In this work, the catalytic pyrolysis of a corn stalk/high-density polyethylene composite for aromatics production over activated carbon in a fixed-bed reactor was investigated. The effects of the ...carbonization temperature and H3PO4 impregnation ratio on the product distributions were studied. Increasing the H3PO4 impregnation ratio (0–2.0) and carbonization temperature (600–750 °C) was found to enhance the selectivity of aromatics. When the activated carbon was synthesized using an H3PO4 impregnation ratio of 1:1 and a carbonization temperature of 700 °C, the yield of aromatics reached a maximum of 86.11% and the selectivity of mono-aromatics reached 64.01%. Moreover, the catalytic performances of biochars obtained at various carbonization temperatures were also studied. No significant catalytic activity of biochar for the formation of aromatics was observed due to the absence of P-containing active functional groups. This work provides an approach for the conversion of wood-plastic composite waste into valuable aromatic production using a low-cost activated carbon catalyst.
•Activated carbon was first applied to the pyrolysis of wood plastics composite.•P-containing activated carbon exhibited excellent catalytic performance.•High selectivity of aromatics (86.11%) were reached in obtained pyrolysis oil.•It provides an approach for converting WPC wastes into aromatics production.
SiO2 and γ‐Al2O3 impregnation with nominal 10 and 20% of cobalt was examined using wet impregnation method starting with Co(NO3)2·6H2O. The samples were dried and analyzed by XPS prior to calcination ...to study the surface species in the solids and the role of the support in the processing of supported cobalt catalysts. The results showed that cobalt introduction alters the few top nanometers of the support materials as there are significant changes recorded in the XPS spectra. Most importantly, there is a remarkable similarity between the O 1s XPS signal of SiO2 and γ‐Al2O3 following Co 20% impregnation, which suggests that these materials could have similar properties in terms of the oxidation ability and the general redox behavior. The shift of Al 2p peaks to higher binding energy (BE) in the XPS investigations and the shift of Si 2p peaks to lower BE were observed for high nominal cobalt loading. These results suggest that the choice of the support in cobalt‐based catalysts would tune the chemical characteristics of cobalt in the final materials.
The present paper aimed to develop an eco-friendly and low-cost adsorbent material from Red-angico residues by its chemical activation and evaluation on cationic dye adsorption. It was carried out ...the characterization of materials produced in natura, NaOH-impregnated and H3PO4-impregnated, as well as adsorption studies of methylene blue. It was possible to observe that the materials produced presented characteristics which play an important role as adsorbent material. Impregnation resulted in a reduction in particle size, changes in porosity and bulk density, and decreased moisture content. The NaOH-impregnated material showed reduced ash content and increased volatile matter, which enhanced its adsorption properties. For the H3PO4-impregnated material, volatile matted decreased, and fixed carbon increased. Thermogravimetric analysis revealed that both treatments led to the degradation of lignocellulosic compounds, with H3PO4 causing more intense degradation. Regarding the kinetic study, it was observed that pseudo-second order model showed the best fit of experimental data, and equilibrium was reached in less than 40 min, been mainly controlled by convective adsorption mechanism. About the isotherm study it was observed an increase on maximum adsorption capacity of 17.79–55.34 mg.g−1 after the impregnation with sodium hydroxide. Therefore, it was possible to observe that the procedures employed allowed the reuse of Red-Angico residues which has led to obtaining of interesting adsorbent materials.
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•Both physisorption and chemisorption of Hg0 occurred on the surface of M6WN5.•Chemisorption process was an absolute predominant route for Hg0 removal by M6WN5.•The effect of NO, H2O, ...SO2 and O2 on Hg0 removal by M6WN5 was investigated.•M6WN5 demonstrated to be a promising Hg0 sorbent in flue gas.
Pyrolyzed biochars from an industrial medicinal residue waste were modified by microwave activation and NH4Cl impregnation. Mercury adsorption of different modified biochars was investigated in a quartz fixed-bed reactor. The results indicated that both physisorption and chemisorption of Hg0 occurred on the surface of M6WN5 which was modified both microwave and 5wt.% NH4Cl loading, and exothermic chemisorption process was a dominant route for Hg0 removal. Microwave activation improved pore properties and NH4Cl impregnation introduced good active sites for biochars. The presence of NO and O2 increased Hg0 adsorption whereas H2O inhibited Hg0 adsorption greatly. A converse effect of SO2 was observed on Hg0 removal, namely, low concentration of SO2 promoted Hg0 removal obviously whereas high concentration of SO2 suppressed Hg0 removal. The Hg0 removal by M6WN5 was mainly due to the reaction of the CCl with Hg0 to form HgCl2, and the active state of CCl* groups might be an intermediate group in this process. Thermodynamic analysis showed that mercury adsorption by the biochars was exothermic process and apparent adsorption energy was 43.3kJ/mol in the range of chemisorption. In spite of low specific surface area, M6WN5 proved to be a promising Hg0 sorbent in flue gas when compared with other sorbents.
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•Supercritical impregnation of mesoglycan into alginate aerogel.•Topical innovative device to be applied on wounds to favor the re-epithelialization.•Pro-migratory role of the ...composite system MSG/CAA.
Mesoglycan (MSG) was impregnated onto calcium alginate aerogel (CAA) to produce an innovative topical device to be applied on wounds. The main purpose of the composite material is to favor the re‐epithelialization through a direct and immediate action, also offering a protective barrier to ensure a favorable and sterilized environment for the wound healing process. Impregnation kinetics and isotherms were determined at 18 MPa and 40 and 60 °C. Composite systems were analyzed using Field Emission Scanning Electron Microscopy (FESEM), Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD), Fourier Transform Infrared (FT-IR) and UV–vis spectroscopies. A functional assay of in vitro wound healing confirmed the pro-migratory role of the composite system MSG/CAA, since an increase of the migration rate on fibroblast (BJ) cells and of the covered distance for keratinocytes (HaCaT) was observed with MSG impregnated on CAA compared to non-treated cells, CAA and pure MSG.
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•Coeffect of pyrolysis temperature and K3PO4 impregnation has been investigated.•K3PO4 impregnation has a pre-aging effect and improved biochar’s stability.•Adsorption mechanism of ...PRBCs to heavy metals varies from pyrolysis temperature.•550 °C is optimal pyrolysis temperature for energy saving and heavy metal adsorption.
Potassium phosphate (K3PO4)-impregnated bamboo was pyrolyzed at temperatures ranging from 350 to 950 °C to explore the coeffect of pyrolysis temperature and K3PO4 impregnation on biochar’s characteristics and adsorption behavior. The degree of aromatization and graphitization in phosphorus-enriched biochars (PRBCs) rose as temperature increased, whereas H/C and O/C ratios, pH value, and O-containing group content decreased. The pre-aging impact of K3PO4 impregnation results in increased stability and adsorption performance of PRBCs. Adsorption mechanism of PRBCs to heavy metal varies from pyrolysis temperature. Micropores dominate medium-temperature PRBCs (prepared at 550 ∼ 750 °C), possessing the highest P-containing group content (116 % that of PRBC-350) and maximal adsorption capacity (greater than289 mg/g). The medium-temperature PRBCs adsorb Cd (II) via the role of O-containing groups, PO43-, and P2O74-, mainly by reactions of organic complexation, precipitation and inorganic complexation, respectively. 550 °C is the optimal pyrolysis temperature for both energy saving and heavy metal adsorption.
•Pyrolysis of H2SO4-impregnated corncobs selectively produced anhydrosugars/furfural.•The maximum yields were obtained from 2.75 wt% H2SO4-impregnated corncobs.•H2SO4 acted as inhibitor and catalyst ...during pyrolysis of H2SO4-impregnated corncobs.
The objective of this study was to selectively coproduce anhydrosugars and furfural from the fast pyrolysis of biomass by H2SO4 impregnation. The pyrolysis behaviors of raw and H2SO4-impregnated corncobs, cellulose and xylan were systematically studied by a thermogravimetric analyzer (TGA) and commercial pyroprobe reactor. The results demonstrate that H2SO4 impregnation can reduce the formation of char and drastically improve the yield of anhydrosugars and furfural. The maximum yields of levoglucosan (38.45 wt% based on cellulose), furfural (19.18 wt% based on hemicellulose) and xylosan (9.49 wt% based on hemicellulose) were obtained by fast pyrolysis of corncobs impregnated with 2.75 wt% H2SO4. By comparing the product distributions from fast pyrolysis of H2SO4-impregnated cellulose, xylan, and raw and demineralized corncobs, it is concluded that H2SO4 can act as an inhibitor to suppress the catalytic functions of structural alkali and alkaline earth metals (AAEM) to improve the yield of anhydrosugars, and H2SO4 can also act as a catalyst to accelerate the dehydration of hemicellulose to form more furfural. It is speculated that H2SO4 could first react with structural AAEM in lignin to form lignosulfonates (e.g., potassium lignosulfonate), thus reducing the catalytic functions of structural AAEM during fast pyrolysis of corncobs. These findings provide a simple and efficient method for the selective coproduction of anhydrosugars and furfural from waste biomass.
Non-healing wounds are among the serious complications of type-2-diabetes around the globe, associated with high incidence of bacterial infection, chronic nerve and blood vessel damage, and ...eventually repeated amputation of limbs and organs. Silver nanoparticles offer strong wound healing potential due to their well-known antibacterial activities. The present study reports the development of silver nanoparticle impregnated chitosan-poly ethylene glycol (PEG) hydrogel to accelerate wound healing in diabetic patients. The aim of the study was to formulate a sustained and slow release of silver nanoparticle using chitosan-PEG-Silver Nitrate based hydrogel for the treatment of chronic diabetic wounds. The silver nanoparticle containing chitosan-PEG pre-polymer solution was synthesized by reducing silver nitrate with PEG and chitosan solution, thereby, transforming the silver ions into silver nanoparticles. The resulted pre-polymer solution was then crosslinked using glutaraldehyde to form the desired hydrogel. The developed silver nanoparticle impregnated chitosan hydrogel was characterized using ultra-violet (UV) visible spectrophotometry, Fourier Transform-infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM) followed by the determination of porosity, and swelling properties. The release of AgNPs from hydrogel was determined by UV-vis spectroscopy followed by antimicrobial and antioxidant assays. The wound healing efficacy of the synthesized hydrogel was evaluated in diabetic rabbits. The results demonstrated a higher porosity, higher degree of swelling and higher water vapor transition rate (WVTR) for silver nanoparticle impregnated hydrogel compared to bare chitosan-PEG hydrogel as well as improved antimicrobial and antioxidant properties in-vitro and enhanced wound healing capability in-vivo in diabetic rabbits. The hydrogel showed a slow and sustained release of AgNPs over a period of at least seven days manifesting the slow biodegradation of developed hydrogels. The improved antimicrobial, antioxidant and wound healing results indicate that the silver nanoparticle impregnated chitosan-PEG hydrogel can be a promising material for wound healing dressing for chronic diabetic wounds.
