn₂O₄, Mg₆MnO₈, and Mn₂O₃. The synthesized nanostructures were characterized using several tools, such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and N₂ adsorption/desorption analysis. The average crystallite size of the G500, G700, and G900 samples is 210.53, 95.27, and 83.43 nm, respectively. The SEM images showed that the G500 sample consists of square and rectangular bars with an average diameter of 3.18 μm. Also, the G700 and G900 samples consist of hexagonal, polyhedral, and irregular shapes with an average diameter of 1.12 and 0.54 μm, respectively. The synthesized nanostructures were further utilized as adsorbents for the efficient removal of tartrazine dye from aqueous media. The experimental data showed a good fit with the Langmuir isotherm and pseudo-first-order model. The maximum adsorption capacities of the G500, G700, and G900 adsorbents toward tartrazine dye are 328.95, 359.71, and 395.26 mg g⁻¹, respectively.

Nanomaterials are the most effective class of substances for use as adsorbents in wastewater treatment.     

Chitin/egg shell membrane@Fe3O4 nanocomposite hydrogel for efficient removal of Pb2+ from aqueous solution

The development of adsorbents by using the byproducts or waste from large-scale industrial and agricultural production is of great significance, and is considered to be an economic and efficient strategy to remove the heavy metals from polluted water. In this work, a novel chitin/EM@Fe₃O₄ nanocomposite hydrogel was obtained from a NaOH/urea aqueous system, where the proteins of egg shell membrane and Fe₃O₄ nanoparticles were chemically bonded to chitin polymer chains with the help of epichlorohydrin. Due to the existence of a large number of –NH₂, –OH, –CONH–, –COOH and hemiacetal groups, the adsorption efficiency for Pb²⁺ into the absorbent was dramatically enhanced. The experimental results revealed that the adsorption behavior strongly depends on various factors, such as initial pH, initial Pb²⁺ concentration, incubation temperature and contact time. The kinetic experiments indicated that the adsorption process for Pb²⁺ in water solution agreed with the pseudo-second-order kinetic equation. The film diffusion or chemical reaction is the rate limiting process in the initial adsorption stage, and the adsorption of Pb²⁺ into the nanocomposite hydrogel can well fit the Langmuir isotherm. Thermodynamic analysis demonstrated that such adsorption behaviors were dominated by an endothermic (ΔH° > 0) and spontaneous (ΔG° < 0) process.

A novel kind of chitin/EM@Fe₃O₄ nanocomposite hydrogel derived from the biowastes of egg shell membrane and chitin was successfully prepared for efficient removal of Pb²⁺ from wastewater solution.     

Microscale flower-like magnesium oxide for highly efficient photocatalytic degradation of organic dyes in aqueous solution

Flower-like MgO microparticles with excellent photocatalytic performance in degradation of various organic dyes (e.g., methylene blue, Congo red, thymol blue, bromothymol blue, eriochrome black T, and their mixture) were synthesized by a facile precipitation method via the reaction between Mg²⁺ and CO₃²⁻ at 70 °C. The reaction time was found to be crucial in determining the final morphology of flower-like MgO. After studying the particles from time-dependent experiments, scanning electron microscope observation, Fourier transform infrared spectra and thermogravimetric analyses demonstrated that the formation of flower-like particles involved a complex process, in which agglomerates or rod-like particles with a formula of xMgCO₃·yH₂O (x = 0.75–0.77 and y = 1.87–1.96) were favorably formed after the initial mixture of the reactants. Owing to the chemical instability, they would turn into flower-like particles, which had a composition of xMgCO₃·yMg(OH)₂·zH₂O (x = 0.84–0.86, y = 0.13–0.23, and z = 0.77–1.15). After calcination, the generated product not only possessed a superior photocatalytic performance in degradation of organic dyes (100 mg L⁻¹) under UV light irradiation in contrast to other morphologies of MgO and other related state-of-the-art photocatalysts (e.g., N-doped TiO₂, Degussa P25 TiO₂, ZnO, WO₃, α-Fe₂O₃, BiVO₄, and g-C₃N₄), but also could be used for five cycles, maintaining its efficiency above 92.2%. These capacities made the flower-like MgO a potential candidate for polluted water treatment. Also, the underlying photocatalysis mechanism of MgO was proposed through radical trapping experiments.

Flower-like MgO microparticles with excellent photocatalytic performance in degradation of various organic dyes were synthesized by a facile precipitation method via the reaction between Mg²⁺ and CO₃²⁻ at 70 °C.     

Facile synthesis of TiO2/Ag3PO4 composites with co-exposed high-energy facets for efficient photodegradation of rhodamine B solution under visible light irradiation

In this study, TiO₂/Ag₃PO₄ composites based on anatase TiO₂ nanocrystals with co-exposed {101}, {010}/{100}, {001} and [111]-facets and Ag₃PO₄ microcrystals with irregular and cubic-like polyhedron morphologies were successfully synthesized by combining hydrothermal and ion-exchange methods. The anatase TiO₂ nanocrystals with different high-energy facets were controllably prepared via hydrothermal treatment of the exfoliated [Ti₄O₉]²⁻/[Ti₂O₅]²⁻ nanosheet solutions at desired pH values. The Ag₃PO₄ microcrystal with different morphologies was prepared via the ion-exchange method in the presence of AgNO₃ and NH₄H₂PO₄ at room temperature, which was used as a substrate to load the as-prepared anatase TiO₂ nanocrystals on its surface and to form TiO₂/Ag₃PO₄ heterostructures. The apparent rate constant of the pH 3.5-TiO₂/Ag₃PO₄ composite was the highest at 12.0 × 10⁻³ min⁻¹, which was approximately 1.1, 1.2, 1.4, 1.6, 13.3, and 24.0 fold higher than that of pH 0.5-TiO₂/Ag₃PO₄ (10.5 × 10⁻³ min⁻¹), pH 7.5-TiO₂/Ag₃PO₄ (10.2 × 10⁻³ min⁻¹), pH 11.5-TiO₂ (8.8 × 10⁻³ min⁻¹), Ag₃PO₄ (7.7 × 10⁻³ min⁻¹), blank sample (0.9 × 10⁻³ min⁻¹), and the commercial TiO₂ (0.5 × 10⁻³ min⁻¹), respectively. The pH 3.5-TiO₂/Ag₃PO₄ composite exhibited the highest visible-light photocatalytic activity which can be attributed to the synergistic effects of its heterostructure, relatively small crystal size, large specific surface area, good crystallinity, and co-exposed high-energy {001} and [111]-facets. The as-prepared TiO₂/Ag₃PO₄ composites still exhibited good photocatalytic activity after three successive experimental runs, indicating that they had remarkable stability. This study provides a new way for the preparation of TiO₂/Ag₃PO₄ composite semiconductor photocatalysts with high energy crystal surfaces and high photocatalytic activity.

TiO₂/Ag₃PO₄ composites with co-exposed {101}, {010}/{100}, {001} and [111]-facets were successfully synthesized by combining hydrothermal and ion-exchange methods.     

Recyclable magnetic carbonaceous porous composites derived from MIL-100(Fe) for superior adsorption and removal of malachite green from aqueous solution

Development of novel porous materials for efficient adsorption and removal of environmental pollutants from aqueous solution is of great importance and interest in environmental science and chemistry. Herein, we reported a facile synthesis of recyclable magnetic carbonaceous porous composite derived from iron-based metal–organic framework MIL-100(Fe) for superior adsorption and removal of malachite green (MG) from aqueous solution. Because of large surface area and high porosity, the synthesized magnetic carbonaceous porous material presented a superior adsorption capacity of 2090 mg g⁻¹ for MG. The adsorption of MG on magnetic carbonaceous porous composite is endothermic and spontaneous. The prepared magnetic carbonaceous porous composite could be separated easily and rapidly from the solution matrix by an external magnet. The rapid adsorption, large adsorption capacity and good reusability make it attractive for practical use in the adsorption and removal of dyes from aqueous solutions.

Magnetic carbonaceous porous composites (MCPCs) showed excellent adsorption capacity (up to 2090 mg g⁻¹) for malachite green with good reusability and stability.     

Highly efficient ethanol vapour detection using g-C3N4/ZnO micro flower-like heterostructural composites

This work proposes precursor pyrolysis, ultrasonic exfoliation and hydrothermal methods as well as high-temperature calcination strategies to fabricate heterostructured g-C₃N₄/ZnO composites with excellent ethanol vapour sensing properties. The structure, composition and morphology of the as-prepared g-C₃N₄/ZnO composites were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). Then, the sensing properties of the g-C₃N₄/ZnO composites for ethanol (C₂H₅OH) were studied, and g-C₃N₄ doping with different mass ratios was used to control the gas-sensing properties of the composites. Compared with pure ZnO and g-C₃N₄, the performance of g-C₃N₄ with 1% doping content is the best, and the gas sensing activity of the 1% g-C₃N₄/ZnO composite is greatly improved at the optimal working temperature (280 °C). The response to 100 ppm ethanol reaches 81.4, which is 3.7 times that of the pure ZnO-based sensor under the same conditions. In addition, the sensor has good selectivity as well as fast response and recovery speeds (24 s and 63 s, respectively). Finally, a reasonable gas sensing enhancement mechanism is proposed, and it is believed that the constructed g-C₃N₄/ZnO micro flower-like heterostructure and the distinct positions of the valence and conduction bands of ZnO and g-C₃N₄ lead to the obtained sensor exhibiting a large specific surface area and increased conductivity, thereby improving the g-C₃N₄/ZnO-based sensor sensing performance.

Heterostructural g-C₃N₄/ZnO composites were synthesized through a facile hydrothermal strategy using as-prepared g-C₃N₄ nanosheets and precursor solutions of ZnO for effective ethanol detection.     

Mxene/alginate composites for lead and copper ion removal from aqueous solutions

Mxene has been widely used as a sorbent to remove heavy metal ions from sewage due to its unique two-dimensional layered structure and abundant oxygen-containing groups. However, Mxene has a relatively limited adsorption capacity for metal ions possibly due to the limited adsorption active sites. Herein, we reported novel Mxene/alginate composites for lead and copper ion removal from wastewater. The Mxene/alginate composites prepared in this study not only enhance the chelation ability of the lead and copper ions, but also accelerate the ion transport efficiency. The combined advantages of high adsorption capacity and short equilibrium time enable the Mxene/alginate composites to achieve the maximum adsorption capacity for Pb²⁺ and Cu²⁺ at 382.7 and 87.6 mg g⁻¹, respectively, and reach the adsorption equilibrium in 15 min. We believe that the composites developed in this study can open a new avenue for designing high adsorption capacity and high efficiency adsorbents.

Studies on Mxene/alginate composite adsorption have opened up a new avenue for designing adsorbents possessing high adsorption capacity and high efficiency.     

Facile preparation of amidoxime-functionalized Fe3O4@SiO2-g-PAMAM-AO magnetic composites for enhanced adsorption of Pb(ii) and Ni(ii) from aqueous solution

In this paper, using amidoxime as a functional monomer, different generations of polyamidoxime dendrimer magnetic microspheres (Fe₃O₄@SiO₂-g-PAMAM-AO) were fabricated to adsorb Pb²⁺ and Ni²⁺ in aqueous solution. The magnetic adsorbents were characterized by FTIR, XRD, SEM, XPS, TEM, EDS, TGA and BET. The effects of different factors (such as solution pH, adsorption time, adsorption temperature, adsorbent dosage etc.) on adsorption were evaluated. Fe₃O₄@SiO₂-g-PAMAM-AO has a maximum Pb(ii) adsorption of 157.25 mg g⁻¹ (100 mg L⁻¹) at pH 5.5. Furthermore, Fe₃O₄@SiO₂-g-PAMAM-AO showed an excellent adsorption performance for the removal of Ni(ii) with a maximum adsorption capacity of 191.78 mg g⁻¹ (100 mg L⁻¹) at pH 8.0. The sorption isotherm data fitted the Freundlich isotherm model well. Adsorption kinetics analysis showed that it was best described by the pseudo-second-order rate model. Desorption experiment results showed that the adsorbent can be reused in the adsorption–desorption cycles.

In this paper, using amidoxime as a functional monomer, different generations of polyamidoxime dendrimer magnetic microspheres (Fe₃O₄@SiO₂-g-PAMAM-AO) were fabricated to adsorb Pb²⁺ and Ni²⁺ in aqueous solution.     

Facile synthesis of MoO2/CaSO4 composites as highly efficient adsorbents for congo red and rhodamine B

A novel rod-shaped MoO₂/CaSO₄ composite was prepared by using hexa-ammonium molybdate and flue gas desulfurization gypsum via a simple mixed-solvothermal route. In this composite, CaSO₄ matrices are decorated with MoO₂ nanoparticles, and non-structural mesopores are formed via particle packing. Moreover, it displays an excellent adsorption capability towards anionic congo red (CR) and cationic rhodamine B (RhB). The adsorption quantities per unit mass and removal efficiencies of the two dyes are significantly influenced by adsorbent dose, solution pH, and temperature. The adsorption isotherm data can be best fitted by the Langmuir model, and the calculated maximum adsorption quantities at 303.5 K are 853.54 mg g⁻¹ for CR and 86.38 mg g⁻¹ for RhB, respectively, which are superior to other common adsorbents. The corresponding kinetic data can be well matched with the pseudo-second-order model. Additionally, the CR adsorption is an exothermic process, while the RhB adsorption is an endothermic process. Both of them are multi-step chemisorption processes influenced by surface adsorption and intra-particle diffusion. This MoO₂/CaSO₄ composite can be applied as an alternative adsorbent for removing organic dyestuffs from printing and dyeing wastewater.

A new kind of rod-shaped MoO₂/CaSO₄ composite, in which MoO₂ nanoparticles are supported on the surface of CaSO₄ matrices, was prepared via a mixed-solvothermal method for efficient removal towards congo red and rhodamine B.     

Synthesis and properties of zeolite/N-doped porous carbon for the efficient removal of chemical oxygen demand and ammonia-nitrogen from aqueous solution

A novel adsorbent zeolite/N-doped porous activated carbon (ZAC) was prepared by the synthesis of zeolite and mesoporous carbon to remove ammonia nitrogen (NH₄⁺–N) and chemical oxygen demand (COD) from aqueous solution. The impacts of adhesives, molding pressure, synthetic temperature and ratio on ZAC preparation were investigated. The prepared adsorbent was characterized by BET surface area measurement, scanning electron microscopy and X-ray diffraction. The adsorption kinetics was better depicted by the pseudo-second-order model than the pseudo-first-order model and the isotherm fitted well with the Langmuir model. The adsorption process was endothermic, spontaneous and favorable according to thermodynamic data. The adsorbent has much potential in the simultaneous removal of COD and NH₄⁺–N from wastewater.

A novel adsorbent zeolite/N-doped porous activated carbon (ZAC) was prepared by the synthesis of zeolite and mesoporous carbon to remove ammonia nitrogen (NH₄⁺–N) and chemical oxygen demand (COD) from aqueous solution.     

One-pot synthesis of spherical nanoscale zero-valent iron/biochar composites for efficient removal of Pb(ii)

In this study, a spherical Fe/C composite (AIBC) was successfully prepared via carbonization of Fe³⁺-crosslinked sodium alginate. The removal capacity and mechanism of AIBC were evaluated for the adsorption of Pb(ii) from aqueous solution and compared with that of commercial nanoscale zero-valent iron (nZVI). The effects of the initial concentration, pH of Pb(ii) solution, the contact time, coexisting anions, and aging under air were investigated. The results showed that the pH had a strong impact on the adsorption of Pb(ii) by AIBC. The adsorption data for AIBC followed the Langmuir model, while the maximum adsorption capacity at pH 5 was 1881.73 mg g⁻¹. The AIBC had a higher adsorption capability than nZVI, especially under the condition of relatively high Pb(ii) concentrations. The oxidation–reduction reaction between Fe and Pb(ii) was the main mechanism for the adsorption of Pb(ii) onto nZVI. AIBC converted the largest amount of Pb(ii) into PbO·XH₂O/Pb(OH)₂ mainly by generating Fe²⁺.

In this study, a spherical Fe/C composite (AIBC) was successfully prepared via carbonization of Fe³⁺-crosslinked sodium alginate.     

Facile synthesis of novel calcium silicate hydrated-nylon 6/66 nanocomposites by solution mixing method

In this article a facile and green procedure for the synthesis of novel calcium silicate hydrated-nylon 6/66 nanocomposites is proposed. Calcium silicate hydrate (CSH) was synthesized by a hydrolysis technique assisted by ultrasound and using sodium dodecyl sulphate (SDS) as surfactant. CSH-nylon 6/66 nanocomposites were obtained by a solution mixing method at CSH loadings of 2.5, 25, 50 and 75 weight percent (samples CA, CD, CB and CC, respectively). The synthesis of CSH was confirmed by DRX and ATR-FTIR techniques; the CSH sample presents as mesoporous with a diameter between 3.34 nm and 52.68 nm and an average size of 27.07 nm; the specific surface area of the CSH sample was 343.99 m² g⁻¹. The formation of the CSH-nylon 6/66 nanocomposites was confirmed by ATR-FTIR, SEM, XRD, TGA, DSC and XPS techniques. The crystallization and melting temperatures (T_m and T_c, respectively) of CSH-nylon 6/66 nanocomposites occur at a slightly lower temperatures than those of neat Ny 6/66. These results suggest a slight decrease of the crystallite size and crystallization rate of nylon 6/66. The fusion enthalpy (ΔH_f) decreases with increase in CSH content in nylon 6/66, which can be associated to a good dispersion. The XRD peaks of the nylon 6/66 at 19.99° and 23.77° were displaced at slightly higher values of 2θ with the incorporation of CSH in the polymer forming nanocomposite materials.

In this work it was possible to synthesize novel CSH-nylon 6/66 nanocomposites using a simple and easy methodology such as the solution mixing method and using green solvents like water, formic acid and ethanol.     

Fabrication of a magnetite/diazonium functionalized-reduced graphene oxide hybrid as an easily regenerated adsorbent for efficient removal of chlorophenols from aqueous solution

A magnetic hybrid nanomaterial, which contains magnetite (Fe₃O₄) particles and diazonium functionalized-reduced graphene oxide (DF-RGO), was fabricated via a three-pot reaction. First, the reduced graphene oxide (RGO) was synthesized via a redox reaction. Second, diazonium functionalized-RGO was prepared via a feasible chemical reaction. Third, Fe₃O₄ particles were loaded onto the surface of DF-RGO by covalent bonding, fabricating the M-DF-RGO hybrid. The fabricated hybrid was characterized by SEM, TEM, AFM, XRD, XPS, FT-IR, TGA, Raman spectroscopy, and magnetometry. The resulting M-DF-RGO hybrid possessed unique magnetic properties and was applied to remove 4-chlorophenol (4-CP) and 2,4-dichlorophenol (2,4-DCP) from aqueous solution. The adsorption of 4-CP and 2,4-DCP on the M-DF-RGO hybrid was performed under various conditions, with respect to initial chlorophenol concentration, pH, and contact time. The results suggest that the adsorption of 4-CP and 2,4-DCP onto the M-DF-RGO hybrid is strongly dependent on pH and weakly dependent on contact time. In addition, the adsorption isotherm of 4-CP and 2,4-DCP on the M-DF-RGO hybrid fits the Freundlich model well and the adsorption capacities of 4-CP and 2,4-DCP on M-DF-RGO reached 55.09 and 127.33 mg g⁻¹, respectively, at pH 6 and 25 °C. In this situation, intermolecular interactions including π–π interactions and hydrogen bonding are operative. The calculated results of density functional theory further demonstrate that 2,4-DCP molecules could be more easily absorbed than 4-CP molecules by the M-DF-RGO hybrid. Moreover, the M-DF-RGO hybrid could be easily separated by a magnetic separation process, and showed good recyclability of more than five cycles.

A magnetite/diazonium functionalized-reduced graphene oxide hybrid is an easily regenerated and recyclable adsorbent for removal of chlorophenols from aqueous solution.     

A novel,recyclable magnetic biochar modified by chitosan–EDTA for the effective removal of Pb(ii) from aqueous solution

We report here the preparation process of a recyclable magnetic biochar functionalized with chitosan and ethylenediaminetetraacetic acid (E-CMBC). This prepared biochar was then evaluated regarding its adsorption performance for Pb(ii) from an aqueous solution along with the potential adsorption mechanisms behind this process. XRD and SEM analyses showed that the magnetite particles were successfully embedded into biochar and the subsequent surface coating of chitosan and ethylenediaminetetraacetic acid modification were also successful. The effects of the adsorbent dosage, ionic strength, initial solution pH, and contact time, on adsorption kinetics, adsorption isotherms, adsorption thermodynamics and regeneration performance were investigated. The removal of Pb(ii) was dramatically improved to 156.68 mg g⁻¹ compared with that by unmodified pristine biochar (10.90 mg g⁻¹) at pH 3.0. In the range of pH 2.0–5.0, the adsorption performance of Pb(ii) by E-CMBC remained above 152.50 mg g⁻¹, which suggested that the adsorption capacity of the novel sorbent was not impacted by the competing adsorption of hydrogen cations under acidic conditions. The adsorption process could be well described by the Avrami fractional-order and Langmuir models. Thermodynamic analysis proved that the adsorption process was spontaneous and endothermic. The magnetic strength of E-CMBC was measured as 3.1 emu g⁻¹, suggesting that the consumed E-CMBC could be separated from water by an external magnet. A regeneration study showed that after three cycles of adsorption–desorption, 78.60% of the sorbent was recovered and 97.26% of the adsorption capacity was retained. The adsorption mechanism investigation indicated that Pb(ii) adsorption was mainly due to the presence of functional amides and carboxyl groups of E-CMBC forming strong chemical complexation. In conclusion, E-CMBC is a novel, recyclable, and highly efficient adsorbent for removal of Pb(ii) from aqueous solution.

EDTA modified magnetic chitosan biochar was synthesized and used as an adsorbent for adsorption of Pb(ii).     

Facile preparation of high loading filled PVDF/BaTiO3 piezoelectric composites for selective laser sintering 3D printing

3D printed piezoelectric devices, due to their sufficient multidimensional deformation and excellent piezoelectric properties, are one of the most promising research directions. However, the lack of high loaded piezoelectric composites is the key bottleneck restricting the enhancement of the piezoelectric output. In this work, we successfully prepared a novel high loaded polyvinylidene fluoride (PVDF)/barium titanate (BaTiO₃) piezoelectric composite suitable for selective laser sintering (SLS) 3D printing via solid state shear milling (S³M) technology. The 50 wt% BaTiO₃ filling made the most outstanding contribution to the piezoelectric properties of the composites. The 3D printed cymbal parts with a stress amplification effect exhibited outstanding piezoelectric conversion efficiency and responsiveness, whose open circuit voltage and short circuit current could reach 20 V and 1.1 μA, respectively. This work not only contributed a new high loaded piezoelectric composite for SLS processing, but also provided a novel piezoelectric performance enhancement strategy by the construction of 3D structure.

A novel PVDF/BaTiO₃ cymbal part with excellent piezoelectric properties and responsiveness is designed and manufactured by selective laser sintering 3D printing technology.     

Facile template-free synthesis of multifunctional 3D cellular carbon from edible rice paper

Edible rice paper wrapper is found to be an interesting precursor of a porous and light-weight carbon material. During pyrolysis, material samples show significant differences in length change, displaying typical 20–25% shrinking in the in-plane directions, and strongly expanding (up to 500%) across their out-of-plane direction. This results in a template-free synthesis of a 3D network of cellular carbon material. The out-of-plane expansion also allows for fabrication of 3D shapes of cellular carbon material from the 2D precursor. The rice paper derived carbon material features a hierarchical porosity, resulting in a specific surface area ranging from 6 m² g⁻¹ to 239 m² g⁻¹ depending on the synthesis temperature. The carbon material has a density of 0.02–0.03 g cm⁻³, and a higher modulus-density ratio than reported for other cellular carbon materials. It is mechanically stiff and exhibits excellent fire-resistant properties.

Edible rice paper wrapper is found to be an interesting precursor for template-free synthesis of lightweight, stiff, and fire-resistant 3D cellular carbon material.     

Solution combustion synthesis of ternary Ni/WC/C composites with efficient electrocatalytic oxygen reduction performance

In this paper, a fast processing route involving a wet-chemical method (solution combustion synthesis, SCS) and carbonization in a CH₄ environment was demonstrated, through which nanosized Ni/WC/C powder with an average size of 80 nm was obtained. In the catalyst powder, Ni was evenly distributed and it could form NiOOH to promote catalysis, and an amorphous carbon (C) layer with a thickness of <10 nm was formed on the surface of the composite particles, improving the stability of the Ni/WC powder and promoting electron transport. Due to the characteristics of uniformity and a large specific surface area and the synergistic effect of Ni, WC, and C, this powder showed significantly improved ORR catalytic activity in alkaline solution. When the amount of Ni doping was 15 wt%, the composite powder showed the smallest particle size and the best ORR catalytic performance. Its cathode peak potential was −0.31 V and the half wave potential was −0.34 V. The number of electrons transferred in the ORR reaction was 3.6. This work provided a fast and cheap method for the preparation of multicomponent composite catalyst materials.

A Ni/WC/C catalyst synthesized via a rapid combustion method showed considerable efficiency in the oxygen reduction reaction. The excellent performance is attributed to a synergistic effect arising from the ternary composite and solution combustion.     

Lead and uranium sorptive removal from aqueous solution using magnetic and nonmagnetic fast pyrolysis rice husk biochars

This paper discusses the sorption characteristics of Pb(ii) and U(vi) on magnetic and nonmagnetic rice husk biochars. The porosity, specific surface area, hydrophobility, and reusability of biochar were effectively improved (1–2 times) after magnetic modification. The optimum adsorption conditions were as follows: biochar loading was 0.4 g L⁻¹, pH value was 7.0, and anion strength of NO₃⁻ and PO₄³⁻ were 0.01 mol L⁻¹ for Pb(ii) and 0.04 mol L⁻¹ for U(vi) respectively. Compared with U(vi), Pb(ii) had the faster adsorption rate and higher adsorption capacity on magnetic biochar (MBC). The adsorption experimental data were well fitted by pseudo-second-order kinetic and Langmuir isotherm models. The maximum adsorption capacity of Pb(ii) and U(vi) on MBC was 129 and 118 mg g⁻¹ at 328 K respectively, which was significantly higher than that of other sources biochars. Pb(ii) was mainly bonded to biochar by physisorption but the adsorption of U(vi) on biochar was mostly chemisorption. Fe oxides in MBC noticeably improved the ion exchange and complexation action between biochar and metal ion especially for U(vi). The experimental results confirmed MBC material can be used as a cost-effective adsorbent for the removal of Pb(ii) and U(vi) and can be separated easily from aqueous solution when application.

This paper discusses the sorption characteristics of Pb(ii) and U(vi) on magnetic and nonmagnetic rice husk biochars.