3D Nanoarchitecture of Polyaniline-MoS2 Hybrid Material for Hg(II) Adsorption Properties

Use of transition metal dichalcogenides (TMDs) in analytical sample preparation applications

Since the discovery of graphene, nano-sized two-dimensional (2D) transition metal dichalcogenides (TMDs) such as MoS2, MoSe2, MoTe2, NbS2, NbSe2, WS2, WSe2, TaS2 and TaSe2, which have been classified as next-generation nanomaterials resembling graphene (G) have complementary basic properties with those of graphene in terms of their practical applications. TMDs are attracting great attention due to their attractive physical, chemical and electronic properties. Despite being overshadowed by graphene in terms of frequency of use, TMDs have been used frequently in many areas in recent years instead of carbon-based materials such as graphene (G), graphene oxide (GO), carbon nanotubes (CNTs) and nanodiamonds (NDs). It is seen that the first and frequent uses of TMDs, which are classified as new generation materials, are in the fields of catalysis, electronic applications, hydrogen production processes and energy storage, but it has been used as an adsorbent in sample preparation techniques in recent years. Similar to graphene, layers of TMDs are held together by weak van der Waals interactions. The sandwiched layers of TMDs provide sufficient and effective interlayer spaces so that foreign molecules, ions and atoms can easily enter these spaces between the layers. Intermolecular interactions increase with the entry of different materials into these spaces, and thus, high activity, adsorption capacity and efficiency are obtained in adsorption-based analytical sample preparation methods. Although there are about 35 research articles using TMDs, which are classified as promising materials in analytical sample preparation techniques, no review studies have been found. This review, which was designed with this awareness, contains important informations on the properties of metal dichalcogenides, their production methods and their use in analytical sample preparation techniques.

Study on the cyclic adsorption performance of biomass composite membrane for Hg(II)

Salix psammophila wood flour /polyvinyl alcohol hydrogel composite membrane (SPPM) with high adsorption capacity and good cycle adsorption performance was prepared by wet spinning technology. The SPPM was characterised by the scanning electron microscope (SEM), specific surface area test (BET), energy dispersive spectrum (EDS) thermal gravimetric analysis (TGA), fourier transform infrared spectroscopy (FT-IR), and x-ray photoelectron spectroscopy (XPS). The results showed that the surface of SPPM is rough and porous, with good pore structure and thermal stability, and mercury ions (Hg(II)) have been successfully adsorbed on SPPM. At the same time, the effects of adsorption conditions (Hg(II) initial concentration, pH, adsorption time, and temperature) on the adsorption performance of SPPM were studied. Results from the adsorption experiment showed that the adsorption capacity of SPPM for Hg(II) can reach 426 mg/g. After four adsorption and desorption experiments, the adsorption capacity can reach 375 mg/g, which indicates that SPPM has good cycle adsorption performance. The adsorption kinetics was better described by the Pseudo-second-order kinetic, and their adsorption isotherms were fitted for the Langmuir model. The obtained results showed that SPPM is an available, economical adsorbent and was found suitable for removing Hg(II) from an aqueous solution.

Design and fabrication of intracellular therapeutic cargo delivery systems based on nanomaterials: current status and future perspectives

Intracellular cargo delivery, the introduction of small molecules, proteins, and nucleic acids into a specific targeted site in a biological system, is an important strategy for deciphering cell function, directing cell fate, and reprogramming cell behavior. With the advancement of nanotechnology, many researchers use nanoparticles (NPs) to break through biological barriers to achieving efficient targeted delivery in biological systems, bringing a new way to realize efficient targeted drug delivery in biological systems. With a similar size to many biomolecules, NPs possess excellent physical and chemical properties and a certain targeting ability after functional modification on the surface of NPs. Currently, intracellular cargo delivery based on NPs has emerged as an important strategy for genome editing regimens and cell therapy. Although researchers can successfully deliver NPs into biological systems, many of them are delivered very inefficiently and are not specifically targeted. Hence, the development of efficient, target-capable, and safe nanoscale drug delivery systems to deliver therapeutic substances to cells or organs is a major challenge today. In this review, on the basis of describing the research overview and classification of NPs, we focused on the current research status of intracellular cargo delivery based on NPs in biological systems, and discuss the current problems and challenges in the delivery process of NPs in biological systems.

Development of a Rapid Tool for Metal Injection Molding Using Aluminum-Filled Epoxy Resins

Metal injection molding (MIM) is a near net-shape manufacturing process combining conventional plastic injection molding and powder metallurgy. Two kinds of injections molds for MIM were developed using conventional mold steel and aluminum (Al)-filled epoxy resins in this study. The characteristics of the mold made by rapid tooling technology (RTT) were evaluated and compared with that of the fabricated conventional machining method through the MIM process. It was found that the service life of the injection mold fabricated by Al-filled epoxy resin is about 1300 molding cycles with the average surface roughness of 158 nm. The mold service life of the injection mold fabricated by Al-filled epoxy resin is about 1.3% that of the conventional mold steel. The reduction in manufacturing cost of an injection mold made by Al-filled epoxy resin is about 30.4% compared with that of the fabricated conventional mold steel. The saving in manufacturing time of an injection mold made by RTT is about 30.3% compared with that of the fabricated conventional machining method.

Synthesis of hyperbranched polyamine dendrimer/chitosan/silica composite for efficient adsorption of Hg(II)

The pollution of water system with Hg(II) exerts hazardous effect to ecosystem and public health. Adsorption is considered to be a promising strategy to remove Hg(II) from aqueous solution. Herein, hyperbranched polyamine dendrimer/chitosan/silica composite (SiO₂-FP) was synthesized for the adsorption of aqueous Hg(II). The adsorption performance of SiO₂-FP was comprehensively determined by considering various influencing factors. SiO₂-FP displays good adsorption performance for Hg(II) with the adsorption capacity of 0.79 mmol·g^-1, which is higher than the corresponding chitosan functionalized silica (SiO₂-CTS) by 46.30 %. The optimal solution pH for the adsorption of Hg(II) is 6. Adsorption kinetic indicates the adsorption for Hg(II) can reach equilibrium at 250 min. Adsorption kinetic process can be well fitted by pseudo-second-order (PSO). Adsorption isotherm reveals the adsorption for Hg(II) can be promoted by increasing initial Hg(II) concentration and adsorption temperature. The adsorption isotherm indicates the adsorption process can be described by Langmuir model and the adsorption is a spontaneous, endothermic and entropy-increased process. SiO₂-FP displays excellent adsorption selectivity and can 100 % adsorb Hg(II) with the coexisting of Ni(II), Zn(II), Pb(II), Mn(II), and Co(II). Adsorption mechanism demonstrates -NH-, -NH₂, CN, CONH, -OH, and CO participated in the adsorption. SiO₂-FP exhibits good regeneration property and the regeneration rate can maintain approximately 90 % after five adsorption-desorption cycles.

Selective mercury adsorption and enrichment enabled by phenylic carboxyl functionalized poly(pyrrole methane)s chelating polymers

Mercury decontamination from water requires highly effective and efficient methods for maintaining public health and environmental protection. Herein, based on the coordination theory between functional groups and metal ions, we proposed phenylic carboxyl group-based poly(pyrrole methane)s (PPDCBAs) as highly efficient mercury removal materials for environmental remediation applications. It was found that PPDCBAs can efficiently adsorb and remove mercury(II) from aqueous solutions by functionalizing the molecular structure with phenylic carboxyl groups. Among the as-prepared PPDCBAs, poly[pyrrole-2, 5-diyl (4-carboxybenzylidane)] (PPD4CBA) with the carboxyl group at the para position can not only adsorb mercury over 1400 mg⋅g^-1 but also achieve a 92.5 % mercury(II) uptake within 100 min by a very low dosage of 0.1 g⋅L^-1. In addition, PPDCBAs exhibited excellent adsorption selectivity for mercury(II) compared with copper(II), cadmium(II), zinc(II) and lead(II). Furthermore, as determined by Fourier transform infrared (FT-IR) spectra, X-ray photoelectron spectroscopy (XPS) and the density functional theory (DFT) calculation, the mercury removal was found to be mainly dependent on the high density of chelating sites, the phenylic carboxyl moieties, which helped us to realize an ultra-trace amount mercury removal (from 10.8 μg⋅L^-1 to 0.6-0.8 μg⋅L^-1) for meeting drinking water standard requirements (1.0 μg⋅L^-1).

Organic-inorganic interface chemistry for sustainable materials

This mini-review focuses on up-to-date advances of hybrid materials consisting of organic and inorganic components and their applications in different chemical processes. The purpose of forming such hybrids is mainly to functionalize and stabilize inorganic supports by attaching an organic linker to enhance their performance towards a target application. The interface chemistry is present with the emphasis on the sustainability of their components, chemical changes in substrates during synthesis, improvements of their physical and chemical properties, and, finally, their implementation. The latter is the main sectioning feature of this review, while we present the most prosperous applications ranging from catalysis, through water purification and energy storage. Emphasis was given to materials that can be classified as green to the best in our consideration. As the summary, the current situation on developing hybrid materials as well as directions towards sustainable future using organic-inorganic hybrids are presented.

Chelating Extractants for Metals

In the present review, works on the classes of chelating extractants for metals, compounds with several amide and carboxyl groups, azomethines, oximes, macrocyclic compounds (crown ethers and calixarenes), phenanthroline derivatives, and others are systematized. This review focuses on the efficiency and selectivity of the extractants in the recovery of metals from industrial wastewater, soil, spent raw materials, and the separation of metal mixtures. As a result of this study, it was found that over the past seven years, the largest number of works has been devoted to the extraction of heavy metals with amino acids (16 articles), azomethines and oximes (12 articles), lanthanids with amide compounds (15 articles), lanthanides and actinides with phenanthroline derivatives (7 articles), and noble metals with calixarenes (4 articles). Analysis of the literature showed that amino acids are especially effective for extracting heavy metals from the soil; thiodiglycolamides and aminocalixarenes for extracting noble metals from industrial waste; amide compounds, azomethines, oximes, and phenanthroline derivatives for extracting actinides; amide compounds for extracting lanthanides; crown ethers for extracting radioactive strontium, rhenium and technetium. The most studied parameters of extraction processes in the reviewed articles were the distribution ratios and separation factors. Based on the reviewed articles, it follows that chelate polydentate compounds are more efficient compounds for the extraction of metals from secondary resources compared to monodentate compounds.

Preconcentration and determination of trace Hg(ii) using ultrasound-assisted dispersive solid phase microextraction

Defect rich molybdenum disulfide (MoS₂) nanosheets were hydrothermally synthesized and their potential for ultrasound assisted dispersive solid phase microextraction of trace Hg(ii) ions was assessed. Ultrasonic dispersion allows the MoS₂ nanosheets to chelate rapidly and evenly with Hg(ii) ions and results in improving the precision and minimizing the extraction time. The multiple defect rich surface was characterized by X-ray diffraction and high-resolution transmission electron microscopy. The surface charge of intrinsically sulfur rich MoS₂ nanosheets and their elemental composition was characterized by zeta potential measurements, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy. The cracks and holes on the basal planes of MoS₂ led to diffusion of the Hg(ii) ions into the interior channels. Inner-sphere chelation along with outer-sphere electrostatic interaction were the proposed mechanism for the Hg(ii) adsorption onto the MoS₂ surface. The experimental data showed good selectivity of MoS₂ nanosheets towards Hg(ii) adsorption. The systematic and constant errors of the proposed method were ruled out by the analysis of the Standard Reference Material (>95% recovery with <5% RSD). The Student's t-test values for the analyzed Standard Reference Material were found to be less than the critical Student's t value at 95% confidence level. The limit of detection (3S) was found to be 0.01 ng mL⁻¹. The MoS₂ nanosheets were successfully employed for the analysis of Hg(ii) in environmental water samples.

Hg(ii) ion adsorption onto an MoS₂ surface.

Flexible Low-Temperature Ammonia Gas Sensor Based on Reduced Graphene Oxide and Molybdenum Disulfide

Owing to harsh working environments and complex industrial requirements, traditional gas sensors are prone to deformation damage, possess a limited detection range, require a high working temperature, and display low reliability, thereby necessitating the development of flexible and low-temperature gas sensors. In this study, we developed a low-temperature polyimide (PI)-based flexible gas sensor comprising a reduced graphene oxide (rGO)/MoS2 composite. The micro-electro-mechanical system technology was used to fabricate Au electrodes on a flexible PI sheet to form a “sandwiched” sensor structure. The rGO/MoS2 composites were synthesized via a one-step hydrothermal method. The gas-sensing response was the highest for the composite comprising 10% rGO. The structure of this material was characterized, and a PI-based flexible gas sensor comprising rGO/MoS2 was fabricated. The optimal working temperature of the sensor was 141 °C, and its response-recovery time was significantly short upon exposure to 50–1500 ppm NH3. Thus, this sensor exhibited high selectivity and a wide NH3 detection range. Furthermore, it possessed the advantages of low power consumption, a short response-recovery time, a low working temperature, flexibility, and variability. Our findings provide a new framework for the development of pollutant sensors that can be utilized in an industrial environment.