Environmentally Benign Sequential Extraction of Heavy Metals from Marine Sediments

Turn-on fluorogenic sensors based on an anthraquinone signaling unit for the detection of Zn(II) and Cd(II) ions

Turn-on fluorescent chemosensors based on an anthraquinone moiety, N,N'-(9,10-dioxo-9,10-dihydroanthracene-1,8-diyl)bis(2-(bis(pyridin-2-ylmethyl)amino)acetamide) (1) and N,N'-(9,10-dioxo-9,10-dihydroanthracene-2,6-diyl)bis(2-(bis(pyridin-2-ylmethyl)amino)acetamide) (2), have been successfully synthesized with the overall yields of 61% and 90%, respectively. The structures of both chemosensors 1 and 2 were elucidated using several spectroscopic techniques such as 1H NMR, 13C NMR, 2D-NMR, FTIR and HRMS. The target chemosensor 1 is a promising tool for the detection of trace levels of d10 metal ions, such as Zn(II) and Cd(II) ions, by exhibiting a significant fluorescence enhancement via a turn-on photoinduced electron transfer (PET) mechanism with a rapid and highly reproducible signal, and low detection limit values of 0.408 μM and 0.246 μM, for Zn(II) and Cd(II), respectively.

Multicolor Emissive Phosphorescent Iridium(III) Complexes Containing L-Alanine Ligands: Photophysical and Electrochemical Properties, DFT Calculations, and Selective Recognition of Cu(II) Ions

Three novel Ir(III) complexes, (ppy)₂Ir(L-alanine) (Ir1) (ppy = 2-phenylpyridine), (F₄ppy)₂Ir(L-alanine) (Ir2) (F₄ppy = 2-(4-fluorophenyl)pyridine), and (F_2,4,5ppy)₂Ir(L-alanine) (Ir3) (F_2,4,5ppy = 2-(2,4,5-trifluorophenyl)pyridine), based on simple L-alanine as ancillary ligands were synthesized and investigated. Due to the introduction of fluorine substituents on the cyclometalated ligands, complexes Ir1-Ir3 exhibited yellow to sky-blue emissions (λ_em = 464-509 nm) in acetonitrile solution. The photoluminescence quantum yields (PLQYs) of Ir1-Ir3 ranged from 0.48-0.69, of which Ir3 with sky-blue luminescence had the highest PLQY of 0.69. The electrochemical study and density functional theory (DFT) calculations show that the highest occupied molecular orbital (HOMOs) energy of Ir1-Ir3 are stabilized by the introduction of fluorine substituents on the cyclometalated ligands, while L-alanine ancillary ligand has little contribution to HOMOs and lowest unoccupied molecular orbitals (LUMOs). Moreover, Ir1-Ir3 presented an excellent response to Cu²⁺ with a high selectivity, strong anti-interference ability, and short response time. Such a detection was based on significant phosphorescence quenching of their emissions, showing the potential application in chemosensors for Cu²⁺.

Platinum-Based Interdigitated Micro-Electrode Arrays for Reagent-Free Detection of Copper

Water is a precious resource that is under threat from a number of pressures, including, for example, release of toxic compounds, that can have damaging effect on ecology and human health. The current methods of water quality monitoring are based on sample collection and analysis at dedicated laboratories. Recently, electrochemical-based methods have attracted a lot of attention for environmental sensing owing to their versatility, sensitivity and their ease of integration with cost effective, smart and portable readout systems. In the present work, we report on the fabrication and characterization of platinum-based interdigitated microband electrodes arrays, and their application for trace detection of copper. Using square wave voltammetry after acidification with mineral acids, a limit of detection of 0.8 μg/L was achieved. Copper detection was also undertaken on river water samples and compared with standard analytical techniques. The possibility of controlling the pH at the surface of the sensors—thereby avoiding the necessity to add mineral acids—was investigated. By applying potentials to drive the water splitting reaction at one comb of the sensor’s electrode (the protonator), it was possible to lower the pH in the vicinity of the sensing electrode. Detection of standard copper solutions down to 5 μg/L (ppb) using this technique is reported. This reagent free method of detection opens the way for autonomous, in situ monitoring of pollutants in water bodies.

Application of biochar for the remediation of polluted sediments

Polluted sediments pose potential threats to environmental and human health and challenges to water management. Biochar is a carbon-rich material produced through pyrolysis of biomass waste, which performs well in soil amendment, climate improvement, and water treatment. Unlike soil and aqueous solutions, sediments are both the sink and source of water pollutants. Regarding in-situ sediment remediation, biochar also shows unique advantages in removing or immobilizing inorganic and organic pollutants (OPs). This paper provides a comprehensive review of the current methods of in-situ biochar amendments specific to polluted sediments. Physicochemical properties (pore structure, surface functional groups, pH and surface charge, mineral components) were influenced by the pyrolysis conditions, feedstock types, and modification of biochar. Furthermore, the remediation mechanisms and efficiency of pollutants (heavy metals [HMs] and OPs) vary with the biochar properties. Biochar influences microbial compositions and benthic organisms in sediments. Depending on the location or flow rate of polluted sediments, potential utilization methods of biochar alone or coupled with other materials are discussed. Finally, future practical challenges of biochar as a sediment amendment are addressed. This review provides an overview and outlook for sediment remediation using biochar, which will be valuable for further scientific research and engineering applications.

Colorimetric determination of copper(II) by using branched-polyethylenimine droplet evaporation on a superhydrophilic-superhydrophobic micropatterned surface

A colorimetric method is described for the determination of Cu(II). It is based on branched polyethylenimine (BPEI) droplet evaporation on a superhydrophilic-superhydrophobic polystyrene micropatterned surface. Exposure to Cu(II) leads to a color change from colorless to light blue and dark blue. The micropatterned surface was fabricated via combining electrospinning with oxygen plasma and served as a detection substrate. Analysis requires only a single drop of blood. The method has a linear response in the 5.0 μM to 2.5 mM Cu(II) concentration range which is within the physiological range (15.7 ∼ 23.6 μM). Compared to an assay in solution, the detection limit is decreased from 386 nM to 89 nM. Excellent selectivity over other metal ions and anions was achieved. Graphical abstract A rapid and sensitive colorimetric detection platform for Cu(II) was fabricated by using branched-polyethylenimine droplet evaporation on a superhydrophilic-superhydrophobic micropatterned surface. Only a single drop of blood was needed for the analysis. The sensitivity was improved about 4.3 times.

Separation of cobalt and nickel using a thermomorphic ionic-liquid-based aqueous biphasic system

A [P44414][Cl]-NaCl-H2O ionic liquid-based aqueous biphasic system shows promising results for the separation of cobalt(II) and nickel(II) by homogeneous liquid-liquid extraction. The extracting phase consists of a hydrophilic ionic liquid that is salted-out by sodium chloride, indicating that there is no need for using hydrophobic ionic liquids.