Low Temperature One-Pot Hydrothermal Carbonization of Corn Straw into Hydrochar for Adsorbing Cadmium (II) in Wastewater

Corn straw, a typical agricultural waste, was directly converted into hydrochar with a yield of 77.56% by hydrothermal carbonization at 140–230 °C for 2 h with a solid–liquid ratio of 1:20. The morphology and surface properties were characterized by elemental analysis, specific surface area and pore size analysis and Fourier transform infrared spectroscopy. The results showed that with the increase of hydrothermal reaction temperature, some physical and chemical properties such as the increase of hydrocarbon content, crystallinity, and specific surface area of hydrochar changed significantly. A series of chemical reactions such as dehydration, decarboxylation, and aromatization occurred in the hydrothermal carbonization process so that the prepared hydrochar had rich oxygen-containing functional groups (-HO, C-O-C, C=O) and unique porous structure made the hydrochar prepared at 170 °C had the best removal effect on Cd2+ in solution (5.84 mg/g). These specific conditions could remove Cd2+ and greatly improve the adsorption performance. The pseudo-second-order kinetic model and Freundlich isotherm model could better describe the adsorption behavior of Cd2+. Therefore, corn straw hydrochar as a potential adsorbent for removing Cd2+ from water.

Removal of Cesium from Radioactive Waste Liquids Using Geomaterials

In this study, we investigated the removal of Cs from aqueous solutions using geomaterials. Adsorption was chosen as an effective method to develop for the removal of Cs from radioactive waste liquids. Geomaterials, including fly ash and slag as raw materials, were prepared as adsorbents using an alkali activator. The materials were characterized by X-ray diffraction (XRD); scanning electron microscopy with energy dispersive spectrometer (SEM-EDS); and BET surface area, pore volume, and pore size analysis. The effects of various parameters, such as pH, contact time, and adsorbent dosage on the adsorption of the Cs were studied. The partition coefficient (PC) as well as the adsorption capacity were evaluated to assess the true performance of the adsorbent in this work. The fly ash-based geomaterials showed a maximum Cs adsorption capacity of 89.32 mg·g−1 and a high PC of 31.02 mg·g−1·mM−1 for the Cs under our experimental conditions. From this work, this method can be regarded being practical for use as a potential adsorbent for treating Cs in wastewater. Furthermore, the immobilization of Cs in geomaterials was explored from a chemical perspective. In conclusion, fly ash-based geomaterials may be a promising option for the treatment and disposal of nuclear-contaminated waste.

Pore structure characteristics and fractal structure evaluation of medium- and high-rank coal

The presence of gas content in medium- and high-rank coal poses a threat to safety production. Safe gas extraction is based on a correct understanding of the pore structure of coal. This work investigates the pore structure characteristics of medium- and high-rank coal and evaluates their fractal structure. The coal samples were collected from Huainan Coalfield and Qinshui Coalfield, and divided into four types, according to the difference in surface bright characteristics. Through adopting low-temperature liquid nitrogen adsorption and desorption, and applying Kelvin equation, we obtain the main pore structure types and main pore size distribution characteristics of various coal briquettes. Electron microscope scanning structure and scientific analysis were used for special adsorption and desorption curves and hysteresis to find the dynamic reason. According to the different adsorption mechanism and Frenkel–Halsey–Hill-based model, with P/ P0 = 0.4 as the dividing point of fractal dimension analysis, the pore structure of coal samples is classified into five grades. The fractal evaluation results are consistent with the results of curve analysis and pore size analysis.

Manufacturing and Characterisation of Polymeric Membranes for Water Treatment and Numerical Investigation of Mechanics of Nanocomposite Membranes

In this study, polyethersulfone (PES) and polyvinylidene fluoride (PVDF) microfiltration membranes containing polyvinylpyrrolidone (PVP) with and without support layers of 130 and 150 μm thickness are manufactured using the phase inversion method and then experimentally characterised. For the characterisation of membranes, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and pore size analysis are performed, the contact angle and water content of membranes are measured and the tensile test is applied to membranes without support layers. Using the results obtained from the tensile tests, the mechanical properties of the halloysite nanotube (HNT) and nano-silicon dioxide (nano SiO2) reinforced nanocomposite membranes are approximately determined by the Mori–Tanaka homogenisation method without applying any further mechanical tests. Then, plain polymeric and PES and PVDF based nanocomposite membranes are modelled using the finite element method to determine the effect of the geometry of the membrane on the mechanical behaviour for fifteen different geometries. The modelled membranes compared in terms of three different criteria: equivalent stress (von Mises), displacement, and in-plane principal strain. Based on the data obtained from the characterisation part of the study and the numerical analysis, the membrane with the best performance is determined. The most appropriate shape and material for a membrane for water treatment is specified as a 1% HNT doped PVDF based elliptical membrane.

Gliadin-mediated green preparation of hybrid zinc oxide nanospheres with antibacterial activity and low toxicity

The development of inorganic antibacterial agents that impart antibacterial properties to biomaterials has attracted wide attention. The paper introduced a kind of hybrid nanosphere antibacterial agent composed of wheat gliadin (WG) and zinc oxide (ZnO), with antibacterial efficacy and low toxicity. The ZnO/WG hybrid nanospheres were environment-friendly integrated by molecular self-assembly co-precipitating and freeze-drying transformation, and were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), atomic absorption spectroscopy (AAS), specific surface and pore size analysis, bacteriostasis test, reactive oxygen species (ROS) determination and safety evaluation. It was found that the prepared hybrid nanospheres were composed of two components, WG and ZnO, with a diameter scope of 100–200 nm; the content of ZnO in the hybrid nanospheres can reach 46.9–70.2% (w/w); the bacteriostasis tests proved that the prepared ZnO/WG nanospheres generating ROS, have a significant inhibitory effect on E. coli and S. aureus; furthermore, the ZnO/WG nanospheres are relatively safe and highly biocompatible in cells and mice. Therefore, the prepared novel ZnO/WG hybrid nanospheres were supposed to apply in the preparation of anti-infective wound dressings, tissue engineering skin scaffold materials, food, and cosmetics preservatives, and so on.

Experimental Study on Influence of Al2O3, CaO and SiO2 on Preparation of Zinc Ferrite

Gossan ore of sulfide zinc deposit contains abundant zinc, iron, and other metal elements, which is a significant resource with complex components and can be utilized. In this study, a new technology of preparing zinc ferrite from zinc sulfide deposit gossan was proposed. The effects of Al2O3, CaO, and SiO2 in gossan on the formation of zinc ferrite were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and specific surface area and pore size analysis (BET). The results show that the presence of Al2O3 and CaO could hinder the formation of zinc ferrite, while silica had no effect on the formation of zinc ferrite. Under the conditions of the molar ratio of ZnO and Fe2O3 to Al2O3, CaO, and SiO2 of 1:1:1, an activation time of 60 min, and a roasting temperature of 750 °C for 120 min, the products, which had good crystallinity, smooth particle surface, and uniform particle size could be obtained. In addition, compared to the roasted products with Al2O3 and CaO, the specific surface area, pore volume, and pore size of the products with SiO2 were the largest.

Characterization of Mesoporous Biphasic Calcium Phosphate Synthesized Using Chitosan and Aloe Vera Template

Biphasic calcium phosphate (BCP) is a bonegraft material which is a mixture of hydroxyapatite (Ca10(PO4)6(OH)2, HA) and betatricalcium phosphate (Ca3(PO4)2, β-TCP). The combination of HA and β-TCP provides faster osseointegration, compared to HA, into parent bone so it can accelerate the bone recovery process. The mesoporous structure of bone graft material is suitable for drug delivery purpose. In order to study the mesoporous structure of BCP, the BCPs were prepared by precipitation method using chitosan, aloe vera, and chitosan-aloe vera hybrid as templates. A solution containing Ca(NO3)2·4H2O and template and a solution containing (NH4)2HPO4 and NH4HCO3 were used as starting materials. All prepared samples were calcined at 900°C for 1 hour. The identification of phases and functional groups of obtained BCP powders were characterized by X-Ray Diffraction technique and Fourier Transform Infrared (FTIR) spectroscopy, repectively. The XRD patterns show typical peaks of both HA and β-TCP crystal phases. FTIR spectra confirm the presence of phosphate functional groups. Morphological analysis using Scanning Electron Microscope (SEM) observed the presence of regular porous structure, however, the mesoporous structure was not seen. Particle size distribution and pore size analysis were analyzed by Particle Size Analyzer and Brunauer–Emmett–Teller (BET) method, respectively.