Hygroelectric cells deliver hydrogen, hydrogen peroxide, and electric current simultaneously at room temperature from liquid water or vapor. Different cell arrangements allowed the electrical ...measurements and the detection and measurement of the reaction products by two methods each. Thermodynamic analysis shows that water dehydrogenation is a non-spontaneous reaction under standard conditions, but it can occur within an open, non-electroneutral system, thus supporting the experimental results. That is a new example of chemical reactivity modification in charged interfaces, analogous to the hydrogen peroxide formation in charged aqueous aerosol droplets. Extension of the experimental methods and the thermodynamic analysis used in this work may allow the prediction of interesting new chemical reactions that are otherwise unexpected. On the other hand, this adds a new facet to the complex behavior of interfaces. Hygroelectric cells shown in this work are built from commodity materials, using standard laboratory or industrial processes that are easily scaled up. Thus, hygroelectricity may eventually become a source of energy and valuable chemicals.
Human population growth and development has been largely dependent on non-renewable natural resources, which cannot be indefinitely sustained. Beyond, coal and other abundant resources cannot ...continue to be used at current rates due to their impact on the environment and climate. It is thus important to replace as much as possible the fossil fuels and scarce minerals as sources of energy and industrial raw materials. Biomass plays a key role in this scenario, since its availability depends on abundant but often misused resources: air, water, sunlight and land. The “oil shocks”, the recognition of impending resource shortages, the global pollution and climate change led many governments and organizations to create roadmaps to Bioeconomy. This includes the growing use of plants and animals to produce energy and raw materials, but it cannot create food scarcity. Agriculture depends on the plant macronutrients N, P and K, and this article discusses their role in plant and animal growth, production and consumption, dependence on non-renewable minerals and energy and perspectives for increasing their efficiency. Special attention is given to Brazilian agriculture that is heavily dependent on imported NPK, requiring strategic action and research.
Production of electricity by friction is well known but poorly understood, and is the source of electrostatic discharge causing serious accidents. Recent results are in agreement with one of the ...conflicting views on this problem, according to which triboelectricity in polymers is triggered by mechanochemical and wear or mass transfer phenomena. These results also challenge the widely accepted paradigm of one-way charge transfer that is the basis of the triboelectric series. Experimental results from powerful analytical techniques coupled to surface charge mapping support the following hypothesis: charge-bearing species are ionic polymer fragments formed through mechanical action. Beyond this, the atmosphere participates through tribocharge build-up and dissipation due to reactive plasma formation and charge exchange at the gas-solid interface, mediated by adsorption of non-neutral water, or ion partition during water adsorption, as in hygroelectricity phenomena.
Mechanochemical reactions during polymer friction or contact produce ionic fragments distributed on positive and negative domains at both surfaces.
Nowadays, bone systems have a series of consequences that compromise the quality of life mainly due to wear and decreased bioactivity, generally in elderly people and children. In this context, the ...combination of montmorillonite (MMT-NPs) in a vitreous system such as nanobioglass facilitates the adsorption of biomolecules on the surface and within the interlamellar spaces, enabling the entry of ions by a cation exchange process focusing on increasing the rate of bone formation. This work aims to synthesize and characterize an eco-friendly hybrid reinforcement containing MMT-NPs with nanobioglass doped with magnesium nanoparticles (MgNPs-BV). In this way, MMT-NPs@MgNPs-BV was synthesized by the impregnation method, where an experimental design was used to verify the synthesis conditions. The ideal condition by experimental design was carried out in terms of the characterization and biological activity, where we demonstrated MMT-NPs of 30% w w–1, MgNPs-BV of 6% w w–1, and a calcination temperature of 1273.15 K with a cell viability around 66.87%, an average crystallite diameter of 12.5 nm, and a contact angle of 17.7°. The characterizations confirmed the impregnation method with an average particle size of 51.4 ± 13.1 nm. The mechanical tests showed a hardness of 2.6 GPa with an apparent porosity of 22.2%, similar to human bone. MMT-NPs@MgNPs-BV showed a cell proliferation of around 96% in osteoblastic cells (OFCOL II), with the formation of the apatite phase containing a relation of Ca/P of around 1.63, a biodegradability of 82%, and rapid release of ions with a Ca/P ratio of 1.42. Therefore, the eco-friendly hybrid reinforcement with MMT-NPs and MgNPs-BV shows potential for application with a matrix for biocompatible nanocomposites for bone regeneration.
The pollution of wastewater with dyes has become a serious environmental problem around the world. In this context, the work aims to synthesize and characterize a supported nanocatalyst (NZ-180) from ...rice husk (RH) and alum sludge (AS) incorporating silver (AgNPs@NZ-180) and titanium nanoparticles (TiNPs@NZ-180) for Rhodamine B (RhB) dye degradation, under UV and visible irradiation. Central rotatable composite design (CRCD) was used to determine ideal conditions, using nanocatalyst and dye concentration such as input variables and degradation percentage like response variable. Samples were characterized by XRD, SEM-EDS, N
2
porosimetry, DLS, and zeta potential analyses. TiNPs@NZ-180 showed the best photocatalytic activity (62.62 and 50.82% under UV and visible irradiation, respectively). Specific surface area has increased from 35.90 to 418.90 m
2
g
−1
for NZ-180 and TiNPs@NZ-180, respectively. Photocatalytic performance of TiNPs@NZ-180 has reduced to 8 and 10% after 5 cycles under UV and visible light irradiation. Ideal conditions found by CRCD were 2.75 g L
−1
and 20 mg L
−1
for nanocatalyst and RhB concentrations, respectively. Therefore, (agro)industrial waste present such an alternative material for application in the removal of wastewater with dyes, which helps in the reduction of the impact of chemicals/pollutants on human and animal health.
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The development of self-healing materials opens perspectives to fabricate devices with unprecedented lifetimes and recyclability that can be integrated with flexible electronics. ...However, the timescale at which these materials operate remains an important challenge to overcome. This article describes the fast self-healing behavior of aluminum/iron polyphosphate metallo-gels and their hybrids with polyaniline and gives a detailed investigation of their electrical behaviors. The samples can be cut, molded and healed by manual handling. The rebuilding process is mediated by water uptake and was directly observed by environmental scanning electron microscopy. Metallo-gels with and without polyaniline can be mixed to give homogeneous samples, where the conducting polymer is uniformly distributed within the inorganic matrix. Cyclic voltammetry experiments showed that polyaniline behaves within the metallo-gel in the same manner as it does in aqueous electrolytes. Furthermore, polyaniline adds electronic conductivity to the originally ion-conducting polyphosphate metallo-gel, as demonstrated by impedance spectroscopy. The ionic and electronic conductivities are 1.3–1.7 × 10−2 S·cm−1 and 5.2 × 10−4 S·cm−1, respectively. Such properties result from the “free” and “bound” water within the hydrogel network and the dynamic nature of the aluminum-phosphate interactions within the supramolecular network. The features presented here make these materials good candidates to be used as moldable electroactive binders in carbon-based electrodes and in all-solid-state flexible separators for repairable electrochemical capacitors and batteries.
Plastic debris is a major environmental concern, and to find effective ways to reuse polystyrene (PS) presents major challenges. Here, it is demonstrated that polystyrene foams impregnated with SnO2 ...are easily generated from plastic debris and can be applied to photocatalytic degradation of dyes. SnO2 nanoparticles were synthesized by a polymeric precursor method, yielding specific surface areas of 15 m2/g after heat treatment to 700 °C. Crystallinity, size, and shape of the SnO2 particles were assessed by X-ray diffraction (XRD) and transmission electron microscopy (TEM), demonstrating the preparation of crystalline spherical nanoparticles with sizes around 20 nm. When incorporated into PS foams, which were generated using a thermally induced phase separation (TIPS) process, the specific surface area increased to 48 m2/g. These PS/SnO2 nanofoams showed very good efficiency for photodegradation of rhodamine B, under UV irradiation, achieving up to 98.2% removal. In addition the PS/SnO2 nanofoams are shown to retain photocatalytic activity for up to five reuse cycles.
Metallic nanoshells have been in evidence as multifunctional particles for optical and biomedical applications. Their surface plasmon resonance can be tuned over the electromagnetic spectrum by ...simply adjusting the shell thickness. Obtaining these particles, however, is a complex and time-consuming process, which involves the preparation and functionalization of silica nanoparticles, synthesis of very small metallic nanoparticles seeds, attachment of these seeds to the silica core, and, finally, growing of the shells in a solution commonly referred as K-gold. Here we present synthetic modifications that allow metallic nanoshells to be obtained in a faster and highly reproducible manner. The main improved steps include a procedure for quick preparation of 2.3 ± 0.5 nm gold particles and a faster approach to synthesize the silica cores. An investigation on the effect of the stirring speed on the shell growth showed that the optimal stirring speeds for gold and silver shells were 190 and 1500 rpm, respectively. In order to demonstrate the performance of the nanoshells fabricated by our method in a typical plasmonic application, a method to immobilize these particles on a glass slide was implemented. The immobilized nanoshells were used as substrates for the surface-enhanced Raman scattering from Nile Blue A.
•E. grandis extract was used for ZnO-NPs.•CCDR 23 showed the optimal condition for TY photodegradation with 76.1%.•ZnO-NPs reuse showed photocatalytic stability (k = 0.0077–0.0067 min−1).•MIC of ...0.625 mg mL−1 against S. Aureus, E. Coli, K. Pneumoniae, and P. Auruginosa.•ZnO-NPs showed biocompatibility against 293T, tumor activity A549, and U87MG.
The present study aims to synthesize/characterize zinc oxide nanoparticles (ZnO-NPs) to evaluate the application of tartrazine yellow (TY) dye removal. ZnO-NPs were synthesized by the biosynthesis method from Eucalyptus grandis extract. X-ray diffraction (XRD), zeta potential (ZP), N2 porosimetry, Field Emission Gun Scanning Electron Microscope (FEG-SEM), zero charge point (pHZCP) and Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) were used to the ZnO-NPs characterization. The antimicrobial activity was performed by the MIC (Minimum Inhibitory Concentration) method against gram-positive (S. aureus) and gram-negative (E. coli, K. pneumoniae and P. aeruginosa) strains. For cellular activity assays, MTT (3-(4,5-Dimethylthiazol-2-yl) and DCFH-DA (2′7′ dichlorofluorescein diacetate) tests were performed with cell lines of the 293T, A549 and U87MG. FEG-SEM micrography indicated a heterogeneous and porous morphology with rod-shaped zinc oxide nanoparticles (particle size ranged from 40 to 50 nm). ZnO-NPs showed a negative charge surface (−11.6 ± 0.2 mV), pHZCP ≈ 7.16 with type III and H1 hysteresis (SBET = 3.9 m2/g, and Dp = 16.2 nm) indicating a mesoporous material with pores open at both ends. The optimal condition was ZnO-NPs = 0.6 g/L, TY = 20 mg/L and pH ≈ 6.0 with 76.1 % (k = 0.0077 min−1) for the TY photodegradation under visible radiation, and after VI cycles of ZnO-NPs recycling, there was a decrease of only 6 %. ZnO-NPs showed antimicrobial activity of 0.625 mg mL−1, as well as a decrease in cell viability in the three tested lines in 100 and 300 µg mL−1. Therefore, ZnO-NPs showed potential application for TY photodegradation to be used in wastewater treatment and nanomedicine.
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•The golden linseed extract was an excellent bioreducer of nanoparticles.•CaO-NPs showed considerable photocatalytic activity.•CaO-NPs showed a positive surface.•CaO-NPs have ...irregular particle sizes.•CaO-NPs showed low stability when reused five times.
Dyes are substances that have a high polluting potential, due to their low biodegradability and chemical stability, causing serious environmental damage when disposed of incorrectly. Yellow tartrazine (YT) dye as an environmental liability requires attention, since it causes toxic effects in fish (Danio rerio) with a potential allergic effect in humans. In this context, the present study aims to synthesize and characterize calcium oxide nanoparticles (CaO-NPs) to evaluate the photocatalytic activity for the YT photodegradation under visible irradiation. CaO-NPs were synthesized by the biosynthesis method from golden linseed (Linum usitatissimum L.) extract. Central Composite Rotational Design (CCRD 23) was used to determine the ideal condition for the photocatalytic tests. X-ray diffraction (XRD), zeta potential (ZP), physical adsorption of N2, zero charge point (pHzcp), Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR), Scanning Electron Microscopy by Energy Dispersive Spectroscopy (SEM-EDS), Diffuse Reflectance Spectroscopy (DRS) and Field Emission Gun – Scanning Electron Microscope (FEG-SEM) were used to the CaO-NPs characterization. Thus, CaO-NPs presented SBET = 14±0.02 m2g−1, Dp = 20.9±0.02 nm and Vp = 0.054±0.004 cm3g−1, characteristic of a mesoporous material. ATR-FTIR spectrum showed characteristic stretches of specific functional groups (–CH, –CO, C = C, Ca-O, –OH) from plant extract and metallic precursor. CaO-NPs showed pHZCP equal to 7.74, positive surface charge (+12.7 mV) and bang gap energy of 2.61 eV. FEG-SEM micrographs showed that has a small agglomeration with defined morphology, but with irregular particle size (around 48 nm), and SEM-EDS micrographs showed an elemental composition (in weight) of the 50.24% oxygen, 3.32% magnesium, 2.29% iron, 10.44% calcium, 14.07% silicon, 3.33% aluminum and 0.63% potassium. Regarding CCRD 23, the ideal condition was the pH = 7.0, CaO-NPs = 1.2 g/L and YT = 20 mg/L, with 76.2% of photodegradation and a pseudo first-order reaction specific reaction rate k = 0.089 min−1. After V cycles of CaO-NPs recycling, there was a decrease of around 22.83%, indicating a saturation of the active sites available in the nanocatalyst Therefore, CaO-NPs showed potential application for TY photodegradation to be used in wastewater treatment being an alternative nanocatalyst, meeting nanotechnology and sustainable development.
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