Electrochemical sensing system for the analysis of emerging contaminants in aquatic environment: A review

The determination of thallium in the environment: A review of conventional and advanced techniques and applications

Thallium (Tl) is a potential toxicity element that poses significant ecological and environmental risks. Recently, a substantial amount of Tl has been released into the environment through natural and human activities, which attracts increasing attention. The determination of this hazardous and trace element is crucial for controlling its pollution. This article summarizes the advancement and progress in optimizing Tl detection techniques, including atomic absorption spectroscopy (AAS), voltammetry, inductively coupled plasma (ICP)-based methods, spectrophotometry, and X-ray-based methods. Additionally, it introduces sampling and pretreatment methods such as diffusive gradients in thin films (DGT), liquid-liquid extraction, solid phase extraction, and cloud point extraction. Among these techniques, ICP-mass spectrometry (MS) is the preferred choice for Tl detection due to its high precision in determining Tl as well as its species and isotopic composition. Meanwhile, some new materials and agents are employed in detection. The application of novel work electrode materials and chromogenic agents is discussed. Emphasis is placed on reducing solvent consumption and utilizing pretreatment techniques such as ultrasound-assisted processes and functionalized magnetic particles. Most detection is performed in aqueous matrices, while X-ray-based methods applied to solid phases are summarized which provide non-destructive analysis. This work improves the understanding of Tl determination technology while serving as a valuable resource for researchers seeking appropriate analytical techniques.

A Comprehensive Review on Modification of Titanium Dioxide-Based Catalysts in Advanced Oxidation Processes for Water Treatment

It has become necessary to develop effective strategies to prevent and reduce water pollution as a result of the increase in dangerous pollutants in water reservoirs. Consequently, there is a need to design new catalyst materials to promote the efficiency of advanced oxidation processes (AOPs) in the field of wastewater treatment plant to ensure the mineralization of trace organic contaminants. A notable approach gaining attention involves the coupling of sulfate radicals-based AOPs to photocatalysis or electrocatalysis processes, aiming to achieve the complete removal of refractory contaminants into water and carbon dioxide. Titanium dioxide as metal oxide has received great attention for its catalytic application in water purification. TiO2 catalysts offer a multitude of advantages in AOPs. They are characterized by their high photocatalytic activity under both ultraviolet and visible light, making them environmentally friendly due to the absence of toxic byproducts during oxidation. Their versatility is remarkable, finding utility in various AOPs, from photocatalysis to photo-Fenton processes. TiO2's durability ensures long-lasting catalytic activity, which is crucial for continuous treatment processes, and their cost-effectiveness is particularly advantageous. Furthermore, their chemical stability allows it to withstand varying pH conditions. However, the large band gap energy and low electrical conductivity hinder the catalytic reaction effectiveness. This review aims to examine various approaches to enhance the catalytic performance of titanium dioxide, with the objective of enabling more efficient water purification methods.

Nanomaterials in electrochemical nanobiosensors of miRNAs

Nanomaterial-based biosensors have received significant attention owing to their unique properties, especially enhanced sensitivity. Recent advancements in biomedical diagnosis have highlighted the role of microRNAs (miRNAs) as sensitive prognostic and diagnostic biomarkers for various diseases. Current diagnostics methods, however, need further improvements with regards to their sensitivity, mainly due to the low concentration levels of miRNAs in the body. The low limit of detection of nanomaterial-based biosensors has turned them into powerful tools for detecting and quantifying these biomarkers. Herein, we assemble an overview of recent developments in the application of different nanomaterials and nanostructures as miRNA electrochemical biosensing platforms, along with their pros and cons. The techniques are categorized based on the nanomaterial used.

Sensors for Emerging Water Contaminants: Overcoming Roadblocks to Innovation

Ensuring water quality and safety requires the effective detection of emerging contaminants, which present significant risks to both human health and the environment. Field deployable low-cost sensors provide solutions to detect contaminants at their source and enable large-scale water quality monitoring and management. Unfortunately, the availability and utilization of such sensors remain limited. This Perspective examines current sensing technologies for detecting emerging contaminants and analyzes critical barriers, such as high costs, lack of reliability, difficulties in implementation in real-world settings, and lack of stakeholder involvement in sensor design. These technical and nontechnical barriers severely hinder progression from proof-of-concepts and negatively impact user experience factors such as ease-of-use and actionability using sensing data, ultimately affecting successful translation and widespread adoption of these technologies. We provide examples of specific sensing systems and explore key strategies to address the remaining scientific challenges that must be overcome to translate these technologies into the field such as improving sensitivity, selectivity, robustness, and performance in real-world water environments. Other critical aspects such as tailoring research to meet end-users' requirements, integrating cost considerations and consumer needs into the early prototype design, establishing standardized evaluation and validation protocols, fostering academia-industry collaborations, maximizing data value by establishing data sharing initiatives, and promoting workforce development are also discussed. The Perspective describes a set of guidelines for the development, translation, and implementation of water quality sensors to swiftly and accurately detect, analyze, track, and manage contamination.

Triangle-Shaped Cerium Tungstate Nanoparticles Used to Modify Carbon Paste Electrode for Sensitive Hydroquinone Detection in Water Samples

In this study, we propose an eco-friendly method for synthesizing cerium tungstate nanoparticles using hydrothermal techniques. We used scanning, transmission electron microscopy, and X-ray diffraction to analyze the morphology of the synthesized nanoparticles. The results showed that the synthesized nanoparticles were uniform and highly crystalline, with a particle size of about 50 nm. The electrocatalytic properties of the nanoparticles were then investigated using cyclic voltammetry and electrochemical impedance spectroscopy. We further used the synthesized nanoparticles to develop an electrochemical sensor based on a carbon paste electrode that can detect hydroquinone. By optimizing the differential pulse voltammetric method, a wide linearity range of 0.4 to 45 µM and a low detection limit of 0.06 µM were obtained. The developed sensor also expressed excellent repeatability (RSD up to 3.8%) and reproducibility (RSD below 5%). Interferences had an insignificant impact on the determination of analytes, making it possible to use this method for monitoring hydroquinone concentrations in tap water. This study introduces a new approach to the chemistry of materials and the environment and demonstrates that a careful selection of components can lead to new horizons in analytical chemistry.

Voltammetric determination of organic UV filters by carbon paste electrodes modified with pyridinium-based ionic liquids

The rapid and sensitive voltammetric determination of organic UV filters benzophenone-3 (BP-3) and avobenzone (AVO) was performed by an ionic liquid carbon paste electrode (IL-CPE). Namely, the synthesized pyridinium-based ILs, 1-butyl-3-methylpyridinium chloride ([N-C4-3C1Py]Cl) and 1-ethoxyethyl-3-methylpyridinium chloride ([N-C2OC2-3C1Py]Cl) were compared as bulk CPE modifiers for BP-3 determination. [N-C4-3C1Py]Cl-CPE showed more favorable interactions with the target analyte, and it was tested for AVO determination, too. Cyclic voltammetric (CV) studies suggested that the irreversible electrode reaction is adsorption controlled in the case of both UV filters. Also, the square-wave adsorptive stripping voltammetric (SW-AdSV) method was optimized for quantifying selected UV filters. In the model solutions, the linear calibration curve was obtained by the SW-AdSV method in the concentration range from 0.05 to 0.89 μg mL-1 at pH 3.0 for BP-3 (Eacc = -0.7 V, tacc = 100 s), and from 0.05 to 1.77 μg mL-1 at pH 11.98 for AVO (Eacc = 0.2 V, tacc = 100 s). The evaluated limit of detection (LOD) was 0.015 μg mL-1 in both cases, while the relative standard deviation (RSD) was lower than 1.5%. The affordable IL-based voltammetric sensor fulfills the main requirements for application in real samples due to an adequate selectivity towards selected analytes in the presence of interferents usually found in swimming pool water. Therefore, the BP-3 and AVO were quantified in a swimming pool water matrix with good repeatability and recovery. The obtained results demonstrate an excellent potential of the IL-CPEs, especially of the [N-C4-3C1Py]Cl-CPE, for determining selected UV filters in various real samples.

Development of recycled and miniaturized electroanalytical sensor: Probing isoniazid determination in environmental water matrices

Surface water pollution has become relevant because growing population and intense industrial activities. Thus, to protect the environment from contamination, recently the electroanalytical sensors that require small sample volume and easy preparation have shown a prominent performance for pharmaceuticals monitoring. For this purpose, a miniaturized electrochemical platform was developed based on recycling obsolete computer integrated circuits (microchips), fitting with the ideals of green chemistry and circular economy. The gold microelectrodes array (Au-μEA) was easily exposed by polishing the device surface and then characterized by optical microscopy, scanning electron microscopy and cyclic voltammetry. To enhance the analytical performance for isoniazid detection, the Au-μEA was modified with electrochemically reduced graphene oxide (ERGO). The developed sensor presented a linear range between 5 and 100 μmol L-1 and a limit of detection of 1.38 μmol L-1 demonstrating a reliable performance. Looking to its environmental application, the ERGO/Au-μEA sensor was used for isoniazid quantification in lagoon, river, tap water and synthetic effluent spiked samples with recovery values between 92.5 and 108.4%. Thus, this research field opens up new possibilities in global water-related issues contributing with innovative sustainable solutions.

Electrochemical simultaneous determination of hydroquinone, catechol, bisphenol A, and bisphenol S using a novel mesoporous nickel-modified carbon sensor

The widespread occurrence of endocrine disruptor compounds in wastewater has garnered significant attention owing to their toxicity, even at low concentrations, and their persistence in the water body. Among various analytical techniques, electrochemical sensors become popular for the environmental monitoring of water pollutants due to their low cost, rapid detection, high sensitivity, and selectivity. In this study, the mesoporous Ni (MNi) material was synthesized with an innovative method using Pluronic™ F-127 as a soft template and applied as a modifier for the simultaneous electrochemical sensing of hydroquinone (HQ), catechol (CC), bisphenol A (BPA), and bisphenol S (BPS). MNi with high porosity efficiently enhanced the redox-active surface area and conductivity of the glassy carbon electrode contributing to a significantly improved sensitivity in the detection of target chemicals. The pore size and surface area of MNi were estimated based on atomic force microscopy and Brunauer Emmett and Teller techniques to be ∼14.2 nm and 31.1 m2 g-1, respectively. The limit of detection for HQ, CC, BPA, and BPS was determined to be 5.3, 5.7, 5.6, and 61.5 nM, respectively. The electrochemical sensor presented in this study holds promise as a platform for developing portable and miniaturized tools offering the rapid and sensitive detection of these hazardous phenolic compounds in environmental water samples.

Electronic tongue for the simple and rapid determination of taste and odor compounds in water

Taste and odor (T&O) compounds present in natural water bodies could originate from algae. In this study, alga-generated compounds that can cause T&O issues in water, such as geosmin (GE), 2-Methylisoborneol (MIB), 2,4,6-Trichloroanisole (TCA), 2-Methylbenzofuran (MB), 2-Isopropyl-3-methoxypyrazine (IPMP), 2-Isobutyl-3-methoxypyrazine (IBMP), cis-3-Hexenyl acetate (HA), trans,trans-2,4-Heptadienal (HD), trans,cis-2,6-Nonadienal (ND), and trans-2-Decenal (DN), were determined through solid-phase microextraction coupled with gas chromatography/mass spectrometry (HS-SPME GC/MS) and electronic tongue (E-tongue), and the results from the two techniques were compared. Although HS-SPME GC/MS facilitates the detection and quantification of T&O compounds with high precision and accuracy, the sample preparation and handling is difficult and the analysis time (1 h) is longer than those of other analytical methods. E-tongue can be used as an alternative analytical method for water quality analysis and risk management because it enables controlled and rapid analysis (3 min) of T&O compounds in water at a low cost. Notably, principal component analysis indicated that E-tongue can discriminate and quantify eight T&O compounds at as low as 0.02 μg L-1 concentration. Further, partial least squares analysis confirmed that the sensor exhibits high sensitivity to concentration changes. The sensors with the highest variable importance in projection scores were determined to be SCS (1.39 and 1.38) for GE and MIB, CTS (1.34) for IPMP, CPS (1.33) for IBMP, AHS (1.42) for HA, ANS (1.22) for HD, and NMS (1.14 and 1.19) for ND and DN.

CaCu3Ti4O12 Perovskite Materials for Advanced Oxidation Processes for Water Treatment

The many pollutants detected in water represent a global environmental issue. Emerging and persistent organic pollutants are particularly difficult to remove using traditional treatment methods. Electro-oxidation and sulfate-radical-based advanced oxidation processes are innovative removal methods for these contaminants. These approaches rely on the generation of hydroxyl and sulfate radicals during electro-oxidation and sulfate activation, respectively. In addition, hybrid activation, in which these methods are combined, is interesting because of the synergistic effect of hydroxyl and sulfate radicals. Hybrid activation effectiveness in pollutant removal can be influenced by various factors, particularly the materials used for the anode. This review focuses on various organic pollutants. However, it focuses more on pharmaceutical pollutants, particularly paracetamol, as this is the most frequently detected emerging pollutant. It then discusses electro-oxidation, photocatalysis and sulfate radicals, highlighting their unique advantages and their performance for water treatment. It focuses on perovskite oxides as an anode material, with a particular interest in calcium copper titanate (CCTO), due to its unique properties. The review describes different CCTO synthesis techniques, modifications, and applications for water remediation.

Toxicological effect of endocrine disrupting insecticide (deltamethrin) on enzymatical, haematological and histopathological changes in the freshwater iridescent shark, Pangasius hypothalamus

This study investigated the deltamethrin (DMN) induced harmful effects on Pangasius hypophthalmus using enzymatic activity, haematological, and histopathological changes. LC₅₀ value was 0.021mg/L at 96h, and sublethal toxicity was tested for 45 days at two `concentrations (i.e., 1/5^th and 1/10^th of LC₅₀). Haematological parameters and enzymatic activities significantly changed between DMN-exposed and control groups (p<0.05). Histopathologically, both DMN doses induced liver hyperemia, hepatic cell rupture, necrosis, hypertrepheoid bile duct, shifting nuclei, vascular haemorrhage, and hepatocyte degeneration, while in gill, secondary lamellae destruction, a fusion of adjacent gill lamellae, hypertrophy, hyperplasia, adhesion, and fusion were noticed. Kidney developed melanomacrophages, increased periglomerular and peritubular space, vacuolation, decreased glomerulus, hyaline droplets in tubular cells, loss of tubular epithelium, distal convoluted segment hypertrophy, and granular layer in brain pyramid and Purkinje cell nucleus. But, limiting pesticide impacts on freshwater fish and their habitat requires a holistic, cradle-to-grave approach and toxicological studies.

New insights into the bioremediation of petroleum contaminants: A systematic review

Petroleum product is an essential resource for energy, that has been exploited by wide range of industries and regular life. A carbonaceous contamination of marine and terrestrial environments caused by errant runoffs of consequential petroleum-derived contaminants. Additionally, petroleum hydrocarbons can have adverse effects on human health and global ecosystems and also have negative demographic consequences in petroleum industries. Key contaminants of petroleum products, primarily includes aliphatic hydrocarbons, benzene, toluene, ethylbenzene, and xylene (BTEX), polycyclic aromatic hydrocarbons (PAHs), resins, and asphaltenes. On environmental interaction, these pollutants result in ecotoxicity as well as human toxicity. Oxidative stress, mitochondrial damage, DNA mutations, and protein dysfunction are a few key causative mechanisms behind the toxic impacts. Henceforth, it becomes very evident to have certain remedial strategies which could help on eliminating these xenobiotics from the environment. This brings the efficacious application of bioremediation to remove or degrade pollutants from the ecosystems. In the recent scenario, extensive research and experimentation have been implemented towards bio-benign remediation of these petroleum-based pollutants, aiming to reduce the load of these toxic molecules in the environment. This review gives a detailed overview of petroleum pollutants, and their toxicity. Methods used for degrading them in the environment using microbes, periphytes, phyto-microbial interactions, genetically modified organisms, and nano-microbial remediation. All of these methods could have a significant impact on environmental management.

Polymeric Micellar Systems-A Special Emphasis on "Smart" Drug Delivery

Concurrent developments in anticancer nanotechnological treatments have been observed as the burden of cancer increases every year. The 21st century has seen a transformation in the study of medicine thanks to the advancement in the field of material science and nanomedicine. Improved drug delivery systems with proven efficacy and fewer side effects have been made possible. Nanoformulations with varied functions are being created using lipids, polymers, and inorganic and peptide-based nanomedicines. Therefore, thorough knowledge of these intelligent nanomedicines is crucial for developing very promising drug delivery systems. Polymeric micelles are often simple to make and have high solubilization characteristics; as a result, they seem to be a promising alternative to other nanosystems. Even though recent studies have provided an overview of polymeric micelles, here we included a discussion on the "intelligent" drug delivery from these systems. We also summarized the state-of-the-art and the most recent developments of polymeric micellar systems with respect to cancer treatments. Additionally, we gave significant attention to the clinical translation potential of polymeric micellar systems in the treatment of various cancers.

Self-assembly of CdSe 3D urchins and their photocatalytic response

Photocatalysis is found to be one of the best suited processes that respond to the purification of water systems and the semiconductor nanomaterials are learned to be incredible materials which carry out the photocatalytic process as they readily decompose the pollutants effectively. In this present work, CdSe nanoparticles belonging to II-VI group semiconductor compounds were synthesized using a facile hydrothermal process with different precursor concentrations and were analysed for various characterization studies such as X-ray diffraction (XRD), Transmission electron microscopy (TEM), UV-vis absorption spectroscopy, Fourier transform infrared spectroscopy (FTIR) and Photoluminescence (PL) studies. The XRD study of the synthesized CdSe nanostructures revealed that the average crystallite size was ranging from 18.5 nm to 24 nm pointing out the increase in size with increase in molar concentrations. The morphological structure of synthesized CdSe samples exhibited urchin-like structure for a lower concentration with several rod-like projections appearing in diverse directions. These CdSe nano-urchins synthesized with lower concentrations are found suitable to carry out the process of photocatalytic activity. The process was carried out under visible light radiation for 180 min with aqueous solution of methylene blue (MB) as the ideal toxin to be degraded. The attained degradation efficiency was nearly 80% clearly displaying that the synthesized samples are good photocatalysts. By tuning the bandgap, through the optimization of the precursor concentrations, greater efficiency can be achieved in future.

Green synthesis, characterization, and application of metal oxide nanoparticles for mercury removal from aqueous solution

In this work, a novel surface-modified, green-based wheat straw-supported magnetite nanoparticles (Fe₃O₄-NPs) were synthesized via the green synthesis method, and the adsorption of mercury (Hg(II)) ion from aqueous solutions was methodically investigated. The synthesized wheat straw-supported magnetite (Fe₃O₄-WSS) NPs were characterized using X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and scanning electron microscopic (SEM) methods. FT-IR and TGA confirmed that the surface of Fe₃O₄-NPs was functionalized well. The XRD analysis revealed the existence of magnetite in the synthesized wheat straw-supported Fe₃O₄-NPs of 19.83 nm average crystalline size. SEM analysis showed Fe₃O₄-NPs were almost spherical, with an average particle size of 22.48 nm. Adsorption studies were carried out to investigate the adsorption of Hg(II) ions onto Fe₃O₄-WSS NPs and the effect of various adsorption parameters such as pH, time, adsorbent dosage, and Hg(II) ion concentration. The optimum adsorption conditions were obtained: pH of 6, contact time of 45 min, adsorbate of 40 mg/L, and adsorbent of 1 g. A maximum of 98.04% Hg(II) ion removal efficiency was obtained at these optimum conditions. FT-IR analysis also indicated that surface functional groups such as C = C,-OH, and C-C of the newly produced Fe₃O₄-NPs led to the more efficient removal of Hg(II) from aqueous solution. The synthesized nano-adsorbent showed an excellent adsorption capability of 101.01 mg/g. Hg(II) ions adsorption onto Fe₃O₄-WSS NPs fitted well with the Langmuir adsorption isotherm model. Therefore, these reasonable findings reveal that Fe₃O₄-WSS NPs are an efficient and promising adsorbent for Hg(II) removal from aqueous water environments.

Recent advances in electrochemical-based sensors amplified with carbon-based nanomaterials (CNMs) for sensing pharmaceutical and food pollutants

Foodborne-related infections due to additives and pollutants pose a considerable task for food processing enterprises. Therefore, the competent, cost-effective, and quick investigation of nutrition additives and contaminants is essential to reduce the threat of public fitness problems. The electrochemical sensor (ECS) shows facile and potent analytical approaches desirable for food protection and quality inspection over traditional methods. The consequence of a broad display of nanomaterials has paved the path for their relevance in designing high-performance ECSs appliances for medical diagnostics and conditions and food protection. This review article has discussed the importance of electrochemical-based sensors amplified with carbon-based nanomaterials (CNMs). Initially, we have demonstrated the types of pharmaceutical and food/agriculture pollutants (such as pesticides, heavy metals, antibiotics and other medical drugs) present in water. Subsequently, we have compiled the information on electrochemical techniques (such as voltammetric and electrochemical impedance spectroscopy) and their crucial parameters for detecting pollutants. Further, the applications of CNMs for sensing pharmaceutical and food pollutants have been demonstrated in detail. Finally, the topic has been concluded with existing challenges and future prospects.

Green synthesis of curcumin-silver nanoparticle and its modified electrode assisted amperometric sensor for the determination of paracetamol

Contamination of paracetamol, a primary analgesic was wide spread in the water system that affects the eco-system. High-dosage of paracetamol to humans cause organ damages and showed adverse effect. It is important to monitor the paracetamol concentration in environmental and human samples periodically. Conventional methods associated with chromatography is found to be high-cost, time consuming and requires high-end instrumentation, Herein, we investigated the role of curcumin during bio-synthesis of silver nanoparticles. The curcumin functionalized silver nanoparticles were further chemically modifying on the electrode surface and the resulting modified electrode was applied for electrocatalytic oxidation of paracetamol. The experimental finding proved that the modified electrode is capable of sensing paracetamol by applying oxidation potential 0.4 V. Both the synthesised material and modified electrode surface were characterized for its physic-chemical properties using spectroscopy and microscopy techniques. The HR-TEM, FESEM and AFM results showed that the distribution of nanoparticle with the size range from 25 to 70 nm and the UV-Vis and Raman spectrophotometer characterization confirms the coordination between SNP and curcumin. Under optimized condition, in 0.1 M NH₄Cl (pH 7) at the scan rate of 50 mVs^-1. The modified electrode enhanced the sensitivity towards the detection of paracetamol in trace level. The modified electrode is capable of sensing paracetamol in a linear range between 0.59 × 10^-6 and 342.1 × 10^-6 M, with LOD of 0.29 μM, and linear regression equation of y = 0.092x+502.6 with a correlation coefficient of R² = 0.996.

Differential pulse voltammetry determination of salbutamol using disulfite tungsten/activated carbon modified glassy carbon electrode

In the present article, the disulfide tungsten/activated carbon derived from Eichhornia crassipes (WS₂/AC) was synthesized by the hydrothermal process. The received materials were examined by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray - mapping, and nitrogen adsorption/desorption isotherms. The morphology of WS₂/AC was tailored to have a micro/meso/macro structure that facilized large electric conductivity and quick ion diffusion. The WS₂/AC sample was used as an electrode modifier for developing an electrochemical sensor for salbutamol detection. WS₂/AC exhibited excellent oxidation toward salbutamol. Through some optimized conditions, the electrochemical signal of the proposed sensor varied linearly to the salbutamol concentration ranging from 1 to 210 μM with a low LOD (detection limit) of 0.52 μM. The developed sensor showed several merits: easy producing, convenient usage, fabulous selectivity, and good repeatability as well as reproducibility. Finally, the suggested technique can be applied to determine salbutamol in people's biological fluid with satisfactory recoveries of 98.5-104.4% and without statistics different from standard HPLC.

An efficient optical properties of Sn doped ZnO/CdS based solar light driven nanocomposites for enhanced photocatalytic degradation applications

Metal sulfide - semiconductor nanocomposites synthesized with well-defined tin metal, exhibited the wide bandgap, the absorptions are limited to the UV-vis region for reduction of Reactive Blue 160 (RB 160) under solar light irradiation. The prepared samples were characterized using optoelectronic techniques. Conveniently, a wider range of wavelengths and physical properties can be enabled by doping these metal oxide nanoparticles. Whereas the photoreduction of RB 160 is unambiguously associated within charge separation and transmission progression from the excited Sn doped ZnO/CdS. Furthermore, Photocatalytic degradation efficiency for the Sn doped ZnO/CdS composites still reliant on the excitation strength, indicating the several electrons and protons were precise as a result of charge separation and transmission in prepared catalyst. Sn doped ZnO/CdS composites shows 94% Photocatalytic degradation efficiency within 120 min under sunlight irradiation. This photocatalytic nanocomposites may find capable applications in solar cells to power stretchable and also in wearable electronics.

Unlocking All-Solid Ion Selective Electrodes: Prospects in Crop Detection

This paper reviews the development of all-solid-state ion-selective electrodes (ASSISEs) for agricultural crop detection. Both nutrient ions and heavy metal ions inside and outside the plant have a significant influence on crop growth. This review begins with the detection principle of ASSISEs. The second section introduces the key characteristics of ASSISE and demonstrates its feasibility in crop detection based on previous research. The third section considers the development of ASSISEs in the detection of corps internally and externally (e.g., crop nutrition, heavy metal pollution, soil salinization, N enrichment, and sensor miniaturization, etc.) and discusses the interference of the test environment. The suggestions and conclusions discussed in this paper may provide the foundation for additional research into ion detection for crops.

Environmental photochemistry by cobalt doped magnesium ferrites: UV light assisted degradation of anionic azo and cationic thiazine dyes

In the current study, cobalt magnesium ferrites (Mg_0.8-xCo_xFe₂O₄ for x values 0.2, 0.4 and 0.6) nanoparticles are prepared by combustion method. The morphology, optical, structural, photocatalytic, compositional and vibrational properties of Mg_0.8-xCo_xFe₂O₄ by the influence of cobalt doping is investigated. Fourier Transform Infrared (FTIR) Spectroscopy and X-ray diffraction (XRD) confirms the formation of spinel cubic phase of the prepared ferrites samples. The optical band gap energy shows a strong effect on crystallite size and increases from 4.2 to 4.4 eV as the concentration of cobalt gets increased. TEM images of Mg_0.8-xCo_xFe₂O₄ clearly reveal spherical nanoparticles with decreasing particle size which ranges from 16 to 10 nm. EDAX spectrum confirms the existence of Fe, Co, Mg and oxygen. The photocatalytic studies of Mg_0.8-xCo_xFe₂O₄ are performed for anionic and cationic dyes. The rate constant values of methylene blue are found as 0.017/min, 0.019/min and 0.022/min for Mg_0.8-xCo_xFe₂O₄ for x values 0.2, 0.4 and 0.6 respectively. The degradation efficacy of the prepared samples to degrade methylene blue is high (95%) and it indicates that they may be efficient in degrading environmental pollutants and may prove out to be competent photo-catalyst.

Development of lab-on-chip biosensor for the detection of toxic heavy metals: A review

Recently, a decrease in water availability and quality has been raised due to rapid industrialization, unsustainable agricultural activities and anthropogenic activities. Heavy metals are considered significant pollutants in the water environment, cause environmental hazards and health effects to humans. For monitoring water contaminants utilized different conventional techniques. Still, they have some drawbacks, such as cost expensive, ecological issues, and processing time, requiring technicians and researchers to operate them effectively. Biosensors have become reasonable devices for screening and identifying environmental contaminants because of their different benefits contrasted with other detecting techniques. This review summarizes the toxic effect of heavy metal and their source, occurrence. A detailed discussion is provided on the heavy metal recognition materials for detecting heavy metals in wastewater. Lab on chip (LOC) is an emerging micro-electrical mechanical system (MEMS) device that intakes liquid and makes it move through the micro-channels, to accomplish fast, cost-effective and profoundly sensitive analysis with significant yield. LOC also provided a discussion on numerous laboratory functions on a single platform. This article attempts to discuss the detection of heavy metals using lab on a chip by suitable recognition materials. Further, the design and fabrication mechanism and their recognition abilities of LOC were also reviewed. The review mainly focuses on the application of LOC biosensors, pros, and cons, and suggests a roadmap towards future development to enhance the practical use in pollutant monitoring.

Chitosan/Gold Nanoparticles Nanocomposite Film for Bisphenol A Electrochemical Sensing

Bisphenol A (BPA) is considered an endocrine-disrupting compound and can cause toxicological effects, even at low doses. The development of sensitive and reliable sensors that would allow the detection of such contaminant is highly pursued. Herein, we report an electrochemical sensing strategy based on a simple and low-cost nanocomposite film sensor platform for BPA detection. The platform was developed by modifying a fluorine-doped tin oxide (FTO) electrode with layer-by-layer (LbL) films of chitosan (Chi) and gold nanoparticles functionalized with a polythiophene derivative (AuNPs:PTS). The growth of the Chi/AuNPs:PTS LbL films was monitored by UV–Vis spectroscopy. Electrochemical characterization revealed that the three-bilayer film exhibited the highest electrocatalytic performance and differential-pulse voltammetry (DPV) measurements demonstrated that the modified electrode was suitable for BPA detection through a quasi-reversible and adsorption-controlled electrochemical oxidation and reduction process. The developed sensor exhibited a linear response range from 0.4 to 20 μmol L−1, with a detection limit of 0.32 μmol L−1. The sensor showed good reproducibility with relative standard deviations of 2.12% and 3.73% to intra- and inter-electrode, respectively. Furthermore, the platform demonstrated to be suitable to detect BPA in real water samples, as well as selective for BPA detection in solutions with 100-fold excess of common interfering compounds.