Current Analytical Chemistry - Volume 17, Issue 2, 2021

Background: Nano-photocatalysis through semiconductor-based materials has become an emerging and eye-catching approach for detoxification of hazardous heavy metals in the aqueous environment. Methods: In this article, photocatalysis, being a green technique along with several other detoxification technologies for toxic heavy metals, has been reviewed. Furthermore, the adverse effects of heavy metals on human health, agricultural lands, environment, and aquatic systems were investigated. Toxic heavy-metals contribute to numerous environmental issues based on their toxicity. Result: Various types of photocatalysts have been discussed in recent literature for the detoxification of heavy metals. The recycling of photocatalysts may be anticipated as a worthy method for wastewater treatment which is also discussed with recent examples. Conclusion: Moreover, it concludes with efficiency, challenges and new future perspectives for heavy metal detoxification using photocatalysis.

Background: The aim of the current study is to understand the application of Nanotechnology in the field of water and waste water treatment processes due to the increasing scarcity of water with the passage of time. The knowledge about the effect of various photo catalysts on the treatment of waste water is also compiled here. Introduction: In recent years, many researches have been working on the projects for the removal of organic and inorganic pollutants from water using photo catalysts, which provide more efficient, economical and as well as pollution free processes to some extent. Nanomaterials are found in large research categories and are used in a variety of applications. Methods: Photo catalysis using Iron, Zinc, Silver, Metal oxides, SnO2, Carbon Nano-tubes, Nano composites and Membranes are focused in this paper. Result: Discussion regarding various parameters as well as future aspects of nanoparticles on waste water treatment are highlighted. Impacts of nanoparticles on health are also incorporated here. Conclusion: Considering the current speed of development and revolution in tech, nano materials for this type of applications seems very promising.

Background: The present scenario of rapid industrial and population growth has become a serious threat to environmental and energy concerns. Extremely noxious pollutants like dyes, heavy metal ions, phenols, antibiotics and pesticides in water are the reason behind deprived water quality leading to inadequate access to clean water. Photocatalysis is a prominent strategy for environmental remediation as photocatalytic materials not only convert solar energy into usable energy expedient but also shows potential application in pollutant mitigation. An effectual photocatalytic system must possess wide visible absorption range, high physio-chemical firmness, and effective space-charge separation along with strong redox ability. Polymeric graphitic carbon nitride a metal-free semiconductor photocatalyst has outshined as a robust photocatalyst for various photocatalytic applications. Methods: Hybridizing polymeric g-C3N4 with other semiconductor photocatalysts has not only conquer the limitations related to pristine g-C3N4 but also displayed improved photoactivity. Different photocatalytic systems involving g-C3N4 coupled metal-oxides, metal-free systems and complex heterojunction systems are reviewed. Moreover, an all-embracing study based on g-C3N4 based nanocatalysts is explored via heterojunction formation taking g-C3N4 as one component. Results: Photocatalytic experiments involving photodegradation of pollutants, revealed the significance of metal-free g-C3N4 in the heterojunction system which remarkably boost the photoactivity through effective separation and migration of photocarriers. Moreover, from recyclability experiments, exceptional photostability of g-C3N4 based photocatalysts was observed. Photocatalytic pollutant degradation is a complex phenomenon which requires significant experimental techniques to support the mechanism. With the help of photoelectrochemical analysis, the mechanisms behind photodegradation can be evaluated and explored. Conclusion: Metal-free polymeric g-C3N4 is a potential semiconductor photocatalyst which can be optimally utilized for wastewater treatment. Coupling g-C3N4 with another semiconductor material with an appropriate band edge can effectively enhance the photocatalytic efficacy. Herein, g-C3N4 derived metal-oxide, metal-free and complex heterojunction systems are explored and their photocatalytic efficiency is evaluated for pollutant degradation. However, more effective research efforts are needed for large-scale applications of g-C3N4 based photocatalysts.

Background: Industrialization plays an important role in the growth of a nation. But it is also one of the causes of the deteriorating condition of our ecosystem. The pollution, be it aquatic, terrestrial, or air-borne, has affected our environment drastically, and industrial and domestic wastewater plays a major role in it. As the Earth transforms into urban sprawl, industries flourish, pollution increases and the natural resources deplete. Recently nano-engineering based technologies have been explored for the purpose of wastewater treatment, which helps in the detection and remediation of the pollutants present in wastewater. Various nano-material based technologies deployed in wastewater treatment are discussed in this article. Methods: A thorough survey of the literature was effectuated, and the study was focused mainly on the different types of nanomaterials applied for the purpose of wastewater management and the diverse treatment methods related to them. Literature was also studied to confirm the functionalization of nanomaterials as pollution sensors. Results: There are four main kinds of nano-materials employed for the purpose of wastewater remediation, i.e. metallic nanomaterials, carbon-based nanomaterials, nanocomposites, and dendrimers. The treatment technologies utilizing these materials include nanofiltration, nanoadsorption, nano-photocatalysis, and disinfection. Conclusion: Nanomaterials are quite efficient in removing pollutants from different kinds of wastewater. But drawbacks such as expenditure and effect of the materials in the environment make it difficult for real-time utilization. Since the nano-scaled elements behave differently than their standard-sized counterparts, the consequence of these materials in the human life cycle is unknown. This knowledge gap should be filled so that these materials can be adopted worldwide.

Background: TiO2 has been proved as an effective photocatalyst for air purification that can produce hydroxyl radicals and superoxide radicals by the illumination of light with suitable energy. These radicals are extremely powerful agents in the degradation of gaseous pollutants. A major drawback of TiO2 is its wide energy band gaps of 3.2 and 3.0 eV for anatase and rutile phases, respectively, which are mostly equivalent to the photon wavelength absorption in the range of UV region. Methods: The modification strategies of TiO2 as photocatalysts for air treatment, such as metal doping, non-metal doping, co-doping, and coupling with other semiconductors are discussed. The photocatalytic performance of the pristine TiO2 and modified TiO2 for degradations of gaseous pollutants are reviewed. Results: Various parameters can affect the photocatalytic removal efficiencies of gaseous pollutants, such as the initial concentration of pollutants, relative humidity, light source, irradiation time, and the preparation of TiO2 photocatalysts. The optimal content of dopants and the combinedsemiconductors should be considered for preventing the recombination of electrons and holes during irradiation. Conclusion: Doping with heteroatoms and coupling could enhance the photocatalytic activity of TiO2. The modified photocatalysts could be applied for photocatalytic degradation of gaseous pollutants, including volatile organic compounds (VOCs), nitrogen oxides (NOx), and sulfur oxides (SOx).

Background: Depletion and contamination of environmental resources such as water, air and soil caused by human activities is an increasingly important challenge faced around the world. The consequences of environmental pollution are felt acutely by all living beings, both on a short and long-term basis, thereby making methods of remediation of environmental pollution an urgent requirement. Objectives: The objective of this review is to dissect the complications caused by environmental degradation, highlight advancements in the field of nanotechnology and to scrutinize its applications in environmental remediation. Furthermore, the review aims to concisely explain the merits and drawbacks of nanotechnology compared to existing methods. Conclusion: The current and potential applications of nanomaterials and nanocomposites in the prevention, control and reduction of air, water and soil pollution and the mechanisms involved have been elucidated, with their various merits and demerits. The applications of nanotechnology in the fields of carbon capture and agriculture have also been discussed in this review.

Background: Nanoparticles have become an important part of many modern scientific technologies. Also, many naturally occurring nanoparticles play an important role in various natural and synthetic processes. The detection of these nanoparticles is expensive and challenging. This review paper explains in detail about various sensor-based methods used for the detection of nanoparticles. Methodology: Sensor-based analytical techniques are more accurate than other techniques. Nanoparticles may occur in air, water, solid surface and human or other living organisms’ physical environments. The detection methods include spectroscopic techniques, electrochemical methods, microcavities and microlasers based detection, optical techniques and many other highly sensitive methods. All these methods and their principles are explained in this study. The importance and the ill effects of the nanoparticles are explained in this article. Further, the detection of a particular single nanoparticle is also discussed. Conclusion: The detailed comparative analysis of these methods has shown that sensor-based methods are highly efficient for the detection of nanoparticles. Further research in this field may introduce many cost-effective and high efficient detection techniques that would revolutionize the medical and other application fields.

Aim: The review paper aims to explore the effect of plant extracts on nanomaterial adsorbent for the removal of toxic metals present in industrial effluents. Background: Water plays a major role in the sustainability of human life and its existence. Rapid industrialization and urbanization lead to an increase in the pollution and accumulation of hazardous substances which causes the degradation of the aquatic ecosystem. Heavy metals are considered to be a major threat to the environment. Among various metals, the International Union of Pure applied chemistry (IUPAC) has characterized heavy metals based on their intensity of toxicity and hazardous effects. Nanoparticles, due to their unique properties of particle size, exist in the range between 1- 100nm, which represents the possibility to introduce modified chemical groups on their surface functioning as capping agents. Nanoparticles with the increased surface area have specified functional groups which induce the capability of the catalytic reduction reaction and their optical characteristics impact the industrial, agricultural and environmental sectors. Objective: Magnetic nanoparticles incorporated with the enzymes and metallic sites have been widely used in both the synthesis of bio valuable products as well as in the degradation of many hazardous substances like dyes, phenolic compounds, etc. Also, they are used in the removal of metal ions present in wastewater. Methods: Superparamagnetic support nanomaterials (SPIONs) are prepared using the compounds of Fe, Cu, Ni, Mn and Mg for the distinct and unique characteristics of reusability. These metallic nanomaterials are coated with distinct materials like mesoporous and amorphous silica, polyvinyl alcohol and pyrrolidine, polyethylene glycol, polystyrene, chitosan, dextran, starch, gelatin, polystyrene, polyacrylic acid, and polymethyl methacrylate to enhance the stability of the nanomaterials. Results: In comparison to the different nanomaterials, metal oxide NPs possess increased stability, magnetic inertness, optical and electrical properties. Nanomaterials that are used in the medical applications are also used as the adsorbents to remove heavy metals from the industrial wastewater. The presence of polyphenolic compounds and flavonoids makes the plant extracts effective antimicrobial agents that impact pathogens. Moreover, these plant extracts, coupled with other nanomaterials, play a significant role in the removal of toxic pollutants from the environment. Conclusion: Polyphenolic compounds present in plant extract function as natural reducing agents; hence, integrating plant extract with metal/metal oxide nanoparticles proves to be efficient in comparison with the catalysts synthesized by using other chemical methods. These surface modified nanocatalysts tend to possess enhanced stability and specific reactivity in the system and are used in the elimination of organic and inorganic pollutants in the industrial wastewater.

Background: A Book Review on Nanotechnology: Food and environmental paradigm, is edited by Ram Prasad, Vivek Kumar and Manoj Kumar, Springer Nature Singapore, 2017, 340 Pages, ISBN 978-981-10-4677-3, DOI 10.1007/978-981-10-4678-0. This book aims to study the effects of nanomaterials on the environment and food and emphasizes the advantages gained through the application of nanotechnology in the broader area of food and environment. Methods: Food web is the core of ecological balance for a sustainable environment. The presence of undesired nanomaterials in the food chain or web causes unwanted toxicity to the plants and animals of the food chain. In majority cases, the presence of nanomaterials in food web causes toxicity, impairment of organs and/ or heavy loss to one or more population. Thus, it is highly required to limit the release of nanomaterials in the environment. It is also necessary to set the norms for the production, use and discard of nanomaterials. Results: This book consists of 16 chapters, which all together address a large dimension on the positive and negative effects of nanomaterials and the application of nanotechnology in various fields of food, agriculture and pharmaceutical industry. It is also important to evaluate the cost before implementing any new technology. It is not necessary that good research which performed well in the laboratory must also do well on the industrial scale. A major barrier which can be encountered is actually the cost, which must be less to be implemented. Conclusion: Application of desired nanomaterials is advantageous for many industries and quality life. Nano-fertilizers and nanopesticides enhance crop production. Nanotechnology plays a significant role in the food industry, from production, processing to packaging. Diagnostics is a field where nanotechnology is applied too much. New diagnostic methods using nanosensors, nanochips and nanocatalysts are evolving day by day.

Background: A Book Review on Layered Materials for Energy Storage and Conversion Edited by Dongsheng Geng, Yuan Cheng and Gang Zhang, The Royal Society of Chemistry, 2019, 315 Pages, Print ISBN 978-1-78801-426-7, Print ISSN 2046-0066, DOI: 10.1039/9781788016193- FP001. In the earlier decade, the extensive research hot-spot in two-dimensional (2D) layered materials, especially graphene, metal-organic frameworks (MOFs) and transition metal dichalcogenides (TMDCs) benefited from their exceptional chemical, physical, optical, mechanical and electronic properties. This book provides an up-to-date comprehensive overview of synthesis approaches and functionalization routes of graphene and TMDCs and functional properties of intercalated layered materials and its energy applications. Methods: The chemistry of layered two-dimensional materials towards its allied applications in electrocatalysis, lithium-ion batteries, sodium-ion batteries, thermoelectric materials, watersplitting and performance of photovoltaic devices are the core issues of energy storage and conversion and they are well addressed in this book. Results: This book consists of nine chapters. Altogether they discuss layered materials, energy storage, substitute energy storage and conversion specifically as it is not possible to discuss each and everything in detail. The chapters are written well by reputed experts around the globe. That makes this book an outstandingly important and reliable source of information. It is valuable for a book to provide updated information, review the work done to date, do proper analysis, compare the pros and cons of comparable existing technologies and guide the readers to the research gaps and places where improvement is required. Conclusion: This book is an essential reference guide for students, researchers, engineers and professionals in the advanced materials community and energy-related sectors such as photovoltaics, water-splitting, supercapacitor, and batteries, etc.

Objective: Herein, we reported a simple and effective approach to synthesis of pure and Ni²⁺ doped TiO2 nanorods by a photon-induced method (PIM) followed by calcination at 850 ºC in air atmosphere. Methods: Basically, the PIM was used to tuning the properties of as-prepared TiO2 photocatalyst. These obtained samples were further characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM) and UV-visible diffuse reflectance spectroscopy (UV-vis DRS) analysis. XRD results reveals that the both pure TiO2 and Ni doped TiO2 nanorods has anatase phase up to 850°C. Results: The HR-TEM analysis indicates that doping Ni is favourable to the formation of rod-like TiO2 sample. Also, the observed photocatalytic results demonstrates that the Ni doped TiO2 can be achieved a complete degradation of methylene blue (MB) within 30 min under direct sunlight irradiation as compared to pure TiO2. Conclusion: Therefore, this work revealing the doped Ni has a good potential to modification of TiO2 with an excellent photocatalytic activity for water treatment applications.