Pelagic Sargassum spp. capture CO2 and produce calcite Paraguay-Delgado, Francisco; Carreño-Gallardo, Caleb; Estrada-Guel, Ivanovich ...
Environmental science and pollution research international,
07/2020, Letnik:
27, Številka:
20
Journal Article
Recenzirano
Pelagic
Sargassum
is considered an ecological plague that is causing adverse economic impacts to the tourist and fishing industries in the Caribbean. However, its proliferation might be playing an ...important role to reduce global warming, as it removes a high content of CO
2
from the atmosphere and transforms it into calcium carbonate, in its calcite phase, producing sediment after it dies. We quantified the amount of calcite in
Sargassum
samples collected from the Mexican Caribbean coast in 2019. Samples were divided into three parts: vesicles, thallus, and leaves. In each part, the amount of carbon, oxygen, and calcium was determined by means of X-ray energy dispersion to confirm the existence of a calcite crystalline phase. Imaging methodologies and IR spectroscopy complemented the structural studies. The thermogravimetric analysis determined that approximately 5% of the CO
2
captured by the
Sargassum
was converted into calcite. Thus, by extrapolation, the Atlantic Sargasso Belt retained approximately 19.3 million tons of CO
2
from 2011 to 2019.
The effect of extrusion cooking on bioactive compounds in third-generation snacks (TGSE) and microwave-expanded snacks (MWSE) prepared using black bean, blue maize, and chard (FBCS) was evaluated. ...FBCS was extruded at different moisture contents (MC; 22.2–35.7%), extrusion temperatures (ET; 102–142 °C), and screw speeds (SP; 96–171 rpm). Total anthocyanin content (TAC), contents of individual anthocyanins, viz., cyanidin-3-glucoside, malvidin-3-glucoside, pelargonidin-3-glucoside, pelargonidin-3-5-diglucoside, and delphinidin-3-glucoside chloride, total phenolic content (TPC), antioxidant activity (AA), and color parameters were determined. TAC and individual anthocyanin levels increased with the reduction in ET. ET and MC affected the chemical and color properties; increase in ET caused a significant reduction in TPC and AA. Microwave expansion reduced anthocyanin content and AA, and increased TPC. Extrusion under optimal conditions (29% MC, 111 rpm, and 120 °C) generated products with a high retention of functional compounds, with high TAC (41.81%) and TPC (28.23%). Experimental validation of optimized process parameters yielded an average error of 13.73% from the predicted contents of individual anthocyanins. Results suggest that the TGSE of FBCS obtained by combining extrusion and microwave expansion achieved significant retention of bioactive compounds having potential physiological benefits for humans.
Although the dry ice method used to synthesize turbostratic carbon/graphene is little known and used, it has significant advantages over others, such as the following: it is low cost, simple, and a ...large quantity of material can be obtained using some inorganic and highly available acids (which can be reused). Despite the above advantages, the main reason for its incipient development is the resulting presence of magnesium oxide in the final product. In the present work, three different treatments were tested to remove this remnant using some acid chemical leaching processes, including hydrochloric acid, aqua regia, and piranha solution. Based on the experimental evidence, it was determined that using aqua regia and combining the leaching process with mechanical milling was the most efficient way of removing such a remnant, the residue being only 0.9 wt.%. This value is low compared to that obtained with the other acid leaching solutions and purification processes (2.8-29.6 wt.%). A mandatory high-energy mechanical milling stage was necessary during this treatment to expose and dissolve the highly insoluble oxide without secondary chemical reactions on the turbostratic carbon. High-energy mechanical milling is an effective route to exfoliate graphite, which allows the magnesium oxide to be more susceptible to acid treatment. A yield of turbostratic carbon/graphene of 1 wt.% was obtained from the metallic Mg. The obtained surface area was 504.8 m
g
; this high value resulting from the intense exfoliation can potentiate the use of this material for a wide variety of applications.
Groundwater samples from eight deep drinking water wells that cover three aquifers in Chihuahua City, northern Mexico, were fully characterized. Water is naturally contaminated with arsenic, ...fluoride, and uranium, according to the Environmental Protection Agency (EPA) and local standards. The results from the Geochemist’s Workbench (GWB) program revealed that the minerals in equilibrium with the groundwater were calcite and dolomite, while others, such as fluoride, schoepite, rutherfordite and K(UO2)(AsO4), were also dissolved. The hydrogeochemical characterization of water samples indicates that they were sodium bicarbonate-type water samples at neutral to slightly alkaline pH (7.6–8.3). A batch equilibrium sorption procedure was implemented using natural groundwater, a synthesized chitosan network (net-CS) and a chitosan binary network grafted with N-vinylcaprolactam/N-N-dimethylacrylamide (net-CS)-g-NVCL/DMAAm hydrogels. Isotherms and kinetics sorption tests were evaluated. The adsorption capacity of net-CS hydrogels for As ions was 0.0022 mg/g and F ions 0.15 mg/g after 50 h. Scanning electron microscopy coupled with energy-dispersive spectroscopy (SEM-EDS) was used to investigate the hydrogel surface before and after the sorption process, and TGA was used to evaluate the stability of the adsorbents. Freundlich adsorption isotherm constants for As and F ions indicate heterogeneous sorption and the mechanism of retention by physisorption.
Display omitted
•Arsenic, fluoride and uranium in Mexican drinking groundwater, above Maximum Concentration Limits, was detected.•Na-HCO3 water type at neutral to slightly alkaline pH.•Chitosan hydrogels simultaneously removed arsenic and fluoride from groundwater.•Sorption fitted to Freundlich model, thus adsorption energy is heterogeneous.
Additive manufacturing (AM), also known as 3D printing, has revolutionized the production of complex geometric structures across various industries. This study presents an innovative approach by ...integrating zinc carbonate basic (ZCB) precursor with polylactic acid (PLA) to develop composite filaments for fused deposition modeling (FDM) 3D printers. The resulting filaments undergo surface transformation into zinc oxide (ZnO) through high-power laser irradiation. Thermal analysis (TGA-DSC) and Fourier-transform infrared spectroscopy (FTIR) were used to confirm the decomposition of ZCB (ZnCO₃₂·Zn(OH)₂₃) into ZnO during the thermal decomposition stages. The study successfully extruded a composite filament containing 10% of ZCB, which worked adequately in 3D printing. The printed parts were analyzed through tensile tests (based on ASTM D638-5 standard), showing a notable difference in mechanical behavior between the commercial filament PLA and the composite filament (PLAC10). Laser irradiation of these samples facilitated a targeted conversion to ZnO, verified through scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The integration of zinc oxide within the printed structures enhances structural stability and provides surfaces enriched with ZnO, a metal oxide with widely reported applications. Furthermore, an irradiated 3D-printed sample demonstrated chemo-resistive properties upon carbon monoxide (CO) exposure, underlining its potential as a gas sensor and confirming its semiconductor nature. This approach provides a cost-effective and efficient way to develop innovative devices with integrated functional materials.
The effects of red cactus pear encapsulation using spray drying with soluble fiber were evaluated. Cactus pear juice was mixed with 15, 22.5, or 30% soluble fiber and dried at 160, 180, or 200°C. ...Juice showed high levels of polyphenols, quercetin, kaempferol, isoharmetin, betacyanins, betaxanthins, and a high antioxidant activity. Increased soluble fiber amounts significantly (
p
<0.05) increased the pH, aw, water solubility index (WSI), L*, and
b
* values. Levels of polyphenols and betacyanins decreased significantly (
p
<0.05) as the soluble fiber content and the drying temperature increased, respectively. Encapsulation at 160°C and 22.5% of soluble fiber yielded good physical properties and high bioactive compounds. Microscopic analysis showed spherically shaped capsules, the shape was affected by the concentration of added soluble fiber. Low soluble fiber concentrations were associated with more collapsed capsules. Soluble fiber for encapsulating cactus pear resulted in a powder with good properties that can be used as a food ingredient.
We evaluated the effects of solvents with different polarities—methylene chloride (MC), methanol (MT), and hexane (HE) on the extraction of compounds from Mexican red pitaya seed oil. The fatty acid ...composition and the structural, rheological, and thermal properties of the different extracts were characterized. The results indicated that the highest yield of extraction was generated for MC (26.96%), as well as the greatest amount of Mono and Polyunsaturated fatty acids, while the lowest yield was for MT (16.86%). The antioxidant activity was greater in the MT treatment due to extractable compounds from high polarity. The generated extracts contained unsaturated fatty acids, mostly oleic and linoleic acids, and saturated fatty acids such as palmitic acid. The lowest solidification temperature was −6.35 ℃ for MC due to its fatty acid composition, and the degradation temperature was around 240 ℃. The viscosity is a quality parameter; the highest level was generated for the MC treatment, which was significantly different from HE and MT. The composition of the extracts was analyzed using the FT-IR spectroscopy and showed the typical characteristic of absorption bands for triglycerides with high frequency in bands 2852 cm −1 and 2924 cm −1 , which indicated that the samples were rich in unsaturated and polyunsaturated acids. These results suggested that pitaya seed oil is an excellent alternative source of essential fatty acids with potential physiological benefits.
Hydrogen production through sorption enhanced reforming (SER) use a solid CO2 absorbent to increase hydrogen purity (98%) and to perform reforming and WGS reactions in one single step, thus producing ...high methane conversions and important energy savings. Na2ZrO3 is as an alternate synthetic CO2 solid absorbent for SER applications. The present research is aimed to establish CO2 sorption kinetics parameters; reaction order, rate constant, apparent, intrinsic and diffusional activation energies. Na2ZrO3 sorption kinetics was studied through TGA as a function of CO2 concentration and temperature. A global reaction rate of first order in CO2 and a strong dependence in temperature was found. The approximate solution to the shrinking core model was used to fit the data. Modeling results indicated the surface reaction as the main resistance to the reaction rate, controlling reaction kinetics with only a minor contribution of the product layer diffusion resistance toward the end of the reaction.
► Global rate for CO2 absorption by Na2ZrO3 was first order. ► Intrinsic and product layer diffusional activation energies govern the reaction. ► The surface reaction is controlling the reaction kinetics. ► Na2ZrO3 exhibits the fastest reaction kinetics among synthetic CO2 absorbents.
Display omitted
•All types of synthesized nanoparticles had sizes in the range of 22–138 nm.•Nanoparticles were immersed in a geltin matrix.•Sorghum procyanidins–gelatin nanoparticles remained stable ...after in vitro digestion.•The synthesized nanoparticles maintained their antioxidant activity.•Procyanidin B1 could act as a selective inhibitor of (pro-)metalloproteinase-2.
In this research, sorghum procyanidins (PCs) and procyanidin B1 (PB1) were encapsulated in gelatin (Gel) to form nanoparticles as a strategy to maintain their stability and bioactivity and for possible applications as inhibitors of metalloproteinases (MMPs) of the gelatinase type. Encapsulation was carried out by adding either PCs or PB1 to an aqueous solution of A- or B-type Gel (GelA or GelB) at different concentrations and pH. Under this procedure, the nanoparticles PCs–GelA, PCs–GelB, PB1–GelA, and PB1–GelB were synthesized and subsequently characterized by experimental and computational methods. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that all types of nanoparticles had sizes in the range of 22–138 nm and tended to adopt an approximately spherical morphology with a smooth surface, and they were immersed in a Gel matrix. Spectral analysis indicated that the nanoparticles were synthesized by establishing hydrogen bonds and hydrophobic interactions betweenGel and the PCs or PB1. Study of simulated gastrointestinal digestion suggested that PCs were not released from the Gel nanoparticles, and they maintained their morphology (SEM analysis) and antioxidant activity determined by Trolox-equivalent antioxidant capacity (TEAC) assay. Computational characterization carried out through molecular docking studies of PB1 with Gel or (pro-)metalloproteinase-2 (pro-)MMP-2, as a model representative of the PCs, showed very favorable binding energies (around −5.0 kcal/mol) provided by hydrogen bonds, van der Waals interactions, and desolvation. Additionally, it was found that PB1 could act as a selective inhibitor of (pro-)MMP-2.
The effectiveness of maltodextrin (10%) and cactus mucilage (CM) (0%, 0.25%, 0.50%, 0.75%, and 1%) as carrier agents was evaluated in the encapsulation of bioactive amaranth compounds. Spray drying, ...an efficient encapsulation method, achieved high yields (62.9%–68%). The increase in CM concentration significantly augmented the water absorption index (WAI), bulk density, and hygroscopicity of the encapsulated amaranth powders. Conversely, it significantly decreased the moisture content, water activity, and water solubility index (WSI). The glass transition temperatures (>40 °C), Hausner ratio (HR), and Carr's index (CI) values indicated the suitability of powders for handling and processing. Moreover, no cracks were observed in the microcapsules surface, which favoured the bioactive amaranth compounds retention and stability. Thus, low degradation rate constants and long half-life time values were determined for the encapsulated amaranth powders, indicative of its storage appropriateness. Incorporation of 0.75% CM was an efficient concentration to achieve high percentage retention of betacyanins (55.5%), betaxanthins (58%), total polyphenols (73.3%), amaranthine (56.8%), isoamaranthine (62.7%), individual polyphenols (44.6%–81%), and antioxidant activity (79.6%). These results demonstrated the efficiency of CM as an encapsulating agent in the food industry.
PDF
