Rhodol assisted alternating copolymer based chromogenic vesicles for the aqueous detection and quantification of hydrazine via switch-on strategy

Graphitic carbon nitride derived probes for the recognition of heavy metal pollutants of environmental concern in water bodies

Graphitic carbon nitride (g-CN) has a number of valuable features that have been recognized during the studies related to its photocatalytic activity enhancement derived by visible light. Because of these characteristics, g-CN can be used as a detecting signal transducer with different transmission modalities. The latest up-to-date detection capabilities of modified g-CN nanoarchitectures are covered in this study. The structural features and synthetic methodologies have been discussed in a number of reports. Herein, employment of the g-CN as a promising probing modality for the recognition of different toxic heavy metals is the promising feature of the present study.

Emerging contaminants of high concern for the environment: Current trends and future research

Wastewater is contaminated water that must be treated before it may be transferred into other rivers and lakes in order to prevent further groundwater pollution. Over the last decade, research has been conducted on a wide variety of contaminants, but the emerging contaminants are those caused primarily by micropollutants, endocrine disruptors (EDs), pesticides, pharmaceuticals, hormones, and toxins, as well as industrially-related synthetic dyes and dye-containing hazardous pollutants. Most emerging pollutants did not have established guidelines, but even at low concentrations they could have harmful effects on humans and aquatic organisms. In order to combat the above ecological threats, huge efforts have been done with a view to boosting the effectiveness of remediation procedures or developing new techniques for the detection, quantification and efficiency of the samples. The increase of interest in biotechnology and environmental engineering gives an opportunity for the development of more innovative ways to water treatment remediation. The purpose of this article is to provide an overview of emerging sources of contaminants, detection technologies, and treatment strategies. The goal of this review is to evaluate adsorption as a method for treating emerging pollutants, as well as sophisticated and cost-effective approaches for treating emerging contaminants.

Octylamine as environment friendlier colorimetric detection probe for hazardous 2,4,6-Trinitrophenol from wastewater samples

The precise detection of hazardous 2,4,6-Trinitrophenol (TNP) is essential for the environment and human health. TNP is used as a precursor in whistling fireworks in ammunition, mining, agriculture and is a hazardous environmental pollutant generated from leather, chemical, and dye industries. Exploring rapid and low-cost approaches for the detection and quantification of TNP has attracted many scientists nowadays. The proposed chemosensor utilizes the concept of dispersive liquid-liquid micro-extraction coupled with a UV-visible spectrophotometer for its sensing at the ultra-trace level. Significant changes based on intramolecular interactions followed by a distinct color change to orange-red from yellow in the presence of TNP is an attractive feature for the present study. The successive addition of TNP shows ultra-trace sensitivity (3.9831 μA μM^-1 cm^-1) at detection limit (LOD) of 0.0015 ± 0.03 μM (S/N = 3), a linear range of 0 μM-70 μM, and a response time of <5 min. Different types of real samples such as creatinine testing kit reagent, fireflies crackers, serum, and water samples were used and recovery of TNP was calculated by spiking the known concentration of the standard analyte. The obtained recovery was 93.6-103.6% with RSD range of 1.6-4.53% (n = 3) in different samples. The analytical performance of the colorimetric Chemoprobe in terms of its recovery, linearity range, and limit of detection offers an excellent platform for monitoring hazardous TNP. The results show that the proposed colorimetric chemosensor is easy to use, low-cost, environmentally friendly and offers an easily observable visual color change. Based on these features, the chemosensor can be used for large-scale applications for the detection of TNP in water and other samples.

Rhodamine 6G-based efficient chemosensor for trivalent metal ions (Al3+, Cr3+ and Fe3+) upon single excitation with applications in combinational logic circuits and memory devices

A new rhodamine 6G-based chemosensor (L3) was synthesized and characterized by ¹H, ¹³C, IR and mass spectroscopy studies. It exhibited an excellent selective and sensitive CHEF-based recognition of trivalent metal ions M³⁺ (M = Fe, Al and Cr) over mono and di-valent and other trivalent metal ions with prominent enhancement in the absorption and fluorescence intensity for Fe³⁺ (669-fold), Al³⁺ (653-fold) and Cr³⁺ (667-fold) upon the addition of 2.6 equivalent of these metal ions in the probe in H₂O/CH₃CN (7 : 3, v/v, pH 7.2). The corresponding K_d values were evaluated to be 1.94 × 10^-5 (Fe³⁺), 3.15 × 10^-5 (Al³⁺) and 2.26 × 10^-5 M (Cr³⁺). The quantum yields of L3, [L3-Fe³⁺], [L3-Al³⁺] and [L3-Cr³⁺] complexes in H₂O/CH₃CN (7 : 3, v/v, pH 7.2) were found to be 0.0005, 0.335, 0.327 and 0.333, respectively, using rhodamine-6G as the standard. The LODs for Fe³⁺, Al³⁺ and Cr³⁺ were determined by 3σ methods and found to be 2.57, 0.78 and 0.47 μM, respectively. The cyanide ion snatched Fe³⁺ from the [Fe³⁺-L3] complex and quenched its fluorescence via its ring-closed spirolactam form. Advanced level molecular logic devices using different inputs (2 and 4 input) and a memory device were constructed.

A potent multifunctional Ag/Co-polyvinylpyrrolidone nanocomposite for enhanced detection of Cr(III) from environmental samples and its photocatalytic and antibacterial applications

Trivalent chromium (Cr(III)) is considered to exhibit hormesis (bi-phasic dose-response) property, where low dose be beneficial and high dose shows toxic effect. The present work describe the development of a bimetallic Ag/Co-polyvinylpyrrolidone nanocomposite (Ag/Co-PVP NPs) probe to detect and quantify Cr(III) ions from aqueous samples. The hydrodynamic size and zeta potential of the particle was determined to be 29 ± 1.3 nm and -37.19 ± 2.4 mV respectively. The interaction of Cr(III) with Ag/Co-PVP probe showed drastic change in colour of NPs from dark brown to pale yellow, with corresponding blue shift, tapering width and increased peak intensity. The probe showed high specificity towards Cr(III) among the tested metal ions. A linearity was observed between various dilutions of Cr(III) ions (10 to 50 nM) and the absorbance of Ag/Co-PVP NPs at 428 nm with R² value of 0.998. The minimum detectable limit of Cr(III) was calculated to be 0.6 nM. The influence of salinity, temperature and pH on detection was studied. The probe was found to detect Cr(III) at acidic pH effectively. Competitive metal ions did not interfere the detection of Cr(III). The water sample collected from Noyyal river was taken to estimate Cr(III) by using the prepared probe to ensure practical applicability. The sample contains 9.3 nM of Cr(III) that was cross verified with AAS analysis. Hence, it is understood that the reported probe can be used to detect Cr(III) selectively with high accuracy from aqueous samples. In addition, the particles also exhibited excellent photocatalytic activity under visible light. Ag/Co-PVP nanocomposites exhibited excellent antibacterial activity against both gram +ve (B. subtilis) and gram -ve (E. coli) bacteria.

Metal-organic frameworks based adsorbents: A review from removal perspective of various environmental contaminants from wastewater

Rapidly increasing water contamination has turned into a major threat globally. The pollutants such as organic and inorganic compounds, heavy metals, and biological organisms are among the major contributor to water pollution. Therefore, the removal of these contaminants has attracted the researchers a lot. Various methodologies are being carried out for the purpose. Among them, the metal-organic frameworks (MOFs) with several active sites and tailorable porous architectures as adsorbents or photocatalytic removal agents is a fast-growing class of coordination chemistry to remove these agents from water. To date, numerous approaches dealing with water treatment including conservative and advanced technologies have been presented. This article thoroughly reviews the application of MOFs toward how to remove the toxic agents from water. The leading objective is to present up-to-date information and references regarding MOFs based materials toward wastewater treatment applications.

Rhodol-conjugated polymersome sensor for visual and highly-sensitive detection of hydrazine in aqueous media

Hydrazine is a hazardous environmental pollutant, which contaminates land, air and water posturing a severe risk to human health. For the first-hand estimation, a qualitative approach (colorimetric) for recognition of hydrazine could suffice. However, for accurate measurement, under the threshold limit value (TLV), a quantitative technique is desired. We report the polymersome-based sensor for visual detection and quantification of hydrazine in water. The rhodol-functionalized amphiphilic hyperbranched multiarm copolymer (HSP-RDL) was self-assembled into vesicles. The HSP-RDL vesicle probe exhibited high sensitivity and selectivity for hydrazine recognition in presence of various competitive species such as cations, anions, and neutral species. The fast responsive pink color change from colorless could be visualized with naked eye due to spirolactone ring opening by hydrazinolysis triggered strong fluorescence emission. The vesicle probe could detect hydrazine in water with a limit of detection (LOD) value of 2 nM (0.0652 ppb), which is lower than TLV (10 ppb) given by USEPA (United States Environmental Protection Agency). Furthermore, the vesicle probe could quantify hydrazine (recovery ≥ 99 %) in a wastewater sample collected from Huangpu river. The membrane-permeable characteristics of HSP-RDL led hydrazine detection in live cells through confocal fluorescence microscopy.

TiO2/SiO2 decorated carbon nanostructured materials as a multifunctional platform for emerging pollutants removal

Aquatic ecosystem contaminated with hazardous pollutants has become a high priority global concern leading to serious economic and environmental damage. Among various treatment approaches, carbon nanostructured materials have received particular interest as a novel platform for emerging pollutants removal owing to their unique chemical and electrical properties, biocompatibility, high scalability, and infinite functionalization possibility with an array of inorganic nanomaterials and bio-molecules. Within this framework, carbon nanotubes (CNTs) are widely used due to their hollow and layered structure and availability of large specific surface area for the incoming contaminants. Carbon nanotubes can be used either as single-walled, multi-walled, or functionalized nanoconstructs. TiO₂/SiO₂-functionalized CNTs are among the most promising heterogeneous photocatalytic candidates for the degradation of a range of organic compounds, heavy metals reduction, and selective oxidative reactions. Herein, we reviewed recent development in the application of TiO₂ and SiO₂ functionalized nanostructured carbon materials as potential environmental candidates. After a brief overview of synthesis and properties of CNTs, we explicitly discussed the potential applications of TiO₂/SiO₂ functionalized CNTs for the remediation of a variety of environmentally-related pollutants of high concern, including synthetic dyes or dye-based hazardous waste effluents, as polycyclic aromatic hydrocarbons (PAHs), pharmaceutically active compounds, pesticides, toxic heavy elements, remediation of metal-contaminated soil, and miscellaneous organic contaminants. The work is wrapped up by giving information on current challenges and recommended guidelines about future research in the field bearing in mind the conclusions of the current review.

Environmentally-related contaminants of high concern: Potential sources and analytical modalities for detection, quantification, and treatment

In recent years, emerging contaminants (ECs) of high concern are broadly distributed throughout the environmental matrices because of various industrial practices and anthropogenic inputs, i.e., human-made activities. With ever increasing scientific knowledge, technological advancement, socio-economic awareness, people are now more concern about the widespread distribution of environmentally related ECs of high concern. As, ECs possess serious ecological threats and potential risks to human health and aquatic life, even at minor concentrations. The controlled or uncontrolled discharge and long-term persistence of ECs that includes micro-pollutants, endocrine disruptors (EDs), pesticides, pharmaceuticals, hormones, toxins, and industrially-related synthetic dyes and dyes-containing hazardous pollutants, etc. pose a significant challenge to policy regulators, engineers, and scientific community. The conventional treatment technologies are proved ineffective for the complete elimination and removal of an array of contaminants of emerging environmental concern in various biological and environmental samples. In order to overcome the aforementioned ecological threats, tremendous research efforts have been made to boost the efficiency of remediation techniques or develop new modalities to detect, quantify and treat the samples efficiently. The boom in biotechnology and environmental engineering offers potential opportunities to develop advanced and innovative remediation techniques in the field of water treatment. This review discusses the environmental and health hazards associated with a widespread distribution of micro-pollutants, pesticides, pharmaceuticals, hormones, and industrially-related synthetic dyes and dyes-containing hazardous pollutants, etc. in the water bodies, i.e., surface water, groundwater, and industrial wastewater streams. Life-cycle distribution of emerging (micro)-pollutants with suitable examples from various industrial sources viewpoints is also discussed. The later part of the review focuses on innovative and cost-effective remediation (removal) approaches from phase-changing treatment technologies for these ECs of high concern.