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Recent reports on nanoparticles rise significantly as they possess numerous applications in medical, material science, optics, and bioscience etc. Nanoparticles show unique properties as they are an inter-linker between bulk materials and atomic structures. On behalf of large surface area of nanoparticles, they are utilized to a greater extent that leads to contribute in making small bulk of the nanoparticles. Varieties of procedures are already reported but they have too much drawbacks like release of toxic by-products that are hazardous to the environment. To address all these problems, greener method such as plant extract was introduced. In India, Glycyrrhiza glabra, a small traditional perennial herb was used to cure sore throat, cough, ulcers and hepatitis. Hence, the aforementioned plant extract was used to synthesize ZnO nanoparticles. The green synthesized ZnO nanoparticles were analysed to study their morphology and other salient characters by the utilization of UV-Vis spectroscopy, FT-IR, SEM and TEM analysis. In this present study, utilization of this green synthesized ZnO NPs in the photo degradation of azo dyes (Congo red and amaranth dyes) and kinetic expressions were reported. These findings revealed good photocatalytic activity against the azo dyes (Congo red and Amaranth dyes) and an excellent photocatalyst for Congo red dye degradation. This synthetic approach is environmental friendly and can provide new techniques in the management of pollutants. [ABSTRACT FROM AUTHOR]

Herein, a green and facile methodology was used for the structural design of semiconductor nanomaterials and employed as efficient photocatalyst to resolve the environmental issues of water pollutants. Titanium oxide coupled with bismuth oxide (TiO 2 @Bi 2 O 3) nanocomposite was synthesized by employing the seed extract of Sapindus mukorossi (commonly found plant in India) and subsequently used for the elimination of toxic, and persistence industrial pollutants namely bisphenol A (BPA) and methylene blue (MB). Microscopic and spectroscopic techniques revealed particle size of synthesized nanocomposite found less than 50 nm along with high crystallinity. Appearance of stretching vibrations at 459 cm−1 for Bi–O–Ti in the IR spectra of nanocomposite has established the coupling of TiO 2 with Bi 2 O 3. The parameters of degradation were optimized by varying the pollutant concentration, catalytic amount and pH in the presence of natural sunlight. The nanocomposite TiO 2 @Bi 2 O 3 showed maximum degradation (MB: 94% and BPA: 91%) at a minimum concentration of pollutant (50 mgL−1) with catalyst amount (35 mg), neutral pH and reduces half-life of pollutants (BPA: 1h, MB: 0.5h). Owing of higher surface area (80 m2g-1), lower band gap (2.5 eV), and more negative zeta potential value (−40.3 mV) results into excellent photocatalytic properties. The breakage of S–N conjugated system in MB results into rapid degradation as compare to BPA. The degradation followed first-order kinetics and Langmuir adsorption in both the cases. Presence of active radicals during the photocatalysis process was responsible for quick degradation and strongly supported by scavenger analysis. GC-MS analysis revealed the degradation of toxic pollutants into safer metabolites and finally mineralized. Multiple times (n = 8) reusability of green photocatalyst advocated sustainability and appropriate for industrial applications. [Display omitted] • Natural extract based synthesis of TiO 2 @Bi 2 O 3 nanocomposite. • First-order degradation of Bisphenol A (91%) and Methylene Blue (MB) dye(9 4%) by TiO 2 @Bi 2 O 3. • Optimization of concentration, pH, catalyst dose and source of irradiation. • Hybrid nanostructure increased charge separation and prevent e−/h + recombination behavior. • Small non-toxic by-products and excellent reusability (8th cycle) confirm high efficiency. [ABSTRACT FROM AUTHOR]