Current Analytical Chemistry

Volume III of the thematic issue has 3 review papers and 6 research papers. Currently, pollution and scarcity of freshwater threaten human health and natural ecosystems. Among the various water treatment materials, biomass is effective for the removal of contaminants from water, including dyes, pharmaceutical residues, heavy metal ions, etc. Biomass attracted the interest of several researchers in contrast to non-renewable resources attributed to their numerous inherent properties such as renewability, non-toxic nature, biocompatibility, and ease in biodegradability, which pave the way to achieve environmental sustainability. The first review by F. Mashkoor and A. Nasar deals with the utilization of agro-waste derived adsorbents for the elimination of dyes from wastewater. It also includes the effect of various batch factors such as adsorbate/adsorbent contact time, pH of the solution, initial concentration of the dye, adsorbent dose, the temperature on the adsorption process. Thermodynamic, isotherm and kinetics have been systematically surveyed and compiled [1]. Recent trends and applications of cellulose nanofibers from lignocellulosic biomass are discussed by R. Majumdar. In this review, cellulose nanoscale materials and their various preparation methods, properties, reinforcing with other materials and biocomposite applications have also been discussed [2]. The other review focuses on imidazolium-based ionic liquids as a green solvent and catalyst to depolymerize lignin models, especially guaiacol glyceryl ether (GGE) (Guaifenesin). Subsequently, base-catalyzed, acid-catalyzed, metallic catalyzed, supercritical fluids, and ionic liquids-assisted methods are summarized for lignin degradation [3]. Mashkoor et al., develop a process for the utilization of Luffa aegyptiaca peel (LuAP) as a potential, economical, and sustainable adsorbent for the removal of methylene blue (MB) dye from the aqueous solution [4]. El-Shishtawy et al., report the removal of toxic dyes, anionic and cationic dyes (Acid Red 1 and methylene blue (MB) from aqueous solution by amphoteric bioadsorbent, i.e., modified chitin. The adsorption behavior of amphoteric chitin is believed to follow chemical adsorption with an ion-exchange process. The recycling process for few cycles indicates that the loaded adsorbent can be regenerated by simple treatment and retested for removing anionic and cationic dyes without any loss in the adsorbability. Therefore, the study introduces a new and easy approach for the development of amphoteric adsorbent for application in the removal of different dyes from aqueous solutions [5]. Fathy et al., report sugarcane bagasse hydrochar (SCB) derived carbon nanostructures (CNSs) for removing toxic Cr(VI) ions from aqueous solutions. Two modified CNSs samples were successfully prepared from SCB. Adsorption of Cr(VI) highly relies on the initial concentration of Cr(VI), pH, and temperature. The main factors controlling the adsorption behavior of Cr(VI) are the acidic functional groups and the accessible surface area on O-CNSs. Furthermore, the OCNSs attain high stability in recycling tests for Cr(VI) removal [6]. Ayyappa et al., conduct their research on novel background electrolytes supported with DFT calculations and successfully applied to separate sucralose in food samples using an indirect UV detector with capillary electrophoresis. Computational results indicate that the direction of charge transfer from the amine functionality to the glucofuranosyl ring in each amine derivative of sucralose confirms the strong interaction between sucralose and amines, which leads to the baseline separation of sucralose in different food samples [7]. Madhura et al., design a quantitative structure-activity relationship (QSAR) model for the removal of 57 pharmaceuticals and personal care products (PPCPs) from wastewater treatment plants (WWTPs). The target compounds of PPCPs are optimized geometrically using a Forcite- Geometry code, assembled in Material Studio 2016 [8]. Mohsina et al., report the removal of MB dye from synthetically polluted water by jackfruit peel bio adsorbent. It is derived from agriculture waste, a novel and economically feasible adsorbent for the removal of MB from aqueous solutions [9]. In summary, the reviews and research papers presented in this issue are concerned with the removal of toxic pollutants from the environment by the utilization of biomass materials. We offer readers very interesting practical solutions to experimental results, and theoretical research contributions by several authors in the analytical chemistry field. It is fascinating research to readers. We wish all our readers a fruitful reading.

Toxic pollutants in the environment are of concern because of their negative impact on human health and ecosystems. Sustainability and environmental issues have influenced scientists and researchers to work on ecological materials, and this decade has witnessed a remarkable improvement in sustainable chemical engineering. Volume II of the thematic issue has six review papers and three research papers. Wang et al., review the aspects of the design and synthesis of new emerging two-dimensional MXene-based membranes, processes development, and recent explorations in water treatment. Various preparation methods of MXene-based membranes, as well as their separation behaviors in water purification and desalination, are briefly discussed and analyzed [1]. The second review article of Nazir et al., gives an overview of the remediation of heavy metals from aqueous solutions using green biocomposites. It includes advanced techniques, synthesis protocols, important factors and application of biopolymers and their composites, and recent advancements in biopolymers [2]. Kaur et al., report a review on the chromatographic techniques for the analysis of Metformin (in ng/L to μg/L) in aqueous samples, pharmaceutical drugs and biological fluids such as urine and human plasma using high-performance liquid chromatography (HPLC), reverse-phase high-performance liquid chromatography (RP-HPLC), and high-performance thin-layer chromatography [3]. Tang et al., conduct a review to explore the latest developments in various pretreatment technologies, key scientific problems, and the current status of different residual drugs in environmental samples because sample pretreatment has always been the bottleneck restricting the development of residual drug analysis [4]. Vallidevi et al., perform a detailed and comparative analysis of sensor-based water quality monitoring with a Geographical Information System (GIS) for the efficient detection of water pollutants. Further research in this field may introduce many advancements to develop efficient water pollution detection techniques [5]. Nazir et al., summarize various techniques for desulfurization of diesel oil to remove sulfur-containing compounds from diesel, highlighting the recent advancements in the process of desulfurization of diesel oil to explore less energy-intensive and more economical processes [6]. Martínez et al., synthesize manganese oxides in the powder form and coatings were tested for lead ions adsorption capacities [7]. Kanchi et al., demonstrate the utilization of ammonium morpholine-4-carbodithioate (AMC) as a separation enhancement ligand. The present study aims to develop a selective and sensitivity enhancement separation protocol for transition elements in agricultural materials [8]. Arunkumar et al., report the fracture toughness of silicon carbide by varying the composition of MWCNT and ceramics using spark plasma sintering. The fabricated nanocomposites are characterized by analytical techniques and different mechanical properties such as relative density, hardness, and impact strength as per ASTM standards [9]. The scope of these works presented in this Volume II offers an original insight into the progress made across a wide range of sustainable chemical engineering techniques for toxic pollutants in the environment within the field of analytical chemistry. I hope these high-quality articles in this volume II could provide valuable information to students, engineers, and researchers working on analytical chemistry.

Environmental pollution has become a serious concern throughout the world. Therefore, decontamination of wastewater and removal of organic pollutants from the environment by photo/electro/biochemical approaches have emerged as one of the most promising techniques. The special issue of the “Current Analytical Chemistry” journal, named “Toxic Pollutants in the Environment: Challenges in Analytical Chemistry” includes three volumes that will cover various analyzing approaches to the prosperity of analytical chemistry towards environmental remediation applications. We would like to thank Prof. Samuel Achilefy, Editor-in-Chief of the “Current Analytical Chemistry” for accepting a proposal related to this special issue and many thanks to the Editorial Manager, Syed Faizan Akhtar, for the kind help in all steps relating to the production of the selected articles. And also great thanks to world-renowned scientists for their valuable contributions to this special issue. Volume I of the thematic issue contains ten manuscripts; two review papers and eight research papers reporting on recent trends dealing with photo/electro/ biochemical methods, design, properties, characterizations, and analytical applications; from internationally renowned researchers worldwide, including Ireland, China, India, Malaysia, Taiwan, Pakistan, and Saudi Arabia. The first review written by Wei et al. deals with the recent developments in CdS cocatalysts for hydrogen production using water splitting under visible-light irradiation. The factors affecting the photocatalytic performance and new cocatalyst design, as well as the general classification of cocatalysts, which include a single cocatalyst containing noble metals, non-noble metals, metal-complex cocatalysts, metal-free cocatalysts, and multi-cocatalysts designing toward the CdS solar-to-hydrogen energy conversion are described [1]. Another review aimed to provide a detailed discussion about environmental as well as human health behavior and analytic techniques corresponding to sulphonamides in aqueous solution for suitable wastewater treatment by Pavithra et al. It also includes determination techniques such as UV-spectroscopy, enthalpimetry, immunosensor, chromatography, chemiluminescence, photoinduced fluorometric determination and Capillary electrophoresis for sulphonamide determination [2]. Pang et al. designed a series of novel activated carbon/titanium dioxide (AC/TiO2) composites at various weight ratios using the sol-gel method and AC obtained from empty fruit bunch fibres. The characteristic of the composite material was investigated and the photocatalytic properties of malachite green dye removal were compared with those of AC and bare TiO2 [3]. A simple, low cost and highly sensitive catalytic hydrogen wave (CHW) method was developed for the investigation of manganese( II) in ammonium 4-phenylpiperazine-1-dithiocarbamate and ammonium 4-benzylpiperidine-1-dithiocarbamate in various environmental and biological samples using direct current polarography by Thondavada et al. The developed CHW method is highly sensitive, simple and spontaneous for the analysis of Mn(II) in environmental and biological samples. The CHW method is free from interference effect avoiding the removal stages which are made towards placing among utmost sensitive methods for the analysis of Mn(II) in different environmental and biological samples [4]. Aslam et al. proposed an investigation to degrade the harmful pollutants from wastewater, using highly efficient non-toxic Fe2(WO4)3 photocatalyst synthesized via coprecipitation method. The photocatalytic activity of the as-synthesized material was examined by degrading methylene blue (MB) under various conditions. This research signifies that this method is useful for the reclamation of water, making it useful for industry and irrigation [5]. Conventional heavy metal removal from industrial sewages is carried out using numerous treatment technologies, including nano-filtration, precipitation, reverse osmosis, coagulation and flocculation, adsorption, etc. Rahman et al. concentrated their study on palm oil-derived biomass waste and an empty fruit bunch was used to prepare a cellulose- graft copolymer, which can be converted into poly(amidoxime)-poly(hydroxamic acid) ligands suitable for the removal of heavy metals as well as electroplating wastewater [6]. Ahamed et al. synthesized Kraton/polyaniline ionomer composite membrane and the same was used for the Cu(II) ion-selective membrane electrode (ISME). The membrane electrode was widely used for the potentiometric determination of Cu(II) ions [7]. Kunhan et al. investigated an electrode for the powerful, informative, and non-destructive technique to study the electrical properties of different GdAlO3: Co2+ samples [8]. Priyanka et al. synthesized different titania (TiO2) nanostructures doped with La3+ and Ce3+ ions under visible light and are tested for their photocatalytic degradation efficiency under visible light for methylene blue (C16H18ClN3S) and rhodamine blue (C28H31ClN2O3) dyes. Photocatalytic dye degradation was significantly improved for doped nano titania, particularly for Ce3+ doped nano titania compared to the pristine sample. In short, crystal phase, crystallite size, crystallinity, morphology, bandgap, and calcination temperature play key roles in the photocatalytic mechanism [9]. Karanam et al. investigated the anticancer effect of a novel dipeptide isolated from a marine sponge-associated Bacillus pumilus AMK1 by formulating with Zinc oxide (ZnO) nanoparticles for the effective treatment against HepG2 liver cancer cells. The experimental results demonstrate that ZnO nanoparticle conjugated dipeptide has the potential to improve anticancer efficacy against liver cancer cells by inducing apoptosis in cancer cells without affecting normal liver cells and their toxicity evaluation on embryonic zebrafish [10]. Overall, the manuscripts published in this special issue present recent developments, various perspectives, and approaches to the studies of toxic pollutants in the environment. Most of them focus on the use of photo/electro/biochemical approaches for dyes and heavy metals removal, solar-to-hydrogen energy conversion, and anticancer applications. The work compiled in this special issue represents an excellent illustration of modern advances reached by the combinations of fundamental research, applied experimental research and theoretical modeling increasing this knowledge and enabling the progress in toxic pollutants in the environment using analytical chemistry tools by photo/electro/biochemical approaches. We are confident that this Volume I will provide readers with an overview of the latest prospects in this rapidly evolving and interdisciplinary field.

Green Analytical Chemistry principles are progressively applied in most analytical methods. Undoubtedly, environmental analysis is one of the most relevant fields that should take care of the effects of the use of conventional methods and their impact on the environment. The scope of this special issue is to describe the state of the art in both analysis and sample pretreatment with regards to the demands of green perspectives. Analytical scientists were invited to present their new strategies to fulfil all the requirements for reduction of waste, energy consumption, use of solvents, etc. Four comprehensive reviews are included in this mini thematic issue [1-4]. More specifically: Amin et al., in their review “Recent Trends in Development of Green Analytical Methods for the Detection of Environmental Pollutants using Nanomaterials”, provide information about multiple methods that use green nanomaterials for the analytical assessment of environmental pollutants. UV-Vis spectrophotometry and electrochemical analysis using green and reproducible nanomaterials are the major focus of this article. The authors conclude that the use of nanomaterials can drastically change the detection limits due to the large surface area, strong catalytic properties, and tunable possibility. The used nanomaterials could be washed, dried, and reused, which make the methods more proficient, cost-effective and environmentally friendly. Erdem-Yayayürük and Yayayürük, in their review “Recent Advances in Environmental Analysis towards Green Nanomaterials”, discuss strategies of green chemistry, green chemistry metrics, waste management, green nanotechnology/ nanoscience and characterization. The authors conclude that green synthesis of nanomaterials is a safer, energy-efficient and fast method that reduces the use of solvent reagents and preservatives, which are hazardous to both environment and human health. Moreover, the fabrication of nanomaterials using green procedures is a clean, safe, nontoxic, and environmentally friendly method that increases its necessity and demand in large-scale applications. Manousi and Zachariadis, in their review “Green Miniaturized Extraction and Microextraction of Polycyclic Aromatic Hydrocarbons from Foods and Beverages”, discuss the recent advances in the extraction techniques of PAHs from food samples, utilizing novel sample preparation approaches and adsorbents. Compared to the traditional sample preparation techniques, the herein discussed green miniaturized extraction and microextraction techniques offer multiple benefits, including simplicity, reduced sample preparation time, as well as reduced consumption of organic solvents. Tsalbouris et al., in their review “Recent advances in miniaturized microextraction techniques for the determination of bisphenols in environmental samples: An overview of the last two decades”, discuss all recent advances in the development of microextraction techniques, such as solid-phase extraction (SPE), solid-phase microextraction (SPME), magnetic solid-phase microextraction (MSPE), liquid-phase microextraction (LPME), dispersive liquid-liquid microextraction (DLLME), stir bar sorptive extraction (SBSE), matrix solid-phase dispersion (MSPD), that have been successfully applied in the extraction of bisphenols from environmental matrices. The analytical performance of the proposed techniques is critically discussed in this review, highlighting the potential and limitations of each method. The Guest Editor wishes to thank all the authors for their fine contribution.

This special issue of Current Analytical Chemistry titled “Imaging for analysis of materials and biological tissues” is dedicated to the recent developments of advanced imaging methods in three different fields: Materials science, biomedicine, and plant science. Traditional analytical techniques based on a single-point measurement provide satisfactory results when applied to homogenous systems. However, most of the natural materials and biological tissues are inherently heterogeneous. Comprehensive analysis of such materials requires imaging, where an additional spatial coordinate is added to a common analytical tool to visualize variance within the subject. Given that biological tissue is inherently of low contrast, the addition of endogenous probes or applying advanced techniques to improve the contrast is necessary. The objective of this special issue is to provide a forum to present and collate significant and exciting studies involving contrast enhancement aspects of imaging to visualize and understand critical biological phenomena. Thus this issue presents new exciting directions in the areas of contrast probe development, instrumentation techniques, and image analysis toward applications in medicine and life science. In their comprehensive review, a team of scientists led by Yongjian Liu [1] describes an emerging class of imaging agents based on ultrasmall nanoclusters (USNCs). These promising imaging probes, typically with a core size less than 2 nm, have drawn a great deal of attention due to the fact that they exhibit size-dependent physicochemical characteristics. Composed from just a few hundreds of atoms, the majority of which are located on the surface of the nanocluster, USNCs emonstrate unusual properties. Strong fluorescence emission and the ability to tune the emission to the near-infrared spectral range makes USNCs attractive for optical imaging in live animals. Ultrasmall iron oxide NCs (IONCs), with a high ratio of surface magnetic Fe atoms, are well suited for MRI imaging. Labeling the USNCs with radionuclides made these constructs excellent contrast agents in positron emission tomography. Moreover, the ultra-small size of USNCs facilitates renal clearance, which is critical for the development of non-toxic platforms for diagnostic and therapeutic applications. In another review paper, Gabr and Pigge [2] describe an interesting class of luminogens that feature aggregation induced emission (AIE). This class of molecules is typically non-emissive in solution but becomes highly luminescent upon aggregation. Unlike conventional fluorophores that exhibit aggregation-caused quenching, AIE fluorophores exhibit strong turn-on emission with low background signal. In addition, AIE fluorophores feature large Stokes’ shifts and excellent photostability – highly essential and desired properties for efficient imaging. The flexible design of AIE emitters makes them an attractive fit for a number of applications. The review describes the principles behind the design of the AIE bioprobes, from the detection of amino acids and metals to imaging of mitochondria and other organelles. The review also discusses the use of AIE probes as a new generation of diagnostics and therapeutics molecules. Imaging that enables the assessment of the effect of stress on plants’ health and to predict and improve the crop yield is a rapidly growing field in plant science. In order to address the need to remotely visualize freeze injury of plants in its earliest onset, Peng and colleagues have developed a new method based on fluorescence lifetime imaging (FLIM) of leaves. In this paper [3], the team explored the changes in the fluorescence lifetime of chlorophyll molecules in leaves. The authors have demonstrated that the fluorescence lifetime of chlorophyll’s autofluorescence in intact leaves from a model plant periwinkle is correlated with the degree of injury. The method shows a high sensitivity for detecting injury mere minutes after plant exposure to -20oc, while no gross visual differences could be distinguished. Conventional color imaging, reflection, or and steady-state fluorescence intensity showed lower sensitivity in detecting cold stress. The authors suggest that the proposed rapid, remote method for quantitatively measuring cold stress in situ will aid in selecting cold-tolerant plants. The papers presented in this focus thematic issue discuss novel challenges in imaging and present new directions. We believe that the readers of Current Analytical Chemistry will find new stimulating ideas from this thematic issue, and we hope that this issue will encourage researchers to develop novel imaging tools for biomedical and life science applications and beyond. We would like to thank all the authors for their excellent contributions, the Editors of “Current Analytical Chemistry” for this kind invitation to act as a guest editor for this thematic issue, and the valuable assistance by Editorial Manager Syed Faizan Akhtar in the processing and finalization of this special theme issue.

The special issue entitled "Environmental Contamination, Toxicology, and Safety by Nanocatalysts", published in the journal of "Current Analytical Chemistry" reports recent studies and applications of nanostructure and nanocomposite materials for the environment. It is focused on recent research as well as reviews related to the preparation, characterization, and potential applications of various doped and un-doped or intercalated nano-catalyst materials. This topic is covering the promising research focusing on the detoxification of wastewater contaminants. It also covers the advanced topics related to analytical and electrochemical methods covering the scope of various photo-catalysts as well as electro- catalysts. It attracts the huge attention of scientists towards the development of the non-toxic, easy, ecofriendly way of preparation-to-potential applications efficient catalyst on a broad scale. Nowadays, potentially unique research work on environmental pollutants remediation offers various approaches for the development of semiconductor photo-catalyst nanomaterials or nanocomposites. Recently, nanotechnology has developed semiconductor nanostructure materials at the nanoscale as well as nanodimensions which facilitates the application of novel photo-catalytic or electro-catalytic materials in wastewater treatment. The most dynamic area of photo-catalytic research is introduced with potential applications in areas such as sustainable detoxification of toxic chemicals, healthcare safety, total mineralization of colored toxicants, and removal of heavy metal cations or anions. In this issue [1-11], authors have contributed and discussed their findings in the areas such as the role of nano-photocatalysts for detoxification of various heavy metals, the role of nano-catalyst for wastewater treatment, carbon-nitride based noble advanced material for photocatalytic applications, nanotechnology-based solutions for wastewater treatment, TiO2 and their modified forms for air pollution remediation, current development in nanostructure materials and composites for environmental remediation, significance and antagonistic effect of nano-dimensional materials in sensing, nanostructure materials for the detection of metallic ions from various effluents, the study on nanotechnology: food and environmental paradigm, and simple and easy preparation of doped nanostructured materials with improved UV-photo-catalytic performances, etc. We tried to discuss different kinds of analytical methods for detoxifying the organic and inorganic pollutants with various hybrids, composites, and nanocomposites, and nanostructured materials. So, here we sincerely believe that this compiled thematic issue would be very beneficial for the researchers who desire to gain comprehensive knowledge about environmental remediation. It is also anticipated that this issue would be a useful collection for valuable readers from different parts of the world. Hopefully, people will find scientific knowledge of photocatalysis from this complied thematic issue. We also hope that this collection would encourage scientists as well as researchers to attain knowledge in environmental remediation of hazardous and unsafe chemicals and ions by using different kinds of electro- and phot-chemical techniques. Finally, we sincerely thank all authors for their excellent contributions as well as the Editors of “Current Analytical Chemistry” for the kind invitation to act as guest editors for this special thematic issue.

This special issue of “Current Analytical Chemistry” journal, entitled “Photocatalyst for wastewater treatment” is about the in-depth understanding of the relationship between the structure, the properties or the functions of different kinds of photocatalytic material. This special issue combines different articles to explain the current work on wastewater treatment, synthesis, characterization, and applications of the photocatalyst in wastewater treatment. To highlight the importance of photocatalyst, this special issue reports on the current development in the photocatalyst approach to treat wastewater. Several influential scientists contributed to share their ideas in this thematic issue. We would like to thank all of them for their valuable contributions [1-9]. In this thematic issue, there exist seven review papers and two research papers. We tried to combine different kinds of photocatalytic studies, discussed by various authors, to maintenance the riches of the water. Therefore, we believe that this thematic issue will be beneficial for the readers who want to seek broad knowledge on this topic.