Nanomaterials with Tailored Magnetic Properties as Adsorbents of Organic Pollutants from Wastewaters

Water quality has become one of the most critical issue of concern worldwide. The main challenge of the scientific community is to develop innovative and sustainable water treatment technologies with high efficiencies and low production costs. In recent years, the use of nanomaterials with magnetic properties used as adsorbents in the water decontamination process has received considerable attention since they can be easily separated and reused. This review focuses on the state-of-art of magnetic core-shell nanoparticles and nanocomposites developed for the adsorption of organic pollutants from water. Special attention is paid to magnetic nanoadsorbents based on silica, clay composites, carbonaceous materials, polymers and wastes. Furthermore, we compare different synthesis approaches and adsorption performance of every nanomaterials. The data gathered in this review will provide information for the further development of new efficient water treatment technologies.Fil: Peralta, Marcos Emanuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas. Universidad Nacional del Comahue. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas; ArgentinaFil: Ocampo, Santiago. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas. Universidad Nacional del Comahue. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas; ArgentinaFil: Funes, Israel German Aristoteles. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Centro de Investigaciones en Toxicología Ambiental y Agrobiotecnología del Comahue. Universidad Nacional del Comahue. Facultad de Ciencias Agrarias. Centro de Investigaciones en Toxicología Ambiental y Agrobiotecnología del Comahue; ArgentinaFil: Onaga Medina, Florencia Micaela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Centro de Investigaciones en Toxicología Ambiental y Agrobiotecnología del Comahue. Universidad Nacional del Comahue. Facultad de Ciencias Agrarias. Centro de Investigaciones en Toxicología Ambiental y Agrobiotecnología del Comahue; ArgentinaFil: Parolo, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Centro de Investigaciones en Toxicología Ambiental y Agrobiotecnología del Comahue. Universidad Nacional del Comahue. Facultad de Ciencias Agrarias. Centro de Investigaciones en Toxicología Ambiental y Agrobiotecnología del Comahue; ArgentinaFil: Carlos, Luciano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas. Universidad Nacional del Comahue. Instituto de Investigación y Desarrollo en Ingeniería de Procesos, Biotecnología y Energías Alternativas; Argentin

Supercapacitors for the Next Generation

Supercapacitors are presently applied in various devices and have the potential to be used in many fields in the future. For example, the use of supercapacitors is currently limited not only to automobiles, buses, and trucks, which have been electrified recently, but also to railways and aircraft. We believe that these devices are the most suitable physical batteries for absorbing regenerative energy produced during motor regeneration; thus, further research and development in this direction is expected in the future

Recent Progresses in Electrocatalysts for Water Electrolysis

Abstract The study of hydrogen evolution reaction and oxygen evolution reaction electrocatalysts for water electrolysis is a developing field in which noble metal-based materials are commonly used. However, the associated high cost and low abundance of noble metals limit their practical application. Non-noble metal catalysts, aside from being inexpensive, highly abundant and environmental friendly, can possess high electrical conductivity, good structural tunability and comparable electrocatalytic performances to state-of-the-art noble metals, particularly in alkaline media, making them desirable candidates to reduce or replace noble metals as promising electrocatalysts for water electrolysis. This article will review and provide an overview of the fundamental knowledge related to water electrolysis with a focus on the development and progress of non-noble metal-based electrocatalysts in alkaline, polymer exchange membrane and solid oxide electrolysis. A critical analysis of the various catalysts currently available is also provided with discussions on current challenges and future perspectives. In addition, to facilitate future research and development, several possible research directions to overcome these challenges are provided in this article. Graphical Abstrac

Spherical carbons as model supports for Fe, Co and Fe-Co Fischer-Tropsch catalysts

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 2016.The production of liquid transportation fuels and chemicals by the Fischer-Tropsch (FT) synthesis continues to garner attention due to its economic and environmental benefits. This interest is also compounded by the flexibility to use readily available materials as feedstocks for synthesis gas production, with coal, natural gas, biomass and recently shale gas being used. Although this process is over 90 years old, challenges still remain. In this study, we have attempted to understand several FT synthesis challenges by exploring the use of carbon spheres as a model support for Co, Fe and Fe-Co FT catalysts. Thus the synthesis, characterization and application of carbon spheres with distinct architectures are described. The synthesis of solid carbon spheres using a sucrose precursor yielded materials that were mono-dispersed (600 nm) and adopted a necklace-like accreted conformation. Upon further investigation, it was demonstrated that annealing is useful for tuning the properties of the as-prepared materials to have high surface areas (> 500 m2/g), good thermal stability (>660 °C) and a mesoporous (> 2 nm) pore structure. Deposition of a Fe-Co bimetallic catalyst yielded oxides of the monometallic species with relatively small crystallites, with sizes in the range 7.9 – 14.4 nm. Reduction of the bimetallic samples was monitored by using in situ PXRD and TPR techniques, which revealed that a Co-Fe type-alloy is one of the phases formed on Co-rich samples at T > 450 °C. Interestingly, high relative abundances of this alloy did not correlate with high C5+ selectivities in Fischer-Tropsch synthesis; instead Co-rich/Fe-poor catalysts gave the best selectivity. The effect of the support morphology in heterogeneous catalysis was investigated by using high surface area solid and hollow carbon spheres (>560 m2/g) prepared from a resorcinol-formaldehyde precursor as support material. Loading the Co and Fe precursors on these two supports was shown by TEM and PXRD to result in smaller and well dispersed metal particles on the hollow support material. This corresponded with high activities and C5+ selectivities for the Co and Fe catalysts supported on the hollow carbon spheres. TEM studies revealed that the Co and Fe particles tended to sinter significantly when dispersed on a material with a solid architecture. iv Post-synthesis N-doping using a melamine precursor was shown by XPS to incorporate high quantities of nitrogen (up to 13%) on to the surface of the 30 nm thick shells of the hollow carbon spheres. On further investigation, N-doping by this method was shown to have minimal effects on the thermal stability and crystallinity of the materials. The N-doped HCSs were shown to be good anchors of Co particles as displayed by the good dispersion, activity and minimal sintering tendency of catalysts supported on N-doped HCSs. Studies conducted herein have demonstrated the versatility of carbon spheres as a model support, and how their properties can be tailored to suit the desired specifications by simply adjusting the synthesis parameters. We have also highlighted how the chemical inertness of these materials allows for studies on metal-metal interactions at elevated temperatures for bimetallic catalyst systems. The monodisperse, morphology-tunable aspects of carbon spheres were particularly useful in modelling the effect of the support morphology in Fischer-Tropsch synthesis. It is believed that the versatility of CSs demonstrated in this study can also be exploited in other heterogeneous catalytic systems.LG201

Recent advances in graphene-based materials for fuel cell applications

The unique chemical and physical properties of graphene and its derivatives (graphene oxide, heteroatom-doped graphene, and functionalized graphene) have stimulated tremendous efforts and made significant progress in fuel cell applications. This review focuses on the latest advances in the use of graphene-based materials in electrodes, electrolytes, and bipolar plates for fuel cells. The understanding of structure-activity relationships of metal-free heteroatom-doped graphene and graphene-supported catalysts was highlighted. The performances and advantages of graphene-based materials in membranes and bipolar plates were summarized. We also outlined the challenges and perspectives in using graphene-based materials for fuel cell applications

Electrospun nanofibers for efficient adsorption of heavy metals from water and wastewater

Heavy metals (HMs) are persistent and toxic environmental pollutants that pose critical risks toward human health and environmental safety. Their efficient elimination from water and wastewater is essential to protect public health, ensure environmental safety, and enhance sustainability. In the recent decade, nanomaterials have been developed extensively for rapid and effective removal of HMs from water and wastewater and to address the certain economical and operational challenges associated with conventional treatment practices, including chemical precipitation, ion exchange, adsorption, and membrane separation. However, the complicated and expensive manufacturing process of nanoparticles and nanotubes, their reduced adsorption capacity due to the aggregation, and challenging recovery from aqueous solutions limited their widespread applications for HM removal practices. Thus, the nanofibers have emerged as promising adsorbents due to their flexible and facile production process, large surface area, and simple recovery. A growing number of chemical modification methods have been devised to promote the nanofibers\u27 adsorption capacity and stability within the aqueous systems. This paper briefly discusses the challenges regarding the effective and economical application of conventional treatment practices for HM removal. It also identifies the practical challenges for widespread applications of nanomaterials such as nanoparticles and nanotubes as HMs adsorbents. This paper focuses on nanofibers as promising HMs adsorbents and reviews the most recent advances in terms of chemical grafting of nanofibers, using the polymers blend, and producing the composite nanofibers to create highly effective and stable HMs adsorbent materials. Furthermore, the parameters that influence the HM removal by electrospun nanofibers and the reusability of adsorbent nanofibers were discussed. Future research needs to address the gap between laboratory investigations and commercial applications of adsorbent nanofibers for water and wastewater treatment practices are also presented

Green Aspects in Molecularly Imprinted Polymers by Biomass Waste Utilization

Molecular Imprinting Polymer (MIP) technology is a technique to design artificial receptors with a predetermined selectivity and specificity for a given analyte, which can be used as ideal materials in various application fields. In the last decades, MIP technology has gained much attention from the scientific world as summarized in several reviews with this topic. Furthermore, green synthesis in chemistry is nowadays one of the essential aspects to be taken into consideration in the development of novel products. In accordance with this feature, the MIP community more recently devoted considerable research and development efforts on eco-friendly processes. Among other materials, biomass waste, which is a big environmental problem because most of it is discarded, can represent a potential sustainable alternative source in green synthesis, which can be addressed to the production of high-value carbon-based materials with different applications. This review aims to focus and explore in detail the recent progress in the use of biomass waste for imprinted polymers preparation. Specifically, different types of biomass waste in MIP preparation will be exploited: chitosan, cellulose, activated carbon, carbon dots, cyclodextrins, and waste extracts, describing the approaches used in the synthesis of MIPs combined with biomass waste derivatives

Potential Development of N-Doped Carbon Dots and Metal-Oxide Carbon Dot Composites for Chemical and Biosensing

Funding Information: The authors are would like to thank the Department of Chemistry, Government VYT PG Autonomous College Durg, Chhattisgarh, sponsored by DST-FIST (New Delhi), India and the Fundação para a Ciência e a Tecnologia (FCT), Portugal, for the Scientific Employment Stimulus-Institutional Call (CEEC-INST/00102/2018) and the Associate Laboratory for Green Chemistry-LAQV, financed by national funds from FCT/MCTES (UIDB/50006/2020 and UIDP/5006/2020). Publisher Copyright: © 2022 by the authors.Among carbon-based nanomaterials, carbon dots (CDs) have received a surge of interest in recent years due to their attractive features such as tunable photoluminescence, cost effectiveness, nontoxic renewable resources, quick and direct reactions, chemical and superior water solubility, good cell-membrane permeability, and simple operation. CDs and their composites have a large potential for sensing contaminants present in physical systems such as water resources as well as biological systems. Tuning the properties of CDs is a very important subject. This review discusses in detail heteroatom doping (N-doped CDs, N-CDs) and the formation of metal-based CD nanocomposites using a combination of matrices, such as metals and metal oxides. The properties of N-CDs and metal-based CDs nanocomposites, their syntheses, and applications in both chemical sensing and biosensing are reviewed.publishersversionpublishe

Carbon-Based Material for Environmental Protection and Remediation

Carbon-Based Material for Environmental Protection and Remediation presents an overview of carbon-based technologies and processes, and examines their usefulness and efficiency for environmental preservation and remediation. Chapters cover topics ranging from pollutants removal to new processes in materials science. Written for interested readers with strong scientific and technological backgrounds, this book will appeal to scientific advisors at private companies, academics, and graduate students