Green and energy-efficient methods for the production of metallic nanoparticles

In the last decade, researchers paid great attention to the concept of “Green Chemistry”, which aims at development of efficient methods for the synthesis of nanoparticles (NPs) in terms of the least possible impact on human life and environment. Generally, several reagents including precursors, reducing agents, stabilizing agents and solvents are used for the production of NPs and in some cases, energy is needed to reach the optimum temperature for reduction. Therefore, to develop a green approach, researchers had the opportunity to investigate eco-friendly reagents and new energy transfer techniques. In order to substitute the harmful reagents with green ones, researchers worked on different types of saccharides, polyols, carboxylic acids, polyoxometalates and extracts of various plants that can play the role of reducers, stabilizers or solvents. Also, there are some reports on using ultraviolet (UV), gamma and microwave irradiation that are capable of reducing and provide uniform heating. According to the literature, it is possible to use green reagents and novel energy transfer techniques for production of NPs. However, these new synthesis routes should be optimized in terms of performance, cost, product quality (shape and size distribution) and scale-up capability. This paper presents a review on most of the employed green reagents and new energy transfer techniques for the production of metallic NPs

Pine-wood derived nanobiochar for removal of carbamazepine from aqueous media: Adsorption behavior and influential parameters

In recent years, application of biochar for removal of pollutants from aqueous solutions has been of interest due to favorable physicochemical properties and availability of feedstock. However, adsorption behavior has been reported only for raw and micro biochar particles and taking advantage of biochar nanoparticles, which offer superior specific surface area, did not receive any attention. The objective of this study was to investigate the adsorption efficiency of produced nanobiochar from pinewood. For this purpose, removal of carbamazepine (CBZ), a globally prescribed pharmaceutical, at very low concentrations (0.5–20 ppb) on as-produced nanobiochar with average particle size of 60 nm was studied. The results showed that nanobiochar can remove up to 95% of CBZ (74 μg CBZ/g nanobiochar) after 3 h contact time. Adsorption of CBZ on nanobiochar followed Freundlich isotherm model (R2= 0.9822) and pseudo-second order kinetic model (R2= 0.9994). It was found that increasing pH from 3 to 8 can enhance the adsorption efficiency by 2.3 folds. Also, due to the presence of surfactant in wastewater, the addition of Tween 80 as a model surfactant was studied in the range of 0 to 1 (Tween 80 to CBZ molar ratio) and the results showed that adsorption efficiency can be enhanced by 57%. Thus, the nanobiochar obtained from pinewood residues can be a promising sorbent for micropollutants

Green and energy-efficient methods for the production of metallic nanoparticles

In the last decade, researchers paid great attention to the concept of “Green Chemistry”, which aims at development of efficient methods for the synthesis of nanoparticles (NPs) in terms of the least possible impact on human life and environment. Generally, several reagents including precursors, reducing agents, stabilizing agents and solvents are used for the production of NPs and in some cases, energy is needed to reach the optimum temperature for reduction. Therefore, to develop a green approach, researchers had the opportunity to investigate eco-friendly reagents and new energy transfer techniques. In order to substitute the harmful reagents with green ones, researchers worked on different types of saccharides, polyols, carboxylic acids, polyoxometalates and extracts of various plants that can play the role of reducers, stabilizers or solvents. Also, there are some reports on using ultraviolet (UV), gamma and microwave irradiation that are capable of reducing and provide uniform heating. According to the literature, it is possible to use green reagents and novel energy transfer techniques for production of NPs. However, these new synthesis routes should be optimized in terms of performance, cost, product quality (shape and size distribution) and scale-up capability. This paper presents a review on most of the employed green reagents and new energy transfer techniques for the production of metallic NPs

Development of adsorptive membranes by confinement of activated biochar into electrospun nanofibers

Adsorptive membranes have many applications in removal of contaminants, such as heavy metals and organic contaminants from water. Recently, increasing concentrations of pharmaceutically active compounds, especially antibiotics, such as chlortetracycline in water and wastewater sources has raised concerns about their potentially adverse impacts on environment and human health. In this study, a series of polyacrylonitrile (PAN)/activated biochar nanofibrous membranes (NFMs) with different loadings of biochar (0–2%, w/w) were fabricated using electrospinning. The morphology and structure of fabricated membranes was investigated by scanning electron microscopy, Fourier transform infrared and thermogravimetric analysis. The results showed that at 1.5% of biochar loading, the surface area reached the maximum value of 12.4 m2/g and beyond this loading value, agglomeration of particles inhibited fine interaction with nanofibrous matrix. Also, the adsorption tests using chlortetracycline showed that, under environmentally relevant concentrations, the fabricated adsorptive NFMs had a potential for removal of these types of emerging contaminants from water and wastewaters

Pine-wood derived nanobiochar for removal of carbamazepine from aqueous media: Adsorption behavior and influential parameters

In recent years, application of biochar for removal of pollutants from aqueous solutions has been of interest due to favorable physicochemical properties and availability of feedstock. However, adsorption behavior has been reported only for raw and micro biochar particles and taking advantage of biochar nanoparticles, which offer superior specific surface area, did not receive any attention. The objective of this study was to investigate the adsorption efficiency of produced nanobiochar from pinewood. For this purpose, removal of carbamazepine (CBZ), a globally prescribed pharmaceutical, at very low concentrations (0.5–20 ppb) on as-produced nanobiochar with average particle size of 60 nm was studied. The results showed that nanobiochar can remove up to 95% of CBZ (74 μg CBZ/g nanobiochar) after 3 h contact time. Adsorption of CBZ on nanobiochar followed Freundlich isotherm model (R2= 0.9822) and pseudo-second order kinetic model (R2= 0.9994). It was found that increasing pH from 3 to 8 can enhance the adsorption efficiency by 2.3 folds. Also, due to the presence of surfactant in wastewater, the addition of Tween 80 as a model surfactant was studied in the range of 0 to 1 (Tween 80 to CBZ molar ratio) and the results showed that adsorption efficiency can be enhanced by 57%. Thus, the nanobiochar obtained from pinewood residues can be a promising sorbent for micropollutants