Adsorption of uranium from aqueous solution using biochar produced by hydrothermal carbonization

The ability of biochar produced by hydrothermal carbonization (HTC) has been explored for the removal and recovery of uranium from aqueous solutions. The micro-morphology and structure of HTC were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The influences of different experimental parameters such as solution pH, initial concentration, contact time, ionic strength and temperature on adsorption were investigated. The HTC showed the highest uranium sorption capacity at initial pH of 6.0 and contact time of 50 min. Adsorption kinetics was better described by the pseudo-second-order model and adsorption process could be well defined by the Langmuir isotherm. The thermodynamic parameters, △G°(298 K), △H° and △S° were determined to be ?14.4, 36.1 kJ mol^?1 and 169.7 J mol^?1 K^?1, respectively, which demonstrated the sorption process of HTC towards U(VI) was feasible, spontaneous and endothermic in nature. The adsorbed HTC could be effectively regenerated by 0.05 mol/L HCl solution for the removal and recovery of U(VI). Complete removal (99.9 %) of U(VI) from 1.0 L industry wastewater containing 15.0 mg U(VI) ions was possible with 2.0 g HTC.     

Sodium-reduced tantalum powders produced from plumbomicrolite raw materials

Effect of various extractive systems (triisoamyl phosphate/HF+H₂SO₄, n-octanol/HF+H₂SO₄, n-octanol/HF+HNO₃) used to obtain potassium heptafluorotantalate from plumbomicrolite-based raw materials on the purity and characteristics of sodium-reduced tantalum powders was studied. Application of the extractive systems provides production of high-purity potassium heptafluorotantalate from raw materials based on products formed in processing of the plumbomicrolite concentrate.     

Electrochemical hydrogen evolution over MoO3 nanowires produced by microwave-assisted hydrothermal reaction

Molybdenum trioxide (MoO₃) nanowire with unprecedentedly high aspect ratios (>200) and good crystallinity was prepared via decomposition of (NH₄)₆Mo₇O₂₄·4H₂O under a microwave-assisted hydrothermal (MH) process. The nanowire was orthorhombic MoO₃ with 50 nm in diameter and 10–12 μm in length. The conventional hydrothermal (CH) reaction required higher temperature and longer reaction times to produce one-dimensional MoO₃, yet its quality was lower. In the electrochemical hydrogen evolution reaction in a H₂SO₄ solution, MoO₃ nanowire from MH process showed much higher electrocatalytic activity than MoO₃ prepared from CH method and commercial bulk MoO₃ particles. The facile vectorial electron transport along the nanowire axis was considered to be responsible for the excellent electrocatalytic activity of the MH–MoO₃ nanowire.     

Texture and surface properties of carbon-silica nanocomposite materials prepared by the carbonization of high-ash vegetable raw materials in a fluidized catalyst bed

A series of carbon-silica nanocomposite samples prepared by the carbonization of high-ash biomass (using rice husks as an example) in a fluidized-bed reactor with a deep oxidation catalyst at 450–600°C was studied by a set of physicochemical techniques (BET, IR spectroscopy, XPS, and TGA). The dependence of the chemical composition, texture characteristics, and main properties of the resulting materials on carbonization temperature was found.     

Rapid synthesis of LiFePO4 nanoparticles by microwave-assisted hydrothermal method

Lithium iron phosphate (LiFePO₄) nanoparticles have been successfully prepared via microwave-assisted hydrothermal route within ultrashort synthesis-time condition. Electrochemical data reveal that the as-synthesized LiFePO₄ after a post-synthesis heat treatment in an inert atmosphere have excellent rate capability and cycling stability. Ultrashort synthesis-time and higher yield show a possibility of scaling up for industrial production.     

Nano-hydroxyapatite preparation from biogenic raw materials

Hydroxyapatite (HAp) was successfully produced from recycled eggshell, seashell and phosphoric acid. The phases obtained depended on the ratio of calcined eggshell/ seashell to phosphoric acid, the calcination temperature and the mechanochemical activation method (ball milling or attrition milling). The HAp structures were characterized by X-ray diffraction, scanning electron microsopy and infrared spectroscopy. Attrition milling was more effective than ball milling, yielding nanosize, homogenous and pure Hap.      

Novel hydrothermal carbonization of cellulose catalyzed by montmorillonite to produce kerogen-like hydrochar

The conversion of cellulose to petroleum-like fuel is a very challenging yet attractive route to developing biomass-to-fuel technology. Many attempts have been made in liquefaction, pyrolysis and gasification of cellulose to produce fuels or intermediate chemicals. Previous studies indicate that these processes are tough. Hence, the present work is concerned with the development of new technologies for the conversion of cellulose into materials which are analogies to the precursor of petroleum. Montmorillonite-catalyzed hydrothermal carbonization of microcrystalline cellulose for the production of kerogen-like hydrochar under mild conditions was investigated. It was revealed that the hydrothermal carbonization of microcrystalline cellulose alone resulted in hydrochar with type III kerogen-like structure, whereas in the presence of montmorillonite, the hydrothermal carbonization of microcrystalline cellulose yielded a hydrochar-mineral complex, of which the isolated organic fraction was oil-prone type II kerogen-like structure. Results suggested that further improved montmorillonite-aided biomass conversion to more oil-prone kerogen-like solid products could be an alternative efficient route to obtain biofuel and chemicals.     

One-step synthesis of amino-functionalized fluorescent carbon nanoparticles by hydrothermal carbonization of chitosan

Highly amino-functionalized fluorescent carbon nanoparticles (CNPs) were fabricated by hydrothermal carbonization of chitosan at a mild temperature. They were applied to bioimaging of human lung adenocarcinoma A549 cells, showing low cytotoxicity and excellent biocompatibility.     

Continuous wine making by delignified cellulosic materials supported biocatalyst

The continuous making of wine by a delignified cellulosic (DC) material-supported biocatalyst is reported. It was prepared by immobilizing the alcohol resistant strain AXAZ-1 on DC material. The product was found suitable for the continuous process in industrial applications. The operational stability was maintained for 2 mo with monitoring the ethanol concentration, wine, and alcohol productivities as well as the stability of °Be density at the outlet. Wine productivity was three to sixfold higher than obtained by natural fermentation, alcohol concentrations of the wine was in the range of 9.3-211.2% v/v and low volatile acidities of 0.15-20.36 g acetic acid/L were obtained. The effect of total acidity and flow rate of must were also examined. To demonstrate that the operational stability of the bioreactor is due to DC material that promotes the fermentation, and it takes place at even higher ethanol levels, an analogous system of kissiris supported biocatalyst was studied. Likewise, the tolerance in the alcohol concentration, as compared with free cells, were studied by their stability of the activity in the repeated batch fermentation of must.     

Rapid synthesis of carbon materials by microwave-assisted hydrothermal method at low temperature and its adsorption properties for uranium (VI)

The cathelicidin-derived peptide (CDP1) is a human antimicrobial peptide that preferentially targets bacterial membranes in response to infection. CDP1 was functionalised with NODAGA and DOTA for complexation with gallium-68 to evaluate its potential as an infection imaging tracer. The synthesis of [⁶⁸Ga]Ga–NODAGA–CDP1 and [⁶⁸Ga]Ga–DOTA–CDP1 were optimised for pH, molarity, incubation time and temperature, and product purification. The integrity and protein binding were investigated employing [⁶⁸Ga]GaCl₃ and [⁶⁸Ga]Ga–DOTA–TATE as internal references. [⁶⁸Ga]Ga–NODAGA–CDP1 displayed good labelling properties with higher product yield compared to [⁶⁸Ga]Ga–DOTA–CDP1. In contrast, [⁶⁸Ga]Ga–DOTA–CDP1 showed better stability and is the preferred candidate for an in vivo investigation.

     

Carbon encapsulated magnetic nanoparticles produced by hydrothermal reaction

Carbon encapsulated magnetic nanoparticles(CEMNs)were synthesized by heating an aqueous glucose solution containing Fe-Au(Au coated Fe nanoparticles)nanoparticles at 160-180℃ for 2 h.This novel hydrothermal approach is not only simple but alsoprovides the surface of CEMNs with functional groups like-OH.The formation of carbon encapsulated magnetic nanoparticles wasnot favored when using pure Fe nanoparticles as cores because of the oxidation of Fe nanoparticles by H2O during the reaction and,therefore,the surfaces of the naked Fe nanoparticles had to be coated by Au shell in advance.TEM,XRD,XPS and VSMmeasurments characterized that they were uniform carbon spheres containing some embedded Fe-Au nanoparticles,with asaturation of 14.6 emu/g and the size of the typical product is$350 nm.     

Cellulose hydrolysis catalyzed by highly acidic lignin-derived carbonaceous catalyst synthesized via hydrothermal carbonization

Acidic carbonaceous solids were synthesized from mass pine alkali lignin via hydrothermal carbonization followed by sulfonation. Hydrothermal carbonization of lignin in the presence of acrylic acid (LAHC-SO₃H) provided many more carboxylic groups than that in the absence of acrylic acid, allowing subsequent sulfonation to produce a highly active and stable catalyst for cellulose hydrolysis in the [BMIM]Cl-H₂O solvent system. The hydrochar and catalyst were characterized using field emission scanning electron microscopy, X-ray diffractometer, X-ray photoelectron spectroscopy, thermal gravimetric analysis, Fourier transform infrared spectrometer, Brunauer–Emmett–Teller and acid–base titration. Results showed that a high acid content of 5.48 mmol/g, including carboxylic group (2.85 mmol/g), phenolic hydroxyl group (1.05 mmol/g) and sulfonic acid group (1.58 mmol/g), contributed significantly to the highly efficient hydrolysis of cellulose. Further, it was found that addition of trace water in [BMIM]Cl was favorable to cellulose hydrolysis. The highest yield (75.4%) of total reducing sugar (TRS) obtained in [BMIM]Cl-H₂O at a mass ratio of 100:1 was more than twice that (36.1%) achieved in [BMIM]Cl without water; the corresponding reaction conditions were 50 mg of microcrystalline cellulose, 30 mg of catalyst, 1.0 g of [BMIM]Cl, 10 mg of H₂O, reaction temperature of 130 °C and reaction time of 2 h. Furthermore, the TRS yield with 5 cycles for LAHC-SO₃H was higher than 68.1%, and the catalytic activity of catalyst could be fully recovered (74.0% of TRS yield) easily by regeneration.     

Study of combustion processes in firing of a heat-insulator produced from technogenic raw materials from nonferrous metallurgy and power industry

Combustion of heat-insulators produced from technogenic raw materials without use of conventional natural materials were studied. It is shown that most part of volatiles are removed in thermal treatment of heat insulators in the temperature range 400?C600°C, the reduction of iron is considerably accelerated at 1050?C1100°C, and organic compounds can hardly be found in a ceramic material fired at 1100°C.     

Synthesis of copper-core/carbon-sheath nanocables by a surfactant-assisted hydrothermal reduction/carbonization process

A simple hydrothermal method has been developed for the one-step synthesis of copper-core/carbon-sheath nanocables in solution. The obtained nanostructures were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and high-resolution TEM (HRTEM), Raman, and UV-vis spectrum analysis. These copper@carbon nanocables formed through the hydrothermal reduction/carbonization in the presence of surfactant cetyltrimethylammonium bromide (CTAB) acting as the structure-directing agent by hydrothermal treatment. HRTEM and selected-area electron diffraction (SAED) indicate that the resulted Cu nanowires had the preferred [110] growth direction. The influence of the reaction temperature, reaction time, and pH on the final products was investigated in detail. The possible formation mechanism for copper-core/carbon-sheath nanocables was also proposed. Amorphous carbon nanotubes can be obtained by etching the copper core in the nanocables.     

Low-cost reed straw-derived biochar prepared by hydrothermal carbonization for the removal of uranium(VI) from aqueous solution

Journal of Radioanalytical and Nuclear Chemistry - Uranium is the important nuclear fuel and its effective adsorption using low-cost materials is meaningful to environmental protection and...     

Desorption reaction of ferric ions adsorbed on cellulosic materials by acids

Factors affecting the desorption reaction of ferric ions adsorbed on cellulose and oxidized poly(vinyl alcohol) fibers by acids were investigated. The desorbing effect generally increased with increasing acid concentration, treating temperature, and treating time, although the magnitude of this effect varied somewhat from one acid to another. Oxalic acid, hydrochloric acid, sulfuric acid, sulfurous acid, and phosphoric acid are examples of those acids which show large desorbing effects. Scission of the cellulose chain was also observed under the desorption conditions used for such acids. The desorption reaction may be divided into two stages, an initial fast reaction and a subsequent slow reaction; the activation energies were calculated for each reaction, and values of 7–10 kcal/mole and 5–6 kcal/mole were obtained for cellulose and oxidized poly(vinyl alcohol) fibers, respectively.     

Thermal behaviour of lignins extracted from different raw materials

The thermal degradation of lignins extracted from bagasse, rice straw, corn stalk and cotton stalk, have been investigated using the techniques of thermogravimetric analysis (TG) and differential thermal analysis (DTA), between room temperature and 600°C. The actual pyrolysis of all samples starts above 200°C and is slow. The results calculated from TG curves indicated that the activation energy, Efor thermal degradation for different lignins lies in the range 7.949–8.087 kJ mol^?1. The DTA of all studied lignins showed an endothermic tendency around 100°C. In the active pyrolysis temperature range, thermal degradation occurred via two exothermic process at about 320 and 480°C, and a large endothermic pyrolysis region between 375 and 450°C. The first exothermic peak represents the main oxidation and decomposition reaction, the endothermic effect represents completion of the decomposition and the final exothermic peak represents charring.     

Synthesis of rutile titanium dioxide from Russian raw materials

The conditions of the structure formation of rutile titanium dioxide from titanium dioxide (anatase) and titanium hydroxide isolated by thermolysis from the titanium compound (NH₄)₂TiO(SO₄)₂ · H₂O and by thermal hydrolysis of a titanium sulfate(IV) solution, respectively, were studied. It was shown that the mechanical activation of the studied powders causes, in addition to a decrease in the initial grain size, deep destructuring with the formation of the transition phase, which, in the process of the subsequent high-temperature treatment, functions as a matrix for the formation of rutile. The research results will be used for the development of a new variant of the technology for the synthesis of titanium dioxide, which is an important component of compositions for polymeric materials—in particular, the K-300-61 and K-153 adhesives.     

Recovery of metals from raw materials of industrial origin

Interaction of d elements and their compounds (oxides, sulfides, carbonates, and other compounds poorly soluble in water) with organic ligands in aprotic solvents was studied. Methods for recovery of metals from nonaqueous solutions of the resulting complex compounds are suggested.