Search Results (7)

This study presents a comparative analysis of anodization and hydrothermal techniques for synthesizing TiO₂ nanotubes directly on titanium foil. It emphasizes its advantages as a substrate due to its superior conductivity and efficient charge transfer. Optimized synthesis conditions enable a thorough evaluation of the resulting nanotubes’ morphology, structure, and optical properties, ultimately assessing their photoelectrochemical and photocatalytic performances. Scanning electron microscopy (SEM) reveals differences in tube diameter and organization. An X-ray diffraction (XRD) analysis shows a dominant anatase (101) crystal phase in both methods, with the hydrothermally synthesized nanotubes exhibiting a biphase structure after annealing at 500 °C. UV–Vis and photoluminescence analyses indicate slight variations in band gaps (around 0.02 eV) and recombination rates. The anodized TiO₂ nanotubes, exhibiting superior hydrophilicity and order, demonstrate significantly enhanced photocatalytic degradation of a model pollutant, amido black (80 vs. 78%), and achieve a 0.1% higher photoconversion efficiency compared to the hydrothermally synthesized tubes. This study underscores the potential advantages of the anodization method for photocatalytic applications, particularly by demonstrating the efficacy of direct TiO₂ nanotube growth on titanium foil for efficient photocatalysis. Full article

The presence of pollutants in water sources, particularly dyes coming by way of the textile industry, represents a major challenge with far-reaching environmental consequences, including increased scarcity. This phenomenon endangers the health of living organisms and the natural system. Numerous biosorbents have been utilized for the removal of dyes from the textile industry. The aim of this study was to optimize discarded Zygophyllum gaetulum stems as constituting an untreated natural biosorbent for the efficient removal of C.I. Direct Black 80, an azo textile dye, from an aqueous solution, thus offering an ecological and low-cost alternative while recovering the waste for reuse. The biosorbent was subjected to a series of characterization analyses: scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Brunauer–Emmett–Teller (BET) method, X-ray diffraction (XRD), and infrared spectroscopy (IR) were employed to characterize the biosorbent. Additionally, the moisture and ash content of the plant stem were also examined. The absorption phenomenon was studied for several different parameters including the effect of the absorption time (0 to 360 min), the sorbent mass (3 to 40 g/L), the pH of the solution (3 to 11), the dye concentration (5 to 300 mg/L), and the pH of the zero-charge point (2–12). Thermodynamic studies and desorption studies were also carried out. The results showed that an increase in plant mass from 3 to 40 g/L resulted in a notable enhancement in dye adsorption rates, with an observed rise from 63.96% to 97.08%. The pH at the zero-charge point (pHpzc) was determined to be 7.12. The percentage of dye removal was found to be highest for pH values ≤ 7, with a subsequent decline in removal efficiency as the pH increased. Following an initial increase in the amount of adsorbed dye, equilibrium was reached within 2 h of contact. The kinetic parameters of adsorption were investigated using the pseudo-first-order, pseudo-second-order and Elovich models. The results indicated that the pseudo-first-order kinetic model was the most appropriate for the plant adsorbent. The isotherm parameters were determined using the Langmuir, Frendlich, Temkin, and Dubinin–Radushkevich models. The experimental data were more satisfactory and better fitted using the Langmuir model for the adsorption of dye on the plant. This study demonstrated that Zygophyllum gaetulum stems could be employed as an effective adsorbent for the removal of our organic dye from an aqueous solution. Full article

Nitrogen (N) fertilizer and crop residue amendments are important agricultural practices that could increase soil health, fertility, and crop yield. Such practices may also change soil denitrification processes where contradictory observations have been reported on soil N₂O emissions with fewer studies on N₂ emissions due to its large atmospheric background concentrations limiting its soil-borne measurement. This study aims to investigate N₂O production and reduction of N₂ emissions under a conducive denitrifying environment (like anaerobic microsites, 80% WFPS, available N and C) after rice straw amendment and KNO₃ application to three different soil types (fluvo-aquic, black, and paddy soils). In this regard, three treatments for three different soil types were set consisting of (a) a non-amended treatment (control), (b) a KNO₃ treatment (KNO₃, 20 mM KNO₃), and (c) a straw plus KNO₃ treatment (2.5 g rice straw kg⁻¹ dry soil and 20 mM KNO₃), which were incubated under 80% WFPS. Moreover, direct N₂O and N₂ fluxes were measured over 17 days in the current incubation experiment with a robotized incubation system using a helium atmosphere. Results showed that rice straw amendment combined with N fertilizer increased both N₂O and N₂ fluxes compared with control or KNO₃ treatments in all three soil types. Overall, compared with the black and paddy soils, the N₂O and N₂ fluxes were higher in the fluvo-aquic soil, with a maximum of 234.2 ± 6.3 and 590.1 ± 27.3 g N ha⁻¹ from F_SK treatment, respectively, during the incubation period. The general trends in three soil types of both N₂O and N₂ emissions were control < KNO₃ < rice straw plus KNO₃ treatments. Straw amendment in combination with KNO₃ can stimulate a high denitrification rate (less N₂O and higher N₂), whereas their effect on stoichiometric ratios of N₂O/(N₂O + N₂) highly depends on soil nitrate concentration, oxygen level, soil moisture content, and labile C. The current study underscores that the rice straw amendment in combination with N fertilizer can trigger denitrification with less increment on soil N₂O but higher N₂ emissions under conditions favoring denitrification. Full article

Electrical properties and electro-thermal behavior were studied in composites with carbon black (CB) or hybrid filler (CB and graphite) and a matrix of linear low-density polyethylene (LLDPE). LLDPE, a (co)polymer with low crystallinity but with high structural regularity, was less studied for Positive Temperature Coefficient (PTC) applications, but it would be of interest due to its higher flexibility as compared to HDPE. Structural characterization by scanning electron microscopy (SEM) confirmed a segregated structure resulted from preparation by solid state powder mixing followed by hot molding. Direct current (DC) conductivity measurements resulted in a percolation threshold of around 8% (w) for CB/LLDPE composites. Increased filler concentrations resulted in increased alternating current (AC) conductivity, electrical permittivity and loss factor. Resistivity-temperature curves indicate the dependence of the temperature at which the maximum of resistivity is reached (T_max(R)) on the filler concentration, as well as a differentiation in the T_max(R) from the crystalline transition temperatures determined by DSC. These results suggest that crystallinity is not the only determining factor of the PTC mechanism in this case. This behavior is different from similar high-crystallinity composites, and suggests a specific interaction between the conductive filler and the polymeric matrix. A strong dependence of the PTC effect on filler concentration and an optimal concentration range between 14 and 19% were also found. Graphite has a beneficial effect not only on conductivity, but also on PTC behavior. Temperature vs. time experiments, revealed good temperature self-regulation properties and current and voltage limitation, and irrespective of the applied voltage and composite type, the equilibrium superficial temperature did not exceed 80 °C, while the equilibrium current traversing the sample dropped from 22 mA at 35 V to 5 mA at 150 V, proving the limitation capacities of these materials. The concentration effects revealed in this work could open new perspectives for the compositional control of both the self-limiting and interrupting properties for various low-temperature applications. Full article

Textile industries release dangerous wastewater that contain dyes into the environment. Due to their toxic, carcinogenic and mutagenic nature, they must be removed before the discharge. Liquid–liquid extraction has proven to be an efficient method for the removal of these dyes. As extractants, deep eutectic solvents (DESs) have shown excellent results in recent years, as well as presenting several green properties. Therefore, four different hydrophobic DESs based on natural components were prepared thymol:decanoic acid (T:D (1:1)), thymol:DL-menthol (T:M (1:1)), thymol:DL-menthol (T:M (1:2)) and thymol:coumarin (T:C (2:1)) for the extraction of Malachite Green (MG), Brilliant Blue G (BBG), Acid Yellow 73 (AY73), Reactive Red 29 (RR29), Acid Blue 113 (AB113), Reactive Black 5 (RB5), Remazol Brilliant Blue (RBB), Direct Yellow 27 (DY27), Acid Blue 80 (AB80), Direct Blue 15 (DB15) and Acid Violet 43 (AV43) dyes from water. The operational parameters of the liquid–liquid extraction were selected in order to save time and materials, resulting in 30 min of stirring, 15 min of centrifugation and an aqueous:organic ratio of 5:1. In these conditions, the highest values of extraction obtained were 99% for MG, 89% for BBG and 94% for AY73. Based on these results, the influence of the aqueous:organic phase ratio and the number of necessary stages to achieve water decolorization was studied. Full article

The Sun is a huge and clean energy source that must be relied upon to reduce greenhouse gases and promote the renewable and sustainable energy transition. In this paper, the testing of Al, Cu, and Fe metals with different thicknesses, both bare and painted matte black, was investigated for solar water heating systems. The used technique was a direct contact flat solar heating system (DCFSHS). Many experiments were run to assess this system in terms of metals’ thicknesses and their thermal conductivities as well. Thicknesses of around 0.35 mm and 1 mm of Cu gave almost similar feedback. Maximum temperatures in the range of 93–97 °C were achieved during the autumn season in Amman, Jordan, while it was approximately 80 °C in winter. It has been confirmed that high water temperatures can be obtained in all used metals, regardless of their thermal conductivities. It was also found that a white color of the solar heater case inner wall leads to an increase in water temperature of approximately 4 °C in comparison to a black color. Furthermore, a light reflectance % test in the wavelength range of 240–840 nm for the studied metals, with both bare and black-painted surfaces, gave a superb result that was in line with the obtained results of the DCFSHS. Our innovative system design for solar water heating is due to improvements in many aspects, such as design, production costs, environment, and weight. Full article

In this study, we addressed the problem of the spatial variability of plough layer compaction by high-power and no-tillage multifunction units in the management of maize planting in the Great Northern Wilderness in China. A comprehensive field experiment involving high-power and no-tillage multifunction units for 165 acres of maize was conducted and analyzed using GIS. Firstly, the test area was divided into four areas, and points were set at equal horizontal distances to collect data on the compactness, water content, porosity and fatigue of the plough layer at different depths. Secondly, the GIS kriging difference method was used to analyze the impact of longitudinal compaction of the plough layer profile at each depth in different test areas. Thirdly, the GIS kriging difference method was used to analyze the lateral spatial distribution of plough layer compaction. Finally, the spatial longitudinal and transverse variabilities of the plough layer were summarized, and the effect of the high-power and no-tillage multifunction units on the physical ecology of the soil in the plough layer was investigated. The results show that the physical properties of the plough layer can be significantly affected by compaction after spreading in the middle tillage period. The surface soil was most affected, with the greatest change in compactness and porosity; the rate of change of soil compactness reached 143.49% and the rate of change of soil porosity reached 40.57%. With the increase in soil depth, the rate of change of soil compactness and porosity gradually decreased. The greatest variation in soil moisture content was found in the middle layer and reached a maximum of 13.78% at a depth of approximately 20 cm. The results of the spatial variability analysis show that the mean values of c₀/(c₀ + c) for the spatial semi-variance functions of compactness, water content and porosity of the tilled soil in the longitudinal space of each test area before compaction were approximately 15%, 19% and 20%, respectively; after compaction, the mean values were approximately 33%, 23% and 30%, respectively; the mean values of c₀/(c₀ + c) for the spatial semi-variance functions of compactness, water content and porosity change of the tilled soil were approximately 24%, 14% and 12%, respectively. The mean values of c₀/(c₀ + c) for the spatial semi-variance functions of compactness, water content and porosity of the soil at each depth in the lateral space before compaction were approximately 80%, 71% and 78%, respectively, and after compaction the mean values were approximately 40%, 23% and 24%, respectively, with the mean values of c₀/(c₀ + c) along the east–west direction being approximately 8%, 27% and 18%, and the mean values of c₀/(c₀ + c) along the north–south direction being approximately 9%, 0% and 20%. The results show that compaction by high-power and no-tillage multifunction units led to a decrease in the spatial variability of soil physical parameters at each depth of tillage in the black soil layer in the longitudinal space, while the spatial variability of the soil physical parameters at each depth of tillage in the black soil layer in the transverse space increased. Moreover, the degree of influence of compaction by high-power and no-tillage multifunction units on soil physical parameters was higher in both vertical and horizontal spaces. This study can provide a theoretical reference for the analysis of the impact of large units on the compaction of black soil layers from the perspective of GIS. Full article