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Abstract ZnS quantum dots are semiconductor nanoparticles characterized by superior optoelectronic properties. The amenability of these nanoparticles in initiating efficient photo-redox reactions enable their use as photocatalysts for environmental remediation. In the present study, ZnS quantum dots were biosynthesized from Zn tolerant Penicillium sp. under ambient reaction conditions. The biogenic ZnS quantum dots were characterized using TEM, SEM, XRD, FTIR and UV–Vis absorption studies that revealed the formation of spherical particles of average diameter 11.08 nm with a zinc blend crystal structure and the optical properties were in par with chemically synthesized ZnS. The biogenic ZnS were then used for the photodegradation of methylene blue (MB) dye. It was found that the green synthesized ZnS quantum dots exhibited good photocatalytic activity with a half-life of 4 h. Further, the dye degradation efficiency was enhanced as the ZnS nanocatalyst/dye ratio increased and reached equilibrium within 6 h. The present study reports an inexpensive and scalable method to fabricate ZnS nano hybrids with practical applicability in the remediation of pollutants in textile, paper and dyeing industry. Graphical abstract fx1 [ABSTRACT FROM AUTHOR]

Nanotechnology is a rapidly growing scientific field and has attracted a great interest over the last few years because of its abundant applications. Green nanotechnology is a multidisciplinary field that has emerged as a rapidly developing research area, serving as an important technique that emphasize on making the procedure which are clean, non-hazardous, and especially environmentally friendly, in contrast with chemical and physical methods currently employed for nanosynthesis. The biogenic routes could be termed green as these do not involve the use of highly toxic chemicals or elevated energy inputs during the synthesis. Differences in the bio-reducing agents employed for nanosynthesis can lead to the production of nanoparticles (NPs) having distinct shapes, sizes, and bioactivity. The exquitiveness of the green fabricated NPs have capacitated their potential applications in various sectors such as biomedicine, pharmacology, food science, agriculture, and environmental engineering. The present review summarizes current knowledge on various biogenic synthesis methods, relying on plants, waste biomass, and biopolymers and their reducing and stabilizing agents to fabricate nanomaterials. The main emphasis has been given on the current status and future challenges related to the wide-scale fabrication of nanoparticles for environmental remediation, pathogenicity, and agricultural applications. [ABSTRACT FROM AUTHOR]

Freshwater demand will rise in the next couple of decades, with an increase in worldwide population growth and industrial development. The development activities, on one side, have increased the freshwater demand. However, the ground water has been degraded. Among the various organic and inorganic contaminants, arsenic is one of the most toxic elements. Arsenic contamination in ground waters is a major issue worldwide, especially in South and Southeast Asia. Various methods have been applied to provide a remedy to arsenic contamination, including adsorption, ion exchange, oxidation, coagulation-precipitation and filtration, and membrane filtration. Out of these methods, adsorption of As(III)/As(V) using nanomaterials and biopolymers has been used on a wide scale. The present review focuses on recently used nanomaterials and biopolymer composites for As(III)/As(V) sorptive removal. As(III)/As(V) adsorption mechanisms have been explored for various sorbents. The impacts of environmental factors such as pH and co-existing ions on As(III)/As(V) removal, have been discussed. Comparison of various nanosorbents and biopolymer composites for As(III)/As(V) adsorption and regeneration of exhausted materials has been included. Overall, this review will be useful to understand the sorption mechanisms involved in As(III)/As(V) removal by nanomaterials and biopolymer composites and their comparative sorption performances. [Display omitted] • Organic and inorganic contaminants, arsenic is one of the most toxic elements. • Review focuses on nanomaterials and biopolymer composites for As(III)/As(V) sorptive removal. • Regeneration, reusability, and disposal of exhausted nanomaterials were discussed. • As(III)/As(V) adsorption mechanisms have been explored for various sorbents. • Various nanosorbents and biopolymer composites for As(III)/As(V) adsorption has been included. [ABSTRACT FROM AUTHOR]