ABSTRACTThe growing demand for renewable energy sources has driven research efforts towards highly efficient electrochemical processes, especially the Hydrogen Evolution Reaction (HER) which is an ...essential component in renewable hydrogen production. Single Atom Catalysts (SACs) have been recognised as promising catalysts for exceptional HER activities owing to their unique electronic and geometrical features. This comprehensive review highlights the effective correlation between computational modelling and experimental research in fabricating new SACs and better understanding their catalytic mechanisms in the HER. Furthermore, the review briefly describes the choice of metals and tailoring the electronic structure, as well as exploring the influence of the reaction parameters on the catalytic activity of SACs for HER. Concluding remarks alongside future perspectives on the improvement of SACs for HER are emphasised. It is hoped that this review will pave the way for rational design of highly effective, low-cost and stable SACs for sustainable hydrogen production.
To simulate natural photosynthesis, scientists have developed an artificial Z-scheme system that splits water into hydrogen and oxygen using two different semiconductors. Researchers are striving to ...improve the performance of Z-scheme systems by improving light absorption, developing redox couples with high stability, and finding new cocatalysts. Here, we report the synthesis and utilization of LaFeO3/g-C3N4 as a Z-scheme system for water reduction to produce hydrogen and organic dye degradation under visible light irradiation. The as-fabricated photocatalyst revealed exceptional activity for H2 production (i.e., 351 µmol h−1g−1), which is 14.6 times higher compared to that of the single-component g-C3N4 (i.e., 24 µmol h−1g−1). In addition, the composite photocatalyst degraded 87% of Methylene Blue (MB) and 94% of Rhodamine B (RhB) in 2 h. Various experimental analyses confirmed that the exceptional performance of the LaFeO3/g-C3N4 Z-scheme catalyst is due to remarkably enhanced charge carrier separation and improved light absorption. The development of this highly effective Z-scheme heterostructure photocatalyst will pave the way for the sustainable development of newly designed Z-scheme scheme systems that will tackle energy and environmental crises.
The conversion of model waste plastic mixture into high-value liquid product was studied in the presence of hydrogen and composites of zeolite beta catalysts. For the sake of comparison, the ...conversion of actual waste plastic mixture and high-density polyethylene was also carried out. The composite zeolite beta catalysts were synthesized using a range of silica-to-alumina ratios, alkali concentrations, and hydrothermal treatment times. SEM, EDX, XRD, N
2
-BET, FTIR, and py-FTIR were used for the characterization of the catalysts. The catalytic experiments were conducted in a 500 ml stirred batch reactor at 20 bar initial cold H
2
pressure and the temperature of the reaction was varied between 360 and 400 °C. The two composite catalysts, BC27 and BC48, prepared without alkali pretreatment were found to be the most suitable catalysts. With BC27 and BC48 at 400 °C, 93.0 wt% conversion was obtained with actual plastic mixture and the liquid yield exceeded 68.0 wt%. Experiments with the regenerated catalysts showed their performance comparable to the fresh catalysts.
This research work focuses on the isolation and thermo-chemical modification of cellulose and its application as an adsorbent for the removal of organic pollutants. The used cellulose was collected ...from a locally available plant (
) commonly called Zaitoon. The stem branches of Zaitoon were collected and then kept in water for 40-45 days at room temperature to extract the cellulose fibers. These cellulose fibers were then kept in the Soxhlet apparatus for washing in n-hexane for 72 h. The purified cellulose was divided into three parts: one part was subjected to thermal activation (TAC), the second was modified chemically (CMC) with Benzyl Chloride, while the last one remained un-functionalized (UFC). All the three forms of cellulose were characterized via FTIR and SEM, then utilized for the removal of Titan Yellow (TY) dye from aqueous media via adsorption process by varying the contact time, temperature, concentration of dye and type, and dose of adsorbent. The adsorption efficiencies of all adsorbents were compared under different experimental variables. Thermally activated cellulose showed the best results for the removal of TY compared with other materials. The calculated removal percentage of TY was found to be 97.69, 94.83, 94.83, and 98% under equilibrium conditions of contact time, temperature, adsorbent dose, and TY concentration. Similarly, the uptake capacities of TAC under optimal experimental conditions were found to be 19.56, 18.96, 18.52, and 18.75 mg/g. Thermodynamic studies of TAC, CMC, and UFC showed that the values of ΔG are negative, while those of ΔH and ΔS are positive in all cases and at all temperatures. This indicates that the TY elimination process is endothermic and spontaneous with an entropy-driven nature. The obtained results indicate that the as-fabricated low-cost biomaterials can effectively remove dyes from wastewater through physicochemical interactions. The removal process was influenced by the nature of the adsorbent and the operating variables.
ABSTRACTThe quality of water significantly affects the health and walefare of all orginisms, highlighting the importance to develop low-cost and efficient wastewater treatment methods. Herein, we ...report the fabrication, characterization, and utilization of a polymer-based ternary nanocomposite (CuO–SiO2/PVA) for the removal of Nile Blue (NB) and Methylene Blue (MB) contaminants from wastewater, along with exploring its potential biological activities. We have successfully employed the cost-effective sol–gel and in-situ polymerization approaches to fabricate the CuO–SiO2/PVA based ternary composite, utilizing Cu(NO3)2·3H2O:Glycerol:TEOS:PVA in a ratio of 8:2:3:4. The desired fabrication of nanocomposite was confirmed through UV-Visible spectroscopy, SEM (scanning electron microscope), TEM (transmission electron microscope), EDX (energy dispersive X-ray diffraction), FTIR (Fourier transform infrared), DSC (differential scanning calorimetry), and TGA (thermogravimetric analysis). In addition to its biological potentialthe performance of the nanocomposite in catalytic / photocatalytic removal of NB and MB dyes is investigated and compared. The higher photodegradation performance of the composite for NB (85%) dye than for MB (76%) dye indicates that variables such as chemical structure, charge, molecular mass, and pH sensitivity of the dyes can influence the catalyst's removal potential. This composite is considered to have a higher capability for removing pollutants and microorganisms from wastewater.
In this work, potato starch was hydrolyzed by acid (HCl) to form nanoparticles (SNPs) that were esterified with acid Rosin using a green heterogeneous catalyst based on Algerian montmorillonite clay ...known as “Magnhite”. It has a similar activity to the classical Brönsted (H
2
SO
4
) and Lewis (Al
2
O
3
) acids, which implies that it can replace homogeneous acid catalysts. Particular emphasis was devoted to investigate the influence of temperature, reaction time, and amount of catalyst on the degree of substitution (DS) on the reaction conditions to achieve a high DS. Fourier Transform Infrared analysis confirms the esterification of SNPs by the appearance of new bands at 1724 cm
−1
assigned to ester group. X-ray diffraction and scanning electron microscopy indicate that the esterification reaction reduces the crystallinity while the morphology changes from SNPs nanoparticles to a completely destroyed form. Besides, the thermal stability of esterified SNPs has been slightly reduced compared to unmodified starch. The volumetric assay was used to evaluate the DS of the products and the effects of the rosin/glucose anhydrous acid unit in the molar ratio. It is found that DS increases with increasing the molar ratio and reaches its maximum value of 0.135 at a molar ratio of 4:1. Furthermore, antimicrobial activity study of SNPs esterified with rosin acid (DS between 0 and 0.141), revealed that the esterified SNPs were effective against all the tested bacterial strains. Moreover, the DS is directly proportional to the zone of inhibition. This research showcases the importance of the newly designed SNPs-Rosin formulation in the biomedical and food industries.
Organic dyes, especially Congo red, are utilized primarily in the textile industry and consequently discharged into water resources that pollute aquatic environments. This study aims to investigate ...the fabrication of Cr-doped ZnO nanoparticles by sol–gel method to eliminate Congo red dye from wastewater. The obtained Cr-doped ZnO was characterized by scanning electron microscopy, X-ray diffraction, thermogravimetric analysis, and Fourier transform infrared spectroscopy. The Cr-doped ZnO crystallizes within a hexagonal wurtzite structure with a BET surface area equal to 9.5 m
2
. g
−1
. It is found that the variation of dye concentration and pH influence the removal of Congo red by Cr-doped ZnO. Excellent efficiency of 155.52 mg.g
−1
is achieved under optimum operating conditions, i.e., the adsorbent dosage of Cr-doped ZnO (0.400 g/L), contact time of 110 min, and solution pH (7.00). Pseudo-second-order adsorption kinetics and Langmuir isotherm models best fitted Congo red adsorption onto Cr-doped ZnO. The Congo red adsorption mechanism is associated with the chemisorption and hydrogen bond, as indicated by the pH, isotherms, and Fourier transforms infrared spectroscopy studies. The examination of Cr-doped ZnO with other dyes (malachite green, crystal violet, basic fuchsin, methylene blue, and eriochrome black T) suggests the high adsorption capacity of Cr-doped ZnO towards malachite green, crystal violet, and basic fuchsin dyes compared with methylene blue and Eriochrome black T dyes. The findings demonstrate that Cr-doped ZnO nanostructures manifest excellent adsorption capability to remove organic dyes from aqueous solutions.
Graphical abstract
This research work aims to investigate the mechanical alloying of
Fe
15
Co
2
P
3
powder mixture in terms of phases’ formation, microstructural parameters, and magnetic properties as function of ...milling time. Parametric
Rietveld
refinement method, of the obtained X-ray patterns, was performed for qualitative and quantitative phase analysis alongside the determination of structural, microstructural, and mechanical properties. The ball-milled powder mixture crystallized within the face-centered cubic α-
Fe
(P) solid solution in equilibrium with
Co
75
Fe
25
phase. The crystallite size decreases reaching 100 and 200 nm respectively after 3 h of milling. The highest values of the dislocation density, microstrain, and stored energy are registered for the α-
Fe
(P) solid solution. The studied mechanical properties manifest the brittle nature of the α-
Fe
(P) solid solution compared to the
Co
75
Fe
25
phase. The squareness ratio
M
r
/
M
s
and the coercivity values of the milled powders increase with increasing milling time and reach steady state after 2 h. The hysteresis loss energy and maximum permeability reach minimal values of 45 × 10
−4
W/m
3
and 49 × 10
−3
H/m respectively, after 1 h of milling at the opposite of the switching field distribution. The obtained results demonstrate the formation of nanostructured
Fe
15
Co
2
P
3
ternary alloy with optimum characteristics as promising candidate for diverse applications primarily in the biomedical field for diagnostics and therapeutics such as magnetic hyperthermia and vector probes for future imaging technologies.
This research aims to investigate the effect of copper doping on the photocatalysis performance of TiO
2
nanoparticles for disposal wastewater from organic pollutants. X-ray diffraction analysis ...manifests the crystallization of a rutile phase for pure and copper-doped TiO
2
except for 2% resulting in a rutile-to-anatase phase transformation. The crystallite size is found less affected by Cu doping, i.e., ~30 nm. BET analysis indicates a decrease in the specific surface area as the doping loading increases. Scanning electron microscopy observations reveal spherical particles at the nanometer range for pure TiO
2
and then larger agglomerates of ultrafine particles with Cu doping. FTIR analysis notifies the existence of hydroxyl groups, which will promote the photocatalysis process. The photodegradation of azucryl red (AR) has been investigated under different conditions; i.e., Cu-loading, initial concentration of AR, and pH. The kinetics of the photodegradation process is further found to comply with the Lagergren kinetic law, regardless the experimental conditions. Nevertheless, the photodegradation process is not only controlled by the intra-particle diffusion mechanism, but also by mass transfer through a liquid film boundary. The maximum degradation of AR, i.e., 86%, has been achieved at pH = 5.0 during 60 min of contact time for the 2% Cu doping, with effective regeneration. The Freundlich model exhibits a better fitting for AR dye photodegradation equilibrium data, compared to Langmuir, Temkin, and Dubinin-Radushkevich.
The aim of this work consists on the synthesis of a nanomaterial for heavy metal ion removal from aqueous solutions. Al-doped ZnO (ZnO:Al
x
%) nanopowders with 0 to 5% Al content are prepared via an ...amended sol-gel method. The morphology and microstructure of the prepared ZnO:Al
x
% are probed by means of scanning electron microscopy (SEM), X-ray particles diffraction (XRD) analysis, energy dispersive X-ray spectroscopy (EDS) and elemental mapping. The findings reveal the prevalence of the hexagonal wurtzite ZnO structure with increasing crystallite size (45 to 60 nm) as a result of Al doping. SEM images show nearly spherical nanoparticles with considerable aggregation. EDS and elemental mapping analysis confirm the incorporation of Al within ZnO host lattice. The relatively large surface area as estimated from N
2
adsorption makes the nanopowders very favorable for the uptake Cd(II), Cr (IV), Co (II) and Ni(II) from aqueous solution. The ZnO:Al
x
% with 1 wt% Al exhibits the highest uptake rate of heavy metal ions. The adsorption process has been found to be spontaneous and endothermic and obey Langmuir adsorption model. The high tendency of the prepared nanoparticles to eliminate heavy metal ions renders them suitable candidates for environmental remediation. Desorption studies with 0.1 M NaOH indicate that ZnO:Al
x
% can be regenerated effectively.
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