Surfactant-assisted synthesis of MoO3 nanorods and its application in photocatalytic degradation of different dyes in aqueous environment

Frankincense-Based Functionalized Multiwalled Carbon Nanotubes with Iron Oxide Composites for Efficient Removal of Crystal Violet: Kinetic and Equilibrium Analysis

In this study, novel adsorbents were developed by functionalizing multiwalled carbon nanotubes with frankincense (Fr-fMWCNT) and adding iron oxide (Fe3O4) to the adsorbent (Fr-fMWCNT-Fe3O4). The morphology, surface characteristics, and chemical nature of the synthesized samples were analyzed by using various characterization techniques. The prepared adsorbents were then applied for the elimination of the toxic dye, crystal violet (CV), from water-based solutions by employing a batch adsorption method. The effectiveness of materials for the adsorption of CV was investigated by tuning various effective experimental parameters (adsorbent dosage, dye quantity, pH, and contact time). In order to derive adsorption isotherms, the Langmuir and Freundlich adsorption models were investigated and compared. The Fr-fMWCNT and Fr-fMWCNT-Fe3O4 were found to remove 85 and 95% of the CV dye within 30 min of the adsorption experiment at pH 6, respectively. It was found that a pseudo-second-order reaction rate was consistent with the experimental adsorption kinetics. The equilibrium data demonstrated that the Langmuir model adequately explained the adsorption behavior of the CV dye on the Fr-fMWCNT and Fr-fMWCNT-Fe3O4 surfaces, respectively. According to the Langmuir study, the highest adsorption capacities of the dye are 434 mg/g for Fr-fMWCNT and 500 mg/g for Fr-fMWCNT-Fe3O4. Remediation of the CV dye using our novel composite materials has not been reported previously in the literature. The synthesized Fr-fMWCNT and Fr-fMWCNT-Fe3O4 adsorbents can be economical and green materials for the adsorptive elimination of CV dye from wastewater.

A Brief Review of MoO3 and MoO3-Based Materials and Recent Technological Applications in Gas Sensors, Lithium-Ion Batteries, Adsorption, and Photocatalysis

Molybdenum trioxide is an abundant natural, low-cost, and environmentally friendly material that has gained considerable attention from many researchers in a variety of high-impact applications. It is an attractive inorganic oxide that has been widely studied because of its layered structure, which results in intercalation ability through tetrahedral/octahedral holes and extension channels and leads to superior charge transfer. Shape-related properties such as high specific capacities, the presence of exposed active sites on the oxygen-rich structure, and its natural tendency to oxygen vacancy that leads to a high ionic conductivity are also attractive to technological applications. Due to its chemistry with multiple valence states, high thermal and chemical stability, high reduction potential, and electrochemical activity, many studies have focused on the development of molybdenum oxide-based systems in the last few years. Thus, this article aims to briefly review the latest advances in technological applications of MoO3 and MoO3-based materials in gas sensors, lithium-ion batteries, and water pollution treatment using adsorption and photocatalysis techniques, presenting the most relevant and new information on heterostructures, metal doping, and non-stoichiometric MoO3-x.

Multiple phases of yttrium-doped molybdenum trioxide nanorods as efficient dye degrader and bactericidal agents with molecular docking analysis

Contaminants removal is usually becoming an exciting subject of research from water considering their environmental and ecological effects. This work provides pathways to remove organic pollutants from water via nanomaterials and is used as an antibiotic against bacteria like Escherichia coli (E. coli). In this study, molybdenum trioxide (MoO3) and yttrium (Y) doped (2 and 4%) MoO3 nanorods were synthesized by co-precipitation method. Advanced characterization techniques have been introduced to study textural structures, morphological developments, and optical characteristics of produced products. X-ray diffraction studied multiple crystalline structures of prepared samples as hexagonal, orthorhombic, and monoclinic of pure MoO3 with decrease in crystallinity and crystallite size upon Y doping. UV-visible spectroscopy unveiled a redshift (bathochromic effect) in absorption pattern attributed to band gap energy (Eg) decreases. Photoluminescence spectra examined the recombination rate of electrons (e-) and holes (h+) as charge carriers. A sufficient catalytic activity (CA) was observed against methylene blue (MB) dye in an acidic medium (99.74%) and efficient bactericidal action was studied against (E. coli) with zone of inhibition (5.20 mm) for 4% Y-doped MoO3. In addition, in silico docking demonstrated potential inhibitory effect of produced nanomaterials on FabH and FabI enzymes of fatty acid biosynthesis.

Dye Sequestration Using Biosynthesized Silver Nanoparticles Adsorbent in Aqueous Solutions

Nanomaterials have gained much attention in the field of environmental remediation, largely due to their high surface area-to-volume ratio and other unique physical, chemical, and biological characteristics that emerge due to its size effects. Metallic nanoparticles are traditionally manufactured using wet chemical processes; however, the chemicals utilized are generally hazardous and combustible. The biosynthesis of nanoparticles using a variety of plant resources is considered a green technology because it does not use toxic chemicals. This work focuses on the green synthesis of biogenetic silver nanoparticles and their use in the sequestration of colorants from aqueous solution. The extract of aquatic macrophyte Salvinia molesta (water hyacinth) has been employed to prepare silver nanoparticles by chemical reduction reaction. In the UV-visible spectrum of the synthesized silver nanoparticles, the absorbance peak was detected in the 420–430 nm range. The synthesized silver nanoparticles were used to sequester methylene blue (MB) dye in aqueous solution. About 121.04 mg/g was found as the highest adsorption capacity of methylene blue dye on the silver nanoparticles according to the Langmuir isotherm. It was observed that the experimental results and the pseudo-second order kinetics are in good agreement. As a result, the biosynthesized silver nanoparticle might be a potential adsorbent material in the field of environmental rehabilitation and cleanup.

Molybdenum Oxide Nanoparticle Aggregates Grown by Chemical Vapor Transport

In this study, the advanced chemical vapor transport (CVT) method in combination with the quenching effect is introduced for creating molybdenum oxide nanoparticle arrays, composed of the hierarchical structure of fine nanoparticles (NPs), which are vertically grown with a homogeneous coverage on the individual carbon fibers of carbon fiber paper (CFP) substrates. The obtained molybdenum oxide NPs hold a metastable high-temperature γ-Mo₄O₁₁ phase along with a stable α-MoO₃ phase by the quenching effect. Furthermore, such a quenching effect forms thinner and smaller nanoparticle aggregates by suppressing the growth and coalescence of primary particles. The molybdenum oxide nanoparticle aggregates are prepared using two different types of precursors: MoO₃ and a 1:1 (mol/mol) mixture of MoO₃ and activated carbon. The results characterized using X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy show that the relative amount of α-MoO₃ to γ-Mo₄O₁₁ within the prepared NPs is dependent on the precursor type; a lower amount of α-MoO₃ to γ-Mo₄O₁₁ is obtained in the NPs prepared using the mixed precursor of MoO₃ and carbon. This processing–structure landscape study can serve as the groundwork for the development of high-performance nanomaterials in various electronic and catalytic applications.