Aqueous Products Research Articles

A kinetic model for the hydrothermal liquefaction of microalgae, sewage sludge and pine wood with product characterisation of renewable crude

Hydrothermal liquefaction (HTL) of biomass is an emerging technology that is being developed to produce renewable crude oil in water at sub-critical conditions. Different feedstocks and reaction conditions result in different product fractions of renewable crude and co-products of solid, aqueous and gas phase products. Biomass considered as feedstocks for HTL include microalgae, sewage sludge and lignocelluloses. Each of these biomass sources contains varying amounts of lipid, carbohydrate, protein and lignin organic fractions as well as some inorganic components. To develop a bulk kinetic model to predict the yields of crude, solid, aqueous and gas phase products, HTL experiments were conducted at reaction temperatures of 250, 300 and 350 °C over reaction times of 0–60 min with Tetraselmis sp. microalgae, sewage sludge and Radiata pine. The crude was analysed via gas-chromatography mass-spectrometry to identify variations in the compounds in the crude produced from different types of biomass. The highest crude yield was produced from algae at up to 30%, followed by up to 25% from sludge and up to 10% from pine. A reaction temperature of 300 or 350 °C was preferable for maximum crude yield and increasing reaction time over 5 min was seen to cause minimum variation in crude yield for most cases. The variation in product distribution is strongly dependent on both the organic and inorganic content of the biomass feedstock. A unified bulk kinetic model for prediction of crude yield from a wide range of biomass was developed. Predictions showed up to 15% variation from measurements illustrating that further experimental data from HTL of a wider range of feedstocks are required to refine the model and build up model rigour.

Upgrading of the aqueous product stream from hydrothermal liquefaction: Simultaneous removal of minerals and phenolic components using waste-derived hydrochar

We investigated the co-adsorption of AAEM and phenolic components onto hydrochar prepared from the organic fraction of MSW. HCl washing of the char removed more AAEM (up to 1 g L−1) than phenols from the hydrochar and improved the oxygen content from 21.31% to 24.9%. A relationship between the number and type of functional groups of phenolic components determined the order of adsorption: guaiacol > phenol > vanillyl alcohol > resorcinol. For AAEM the order of adsorption was Ca2+ (103 mg g−1) > K+ (95.7 mg g−1) > Na+ (8.7 mg g−1) > Mg2+ (3.4 mg g−1). Removal efficiency increased with an increase in initial adsorbate concentration with values of 94, 94, 91 and 91% (base on original mass present) obtained for Ca2+, K+, Mg2+, and Na+, respectively. Hydrochar could remove 100% of guaiacol, phenol and resorcinol present and 61% of vanillyl alcohol in the presence of AAEMs. The Dubinin-Radushkevich isotherm best fitted the multilayer adsorption of phenolic components with a calculated qmax of 68.7 mg g−1 and 50.3 mg g−1 for vanillyl alcohol and resorcinol respectively. Henry's law best described the adsorption of AAEMs. A mass transfer analysis showed that film diffusion controls the adsorption process at low adsorbate concentrations (Bi < 100). At higher initial sorbate concentration, the rate of transport was controlled by intra-particle diffusion.AAEM components were exchanged for phenolic components to form stronger hydrogen bonds, resulting in initial preferential adsorption of phenolics with AAEM only adsorbing at higher initial concentrations.

Lithium and cobalt recovery for lithium-ion battery recycle using an improved oxalate process with hydrogen peroxide

Lithium cobalt oxide (LiCoO2) is the first and most commercially successful form of layered transition metal oxide cathode used in lithium-ion batteries (LIBs). Recycling LiCoO2 cathodes is critical for stabilizing the Li and Co economy. In this work, a kinetic investigation of a closed-loop oxalate-based process for recovery and separation of Li and Co from LiCoO2 has been developed. Metal extraction from LiCoO2 is a non-catalytic solid-liquid reaction with both solid and aqueous products. To understand the kinetics and identify the rate-limiting mechanism, a combined shrinking core model (cSCM) was used for LiCoO2 digestions. LiCoO2 in the presence of aqueous oxalic acid (H2C2O4) at the optimum concentration of 0.46 M and 100 °C results in efficient extraction and separation of Li and Co. Diffusion of H2C2O4 into LiCoO2 occurs through a product layer of cobalt oxalate dihydrate (CoC2O4·2H2O) that forms on the surface and this process was identified as rate-limiting. The CoC2O4·2H2O was precipitated in a micro-rod morphology when 0.46 M hydrogen peroxide (H2O2) was added along with 0.23 M H2C2O4, and the reaction was carried out at a temperature of 55–75 °C. In this case, the chemical reaction at the LiCoO2 surface was identified as the rate-limiting step. Addition of H2O2 resulted in a 33% reduction in the overall activation energy, a 50% reduction in energy consumption, and a 13% reduction in the cost of reagents. This work signifies the importance of a cost-effective, environmentally-friendly, and energy-efficient process for recovering critical metals such as Li and Co from spent LIB cathodes.

Determining the Role of Acidity, Fate and Formation of IEPOX-Derived SOA in CMAQ

Formation of aerosol from biogenic hydrocarbons relies heavily on anthropogenic emissions since they control the availability of species such as sulfate and nitrate, and through them, aerosol acidity (pH). To elucidate the role that acidity and emissions play in regulating Secondary Organic Aerosol (SOA), we utilize the 2013 Southern Oxidant and Aerosol Study (SOAS) dataset to enhance the extensive mechanism of isoprene epoxydiol (IEPOX)-mediated SOA formation implemented in the Community Multiscale Air Quality (CMAQ) model (Pye et al., 2013), which was then used to investigate the impact of potential future emission controls on IEPOX OA. We found that the Henry’s law coefficient for IEPOX was the most impactful parameter that controls aqueous isoprene OA products, and a value of 1.9 × 107 M atm−1 provides the best agreement with measurements. Non-volatile cations (NVCs) were found in higher-than-expected quantities in CMAQ and exerted a significant influence on IEPOX OA by reducing its production by as much as 30% when present. Consistent with previous literature, a strong correlation of isoprene OA with sulfate, and little correlation with acidity or liquid water content, was found. Future reductions in SO2 emissions are found to not affect this correlation and generally act to increase the sensitivity of IEPOX OA to sulfate, even in extreme cases.

Solubilized ubiquinol for preserving corneal function

Defective cellular metabolism, impaired mitochondrial function, and increased cell death are major problems that adversely affect donor tissues during hypothermic preservation prior to transplantation. These problems are thought to arise from accumulated reactive oxygen species (ROS) inside cells. Oxidative stress acting on the cells of organs and tissues preserved in hypothermic conditions before surgery, as is the case for cornea transplantation, is thought to be a major reason behind cell death prior to surgery and decreased graft survival after transplantation. We have recently discovered that ubiquinol – the reduced and active form of coenzyme Q10 and a powerful antioxidant – significantly enhances mitochondrial function and reduces apoptosis in human donor corneal endothelial cells. However, ubiquinol is highly lipophilic, underscoring the need for an aqueous-based formulation of this molecule. Herein, we report a highly dispersible and stable formulation comprising a complex of ubiquinol and gamma cyclodextrin (γ-CD) for use in aqueous-phase ophthalmic products. Docking studies showed that γ-CD has the strongest binding affinity with ubiquinol compared to α- or β-CD. Complexed ubiquinol showed significantly higher stability compared to free ubiquinol in different aqueous ophthalmic products including Optisol-GS® corneal storage medium, balanced salt solution for intraocular irrigation, and topical Refresh® artificial tear eye drops. Greater ROS scavenging activity was noted in a cell model with high basal metabolism and ROS generation (A549) and in HCEC-B4G12 human corneal endothelial cells after treatment with ubiquinol/γ-CD compared to free ubiquinol. Furthermore, complexed ubiquinol was more effective at lowering ROS, and at far lower concentrations, compared to free ubiquinol. Complexed ubiquinol inhibited lipid peroxidation and protected HCEC-B4G12 cells against erastin-induced ferroptosis. No evidence of cellular toxicity was detected in HCEC-B4G12 cells after treatment with complexed ubiquinol. Using a vertical diffusion system, a topically applied inclusion complex of γ-CD and a lipophilic dye (coumarin-6) demonstrated transcorneal penetrance in porcine corneas and the capacity for the γ-CD vehicle to deliver drug to the corneal endothelium. Using the same model, topically applied ubiquinol/γ-CD complex penetrated the entire thickness of human donor corneas with markedly greater ubiquinol retention in the endothelium compared to free ubiquinol. Lastly, the penetrance of ubiquinol/γ-CD complex was assayed using human donor corneas preserved for 7 days in Optisol-GS® per standard industry practices, and demonstrated higher amounts of ubiquinol retained in the corneal endothelium compared to free ubiquinol. In summary, ubiquinol complexed with γ-CD is a highly stable composition that can be incorporated into a variety of aqueous-phase products for ophthalmic use including donor corneal storage media and topical eye drops to scavenge ROS and protect corneal endothelial cells against oxidative damage.

Comprehensive Stability Study of Vitamin D3 in Aqueous Solutions and Liquid Commercial Products.

Vitamin D3 has numerous beneficial effects, such as musculoskeletal, immunomodulatory, and neuroprotective. However, its instability is the main obstacle to formulating quality products. Despite increased attention and growing use, data on vitamin D3 stability is scarce because data from individual studies is inconclusive and mostly qualitative. Therefore, we have systematically investigated the influence of various factors (temperature, light, oxygen, pH, concentration, and metal ions) on its stability in aqueous media using a stability-indicating HPLC-UV method. First-order kinetics fitted its degradation under all tested conditions except light and oxygen. In both cases, the established models in chemical kinetics were inappropriate and upgraded with the Weibull model. Metal ions and acidic conditions had the main destabilizing effect on vitamin D3 in aqueous media, but these solutions were successfully stabilized after the addition of ethylenediaminetetraacetic acid (EDTA), ascorbic acid, and citric acid, individually and in combination. EDTA showed the most significant stabilizing effect. Synergism among antioxidants was not observed. Our findings on vitamin D3 instability in aqueous media also correlated with its instability in commercial products. Vitamin D3 aqueous products require proper stabilization, thereby signifying the importance and contribution of the obtained results to the formulation of stable and quality products.

Characterization of Products from the Aqueous-Phase Photochemical Oxidation of Benzene-Diols

Chemical processing in atmospheric aqueous phases, including cloud and fog drops, might be significant in reconciling the gap between observed and modeled secondary organic aerosol (SOA) properties. In this work, we conducted a relatively comprehensive investigation of the reaction products generated from the aqueous-phase photochemical oxidation of three benzene-diols (resorcinol, hydroquinone, and methoxyhydroquinone) by hydroxyl radical (·OH), triplet excited state (3C*) 3,4-dimethoxybenzaldehyde (3,4-DMB), and direct photolysis without any added oxidants. The results show that OH-initiated photo-degradation is the fastest of all the reaction systems. For the optical properties, the aqueous oxidation products generated under different reaction conditions all exhibited photo-enhancement upon illumination by simulated sunlight, and the light absorption was wavelength dependent on and increased as a function of the reaction time. The oxygen-to-carbon (O/C) ratio of the products also gradually increased against the irradiation time, indicating the persistent formation of highly oxygenated low-volatility products throughout the aging process. More importantly, aqueous-phase products from photochemical oxidation had an increased oxidative potential (OP) compared with its precursor, indicating they may more adversely impact health. The findings in this work highlight the importance of aqueous-phase photochemical oxidation, with implications for aqueous SOA formation and impacts on both the chemical properties and health effects of OA.

Atmospheric Fate of a New Polyfluoroalkyl Building Block, C3F7OCHFCF2SCH2CH2OH.

Many per- and polyfluoroalkyl substances (PFAS) have been regulated or phased-out of usage due to concerns about persistence, bioaccumulation potential, and toxicity. We investigated the atmospheric fate of a new polyfluorinated alcohol 2-(1,1,2-trifluoro-2-heptafluoropropyloxy-ethylsulfanyl)-ethanol (C3F7OCHFCF2SCH2CH2OH, abbreviated FESOH) by assessing the kinetics and products of the gas-phase reaction of FESOH with chlorine atoms and hydroxyl radicals. Experiments performed in a stainless-steel chamber interfaced to an FTIR were used to determine reaction kinetics and gas-phase products. We report reaction rate constants of k(Cl + FESOH) = (1.5 ± 0.6) × 10-11 cm3 molecule-1 s-1 and k(OH + FESOH) = (4.2 ± 2.0) × 10-12 cm3 molecule-1 s-1. This leads to a calculated FESOH gas-phase lifetime of 2.8 ± 1.3 days with respect to reaction with OH, assuming [OH] = 106 molecule1 cm-3. Gas-phase products of FESOH oxidation included at least two aldehydes, likely C3F7OCHFCF2SCH2C(O)H and C3F7OCHFCF2SC(O)H, and secondary products including COF2, SO2 and C3F7OC(O)F. Additional gas-phase experiments performed in a Teflon chamber were used to assess aqueous products by collecting gaseous samples offline into an aqueous sink prior to analysis with ultrahigh performance liquid chromatography-tandem mass spectrometry, resulting in four acidic products: C3F7OCHFCF2SCH2C(O)OH, C3F7OCHFCF2S(O)(O)OH, C3F7OCHFC(O)OH, and perfluoropropanoic acid (C2F5C(O)OH).

Reviews on Plants Gum and Mucilage I: The Composition and Pharmacological Significance of Turmeric (Curcuma longa) Rhizomes Polysaccharides and Mucilage/their Aqueous Extracts Commercial Products

The utilization of plants’ polysaccharide as hydrocolloid materials within the last four decades, had drawn a significant attention due to their therapeutic and pharmaceutical applications. Among the Zingiberaceae family of plants, Curcuma longa L. rhizomes polyphenolic product like curcuminoids, flavonoids, turmerones and other polyphenolics had gained extensive investigation efforts and reported intensively. Curcuma longa L. rhizomes polysaccharide type mucilage hasn’t received considerable attention by academic authors and researchers. In this survey, we tried to highlight this type of phytomolecules through exploring the issued research articles focusing on their pharmacological importance. Reference books, Scopus, PubMed, Web of Science bibliographic databases and Google scholar scientific search engines besides other open access researches sited on Google were screened for plant polysaccharides significances and uses in addition to their pharmacological activities. Screening was done using six different groups of keywords. All results found by keywords were reviewed and none-relevant articles were excluded by outcome of interests and researcher boundaries of study through a systematic method. It has been stated that, both mucilage and gums types of plants’ polysaccharides had gained great investigation efforts in recent years. Concerning C. longa L. rhizomes; four different polysaccharides had been reported. They were to be isolated, purified and characterized from their polysaccharide mucilage aqueous extract then labelled as Ukonans A, B, C and D. Several biological influences were studied for these polysaccharide compounds and mixtures as well as for their aqueous extracts fractions, including immune busting, anti-inflammatory, anti-ulcerogenic agent, insulin mimetic hypoglycemic agent, anticancer/chemo-preventive and anti-obesity agent activities. Reviewed articles encouges us to conclude the potentiality of investigation of turmeric polysaccharides as pharmaceutical additive/and or co-therapy for several pathological conditions.

Hydrothermal treatment of petrochemical sludge in subcritical and supercritical water: Oil phase degradation and syngas production

The reaction process of petrochemical sludge under hydrothermal conditions was investigated to explore the feasibility of its disposal using hydrothermal treatment. Experiments were conducted in an autoclave for 30 min at 350–450 °C. During the hydrothermal treat of petrochemical sludge, 44.98%–59.64% of the oil (organic matter) in the sludge was decomposed into aqueous and gas products. The gas yield reached 1.37 mol/kg of organic matter at reaction temperature of 450 °C. The H2 yield was 0.26 mol/kg of organic matter. The primary product was still in the aqueous phase. The TOC concentration of the aqueous product was in the range of 14,960–19,050 mg/L. The concentration of COD, total phenol, and total nitrogen of product were in the ranges of 9029–10,870, 13.83–20.10, and 497.5–599.0 mg/L, respectively. The group analysis and GC-MS analysis of the residual oil indicated that the saturated long chain hydrocarbons (C18–C21) in petrochemical sludge had decomposed to form saturated short chain hydrocarbons (C11–C17); however, the short chain saturated hydrocarbons in the sludge had decomposed thoroughly. The removal rate of asphaltenes, resins and aromatic hydrocarbons were low. Finally, a mechanism for treating petrochemical sludge under hydrothermal conditions was proposed. The study provides an experimental basis for the hydrothermal treatment of petrochemical sludge.

Supercritical Water Gasification of Lignin and Cellulose Catalyzed with Co-precipitated CeO2–ZrO2

Lignin and cellulose were gasified at 500 and 600 °C in supercritical water over co-precipitated CeO₂–ZrO₂ catalyst. The addition of CeO₂–ZrO₂ improved the gasification efficiency and hydrogen production, and the catalytic effect was more significant at lower temperatures. The H₂ yield from cellulose gasification at 500 °C increased by over 2.5 times to 8.50 mol/kg with the presence of CeO₂–ZrO₂. The gas chromatography-mass spectrometry (GC-MS) analysis showed that the catalyst reduced the content of cyclopentenone and furan derivatives in the aqueous product but increased the content of refractory phenols. We characterized the fresh and the used catalysts with H₂-temperature-programmed reduction (H₂-TPR), X-ray diffraction (XRD), and scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS) analysis, showing that CeO₂ was the main active component, which catalyzed gasification through redox reactions. ZrO₂ enhanced the catalytic activity of CeO₂ by lowering the reduction temperature in hydrogen, increasing the dispersion of CeO₂, and facilitating H₂ adsorption on the catalyst surface.

Biowaste hydrothermal carbonization aqueous product application in rice paddy: Focus on rice growth and ammonia volatilization

Hydrothermal carbonization (HTC) is known as a green biomass conversion technology. However, it often suffers from the issue of disposing hydrothermal carbonization aqueous products (HCAP). Based on the characterization and composition of acidic HCAP, a rice paddy soil column experiment was conducted to observe the effects of HCAP on ammonia (NH3) volatilization form paddy soil and rice yield. The experiment was designed with five treatments. HCAPs were produced at 220 °C and (SHC220-L) and 260 °C (SHC260-L) derived from poplar sawdust, HCAP produced at 220 °C (WHC220-L) and 260 °C (WHC260-L) derived from wheat straw, and a control group without HCAP application (termed CKU hereafter). The results showed that HCAP treatments increased the rice yield by 4.30%–26.0% compared to CKU. HACPs prepared at lower temperatures (SHC220-L and WHC220-L) mitigated the cumulative NH3 volatilization by 11.2% and 7.6%, respectively, and mitigated yield-scale NH3 volatilization (cumulative NH3 volatilization/total yield) by 14.2% ∼ 22.4%. HCAP significantly improved the N use efficiency of rice. We found that the NH3 volatilization was related to NH4+-N concentration and pH of surface water, soil TOC and NH4+-N oxidation functional genes. This study implied that HCAP could be potentially used as a liquid fertilizer, which will be a potential substitute for chemical N fertilizers. There is still a long way before HCAP can be applied in full-scale for N fertilizer reduction and waste recycle.

Synergetic effect and primary reaction network of corn cob and cattle manure in single and mixed hydrothermal liquefaction

Agricultural waste is a good choice to produce biofuels because of its abundance and environmental friendliness. In this work, corn cob and cattle manure were studied by hydrothermal liquefaction (HTL) in a batch reactor with reaction temperatures from 300 °C to 360 °C alone and in mixtures. HTL products, including bio-oil, aqueous phase, and gas were comparatively analyzed. The maximum bio-oil yields were 22.2% at 300 °C for corn cob and 19.3 % at 360 °C for cattle manure, respectively. Besides, the bio-oil from cattle manure had lower oxygen, higher H/C ratios, and higher HHVs than that from corn cob. N-Heterocycles could be taken as the characteristic compounds of bio-oils from cattle manure, yet organic acids and aldehydes were only detected from corn cob. Although benzenediols and N-heterocycles were major products in water-soluble organic matter (WSOM) for both two feedstocks, the pH values of aqueous phase products are acidic for corn cob and alkali for cattle manure, respectively. This is attributed to the generation of some ammonia from the decomposition of protein in cattle manure pyrolysis. The synergistic effect in mixtures could promote the decomposition of lignin by generating more phenols and benzenediols that improved the quality of bio-oil and increased the yields of WSOM. It could also affect the product of protein decomposition and transfer more N into the aqueous phase. The major component in the gaseous product was all CO2. These results indicate that different compositions could not only react with each other but also change the pH values of the reaction environment and further affect the reaction pathways of other compositions. A predicted primary reaction network of different components from corncob and cattle manure in the HTL was also proposed.

Effect of Accumulative Recycling of Aqueous Phase on the Properties of Hydrothermal Degradation of Dry Biomass and Bio-Crude Oil Formation

For hydrothermal liquefaction of dry biomass to produce liquid fuels, water needs to be added or the aqueous phase products can be recycled. This paper focuses on understanding the relationship between hydrothermal degradation of the dry biomass and oil formation under the condition of accumulative recycling of the aqueous phase. Completely dried corn stalk and deionized water were used for the hydrothermal liquefaction (HTL) experiment. The aqueous products for subsequent recycling were not diluted. It was demonstrated that the recycling of the aqueous can promote the enrichment of organic acids and the conversion of ketones and phenols in the aqueous, improving the yield and quality of Bio-crude oil. After recycling, the yield of Bio-crude oil increased from 20.42% to 24.31% continuously, and the oxygen content decreased from 13.34% to 9.90%. Although the process was accompanied by solid deposition and had a negative impact on the hydrothermal degradation efficiency, the formation of carbon microspheres during the deposition enhanced the utilization of nondegradable solids, while the formation of metal salt particles had a positive impact on oil production. After three rounds of recycling, the solid deposition effect was weakened. At this time, oil production and solids degradation can be promoted simultaneously.

A review of gas chromatographic techniques for identification of aqueous amine degradation products in carbonated environments.

Degradation of amines is a significant issue allied to amine-based carbon dioxide (CO2) absorption in post-combustion CO2 capture. It becomes essential to have a detailed understanding of degradation products for advanced post-combustion CO2 capture technology. Identification and quantification of degradation products of amines help in practicability and environmental assessment of amine-based technology. Gas, liquid, and ion chromatographic techniques are the benchmark tools for qualitative and quantitative analyses of the amines and their derivatives. Among others, gas chromatography has been more in use for this specific application, especially for the identification of degradation products of amines. This review focuses on the critical elucidation of gas chromatographic analysis and development of methods to determine the amine degradation products, highlighting preparation methods for samples and selecting columns and detectors. The choice of detector, column, sample preparation, and method development are reviewed in this manuscript, keeping in view the industry and research applications. Furthermore, obtained results on the quantitative and qualitative analyses using gas chromatography are summarized with future perspectives.

Aqueous Decomposition Behavior of Solid Peroxides: Effect of pH and Buffer Composition on Oxygen and Hydrogen Peroxide Formation

The ability of solid peroxides to provide sustained release of both oxygen and hydrogen peroxide makes them potentially suitable for oxygen release or antibacterial applications. Most recent reports using solid peroxides to augment oxygen levels do so by compounding solid peroxide powders in polymers to retard the aqueous decomposition. Compounds with peroxidase activity may be added to reduce hydrogen peroxide toxicity. Peroxides are rarely pure and are mixed with oxide and themselves decompose to form hydroxides in water. Therefore, even if buffering strategies are used, locally the pH at the surface of aqueously immersed peroxide particles is inevitably alkaline. Since pH affects the decomposition of peroxides and hydrogen peroxide stability, this study compared for the first-time the aqueous decomposition products of hydrogen and inorganic peroxides that are in use or have been used for medical applications of have been evaluated preclinically; calcium peroxide (CaO2), magnesium peroxide (MgO2), zinc peroxide (ZnO2), sodium percarbonate (Na2CO3.1.5H2O2) and hydrogen peroxide (H2O2). Since plasma can be approximated to be carbonate buffered phosphate solution, we maintained pH using carbonate and phosphate buffers and compared results with citrate buffers. For a given peroxide compound, we identified not only a strong effect of pH but also of buffer composition on the extent to which oxygen and hydrogen peroxide formation occurred. The influence of buffer composition was not previously appreciated, thereby establishing in vitro parameters for better design of intentional release of specific decomposition species.

Study on the hydrothermal liquefaction of antibiotic residues with molecular sieve catalysts in the ethanol-water system: focus on product distribution and characterization.

In this study, the antibiotic residue was used as a raw material to catalyze hydrothermal liquefaction (HTL) in an ethanol–water system to prepare bio-oil. The study explored the effects of ethanol–water ratio and three kinds of molecular sieve catalysts (HZSM-5, MCM-41, and γ-Al2O3) on the yield and characterization of bio-oil. The experimental results showed that the highest bio-oil yield was obtained at the ethanol–water ratio of 1 : 1 and the three kinds of molecular sieve catalysts of 15%. GC-MS, 1H NMR, TGA, and CHNS were used for the characterization of bio-oil. Higher carbon (up to 71.44%), hydrogen (up to 9.376%), and a high heating value (HHV, 34.714 MJ kg−1) were observed for catalytically liquefied bio-oil compared to non-catalytically liquefied bio-oil. The analysis of aqueous phase products indicated the existence of valuable nutrients. Besides, the reusability of three kinds of molecular sieve catalysts indicated that catalysts could be successfully reused several times and continuously exhibited the catalyst effect.

Recent Advances and New Discussions on Superhydrophobic Coatings and Admixtures Applied to Cementitious Materials

Increasing the durability of buildings is one of the biggest challenges of the construction industry of the 21st century. The problems concerning durability are usually related to the presence of humidity or to water infiltration in the porous cementitious materials used in buildings. Advances in biomimetics have allowed the development of superhydrophobic surfaces and materials, with contact angles greater than 150°, which are able to repel water and aqueous products. In this context, this work summarizes the recent advances on superhydrophobic coatings and admixtures applied to cementitious materials. Recommendations for the future improvement of such products are made. The synthesis of superhydrophobic coatings generally includes the deposition of a low surface energy material (LSEM), especially fluoroalkylsilanes, on a microroughened surface, which, in cementitious materials, is usually achieved with the help of nanoparticles or micrometric molds. In this sense, variables as the spraying time duration, and the nanoparticles concentration, surface area and average particle size were identified as directly influencing the surface superhydrophobicity. Functionalized nanoparticles can also be introduced in cement matrix during the paste mixing in order to obtain a longer lasting waterproofing effect. In this case, hybrid nanosilica may react with Ca(OH)2 through pozzolanic reaction. The C-S-H formed may incorporate the organic group of hybrid nanosilica, and might present superhydrophobicity as well, modifying the composite’s microstructure. Besides, the cost of fabricating hydrophobic materials is decisive for their market entry. Hence, the partial or total replacement of fluoroalkylsilanes with less expensive LSEMs seems promising and needs to be further explored.

Bimetallic nanoparticle generation from Au − TiO2 film by pulsed laser ablation in an aqueous medium

Bimetallic nanoparticle formation by applying pulsed laser ablation on the gold (Au) - titanium (TiO2) film was demonstrated. Experiments were conducted at room temperature. Au and TiO2 nanoparticles were mixed in different ratios and deposited as the starting material on silicon wafer plates, which were dried and placed in a beaker with distilled water. After a pulsed laser beam was applied, the collected aqueous solution products were analysed by ultraviolet–visible (UV–vis) spectrophotometry and characterised by scanning transmission electron microscopy (STEM) with energy-dispersive X-ray spectroscopy (EDS). The UV spectra indicated that the Au, TiO2, and Au–TiO2 nanoparticles were dispersed in the aqueous solution product. STEM-EDS images showed that spherical bimetallic nanoparticles containing gold and titanium were generated. A core of TiO2 nanoparticles was found to be well surrounded by a shell of Au nanoparticles when colloidal Au and TiO2 nanoparticles at a 1:1 ratio was used as the starting materials. The technique described here is simple and innovative, and this study enhances our understanding of bimetallic nanoparticle synthesis using a pulsed laser beam in a liquid environment.

Restoration of an 18th century frame: 3D modelling, printing and matching color of decorative flowers elements

This paper describes the application of 3D digital technology to support the rebuild of lost decorative elements of an historical frame. The frame belongs to an 18th century painting depicting the portrait of D. José, Prince of Brazil, displayed at the National Palace of Queluz, Portugal. The application of digital technologies has been planned from the very beginning in order to avoid the traditional use of silicone in the reproduction of missing elements. The photogrammetric 3D acquisition, a non-contact methodology, has been used to reduce the manipulation and hence prevent further degradation of the artistic object. Following the 3D modelling operation, new decorative elements were made using an additive printing technology. In the final phase of the work, the post-printing treatment was carried out, in which aqueous products were used. 3D modelling, in addition to facilitate the restoration treatment of the historic frame, can also be useful in the creation of a digital collection of decorative frame elements, i.e. a virtual database.