Solution combustion is an exciting phenomenon, which involves propagation of self-sustained exothermic reactions along an aqueous or sol–gel media. This process allows for the synthesis of a variety of nanoscale materials, including oxides, metals, alloys, and sulfides. This Review focuses on the analysis of new approaches and results in the field of solution combustion synthesis (SCS) obtained during recent years. Thermodynamics and kinetics of reactive solutions used in different chemical routes are considered, and the role of process parameters is discussed, emphasizing the chemical mechanisms that are responsible for rapid self-sustained combustion reactions. The basic principles for controlling the composition, structure, and nanostructure of SCS products, and routes to regulate the size and morphology of the nanoscale materials are also reviewed. Recently developed systems that lead to the formation of novel materials and unique structures (e.g., thin films and two-dimensional crystals) with unusual...

Solution Combustion Synthesis of Nanoscale Materials

The efficient handling of wastewater pollutants is a must, since they are continuously defiling limited fresh water resources, seriously affecting the terrestrial, aquatic, and aerial flora and fauna. Our vision is to undertake an exhaustive examination of current research trends with a focus on nanomaterials (NMs) to considerably improve the performance of classical wastewater treatment technologies, e.g. adsorption, catalysis, separation, and disinfection. Additionally, NM-based sensor technologies are considered, since they have been significantly used for monitoring water contaminants. We also suggest future directions to inform investigators of potentially disruptive NM technologies that have to be investigated in more detail. The fate and environmental transformations of NMs, which need to be addressed before large-scale implementation of NMs for water purification, are also highlighted.

Recent advances in nanomaterials for water protection and monitoring.

Coupling of heterogeneous advanced oxidation processes and photocatalysis in efficient degradation of tetracycline hydrochloride by Fe-based MOFs: Synergistic effect and degradation pathway

Discharging dye contaminants into water is a major concern around the world. Among a variety of methods to treat dye-contaminated water, photocatalytic degradation has gained attention as a tool for treating the colored water. Herein, we review the recent advancements in photocatalysis for dye degradation in industrial effluents by categorizing photocatalyst materials into three generations. First generation photocatalysts are composed of single-component materials (e.g., TiO2, ZnO, and CdS), while second generation photocatalysts are composed of multiple components in a suspension (e.g., WO3/NiWO4, BiOI/ZnTiO3, and C3N4/Ag3VO4). Photocatalysts immobilized on solid substrates are regarded as third generation materials (e.g., FTO/WO3-ZnO, Steel/TiO2-WO3, and Glass/P-TiO2). Photocatalytic degradation mechanisms, factors affecting the dye degradation, and the lesser-debated uncertainties related to the photocatalysis are also discussed to offer better insights into environmental applications. Furthermore, quantum yields of different photocatalysts are calculated, and a performance evaluation method is proposed to compare photocatalyst systems for dye degradation. Finally, we discuss the present limitations of photocatalytic dye degradation for field applications and the future of the technology.

https://link.springer.com/content/pdf/10.1007/s12274-019-2287-0.pdf

Photocatalysts for degradation of dyes in industrial effluents: Opportunities and challenges

An update on synthetic dyes adsorption onto clay based minerals: A state-of-art review

Recent advances in heavy metal removal by chitosan based adsorbents.

A novel cocatalyst free Z-schematic photocatalytic system of Ag/LaVO4/BiVO4 was successfully fabricated for clean hydrogen fuel evolution. The spherical nanoparticles of LaVO4 were prepared in solution combustion method for the first time using glycine as a fuel, BiVO4 was deposited onto LaVO4 through a deposition–precipitation method and Ag was loaded on the surface of LaVO4/BiVO4 composite by photoreduction method. The composites were characterized by XRD, UV–vis DRS, SEM, TEM, EDS and XPS to ensure the successful integration of Ag or (and) BiVO4 with LaVO4. A series of photocatalytic H2 evolution experiments, employing Na2S and Na2SO3 as hole scavengers, showed that the Ag/LaVO4/BiVO4 composite exhibited a superior photocatalytic performance compared to single LaVO4 or BiVO4. Although BiVO4 cannot be used for H2 evolution, it can significantly enhance the H2 evolution performance of LaVO4 through a Z-scheme mechanism with Ag as an electron mediator. Moreover, investigations on photoluminescence and fluorescence lifetime measurements demonstrated the greater separation efficacy of photoinduced excitons in the Z-scheme Ag/LaVO4/BiVO4 photocatalytic system. This newly constructed LaVO4 based Z-scheme system exhibits promising photocatalytic H2 evolution activity with significant longevity and will be useful for potential applications in energy driven technologies.

Cocatalyst free Z-schematic enhanced H-2 evolution over LaVO4/BiVO4 composite photocatalyst using Ag as an electron mediator

Several reports illustrate the wide range applicability of graphene oxide (GO) in water remediation. However, a few layers of graphene oxide tend to aggregate under saline conditions thereby reducing its activity. The effects of aggregation can be minimized by having a random arrangement of GO layers in a three dimensional architecture. The current study emphasizes the potential benefits of highly porous, ultralight graphene oxide foams in environmental applications. These foams were prepared by a facile and cost effective lyophilization technique. The 3D architecture allowed the direct use of these foams in the removal of aqueous pollutants without any pretreatment such as ultrasonication. Due to its macroporous nature, the foams exhibited excellent adsorption abilities towards carcinogenic dyes such as rhodamine B (RB), malachite green (MG) and acriflavine (AF) with respective sorption capacities of 446, 321 and 228 mg g(-1) of foam. These foams were also further investigated for antibacterial activities against E. coli bacteria in aqueous and nutrient growth media. The random arrangement of GO layers in the porous foam architecture allowed it to exhibit excellent antibacterial activity even under physiological conditions by following the classical wrapping-perturbation mechanism. These results demonstrate the vast scope of GO foam in water remediation for both dye removal and antibacterial activity.

/pdf/macroporous-three-dimensional-graphene-oxide-foams-for-dye-4l8oshmt7e.pdf

Macroporous three-dimensional graphene oxide foams for dye adsorption and antibacterial applications

Developmental trends in CO2 methanation using various catalysts

This review summarizes the progress made, in the field of low-cost biosorption of heavy metal ions, over the past few years. It gives a comprehensive summary of the synthesis, performance, modification and regeneration of biosorbent. The review also focused upon optimum operating parameters, isotherm and kinetic studies. Moreover, from an industrial application point of view, fixed-bed column studies have been discussed in this paper. Methods like chemical pretreatment, grafting, immobilization, etc., which improve the biosorbent properties, have been summarized. Operating parameters that affect the biosorption process such as temperature, pH, contact time, agitation speed, etc. have been studied to understand the relationship between factors and removal efficiency. For most of the studies, biosorption process was found to be endothermic, with room temperature being optimum for the process. Grafting was observed to enhance the adsorption capacity of biosorbent enormously. Biosorption process generally followed Langmuir or Freundlich isotherm, whereas mostly the best fit for kinetic model was pseudo-second-order. Desorption process was mostly carried out via acidic eluent. The performance of biosorbents was observed to be appreciable when they were packed into fixed-bed columns.

Satyapaul A. Singh

Papers

Recent advances in heavy metal removal by chitosan based adsorbents.

Cocatalyst free Z-schematic enhanced H-2 evolution over LaVO4/BiVO4 composite photocatalyst using Ag as an electron mediator

Macroporous three-dimensional graphene oxide foams for dye adsorption and antibacterial applications

Developmental trends in CO2 methanation using various catalysts

A review on valorization of biomass in heavy metal removal from wastewater