The world’s water supplies have been contaminated due to large effluents containing toxic pollutants such as dyes, heavy metals, surfactants, personal care products, pesticides, and pharmaceuticals from agricultural, industrial, and municipal resources into water streams. Water contamination and its treatment have emerged out as an escalating challenge globally. Extraordinary efforts have been made to overcome the challenges of wastewater treatment in recent years. Various techniques such as chemical methods like Fenton oxidation and electrochemical oxidation, physical procedures like adsorption and membrane filtration, and several biological techniques have been recognized for the treatment of wastewater. This review communicates insights into recent research developments in different treatment techniques and their applications to eradicate various water contaminants. Research gaps have also been identified regarding multiple strategies for understanding key aspects that are important to pilot-scale or large-scale systems. Based on this review, it can be determined that adsorption is a simple, sustainable, cost-effective, and environmental-friendly technique for wastewater treatment, among all other existing technologies. However, there is a need for further research and development, optimization, and practical implementation of the integrated process for a wide range of applications.

A state-of-the-art review on wastewater treatment techniques: the effectiveness of adsorption method.

Nickel Spinel Ferrites: A review

In this work, we are reporting the facile synthesis of hierarchically porous CuO microspheres and their r-GO based nanohybrid as an electrode material for supercapacitor applications. The fabricated product was characterized by powder X-ray diffraction technique (PXRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray analysis, and Brunauer–Emmett–Teller (BET) analysis. PXRD analysis showed the existence of the monoclinic phase of CuO. The compositional study of the synthesized product was completed via EDX analysis. The FESEM analysis confirmed the hierarchical porous micro-spherical architecture of the product with smaller CuO grain-size particles, quasi-microporous spindle-like nanosheets assembled by nano-grains, and their aggregation to mesoporous nature. The BET analysis revealed that the BET and Langmuir surface area of the hierarchically porous CuO microspheres was 60.02 m²/g and was 86.68 m²/g. Furthermore, the BET results also confirmed the mesoporous structure of the fabricated sample. The hierarchically porous CuO microspheres showed a specific capacitance of 402 F/g at 1 A/g with 75.4% capacitance retention whereas their r-GO based nanohybrid showed 712 F/g at 1 A/g with 96.9% capacitance retention. The greater electrochemical response of r-GO based nanohybrid was due to the greater surface area and higher electrcial conductivity arise from the synergistic effects between the novel structure and r-GO nanosheets. Moreover, apart from the condcutive matrix r-GO also behaves as a capacitive supplement and contributes toward the total capacitance of the nanocomposite. The electrical impedance spectroscopy (EIS) experiments reveal that the addition of the r-GO matrix also facilitates the charge transfer and improves the kinetics of the redox reaction. In short, it can be concluded that r-GO based hierarchically porous CuO microspheres found themselves as a potential candidate in the field of hybrid supercapacitors.

Hierarchically porous CuO microspheres and their r-GO based nanohybrids for electrochemical supercapacitors applications

Mesoporous and macroporous Ag-doped Co3O4 nanosheets and their superior photo-catalytic properties under solar light irradiation

Mn1-xCuxO2/ reduced graphene oxide nanocomposites: Synthesis, characterization, and evaluation of visible light mediated catalytic studies

Silver nanoparticles stabilized in polymer hydrogels for catalytic degradation of azo dyes.

The impact of carbon nanotubes on the optical, electrical, and magnetic parameters of Ni2+ and Co2+ based spinel ferrites

The La1−AAFeO3 (A = Gd, Nd and Dy) nanoparticles were successfully prepared via micro-emulsion route. All the prepared nanoparticles were successfully characterized by various conventional techniques such as x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) etc. The grain size estimated from SEM image of the LaFeO3 nanoparticles is between 50–161 nm. The lanthanide doped LaFeO3 nanoparticles were subjected to dielectric behavior evaluation. The dielectric studies showed the improved dielectric behavior of Lanthanide-doped LaFeO3 nanoparticles. Reduced graphene oxide was prepared via modified chemical route (Hummer's method). The prepared reduced graphene oxide was utilized to make the nanocomposites with as-prepared nanoparticles. The photocatalytic activity of LaFeO3 nanoparticles and their composites with reduced graphene oxide was evaluated in the presence of visible light. Methylene blue was used as model organic compound for the photocatalysis studies. The UV-visible spectra of methylene blue recorded at various intervals showed the good photocatalytic activity of LaFeO3- reduced graphene oxide nanocomposites.

https://iopscience.iop.org/article/10.1088/2053-1591/aacd1d/pdf

Rare earth substituted nanocrystalline LaFeO3 perovskites and their composites with reduced graphene oxide for enhanced photocatalytic and other potential applications

In this article, we reported the two-step wet chemical co-precipitation and ultra-sonication route to synthesize the Ce0.95Fe0.05O2/NiO/rGO (CFN-rGO) ternary composite photocatalyst. The photocatalytic activity of the ternary composite was evaluated by the photodegradation of Rhodamine B (RhB) dye under visible light irradiation. The CFN-rGO photocatalyst exhibited an excellent photocatalytic performance with 97% removal of RhB within 130 min of irradiation time, as compared to the bare Ce0.95Fe0.05O2/NiO (CFN) binary composite photocatalyst. The value of rate constant for RhB degradation was nine times higher with CFN-rGO when compared to the pure CFN catalyst. The superior photocatalytic activity of CFN-rGO is attributed to the presence of reduced graphene oxide (rGO), that effectively suppress the fast recombination of photo-generated electron-hole pairs which in turn find enough time to produce more reactive species for RhB dye degradation. The main photo-active species involved in photodegradation of RhB dye molecules were the hydroxyl radicals ( H O • ). Finally, the recyclability tests performed over CFN-rGO suggested good stability of the photocatalyst even after five cycles and hence, endorsing its potential as a candidate for practical photocatalytic applications.

Facile Synthesis of Ce1-xFexO2/NiO/rGO Ternary Hybrid Heterostructures with Enhanced Visible Light mediated Photocatalytic Activity for Waterborne Pollutants

Sara Musaddiq

Papers

Silver nanoparticles stabilized in polymer hydrogels for catalytic degradation of azo dyes.

The impact of carbon nanotubes on the optical, electrical, and magnetic parameters of Ni2+ and Co2+ based spinel ferrites

Rare earth substituted nanocrystalline LaFeO3 perovskites and their composites with reduced graphene oxide for enhanced photocatalytic and other potential applications

Facile Synthesis of Ce1-xFexO2/NiO/rGO Ternary Hybrid Heterostructures with Enhanced Visible Light mediated Photocatalytic Activity for Waterborne Pollutants

Ecdysteroids from the flowers of Aerva javanica.