Thermal Activation Method Research Articles

Preparation of Tritium-Labeled Hyaluronic Acid by Tritium Thermal Activation Method

Preparation of Tritium-Labeled Hyaluronic Acid by Tritium Thermal Activation Method

Activated Bio-Carbons Prepared from the Residue of Supercritical Extraction of Raw Plants and Their Application for Removal of Nitrogen Dioxide and Hydrogen Sulfide from the Gas Phase.

The waste materials left after supercritical extraction of hop cones and marigold flowers were tested as precursors of activated bio-carbons. Adsorbents were produced by means of the physical (also called thermal) activation method using CO2 as the gasifying agent. All the activated bio-carbons were tested for the removal of NO2 and H2S from the gas phase under dry and wet conditions. The effects of the type of precursor and the activation procedure on the porous structure development, the acid-base properties of the surface, as well as the sorption capacities of the materials produced were also checked. The final products were bio-carbons of medium developed surface area with a basic surface nature, characterized by their high effectiveness in removal of gas pollutants of acidic character, especially nitrogen dioxide (sorption capacities in the range from 12.5 to 102.6 mg/g). It was proved that the toxic gas removal efficiency depends considerably on the sorption conditions and the activation procedure. All materials showed greater effectiveness in gas removal when the process of adsorption was carried out in the presence of steam.

Comparative study on intercalation-exfoliation and thermal activation modified kaolin for heavy metals immobilization during high-organic solid waste pyrolysis

With the new municipal solid waste classification policy implemented in China, attention on achieving the waste-to-energy disposal of “dry waste” has been growing. Pyrolysis conversion of organic waste into value-added chemicals is a promising method to treat solid waste. However, after removing the non-combustible components of “dry waste”, the obtained high-organic solid waste (HSW) contains various heavy metals, which requires urgent attention during thermochemical conversion. To mitigate heavy metals risk, kaolin was employed as additive during HSW pyrolysis, and intercalation–exfoliation and thermal activation modifications were performed on the kaolin to further immobilize and stabilize heavy metals in the derived chars. The characterization results illustrated that the interlayer spacing, pore volume and diameter of kaolin were expanded after intercalation–exfoliation modification, providing more opportunities for the adsorption of metals. The thermal activation method favored the transformation of kaolin into metakaolin via dehydroxylation to enhance its nonhexacoordinated Al proportion and chemisorption. During 450–650 °C, kaolin exhibited an effective solid enrichment performance for targeting heavy metals, and the intercalation–exfoliation and thermal activation modification further enhanced the adsorption capacity of the kaolin for Cd, Cr, Pb and Cr, Cu, Pb, Zn, respectively. Compared with Cu and Zn, additives demonstrated better stabilization effects for Cd, Pb, and Cr, transforming more bioavailable fractions to the residual speciation. Overall, a higher pyrolytic temperature (650 °C) and the addition of effective additives could simultaneously increase the residual fraction and decrease the bioavailable fraction of heavy metals in HSW-derived chars, reducing the potential ecological risk.

Hyaluronic acid adsorption on nanodiamonds: Quantitative characteristics and mechanism

Formation of adsorption complex between hyaluronic acid and detonation nanodiamonds was studied. Nanodiamonds that possess negative and positive zeta-potential in an aqueous suspension were used. To determine the direct amount of hyaluronic acid on the nanodiamond surface tritium label was introduced into the polymer by means of tritium thermal activation method. It was found that hyaluronic acid irreversibly adsorbs on both positively and negatively charged nanodiamonds, but in different quantities. Adsorption of hyaluronic acid on nanodiamonds of positive zeta potential leads to the isoelectric point at the surface coverage close to 100 mg/g, while further increase in surface amount of hyaluronic acid results in the formation of negatively charged particles and the increase of its species diameter comparing with the initial material. In the case of negatively charged nanodiamonds adsorption of hyaluronic acid is also observed, but it was as much as 50 times lower than in the case of positively charged nanodiamonds. Even small amounts of hyaluronic acid adsorbed on nanodiamond surface results in the disaggregation of clusters of nanodiamonds that are formed in an aqueous suspension, while zeta potential was from − 50 to − 40 mV that is around of the value for non-modified material. On the basis of the experimental data, we can suggest that the adsorption mechanism of complex formation between hyaluronic acid and nanodiamonds includes both electrostatic interaction and formation of hydrogen bonds between surface functional groups and adsorbed water molecules.

A thermal activated and differential self-calibrated flexible epidermal biomicrofluidic device for wearable accurate blood glucose monitoring.

This paper reports a flexible electronics-based epidermal biomicrofluidics technique for clinical continuous blood glucose monitoring, overcoming the drawback of the present wearables, unreliable measurements. A thermal activation method is proposed to improve the efficiency of transdermal interstitial fluid (ISF) extraction, enabling extraction with a low current density to notably reduce skin irritation. An Na+ sensor and a correction model are proposed to eliminate the effect of individual differences, which leads to fluctuations in the amount of ISF extraction. An electrochemical sensor with a 3D nanostructured working electrode surface is designed to enable precise in situ glucose measurement. A differential structure is proposed to eliminate the effect of passive perspiration, which leads to inaccurate blood glucose prediction. Fabrications of the epidermal biomicrofluidic device including formation of flexible electrodes, nanomaterial modification, and enzyme immobilization are fully realized by inkjet printing to enable facile manufacturing with low cost, which benefits practical production.

Smectite clay waste as an additive for Portland cement

This study aims at investigating the possibility of using smectite clay waste, generated during the oil bleaching process as an additive for Portland cement. The smectite clay waste consists of montmorillonite, quartz, anorthite, calcium sulfate, and amorphous phase. For the regeneration of this waste, the extraction with hexane and thermal method were chosen. The results showed that the extraction of smectite clay waste with hexane significantly increased the pozzolanic activity of this waste; however, the extracted additive prolonged the induction period of Portland cement hydration, slowing down initial cement hydration, and reduced the compressive strength of Portland cement samples.The thermal activation method achieves the best results by calcining smectite clay waste at 600 °C. The calcined additive indicated the strong pozzolanic activity. However, this phenomenon is associated with the formation of the amorphous phase by activating the smectite clay with the sulfuric acid rather than the degradation of the clay minerals during the combustion. The calcined smectite clay waste (CSCW) accelerates the hydration of calcium silicates in the second period of the exothermic reaction. The results of the investigation showed that in samples with the CSCW additive proceed the intense pozzolanic reaction, which can be clearly identified after 28 days of hydration. Up to 15 wt% of the Portland cement can be replaced by the smectite clay waste additive calcined at 600 °C without reducing the compressive strength of Portland cement samples.

Effect of Graphene Oxide and Carbon Nanotubes on the Reaction of Tritium Atoms with Dalargin

Effect of carbon substrates materials (graphene oxide, reduced graphene oxide, single-walled carbon nanotubes) on the result of tritium introduction into dalargin peptide was studied by the thermal activation method. It was shown that, when dalargin is deposited onto carbon substrates, the distribution of tritium over amino-acid residues strongly changes as compared with a thick target deposited directly onto glass walls of a vessel. It was demonstrated that, when dalargin is deposited onto the carbon materials studied, the content of tritium in phenylalanine substantially increases, which indicates that the isotope exchange reaction occurs by the electrophilic mechanism. It was also found that the content of tritium in other amino-acid residues substantially changes, which is due to the difference between the structures of adsorption layers of the peptide, formed n the carbon materials under consideration.

Removal of metoprolol from aqueous solutions by the activated carbon prepared from pine cones

Background: Metoprolol (MTP) with its low biodegradability is one of the most dominant micropollutant in the effluent of wastewater treatment plants. The aim of this study was to investigate the removal of metoprolol from aqueous solutions by the activated carbon prepared from pine cones. Methods: The pine cones were activated using thermal activation method. Characteristics of the adsorbent were determined using Brunauer-Emmett-Teller (BET) and scanning electron microscopy (SEM). In this study, the influent of different parameters such as pH, contact time, initial concentrations of metoprolol, adsorbent dose, temperature, adsorption isotherms, and kinetics were investigated. Results: The maximum removal efficiency of MTP (89.2%) was obtained at pH=8.5, adsorbent dose=1.5 g, contact time=60 min, and initial concentration=50 mg/L. By increasing the adsorbent dose, the removal efficiency also increased, but the adsorption capacity decreased, however, by increasing the initial concentration, the removal efficiency decreased, but the adsorption capacity increased. The isotherm experimental data for metoprolol was best fitted using the Langmuir model, and kinetic data were better described by pseudo-second-order kinetic model. The thermodynamic study indicated that the adsorption of MTP by the adsorbent was feasible, spontaneous, and endothermic. Conclusion: MTP removal by the activated carbon prepared from pine cones showed that this natural adsorbent is appropriate for removal of metoprolol from aqueous solutions regarding cost, efficiency, and production method.

Template Assisted Synthesis of Nanoporous Carbon from Bio-Weed of Ipomoea carnea Stems for Supercapacitor Applications

In this study, we report the hierarchically nanoporous activated carbons syntheses from most abundant bio-weed source of Ipomoea carnea stems by nickel foam template assisted with chemical and thermal activation method. The mixture of ferric chloride and diethyl ether of the activating agent and the impregnation ratios are investigated under constant temperature at 800 °C for 2 h. The effective novel synthesized scheme and hierarchical nanoporous carbon structure with large specific surface areas of 1264.9 m2 g-1 and mean pore diameter of 2.1628 nm. The electrochemical performance of prepared nanoporous structured carbon electrode is studied in non-aqueous (TEABF4) electrolyte, which exhibits high specific capacitance of 257 Fg-1 maximum energy density of 61.46 Wh kg-1 and power density of 13.32 kW kg-1 at 1 Ag-1 with remarkable capacity retention of 90 % for 10000 cycles. Therefore the present results show the suitability of synthesized material for use in energy storage applications. The representing promising application as a green route to synthesis advance nanoporous carbon materials from Ipomoea carnea biomass for high-capacity supercapaciors.

Fly Ash Catalyzed Microwave Assisted Multicomponent Synthesis of Trisubstituted Imidazole Derivatives

Background: Imidazoles are important class of heterocyclic compounds showing biological activities. Several methods have been investigated till today for the synthesis of triaryl imidazoles. Some of these classical as well as nonclassical methods experiences drawbacks for instance elongated reaction time, expensive catalyst, low yield of product etc. Hence improvement of a competent method is still necessary. This paper reveals greener protocol for the synthesis of triaryl imidazoles by cyclocondensation of aromatic aldehydes, benzil and ammonium acetate in existence of fly ash as an efficient heterogeneous catalyst by means of microwaves. Methods: Heterogeneous catalyst fly ash was prepared by simple thermal activation method. The catalyst was systematically characterized through wet chemical analysis, XRD, FT-IR, SEM and EDS. The structural analysis was done using XRD and IR. Morphological study was performed using SEM and elemental composition studied by EDS technique. This activated fly ash catalyst was applied in the synthesis of trisubstituted imidazoles. The progress of reaction was checked by TLC and the synthesized compounds were further confirmed by FT-IR, 1H-NMR and 13C-NMR spectroscopy. Results: To check feasibility of activated fly ash for trisubstituted imidazole synthesis, reactions under microwave irradiation employed. The products were obtained in higher yield (92-98%). Conclusion: The fly ash was found to be highly effective in the synthesis of trisubstituted imidazoles under microwave irradiation. The significant features of this protocol are rate enhancement, uncomplicated work up process, high yields and employ of ecofriendly catalyst. Keywords: Wet chemical analysis, microwave, fly ash, heterogeneous, catalyst, imidazole.

Presonication of nanodiamond hydrosols in radiolabeling by a tritium thermal activation method

Specific radioactivity of tritium-labeled nanodiamonds obtained by a tritium thermal activation method can be increased by presonication only if this treatment reduces the diameter of nanodiamond aggregates in an aqueous suspension by a factor of 2 or more.

A reconfiguring and self-healing thermoset epoxy/chain-extended bismaleimide resin system with thermally dynamic covalent bonds

Muti-functional shape memory materials based on epoxy resins (EP) with different concentration of chain-extended bismaleimide resins (CBMI) were fabricated. The resulting EP/CBMI polymers have high glass transition temperature (Tg: 93–125 °C), excellent thermal stability and good mechanical property. Unlike traditional shape memory polymers (SMPs), EP/CBMI SMPs are capable of shape reconfiguration and self-healing abilities. EP/CBMI polymers have high cycle-life shape memory property at high temperature, and their original shapes can be quickly recovered within 21 s by thermal activation method. Because of dynamic transesterification, EP/CBMI polymers can exhibit plasticity and reconfigure their shapes when heated to the temperature of dynamic transesterification (200 °C). For the same reason, EP/CBMI polymers also exhibit good healing behavior, and a 77.5–86.5% recovery of fracture toughness can be obtained after the fractured EP/CBMI polymers are healed at 200 °C/2 h.

Synthesis and Electrochemical Investigation of Mono‐ and Di‐phosphite substituted [FeFe]‐Hydrogenase H‐Cluster Mimics

In this paper, the monosubstituted [Fe2(CO)5P(OMe)3{μ‐(edt)}] (2) and the disubstituted [Fe2(CO)4(P(OMe)3)2{μ‐(edt)}] (3) complexes we re‐synthesized by CO substitution using thermal activation method. In contrast, Darchen and co‐workers prepared complexes 2 and 3 by electron transfer catalysis method. The resulting complexes were characterized by different spectroscopic techniques. A detailed electrochemical study of complexes 2 and 3 in the absence and presence of the weak acetic acid, AcOH, was also reported. The structure of complexes 2 and 3 were confirmed by X‐ray diffraction analysis.

Investigation on the thermal activation of montmorillonite and its application for the removal of U(VI) in aqueous solution

The application for montmorillonite to deal with toxic metals (including radionuclides) becomes interesting based on its excellent physicochemical properties. In this work, the thermal activation method was utilized to pre-treat montmorillonite before use. The sample was characterized by FTIR, XRD, zeta potential, BET and potentiometric titration to clarify the variation of montmorillonite before and after thermal activation. Batch techniques were used to investigate the sorption ability of montmorillonite to U(VI) under different environmental conditions. The electrical double layer model has been introduced to describe the variation of pre-treated sample as well as the principal mechanism for U(VI) uptake. In addition, the irradiation effects of samples for U(VI) sorption was also investigated. Based on the optimum condition for U(VI) uptake, it can be deduced that the thermally activated montmorillonite has potential application for the removal of U(VI) in wastewater.

Preparation of tritium-labeled modified single-walled carbon nanotubes for pharmacokinetic studies

Tritium was introduced by the thermal activation method into samples of single-walled carbon nanotubes modified with diaminotriethylene glycol. Chemical linking of the modifier considerably increased the specific radioactivity of the product. The maximal specific radioactivity was reached when “hot” (2000 K) tritium atoms acted on targets of modified nanotubes kept at 295 K. The main pharmacokinetic parameters of tritium-labeled modified carbon nanotubes upon intravenous administration into mongrel rats chosen as a model were determined.

Low temperature synthesis of nano Ti(C,N) by novel mechanical and thermal activation method

This paper presents a novel mechanical and thermal activation assisted carbothermal reduction (CR) method for synthesising Ti(C,N) powder at lower temperatures. Nano Ti(C,N) powder with approximately 30 nm grain size was synthesised by mixing powders of titanium, anatase, and carbon black. The starting powders were first milled for 10 to 40 h under N2/Ar atmosphere, and then vacuum heat treated for 1 h at 800 to 1050°C. Consequently, nano Ti(C,N) powder with approximately 30 nm grain size was synthesised. X-ray diffraction analysis shows that Ti(C,N) is partially formed during mechanical milling, and the remaining reactants react completely below 1050°C. However, when the unmilled starting powders are heat treated at 1050°C under N2 for 1 h, large amounts of reactants remain. Thermogravimetry and differential scanning calorimetry analysis shows that the CR reaction of activated TiO2 occurs at a lower temperature under N2 than under Ar or vacuum.

Myramistin adsorption on detonation nanodiamonds in the development of drug delivery platforms

Detonation nanodiamonds (NDs) are considered to be potential carriers in drug delivery platforms because of their low cytotoxicity (4–5nm particles), biocompatibility, highly developed surface area, chemically inert core and intrinsically hydrophilic surface. The adsorption/desorption processes of physiologically active compounds on ND surfaces play an important role in drug design. The electrostatic attraction between ND surface groups and the functional groups of adsorbates is the most commonly described mechanism of the adsorption process. However, the role of hydrophobic interactions has not yet been described. Here, we show that a positively charged antiseptic agent (Myramistin®) binds to a ND possessing a positive zeta potential via hydrophobic interactions between the hydrocarbon fragment of Myramistin and graphitic carbon of the ND surface. To achieve a reliable determination of low values of adsorption, a radioactive label was introduced into Myramistin molecules. Tritium was used as a labeling agent and it was introduced into Myramistin by means of tritium thermal activation method. The obtained value of the binding strength indicates easy drug release, as confirmed by in vitro release studies. We anticipate that our assay and the results obtained to be a starting point for more sophisticated models of drug adsorption/desorption processes of nanodiamond drug delivery platforms.

A novel approach radiolabeling detonation nanodiamonds through the tritium thermal activation method

Abstract Tritium labeling was introduced into detonation nanodiamonds (ND) through the tritium thermal activation method. Two target preparation techniques were developed to increase the radioactivity and the specific radioactivity of the labeled product: the desiccation of the waterless solvent suspension and the lyophilization of the hydrosol. The specific radioactivity of the labeled product was shown to correlate with the hydrogen content in the starting material and to achieve 2.6 TBq/g.

Improvement on pozzolanic reactivity of coal gangue by integrated thermal and chemical activation

In order to effectively utilize coal gangue and its calorific value (4180–12,540kJ/kg), coal gangue was converted into energy-saved cement by activating at 800°C with an integrated thermal and chemical activation method. Microanalysis with XRD and NMR indicates that improved pozzolanic reactivity for coal gangue contributes to the mineral phase change with amorphous status during thermal and chemical activation process. In the chemical activation process, amorphous materials composed of Q3(0Al), Q3(1Al) and Q0 units were formed from parts of aluminosilicate minerals (quartz and K-feldspar). With the physical and mechanical testing, it shows that CaSO4+CaO is the most effective additive during the chemical activation, which is a non-equilibrium reaction between coal gangue and CaSO4+CaO during calcination process. A prototype plant in cement industry also proofs these results. Eco-cement containing 56% of activated coal gangue had been successfully produced for road pavement application with a 28-days concrete compressive strength of 35.9MPa. Compared with the traditional clinker producing process, energy consumption for producing activated coal gangue could save 90.7kg/ton equivalently, which is due to its low calcination temperature at 800°C and calorific value (about 6688kJ/kg) of the coal gangue.

Radiochemical approach in studying competitive adsorption of human serum albumin and ionic surfactants at the water/p-xylene interface

The competitive adsorption and distribution in the bulk of the aqueous solution/p-xylene system was studied, using tritium labeling and the scintillation phase method, for human serum albumin (HSA) and ionic surfactants: dodecyltrimethylammonium bromide (DTAB) and sodium dodecyl sulfate (SDS). Tritiumlabeled HSA, DTAB, and SDS of high specific radioactivity were obtained by the tritium thermal activation method and were purified by chromatography. Physicochemical studies were performed with HSA-SDS and HSA-DTAB mixtures at a protein concentration of 0.06 g l−1 and varied surfactant concentrations from 0.3 to 8.0 μM. The distribution ratio and the adsorption isotherm were obtained for each component of the mixture by the scintillation phase method. The effect of ultralow concentrations of surfactants on the competitive adsorption in mixtures with HSA and on the bulk distribution of the substances in the two-phase system was found. The parameters of intermolecular interaction in the adsorption layer were calculated, and a mechanism of formation of the adsorption layer was suggested.