Facile synthesis, growth process, characterisation of a nanourchin-structured α-MnO2 and their application on ultrasonic-assisted adsorptive removal of cationic dyes: A half-life and half-capacity concentration approach

Bio-inspired magnetic chitosan/Iron oxide macromolecules for multiple anionic dyes adsorption from aqueous media

Organic anionic dyes are major water pollutants due to their low degradability caused by complex aromatic structures. Not only do they exert toxic, mutagenic, teratogenic, tumorigenic, and genotoxic effects, but they also decrease fertility and cause irritation to the skin and respiratory system in humans. This long-term toxicity has detrimental effects on aquatic organisms and their surroundings, resulting in an imbalanced ecosystem. In this study, a Cs@Fe3O4 magnetic biosorbent was synthesised to uptake three anionic dyes and characterised for FTIR, BET/BJH, XRD, TGA, VSM, and FESEM analyses. The biosorbent average surface area was confirmed to be 52.6524 m2/g, with average pore sizes of 7.3606 nm and 6.9823 nm for adsorption-desorption processes, respectively. Batch adsorption studies pH values, contact times, temperature, initial dye concentrations, and adsorbent dosages were examined. Several isotherm and kinetic models were studied to determine the adsorption mechanism. The adsorption data of these dyes at equilibrium was observed to match Langmuir's isotherm and pseudo-second-order kinetic models. The thermodynamic study revealed that the adsorption process for these dyes was an exothermic reaction. Maximum adsorption capacities for congo red, methyl orange, and metanil yellow were 117.77 mg/g, 137.77 mg/g, and 155.57 mg/g, respectively. The reusability of recovered Cs@Fe3O4 after dye adsorption was evaluated up to five continuous adsorption-desorption cycles for its possible industrial applications.

Plant-mediated synthesis of silver-doped ZnO nanoparticles with high sonocatalytic activity: Sonocatalytic behavior, kinetic and thermodynamic study

Together with the rapid growth of technology, the discharge of wastewater from industry into environment had become a hot topic among society nowadays. More attention had been given to the development of water treatment techniques. In this study, sonocatalysis was proposed to degrade the organic pollutants using silver-doped zinc oxide (Ag-ZnO) nanoparticles which were synthesized via green synthesis process using Clitoria ternatea Linn (Asian Pigeonwings flower). The characterization results revealed that the incorporation of Ag into the ZnO lattice decreased the crystallite size and increased the specific surface area of ZnO nanoparticles. It is noteworthy that about 98% of sonocatalytic degradation efficiency of malachite green (MG) was successfully achieved within 30 min in the presence of 5 wt.% Ag-ZnO with 1.0 g/L of catalyst loading under 500 mg/L of initial dye concentration, 80 W of ultrasonic power, 45 kHz of ultrasound frequency, and 2.0 mM of oxidant concentration. The kinetic study showed that the sonocatalytic degradation of organic dye was fitted well into second-order kinetic model with high R2 value (0.9531). In the thermodynamic study, negative value of standard Gibbs free energy and low value of activation energy (+ 24.43 kJ/mol) were obtained in the sonocatalytic degradation of MG using the green-synthesized Ag-ZnO sample. HIGHLIGHTS: • Facile synthesis of silver-doped zinc oxide nanoparticles using plant extract which act as reducing and stabilizing agents • Optical, physical, and chemical characterization of green-synthesized nanomaterials were performed • Evaluation of sonocatalytic degradation of organic dye using green-synthesized nanomaterials • Sonocatalytic behavior, kinetic and thermodynamic studies of sonocatalytic reaction.

Comparative catalytic reduction and degradation with biodegradable sodium alginate based nanocomposite: Zinc oxide/N-doped carbon nitride/sodium alginate

Sodium alginate (SA) is a biodegradable macromolecule which is used to synthesize nanocomposites and their further use as catalysis. Zinc oxide (ZnO) and nitrogen doped carbon nitride (ND-C3N4) nanoparticles are prepared using solvothermal and hydrothermal methods, respectively. ZnO/ND-C3N4/SA nanocomposites are successfully synthesized by employing in-situ polymerization. The presence of essential functional groups is confirmed by Fourier transform infrared (FTIR) spectroscopic analysis. Controlled spherical morphology for ZnO nanoparticles, with an average diameter of ∼52 nm, is shown by Scanning electron microscopic (SEM) analysis, while rice-like grain structure with an average grain size ∼62 nm is exhibited by ND-C3N4 nanoparticles. The presence of required elements is confirmed by Energy dispersive X-ray spectroscopic (EDX) analysis. The crystalline nature of nanocomposites is verified by X-ray diffraction spectroscopic (XRD) analysis. The investigation of the catalytic efficiency for degradation and reduction of various organic dyes is carried out on nanoparticles and nanocomposites. Thorough examination and comparison of parameters, such as apparent rate constant (kapp), reduction time, percentage reduction, reduced concentration and half-life, are conducted for all substrates. The nanocomposites show greater efficiency than nanoparticles in both reactions: catalytic reduction and catalytic degradation.

Simple one-step synthesis of urchin-like Fe–Mn nanostructures via statistical design and their effects on the morphology

In the current investigation, a new urchin-like nanostructure using an authorized one-pot precipitation technique was synthesized using Taguchi statistical design. The effect of factors, including the concentration of FeSO4⋅7H2O, KMnO4, NaOH, and reaction temperature, on the diameter-to-length ratio of the nanoneedles and the regularity or irregularity morphology of other samples, was investigated. KMnO4 and FeSO4⋅7H2O, with a contribution of 32.62% and 30.9%, had the most substantial effect on the nanoneedles' diameter. The surface morphology and chemical composition of the as-prepared samples were studied using field emission scanning electron microscopy, X-ray diffraction, and energy dispersive spectroscopy (EDX) analyses. The length and needle diameter was obtained 140 and 17 nm, respectively. The result of BET analysis for the highest and the lowest value of D/L shows that the smallest ratio of diameter to length has a high specific surface area. The results show that sample S4 has a particular surface area of 74 m2/g, much more than S3 (25 m2/g). The estimated crystallite size in synthesized S3 and S4 samples are 41.64 and 26.49 nm, respectively.

Adsorption Behaviour of Reactive Blue 194 on Raw Ramie Yarn in Palm Oil and Water Media

As an edible oil, palm oil is also safe and reliable in dyeing, and the residual palm oil after dyeing can be recycled and used continuously, which is green and environmentally friendly and has great research prospects. In this research, raw ramie yarn, used for traditional grass cloth, was dyed in a palm oil medium using Reactive Blue 194. Studying the adsorption and diffusion behaviour in the dyeing process is necessary. Additionally, the kinetics and isotherm model of dyeing raw ramie yarn with Reactive Blue 194 in palm oil is studied, and the adsorption behaviour between them is discussed. For a better understanding, the raw ramie yarn dyeing adsorption behaviour was also carried out in a water medium. It was found that the dyeing rates in palm oil are distinctly faster than in water. Kinetics data suggested that the pseudo-second-order model fitted for both dyeing mediums (palm oil and water) of the adsorption of the Reactive Blue 194 dye onto raw ramie yarn. Afterward, the adsorption isotherms' results denote that the Langmuir model was suitable for palm oil dyeing medium while the Freundlich model was suited for water medium. Overall, this study has demonstrated that raw ramie yarn dyeing in a palm oil medium could be a sustainable colouration route for textile fibres with a greater dye exhaustion percentage.

Formulation and clinical advancement of nanourchins: a novel multibranched nanoparticulate drug-delivery system

Nanourchins are multibranched nanoparticles with unique optical properties and surface spikes. Because of their unique properties, gold nanourchins have advantages over gold nanoparticles. The most used nanourchins are gold, tungsten, carbon, vanadium and sea urchins. The synthesis of various nanourchins and their clinical advancement are discussed in this review. ZFNs, TALENs and CRISPR/Cas9 are discussed to facilitate understanding of advancements in nanourchins. Nanourchins have been studied for Parkinson's disease, Alzheimer's disease and bioimaging. The synthesis of molybdenum diselenide nanourchins and their bioconjugations are also discussed. Nanourchins can be further explored to improve drug targeting and delivery. Researchers from several fields may contribute to the study of nanourchins as prospective nanocarriers with target specificity.

Insight into the surface activity of defect structure in α-MnO2 nanorod: first-principles research

The contribution of defect structure to the catalytic property of α-MnO₂ nanorod still keeps mysterious right now. Using microfacet models representing defect structure and bulk models with high Miller index, several parameters, such as cohesive energy, surface energy, density of state, electrostatic potential, et al., have been used to investigate the internal mechanism of their chemical activities by first-principles calculation. The results show that the trend in surface energies of microfacet models follows as E_surface[(112 × 211)] > E_surface[(110 × 211)] > E_surface[(100 × 211)] > E_surface[(111 × 211)] > E_surface[(112 × 112)] > E_surface[(111 × 112)], wherein all of them are larger than that of bulk models. So the chemical activity of defect structure is much more powerful than that of bulk surface. Deep researches on electronic structure show that the excellent chemical activity of microfacet structure has larger value in dipole moments and electrostatic potential than that of bulk surface layer. And the microfacet models possess much more peaks of valent electrons in deformantion electronic density and molecular orbital. Density of state indicates that the excellent chemical activity of defect structure comes from their proper hybridization in p and d orbitals.

Removal of cadmium heavy metal ions from wastewater by electrosorption using modified activated carbon felt electrodes

Cadmium contamination in industrial wastewater is an environmental issue posing a great threat to human and animal life. However, the available methods for the removal of cadmium at lower concentrations are limited. Such processes are often accompanied by sludge formation and lead to heavy metal wastage. This paper focuses on the application of an electrosorption process using modified activated carbon felt (MACF) electrodes for the removal and recovery of lower concentration of cadmium from a simulated wastewater sample without sludge formation. Activated carbon felt (ACF) electrodes were treated with 20% HNO₃ for removing surface impurities and improving the surface area. The effect of the electrode modification was analyzed by performing various characterizations including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and cyclic voltammetry. The adsorption isotherm and kinetic models have also been studied. The effect of operating parameters including pH, voltage, initial concentration and time were analyzed and optimized using Box-Behnken design and were obtained as 6.42, 1.44 V, 0.50 mg/L and 131.51 min respectively. During the regeneration of electrodes, a concentrated cadmium solution of 18.55 mg/L was obtained, which showed the possibility of cadmium recovery. The maximum cadmium removal was 60.60% at the optimized conditions, revealing the significance of electrosorption for heavy metal treatment.