ZnMn2O4 nanostructures: Synthesis via two different chemical methods, characterization, and photocatalytic applications for the degradation of new dyes

Water pollution have become contentious among researchers. By increasing industrialization, the availability of clean water has been reduced. Industrial dyestuffs contribute to the escalation of environmental pollution and are the largest group of organic compounds. The aim of the present work is the synthesis of nanostructures that accelerate the removal of organic dyes from water. To reach this aim, first, ZnMn2O4 nanostructures were synthesized by hydrothermal and co-precipitation methods using maleic acid and phenylalanine as a capping agent. Second, the nanostructures were characterized. XRD analysis revealed the formation of ZnMn2O4 with diameters about 32.3 nm. SEM analysis showed the formation of the agglomerated spherical ZnMn2O4 nanostructures with diameters lower than 50 nm. EDX analysis confirmed the purity of the prepared samples with the presence of Zn, Mn, and O. FT-IR analysis confirmed the bonding between Mn and O at about 620 cm-1. ZnMn2O4 nanostructures showed antiferromagnetic behaviors due to the super-exchange interactions between manganese ions. Finally, the photocatalytic behavior of the nanostructures was investigated for degradation of the anionic and cationic dyes. The results of the photocatalytic tests of two as-prepared samples via different methods were similar. The results exhibit a promising photocatalytic activity in the presence of 0.03 g photocatalyst for degradation of a dye solution with 10 ppm concentration. We introduced these conditions as optimum conditions and achieved maximum decolorization (92.43 %) in the 10 ppm of MV solution after 90 min. Also, we repeated six consecutive reaction cycles and observed a little activity loss after six reactions. We related this result to the high stability of the photocatalyst. We performed scavenging experiments to evaluate the active species involved in the photocatalytic process and plausible mechanisms. The photocatalytic degradation of MV decreased in the presence of TBA and BQ, respectively. This decrease indicated that OH° and O2°- radicals are important active species in the MV degradation process.

Composite Nanoarchitectonics of Magnetic Silicon Dioxide-Modified Chitosan for Doxorubicin Delivery and In Vitro Cytotoxicity Assay

Developing drug delivery carriers for highly selective, controlled, and sustained release of the anti-cancer drugs is one of the crucial issues in the cancer strive. We herein report the synthesis of Fe3O4 (M) and SiO2 (S) nanoparticles and their nanocomposites with chitosan (CS) for high loading efficiency and subsequent release potentiality of Doxorubicin (DOX) anticancer drug. The as-synthesized nanostructures were characterized using Fourier transform infrared (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), and thermal analysis techniques. The average crystallite sizes of the as-prepared M, S, CS/M, CS/S, and CS/M/S nanostructures were found to be 5, 15, 70, 22, and 29 nm, respectively. The loading and cumulative release of Doxorubicin for the produced nanostructures were examined, and the results exhibited loading efficacy of 71%, 95%, 96%, 79%, 17%, and 42% for M, S, CS, CS/M, CS/S, and CS/M/S nanostructures, respectively. The Doxorubicin releasing results revealed a promising cumulative release percentages at pH 4.2 and pH 5 compared with those at pH 7.4. At pH 4.2, the cumulative release percentages for DOX-M, DOX-S, DOX-CS, DOX/M, and DOX/CS/M/S were 94%, 96%, 92%, 95%, and 98%, respectively. While the corresponding percentages at pH 5 were 97%, 90%, 46%, 43%, and 70%. The percentage for DOX-CS/S was 60% at pH 5, though. The in-vitro cytotoxicity of M-DOX, CS-DOX, and M/CS-DOX was explored against two human cancer cell lines (MCF-7 and Hep-G2) using SRB (Sulforhodamine B) assay. The DOX-loaded M/CS exhibited the highest cytotoxicity and its IC50 values were 2.65 and 2.25 μg/mL against Hep-G2 and MCF-7 cell lines, respectively, compared to the corresponding values of 5.1 and 4.5 μg/mL for free DOX. The results indicated that M/CS nanocomposite is a good candidate as drug delivery nano-carrier for the Doxorubicin anti-cancer drug.

Altered zirconium dioxide based photocatalyst for enhancement of organic pollutants degradation: A review

Heterogeneous advanced oxidation processes are a promising approach for cost-efficient removal of pollutants using semiconductors. Zirconium dioxide (ZrO₂) is an auspicious material for photocatalytic activity owning to its suitable bandgap, stability, and low cost. However, ZrO₂ suffers from fast recombination rate, and poor light harvesting ability. Nonetheless, extra modification has also shown improvements and therefore is worth investigating. The endeavour of this paper initially discusses the fundamentals with respect to reactive species, classification, and synthesis methods for ZrO₂. Furthermore, with particular consideration to stability and reusability, several additional modification approaches for ZrO₂-based photocatalysts such as doping and noble metals loading. Furthermore, the formation of heterojunctions has also been shown to boost photocatalytic activity while inhibiting charge carrier recombination. Finally, photocatalyst separation via magnetic-based photocatalysts are elucidated. As a result, ZrO₂-based photocatalysts are regarded as a promising emerging technology that warrants further development and research.

A controllable one-pot hydrothermal synthesis of spherical cobalt ferrite nanoparticles: synthesis, characterization, and optical properties

We herein report the controllable synthesis of spherical cobalt ferrite nanoparticles with average crystallite size in the range of 3.6–12.9 nm using a facile, eco-friendly, hydrothermal method. The hydrothermal treatment was carried out by utilizing cobalt nitrate, ferric nitrate, and ammonium hydroxide in the presence and absence of Arabic gum as a surfactant agent. The purity and crystallinity of the products were tuned by varying reaction conditions such as reaction time (0.5–8 h), reaction temperature (120–180 °C), percentage of ethylene glycol (0–100% (v/v)), pH (8–9.6), and amount of Arabic gum (0–2 g). We characterized the prepared products using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FT-IR), high-resolution transmission electron microscopy (HR-TEM), energy-dispersive X-ray spectroscopy analysis (EDS), selected area electron diffraction (SAED) patterns, and UV-visible diffuse reflectance spectra (DRS). The optimal hydrothermal treatment was performed at 180 °C and pH 9.6 for 4 h in aqueous media. The results also revealed that the as-prepared spinel cobalt ferrite nanoparticles have an estimated optical band gap energy in the range of ca. 1.6–1.9 eV, indicating the semiconducting characteristics of the products.

A controllable synthesis of spherical cobalt ferrite nanoparticles with average crystallite size in the range of 3.6–12.9 nm using a facile, eco-friendly, hydrothermal method.

Magnetic Porous Controlled Fe3O4-Chitosan Nanostructure: An Ecofriendly Adsorbent for Efficient Removal of Azo Dyes

In this work, chitosan/magnetite nanoparticles (ChM) were quickly synthesized according to our previous report based on co-precipitation reaction under ultrasound (US) irradiation. Besides ChM was in-depth structurally characterized, showing a crystalline phase corresponding to magnetite and presenting a spheric morphology, a "nanorod"-type morphology was also obtained after increasing reaction time for eight minutes. Successfully, both morphologies presented a nanoscale range with an average particle size of approximately 5-30 nm, providing a superparamagnetic behavior with saturation magnetization ranging from 44 to 57 emu·g^-1. As ChM nanocomposites have shown great versatility considering their properties, we proposed a comparative study using three different amine-based nanoparticles, non-surface-modified and surface-modified, for removal of azo dyes from aqueous solutions. From nitrogen adsorption-desorption isotherm results, the surface-modified ChMs increased the specific surface area and pore size. Additionally, the adsorption of anionic azo dyes (reactive black 5 (RB5) and methyl orange (MO)) on nanocomposites surface was pH-dependent, where surface-modified samples presented a better response under pH 4 and non-modified one under pH 8. Indeed, adsorption capacity results also showed different adsorption mechanisms, molecular size effect and electrostatic attraction, for unmodified and modified ChMs, respectively. Herein, considering all results and nanocomposite-type structure, ChM nanoparticles seem to be a suitable potential alternative for conventional anionic dyes adsorbents, as well as both primary materials source, chitosan and magnetite, are costless and easily supplied.

pH Transitions and electrochemical behavior during the synthesis of iron oxide nanoparticles with gas-diffusion electrodes

Gas diffusion electrocrystallization (GDEx) was explored for the synthesis of iron oxide nanoparticles (IONPs). A gas-diffusion cathode was employed to reduce oxygen, producing hydroxyl ions (OH^-) and oxidants (H₂O₂ and HO₂ ^-), which acted as reactive intermediates for the formation of stable IONPs. The IONPs were mainly composed of pure magnetite. However, their composition strongly depended on the presence of a weak acid, i.e., ammonium chloride (NH₄Cl), and on the applied electrode potential. Pure magnetite was obtained due to the simultaneous action of H₂O₂ and the buffer capacity of the added NH₄Cl. Magnetite and goethite were identified as products under different operating conditions. The presence of NH₄Cl facilitated an acid-base reaction and, in some cases, led to cathodic deprotonation, forming a surplus of hydrogen peroxide, while adding the weak acid promoted gradual changes in the pH by slightly enhancing H₂O₂ production when increasing the applied potential. This also resulted in smaller average crystallite sizes as follows: 20.3 ± 0.6 at -0.350 V, 14.7 ± 2.1 at -0.550 and 12.0 ± 2.0 at -0.750 V. GDEx is also demonstrated to be a green, effective, and efficient cathodic process to recover soluble iron to IONPs, being capable of removing >99% of the iron initially present in the solution.

Nano-engineered Adsorbent for the Removal of Dyes from Water: A Review

Background:

The huge quantity of wastewater, containing poisonous and hazardous dyes, is released by various industries which pollute water in direct and indirect ways. Most of the dyes are a dangerous class of water contaminants which have affected the environment drastically. Some dyes such as congo red, rhodamine B, methylene blue, methyl violet, and crystal violet are a serious threat to human beings.

Remediation Method:

Numerous methods are available for the removal of dyes from water. Adsorption, being a superior and eco-friendly technique, has advantage of eliminating organic dyes because of the availability of materials as adsorbents. The inexpensive nanomaterials are a more attractive choice for remediation of various dyes due to their unique properties and offer an adequate pathway to adsorb any organic dye from water to overcome its hazardous effects on human health.

Results:

In this review, we have discussed the latest literature related to various types of synthesis, characterization and uses as adsorbent for highly adsorptive removal capacity of nanoparticles for organic dyes.

Conclusion:

Adsorption technology provides an attractive pathway for further research and improvement in more efficient nanoparticles, with higher adsorption capacity, for numerous dyes to eliminate the dyes discharged from various industries and thus reduce the contamination of water. Therefore, nanocomposites may contribute to future prospective water treatment process.

The High Efficiency of Anionic Dye Removal Using Ce-Al13/Pillared Clay from Darbandikhan Natural Clay

Natural clay from Darbandikhan (DC) was evaluated in its natural form, after acid activation (ADC), and after pillaring (PILDC) as a potential adsorbent for the adsorption of methyl orange (MO) as a model anionic dye adsorbate. The effect of different clay treatments was investigated using X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF), Scanning Electron Microscope (SEM) and Fourier-Transform Infrared Spectroscopy (FT-IR), and N₂ physisorption analysis. Both acid activation and pillaring resulted in a significant increase in adsorption affinity, respectively. The adsorption favored acidic pH for the anionic dye (MO). The adsorption process was found to follow pseudo-second-order kinetics with activation energies of 5.9 and 40.1 kJ·mol⁻¹ for the adsorption of MO on ADC and PILDC, respectively, which are characteristic of physical adsorption. The adsorption isotherms (Langmuir, Redlich-Peterson and Freundlich) were fitted well to the experimental data. The specific surface area of the natural clay was very low (22.4 m²·g⁻¹) compared to high-class adsorbent materials. This value was increased to 53.2 m²·g⁻¹ by the pillaring process. Nevertheless, because of its local availability, the activated materials may be useful for the cleaning of local industrial wastewaters.

A simple approach for the sonochemical loading of Au, Ag and Pd nanoparticle on functionalized MWCNT and subsequent dispersion studies for removal of organic dyes: Artificial neural network and response surface methodology studies

In this study, the artificial neural network (ANN) and response surface methodology (RSM) based on central composite design (CCD) were applied for modeling and optimization of the simultaneous ultrasound-assisted removal of quinoline yellow (QY) and eosin B (EB). The MWCNT-NH₂ and its composites were prepared by sonochemistry method and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) analysis's. Initial dyes concentrations, adsorbent mass, sonication time and pH contribution on QY and EB removal percentage were investigated by CCD and replication of experiments at conditions suggested by model has results which statistically are close to experimented data. The ultrasound irradiation is associated with raising mass transfer of process so that small amount of the adsorbent (0.025 g) is able to remove high percentage (88.00% and 91.00%) of QY and EB, respectively in short time (6.0 min) at pH = 6. Analysis of experimental data by conventional models is good indication of Langmuir efficiency for fitting and explanation of experimented data. The ANN based on the Levenberg-Marquardt algorithm (LMA) combined of linear transfer function at output layer and tangent sigmoid transfer function at hidden layer with 20 hidden neurons supply best operation conditions for good prediction of adsorption data. Accurate and efficient artificial neural network was obtained by changing the number of neurons in the hidden layer, while data was divided into training, test and validation sets which contained 70, 15 and 15% of data points respectively. The Average absolute deviation (AAD)% of a collection of 128 data points for MWCNT-NH₂ and composites is 0.58%.for EB and 0.55 for YQ.

Structural study on PVA assisted self-assembled 3D hierarchical iron (hydr)oxides

Polymers with hydroxyl groups may have great influence on the formation process of metal oxides due to complexation.

Preparation of dithiocarbamate polymer brush grafted nanocomposites for rapid and enhanced capture of heavy metal ions

A core-brush nanocomposite for rapid and enhanced adsorption of heavy metal ions was explored by combining SI-ATRP and DTC functionalization.

Synthesis and characterization of a ZnMn2O4nanostructure as a chemical nanosensor: a facile and new approach for colorimetric determination of omeprazole and lansoprazole drugs

ZnMn₂O₄nanostructure was preparedviaan auto-combustion method using different fuels, and it was used as a chemical sensor for determination of omeprazole and lansoprazole drugs.

Design and construction of a bifunctional magnetically recyclable 3D CoMn2O4/CF hybrid as an adsorptive photocatalyst for the effective removal of contaminants

Herein, a magnetic microsphere CoMn₂O₄ (MS-CoMn₂O₄) with a 3D architecture was constructed directly on cellulose fiber (CF) substrates from wastepaper by a solvothermal synthesis method with further calcination treatment.

Tunable auto-combustion preparation of TiO2nanostructures as efficient adsorbents for the removal of an anionic textile dye

We have developed a new route for the synthesis of pure TiO₂nanostructuresviaa facile auto-combustion method followed by heat treatment.

A facile Pechini sol–gel synthesis of TiO2/Zn2TiO2/ZnO/C nanocomposite: an efficient catalyst for the photocatalytic degradation of Orange G textile dye

We have developed an efficient route for the synthesis of TiO₂/Zn₂TiO₂/ZnO/C nanocomposites through a Pechini sol–gel method followed by heat treatment at 550 °C for 30 min.

Preparation of diethylenetriamine-modified magnetic chitosan nanoparticles for adsorption of rare-earth metal ions

The development of a sustainable method to conveniently separate rare-earth metal ions remains a challenge waiting for breakthrough in numerous of advanced technologies.

Magnetism in CoFe2O4nanoparticles produced at sub- and near-supercritical conditions of water

Size and size distribution investigation of magnetic CoFe₂O₄, hydrothermally synthesized using three different heating rates from 0.15 °C s⁻¹to ∼500 °C s⁻¹.

Augmenting the catalytic performance of spinel nanoferrites (CoFe2O4 and NiFe2O4) via incorporation of Al into the lattice

Augmentation in the catalytic performance via incorporation of Al³⁺ ions into the lattice of spinel nanoferrites owing to the synergistic interactions among the metal ions present in the surface exposed catalytically active octahedral sites.

Adsorption kinetics and isotherms of bioactive antioxidant quercetin onto amino-functionalized silica nanoparticles in aqueous ethanol solutions

Nano-structural particles of silica were synthesized from low-cost rice husk by acid leaching and further annealing at different temperatures.

Preparation of a macroporous CuAl2O4 spinel monolith and its rapid selective adsorption towards some anionic dyes

Macroporous CuAl₂O₄ spinel, which was first synthesized, showed excellent selective adsorption performance towards some anionic dyes.

n-Capric acid-anchored silanized silica gel: its application to sample clean-up of Th(iv) sorbed as a dinuclear species in quantified H-bonded dimeric metal-trapping cores

nCA anchored to SSG surface generates 121 μM g⁻¹ H-bonded metal-trapping cores with 10-fold increase in surface area for selective uptake of {Th₂(OH)₂(H₂O)₂}⁶⁺.

A novel nano-sized binuclear nickel(ii) Schiff base complex as a precursor for NiO nanoparticles: synthesis, characterization, DFT study and antibacterial activity

We prepared a new nano-hexadentate Schiff base and its nickel(ii) complex using an ultrasonic method, which produced NiO with an average size of 53 nm.