Facile synthesis of Cu NPs@Fe3O4-lignosulfonate: Study of catalytic and antibacterial/antioxidant activities.

Environmental pollution is one of the important concerns for human health. There are different types of pollutants and techniques to eliminate them from the environment. We hereby report an efficient method for the remediation of environmental contaminants through the catalytic reduction of the selected pollutants. A green method has been developed for the immobilization of copper nanoparticles on magnetic lignosulfonate (Cu NPs@Fe3O4-LS) using the aqueous extract of Filago arvensis L. as a non-toxic reducing and stabilizing agent. The characterization of the prepared Cu NPs@Fe3O4-LS was achieved by vibrating sample magnetometer (VSM), Fourier-transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), high resolution TEM (HRTEM), X-ray diffraction (XRD), scanning TEM (STEM), thermogravimetry-differential thermal analysis (TG/DTA), fast Fourier transform (FFT), energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron (XPS) analyses. The synthesized Cu NPs@Fe3O4-LS was applied as a magnetic and green catalyst in the reduction of congo red (CR), 4-nitrophenol (4-NP), and methylene blue (MB). The progress of the reduction reactions was monitored by UV-Vis spectroscopy. Finally, the biological properties of Cu NPs@Fe3O4-LS were investigated. The prepared catalyst demonstrated excellent catalytic efficiency in the reduction of CR, 4-NP, and MB in the presence of sodium borohydride (NaBH4) as the reducing agent. The appropriate magnetism of Cu NPs@Fe3O4-LS made its recovery very simple. The advantages of this process include a simple reaction set-up, high and catalytic antibacterial/antioxidant activities, short reaction time, environmentally friendliness, high stability, and easy separation of the catalyst. In addition, the prepared Cu NPs@Fe3O4-LS could be reused for four cycles with no significant decline in performance.

Progresses in chitin, chitosan, starch, cellulose, pectin, alginate, gelatin and gum based (nano)catalysts for the Heck coupling reactions: A review.

Heck cross-coupling reaction (HCR) is one of the few transition metal catalyzed CC bond-forming reactions, which has been considered as the most effective, direct, and atom economical synthetic method using various catalytic systems. Heck reaction is widely employed in numerous syntheses including preparation of pharmaceutical and biologically active compounds, agrochemicals, natural products, fine chemicals, etc. Commonly, Pd-based catalysts have been used in HCR. In recent decades, the application of biopolymers as natural and effective supports has received attention due to their being cost effective, abundance, and non-toxicity. In fact, recent studies demonstrated that biopolymer-based catalysts had high sorption capacities, chelating activities, versatility, and stability, which make them potentially applicable as green materials (supports) in HCR. These catalytic systems present high stability and recyclability after several cycles of reaction. This review aims at providing an overview of the current progresses made towards the application of various polysaccharide and gelatin-supported metal catalysts in HCR in recent years. Natural polymers such as starch, gum, pectin, chitin, chitosan, cellulose, alginate and gelatin have been used as natural supports for metal-based catalysts in HCR. Diverse aspects of the reactions, different methods of preparation and application of polysaccharide and gelatin-based catalysts and their reusability have been reviewed.

Polysaccharide-based (nano)materials for Cr(VI) removal.

Chromium is a potentially poisonous and carcinogenic species, which originates from human activities and various industries such as leather, steel, iron, and electroplating industries. Chromium is present in various oxidation states, among which hexavalent chromium (Cr(VI)) is highly toxic as a natural contaminant. Therefore, chromium, particularly Cr(VI), must be eliminated from the environment, soil, and water to overcome significant problems due to its accumulation in the environment. There are different approaches such as adsorption, ion exchange, photocatalytic reduction, etc. for removing Cr(VI) from the environment. By converting Cr(VI) to Cr(III), its toxicity is reduced. Cr(III) is essential for the human diet, even in small amounts. Today, biopolymers such as alginate, cellulose, gum, pectin, starch, chitin, and chitosan have received much attention for the removal of environmental pollutants. Biopolymers, particularly polysaccharides, are very useful compounds due to their OH and NH2 functional groups and some advantages such as biodegradability, biocompatibility, and accessibility. Therefore, they can be widely applied in catalytic applications and as efficient adsorbents for the removal of toxic compounds from the environment. This review briefly investigates the application of polysaccharide-based (nano)materials for efficient Cr(VI) removal from the environment using adsorption/reduction, photocatalytic, and chemical reduction mechanisms.

Biopolymer-derived (nano)catalysts for hydrogen evolution via hydrolysis of hydrides and electrochemical and photocatalytic techniques: A review.

Over the course of a few decades, the concern of environmental damages of fossil fuels, an increase in CO2 emission and a decrease of hydrogen have been growing more and more. Accordingly, hydrogen production is a crucial issue nowadays. Different polymers are applied to attain the purpose. Among all polymers, biodegradables polymers are the best choices to develop the main aim. Polysaccharides and proteins are biodegradable polymers with unique places and advantages with regards to their ecofriendly properties. There are different techniques to apply and achieve the foremost purpose. It is worthwhile to mention that green and facile methods are always attracting attention in different aspects and fields. The three non-polluting and economical techniques, that is, electrochemical hydrogen evolution reaction (HER), photocatalytic technique, and hydrolysis of hydrides, are reviewed in this paper. This review helps researchers, who are environment supporters, to evaluate and choose the most ecological biopolymers and processes in their work.

Valorisation of Fruits, their Juices and Residues into Valuable (Nano)materials for Applications in Chemical Catalysis and Environment.

One of the most abundant wastes from all around the world is nutrient resources. Among them, fruits, their extracts, and residues comprise a major portion, which contain many valuable components that get lost during disposal or become burden on the shrinking landfills. These concerns are addressed by seeking sustainable processing methods that would have a minimal environmental impact. The crops contain renewable chemicals which are useful for catalysis, wastewater treatment, or preparation of nanomaterials; there has been an upsurge for the industrial applications of (nano)materials as their environmental and catalytic appliances is a fascinating subject to design cheaper and safer catalytic systems. Due to the excellent chemical properties of the fruit extracts, they have garnered attention as cost-effective catalysts and support materials. This review focuses on the preparation of (nano)materials and their catalytic and environmental applications and highlights the potential appliances and industrial benefits derived from these low-cost renewable and sustainable greener sources thus essentially converting waste into wealth.

Recent progresses in the application of cellulose, starch, alginate, gum, pectin, chitin and chitosan based (nano)catalysts in sustainable and selective oxidation reactions: A review.

Exploitation of polymers as effective starting materials to produce various valuable catalysts is attracting the attention of industrial and academic researchers. Moreover, among all polymers, natural polysaccharides such as cellulose, starch, alginate, gum, pectin, chitin and chitosan have drawn the most attention in recent years due to their unique structural features and important potential applications. A lot of studies have been performed on the synthesis of polysaccharide based (nano)catalysts and their application in chemical transformations. The present review provides recent developments on polysaccharides as green resources for the production of (nano)catalysts. Herein, the application of polysaccharide based (nano)catalysts derived from different organisms, plants or animals in oxidative transformations has been reviewed. These compounds can be used as economical and recyclable catalytic materials for various oxidation reactions including oxidation of alcohols, phenols, sulfides etc. The challenges in the application of polysaccharide based (nano)catalysts have also been discussed.