Real Aqueous Samples Research Articles

Collaborative adsorption and photocatalytic degradation of high concentration pharmaceutical pollutants in water using a novel dendritic fibrous nano-silica modified with chitosan and UiO-66

This study presents a novel hybrid mesoporous material for degrading drug pollutants in water. The hybrid materials, derived from UiO-66 metal-organic framework and chitosan, coated on nano-silica, showed excellent drug adsorption through hydrogen-bonding interactions and efficient photodegradation of antibiotics. The hybrid material's enhanced conductivity and reduced band gap significantly improved pollution reduction by minimising electron-hole recombination. This allows for more efficient charge transport and better light absorption, boosting the material's ability to break down pollutants. Structural and morphological analyses were conducted using various techniques, including scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, Brunauer-Emmett-Teller analysis, X-ray photoelectron spectroscopy, and thermogravimetric analysis. Optimising the adsorption-photodegradation process involved investigating pH, catalyst dose, and radiation time. Non-linear optimisation revealed an efficiency exceeding 85 % for 400 mg/L tetracycline and doxycycline, the model antibiotics. The optimal parameters for maximal elimination were determined as pH = 4.3, hybrid mesosphere dose = 4.0 mg/mL, and radiation time = 10 min. Kinetic studies favored pseudo-second-order diffusion models over pseudo-first-order models. The hybrid mesosphere showed sustained efficiency after three cycles and performed well in real aqueous samples, removing over 80 % of each antibiotic. This study demonstrates the potential of the hybrid mesoporous material for removing pharmaceutical pollutants in water systems.

Monitoring Poly(methyl methacrylate) and Polyvinyl Dichloride Micro/Nanoplastics in Water by Direct Solid-Phase Microextraction Coupled to Gas Chromatography-Mass Spectrometry.

A simple, sustainable, and sensitive monitoring approach of micro/nanoplastics (MNPs) in aqueous samples is crucial since it helps in assessing the extent of contamination and understanding the potential risks associated with their presence without causing additional stress to the environment. In this study, a novel strategy for qualitative and quantitative determination of MNPs in water by direct solid-phase microextraction (SPME) coupled with gas chromatography-mass spectrometry (GC-MS) was proposed for the first time. Spherical poly(methyl methacrylate) (PMMA) and irregularly shaped polyvinyl dichloride (PVDC) were used to evaluate the feasibility and performance of the proposed method. The results demonstrated that both PMMA and PVDC MNPs were efficiently extracted by the homemade SPME coating of nitrogen-doped porous carbons (N-SPCs) and exhibited sufficient thermal decomposition in the GC-MS injection port. Excellent extraction performances of N-SPCs coating for MNPs are attributed to hydrophobic cross-linking, electrostatic forcing, hydrogen bonding, and pore trapping. Methyl methacrylate was identified as the marker for PMMA, while 1,3-dichlorobenzene and 1,3,5-trichlorobenzene were the indicators for PVDC. Under the optimal extraction and decomposition conditions, the proposed method exhibited ultrahigh sensitivity, with a limit of detection of 0.0041 μg/L for PMMA and 0.0054 μg/L for PVDC. Notably, a programmed temperature strategy for the GC-MS injector was developed to discriminate and eliminate the potential interferences of intrinsic indicator compounds. Owing to the integration of sampling, extraction, injection, and decomposition into one step by SPME, the proposed method demonstrates exceptional sensitivity, eliminating the necessity for complex sample pretreatment procedures and the use of organic solvents. Finally, the proposed method was successfully applied in the determination of PMMA and PVDC MNPs in real aqueous samples.

Identification of medium- and mechanism-related pitfalls towards improved performance and applicability of electrochemical mercury(II) aptasensors.

The importance of understanding the mercury (II) ion interactions with thymine-rich DNA sequences is the reason for multiple comparative investigations carried out with the use of optical detection techniques directly in the depth of solution. However, the results of such investigations have limited applicability in the interpretation of the Hg2+ binding phenomenon by DNA sequences in thin, interfacial (electrode/solution), self-organized monolayers immobilized on polarizable surfaces, often used forsensing purposes in electrochemical biosensors. Overlooking the careful optimization of the measurement conditions is the source of discrepancies in the interpretation of the registered electrochemical signal. In this study, the chosen effects accompanying the efficiency of surface related recognition of Hg2+ by polyThymine DNA sequences labelled with methylene blue were investigated by voltammetry, QCM and spectro-electrochemical techniques. As was shown, the composition of the biosensing layer and buffers or the analytical procedures have a significant impact on the registered electrochemical readout which translates into signal stability, the biosensor's working parameters or even the mechanism of detection. After elucidation of the above factors, the complete and ready-to-use biosensor-based analytical solution was proposed offering subpicomolar mercury ion determination with high selectivity (also in aqueous real samples), reusability, and high signal stability even after long-term storage. The developed procedures were successfully used during the miniaturization process with self-prepared (PVD) elastic transducers. The obtained sensor, together with the simplicity of its use, low manufacturing cost, and attractive analytical parameters (i.e., LOD < < Hg2+ WHO limit) can present an interesting alternative for on-site mercury ion detection in environmental samples.

Molecular engineering of a new method for effective removal of cadmium from water

Cadmium (Cd) is a widespread and highly toxic environmental pollutant, seriously threatening animal and plant growth. Therefore, monitoring and employing robust tools to enrich and remove Cd from the environment is a major challenge. In this work, by conjugating a fluorescent indicator (CCP) with a functionalized glass slide, a special composite material (CCPB) was constructed to enrich, remove, and monitor Cd2+ in water rapidly. Then Cd2+ could be effectively eluted by immersing the Cd-enriched CCPB in an ethylenediaminetetraacetic acid (EDTA) solution. With this, the CCPB was continuously reused. Its recovery of Cd2+was above and below 100 % after multiple uses by flame atomic absorption spectrometry (FAAS), which was excellent for practical use in enriching and removing Cd2+ in real aqueous samples. Therefore, CCPB is an ideal material for monitoring, enriching, and removing Cd2+ in wastewater, providing a robust tool for future practical applications of Cd enrichment and removal in the environment.

Spindle-shaped Cu-Ru mesoporous nanospheres with enhanced enzyme-like activity for visual differentiation of toxic o-/m-aminophenol and recognition mechanisms

To effectively differentiate toxic aminophenol isomers, a kind of spindle-shaped Cu-Ru bimetal mesoporous nanozyme (Cu-Ru MPNZ) with high specific surface was developed by one-pot homogeneous reduction method, directed by hexadecyl trimethyl ammonium bromide (CTAB) in this work. By virtue of the distinctive microstructure, Cu-Ru MPNZ expressed superior bi-functional oxidase- and peroxidase-mimic activity to catalyze the oxidation of 3,3′,5,5,’-tetramethylbenzidine (TMB) and 2,2′-azinobis (3-ethylbenzothiazoline-6- sulfonic acid) ammonium salt (ABTS) with low Michaelis-Menten constants and quick reaction rates. Especially, toxic aminophenol isomers could exclusively react with the oxydates of TMB or ABTS to express differentiable signals in color. Under the optimal conditions, Cu-Ru MPNZ was successfully applied for visual differentiation of toxic aminophenol isomers in real aqueous, juices and medicinal samples with low detection limits (1.60 × 10−8 mol/L for o-aminophenol and 3.25 × 10−8 mol/L for m-aminophenol) and satisfactory recoveries (96.6–103.5%). The different recognition mechanisms of Cu-Ru MPNZ to toxic o- and m-aminophenol isomers were proposed for the first time as far as we known. This work will provide a potential way to monitor different organic isomer pollution in future.

Diamine@halloysite/C60 composite-based Bisphenol A electrochemical sensor

An interlayer space diamine functionalised halloysite/C60 tandem was successfully used as glassy carbon electrode modifier to determine the endocrine disruptor chemical Bisphenol A in aqueous media. The as-synthesised organohalloysite was successfully characterised by scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, thermogravimetric analysis, electrochemical impedance spectroscopy and by permeation studies. Under optimum differential pulse voltammetry conditions, the peak current varied linearly with Bisphenol A concentration in the range from 12.6 to 1630 nM. A detection limit of 1.48 nM was obtained based on a signal to noise ratio of 3. The developed electroanalytical method was successfully applied to the determination of Bisphenol A in real aqueous samples.

Selective fluorescent probe for sensitive determination of bisphenol A based on molecularly imprinted polymers decorated carbon dots derived from citric acid and ethylenediamine

Bisphenol A (BPA) is an endocrine disrupting chemical and poses a grave threat to the human health. Herein, a fluorescent probe constructed with molecularly imprinted polymers decorated carbon dots (CDs@MIPs) was proposed for determination of BPA with high selectivity. The CDs@MIPs were constructed using BPA, 4-vinylpyridine and ethylene glycol dimethacrylate as template, functional monomer and cross linker, respectively. The obtained fluorescent probe not only owned a highly selective recognition function derived from MIPs but also displayed an excellent sensitivity for sensing BPA stemmed from CDs. The fluorescence intensity of CDs@MIPs was varied before and after the removal of BPA templates. The fluorescent decrease fraction of the fluorescent probe demonstrates a nice linearity in BPA concentration range of 10–2000 nM (r2 = 0.9998) and the detection limit is as low as 1.5 nM. The fluorescent probe was triumphantly utilized to sense the level of BPA in real aqueous and plastic samples with good results. Moreover, the fluorescent probe offered a wonderful means for fast identification and sensitive detection of BPA from environmental aqueous samples.

A New Electrochemical Sensor for the Detection of Ketoconazole Using Carbon Paste Electrode Modified with Sheaf-like Ce-BTC MOF Nanostructure and Ionic Liquid.

An ultrasensitive and selective voltammetric sensor with an ultratrace-level detection limit is introduced for ketoconazole (KTC) determination in real samples using a modified carbon paste electrode with a sheaf-like Ce-BTC MOF nanostructure and ionic liquid. The as-synthesized nanostructure was characterized by several techniques, including energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and field emission scanning electron microscopy (FE-SEM). The electrocatalytic performance of the developed electrode was observed by cyclic voltammetry (CV), differential pulse voltammetry (DPV), linear sweep voltammetry (LSV), and chronoamperometry. The limit of detection (LOD) of the developed sensor for KTC is 0.04 μM, and the response was found to be in the dynamic concentration range of 0.1-110.0 μM in a phosphate buffer solution. The proposed electrode exhibits acceptable electrocatalytic activity for KTC oxidation with a high sensitivity of 0.1342 μA·μM-1. The ability of the fabricated sensor to monitor KTC in real aqueous samples is demonstrated using standard addition data.

Polybutylene succinate/modified cellulose bionanocomposites as sorbent for needle trap microextraction

In this work, different polybutylene succinate/modified cellulose bio-nanocomposites were synthesized by solving the casting method and then used as a new sorbent for needle trap microextraction of some polycyclic aromatic hydrocarbons from the water samples in headspace mode. The surface of cellulose nanocrystalline was modified using aminosilane groups to improve the dispersion of nanoparticles in the polybutylene succinate matrix. The characterization of synthesized nanocomposites, were performed using TGA, SEM, BET analysis and FT-IR spectroscopy. Adding modified nanocrystalline cellulose to a polybutylene succinate matrix increased the surface area, and thermal and mechanical stabilities. The significant parameters of the sorbent extraction process, including the amount of modified cellulose nanoparticles, the extraction time, and temperatures and salt content, were studied and optimized. Under the optimized extraction conditions (extraction time of 25 min, and extraction temperature of 50 °C), an analytical method for selected polycyclic aromatic hydrocarbons with low detection limits (0.75–1 ng L−1) and the quantification limit (3–5 ng L−1), good repeatability (3–7% at 20 ng L−1), and reproducibility (9%–14%, n = 3) was developed. The linearity of the method was obtained in the range of 5–1000 ng L−1 with R2 > 0.9996. The enrichment factor was obtained for the spiked real aqueous samples (at 50 ng L−1) in the range of 276–311. Also, the performance of the developed method was studied via the extraction of selected analytes in real water samples, and the relative recovery values were found to be in the range of 98–103%.

A novel sensing platform for electrochemical detection of metronidazole antibiotic based on green-synthesized magnetic Fe3O4 nanoparticles

The spread of antibiotic resistant genes has become a serious global concern. Thus, the development of efficient antibiotic monitoring systems to reduce their environmental risks is of great importance. Here, a potent electrochemical sensor was fabricated to detect metronidazole (MNZ) on the basis of green synthesis of Fe3O4 nanoparticles (NPs) using Sambucus ebulus L. leaves alcoholic plant extract as a safe and impressive reducing and stabilizing agent. Several analyses such as X-ray diffraction (XRD), Fourier transform infrared spectrophotometer (FTIR), thermogravimetric analysis (TGA), field emission scanning electron microscope (FESEM), energy dispersive X-ray spectroscopy (EDX), and dynamic light scattering (DLS) confirmed the production of homogeneous, monodisperse, regular, and stable magnetite NPs with a spherical morphology. The as-prepared Fe3O4NPs were afterwards applied to evaluate the electrochemical activity of MNZ by merging them with graphene nanosheets (GR NSs) on the glassy carbon electrode (GCE). The GR/Fe3O4NPs/GCE represented extraordinary catalytic activity toward MNZ with two dynamic ranges of 0.05–5 μM and 5–120 μM, limit of detection (LOD) of 0.23 nM, limit of quantification (LOQ) of 0.76 nM, and sensitivity of 7.34 μA μM−1 cm−2. The fabricated sensor was further employed as a practical tool for electrochemical detection of MNZ in real aqueous samples.

Effective and selective measurement of 2,4-dinitroaniline utilizing constructed fluorescent carbon dots sensor derived from vitamin B1

2,4-Dinitroaniline is a multifunctional product and has been applicated in various fields. It has absorbed much concerns due to its large consumption and occurrence in many environmental matrices. It is urgent to explore reliable and sensitive measurement technology. Present study described an outstanding fluorescence sensor constructed with carbon dots (CDs) derived from vitamin B1. The CDs were fabricated by dealing with a facile hydrothermal process, and exhibited good water solubility, fluorescence stability and highly fluorescence quenching characteristics in presence of 2,4-dinitroaniline. The excitation and emission wavelengths of the obtained CDs were 305 and 378 nm, respectively. The sensor displayed good selectivity and sensitivity for 2,4-dinitroaniline. Good linearity can be achieved in two-stage of 0.2–3 μmol L−1 and 3–20 μmol L−1. The sensor earned low detection limit for 2,4-dinitroaniline down to 0.05 μmol L−1. The sensor has been commendably employed for analysis of 2,4-dinitroaniline in real aqueous samples with spiked recoveries in the range of 95.0–99.6%. The proposed sensor provided a promising alternative for analysis of environmental pollutants or other meaningful employment.

Benzo‐γ‐pyrone‐based diorganotin (IV) chelates as fluorescent probes for the detection of picric acid from soil and aqueous samples

Four chelates of diorganotin (IV) from benzo‐γ‐pyrone ligands have been derived and their structural features are investigated. Benzo‐γ‐pyrone ligands (L1–L2) behave as bidentate chelating agents and form [L2SnR2] type of chelates (1–4; where L = ligand, R = C4H9, CH3) with “skew‐trapezoidal bipyramidal” arrangement. The fluorescent nature, electron‐rich sites, and photostability of the test diorganotin (IV) chelate 1 make it a suitable probe for the recognition of picric acid (PA). The optimized analytical protocol demonstrates the detection limit of 45.19 nM of PA with a linear range of 0.49–12.66 μM and a quick response time of 10 s. Moreover, soil and aqueous sample analysis along with fabrication of SiO2@Al strips for the visual response display the real‐time application of the synthesized chelate. The high recovery rate of 92.5% to 100.4% with significant precision of 0.36%–3.63% in real samples makes the probe a good chemosensor for the PA. Further stability of the synthesized compounds in water explored the tendency of the probe to detect PA in real aqueous samples.

Diallylcalix[4]arene incorporated polystyrene nanofibers for the removal of endosulfan from an aqueous environment

The current study was designed to utilize of 25,27-diallyloxy-26,28-dihydroxycalix[4]arene based nanofibers (NFs) for the removal of α and β endosulfan from aqueous media. The synthesized Polystyrene/25,27-diallyloxy-26,28-dihydroxycalix[4]arene NFs (PS-CLX) were characterized by ATR-FTIR and scanning electron microscope (SEM). The removal efficiency of PS and PS-CLX NFs for endosulfan was evaluated by performing batch adsorption experiments. In order to obtain maximum removal efficiency of NFs various parameters were optimized including pH (2−12), contact time (20–120 min), adsorbent dosage (1–10 mg), shaking speed (20–150 rpm) and pesticide concentrations (0.025–0.3 mg/L). The PS-CLX NFs showed maximum adsorption at pH 7 with contact time of 60 min, shaking speed of 120 rpm and adsorbent dosage of 7.5 mg. Adsorption process was validated by using Freundlich and Langmuir adsorption isotherm models. The data obtained in both models revealed that the adsorption is favorable. Kinetics studies showed that PS-CLX NFs obey pseudo second order rate equation. The maximum adsorption capacity (qo) of the PS-CLX NFs was found as 22.12 mg. g−1 and 20.11 mg. g−1 for α and β endosulfan, respectively. The NFs had been used for the removal of endosulfan from real aqueous samples and the results showed that PS-CLX NFs are excellent adsorbent for removing endosulfan from contaminated aqueous environment.

The Schiff Base Probe With J-aggregation Induced Emission for Selective Detection of Cu2.

Here, three Schiff bases 3a-c, differing by the substitutions (-H, -Cl, and -N(CH3)2) on the phenyl ring, have been designed and synthesized via the reaction of ortho-aminophenol with benzaldehyde, 2,4-dichlorobenzaldehyde and para-dimethylamine benzaldehyde in 1:1 molar ratio with favourable yields of 89-92%, respectively. Their structural characterizations were studied by FT-IR, NMR, MALDI-MS and elemental analysis. The fluorescence behaviours of compounds 3a and 3b exhibited a severe aggregation caused quenching (ACQ) effect in EtOH/water system. On the contrary, compound 3c had an obvious J-aggregation induced emission (AIE) feature in EtOH/water mixture (v/v = 1:1), and exhibited excellent sensitivity and anti-interference towards Cu2+ with the limit of detection (LOD) of 1.35 × 10-8M. Job's plot analysis and MS spectroscopic study revealed the 2:1 complexation of probe 3c and Cu2+. In addition, probe 3c was successfully applied to the determination of Cu2+ in real aqueous samples.

Preparation of boronate-modified larger mesoporous polymer microspheres with fumed silica nanoparticle and toluene as synergistic porogen for selective separation of sulfonamides

Larger mesopores can effectively reduce the diffusion resistance of target molecules in microspheres. Therefore, the photoinitiated suspension polymerization was used to fabricate a novel mesoporous polymer microsphere (MPM), in which large macropores resulted from the synergy of fumed silica nanoparticle as solid porogen and toluene as auxiliary porogen. The spherical MPM had 35.9 nm of larger mesopores and was suitable for solid phase extraction (SPE) adsorbent. To improve the selectivity and adsorption capacity, the MPM was first grafted with polyethyleneimine as amplifier, and further modified with boronic acid moieties. The successful synthesis of the boronate-modified MPM (BMPM) was confirmed by detailed characterization. Due to the combination of B-N coordination and hydrophobic (or π-π) interaction, the resultant BMPM exhibited excellent adsorption performance for nitrogen-containing sulfonamides, which was successfully fitted with Langmuir, pseudo-first-order and pseudo-second-order kinetic models, respectively. Therefore, the BMPM as SPE adsorbent was used for enrichment and separation of sulfonamides. The BMPM-based SPE process was optimized in detail, and combined with high performance liquid chromatography (HPLC) analysis for simultaneous determination of sulfonamides from real aqueous samples. The proposed BMPM-based SPE combined with HPLC strategy showed low limit of detection ranged from 0.81 to 2.50 ng mL−1. The recoveries of sulfonamides at three spiked levels ranged from 90.2% to 105.5%, 80.9% to 104.7% and 81.0% to 104.5% for tap, lake and river water, respectively. The intra- and inter-day relative standard deviations (n = 5) were no more than 5.0% and 6.7%, respectively. These results indicated that the BMPM was very promising adsorbent for selective capture of other nitrogen-containing substances and the MPM could be performed functionalization by various affinity units.

Behavior and mechanism of the adsorption of lead by an eco-friendly porous double-network hydrogel derived from keratin

In this study, a novel eco-friendly porous double-network keratin/polyacrylic acid (keratin-PAA) hydrogel was prepared using the one-pot method to improve the adsorption performance of the hydrogel toward Pb(II). The obtained porous keratin-PAA hydrogel was then characterized using nitrogen adsorption–desorption isotherms, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The interaction mechanism of Pb(II) and the keratin-PAA hydrogel was further investigated using X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The results showed that keratin-PAA hydrogel was successfully synthesized, with a specific surface area of 49.35 m2/g and a uniform pore distribution of 6.20 nm. The synthesized keratin-PAA hydrogel only took 6 min to adsorb nearly 70% of Pb(II) from the solution because of the interconnected porous network. The keratin-PAA hydrogel also showed a maximal adsorption amount of 234.6 mg/g, and satisfactory selectivity toward Pb(II). The adsorption kinetics of the keratin-PAA hydrogel binding to Pb(II) could be better described by the pseudo-second-order model, whereas the adsorption isotherms could be fitted using the Langmuir equation; this suggested that chemisorption was the main rate-limiting step. The XPS and FT-IR analysis results indicated that the sulfur-, nitrogen- and oxygen-containing groups in the keratin-PAA hydrogel were the main binding sites for Pb(II). In real aqueous samples, the keratin-PAA hydrogel could remove 93–104% of Pb(II). It is clear that the keratin-PAA hydrogel is an outstanding adsorbent material for the removal of Pb(II) from aqueous samples.

Hydrophobic polymer tethered magnetic zirconium-based metal-organic framework as advance and recyclable adsorbent for microwave-assisted extraction of polycyclic aromatic hydrocarbons from environmental water samples

Hydrophobic poly (glycidyl methacrylate) tethered magnetic amino-functional zirconium metal-organic framework (UiO-66-NH2) was fabricated for the first time for rapid microwave-assisted magnetic solid-phase extraction of trace polycyclic aromatic hydrocarbons from environmental water samples. UiO-66-NH2 endowed the nanocomposite with remarkable specific surface area (175.2 m2/g) and short diffusion route, while poly (glycidyl methacrylate) provided hydrophobic interaction towards hydrophobic polycyclic aromatic hydrocarbons, both of which contributed to the satisfactory extraction performance. The successful preparation of the nanocomposite was confirmed by transmission electronic microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, N2 adsorption-desorption experiment, powder X-ray diffraction patterns, contact angle measurement and vibrating sample magnetometry. In addition, an optimized protocol for microwave-assisted magnetic solid-phase extraction was carried out, including adsorbent amount (20–160 mg), adsorption time (30–150 s), desorption time (10–80 s) and desorption solvents (methanol, acetonitrile, acetone and ethyl acetate). Under the most favorable conditions, the microwave-assisted method afforded magnetic solid-phase extraction with short extraction time (1 min), a wide linear response (1.56–200 μg/L), good linearity (R2 ≥ 97.83%), low limits of detection (0.04–4.68 μg/L) and good precision (RSD ≤ 6.39%) for six polycyclic aromatic hydrocarbons. The proposed method was successfully applied in analysis of real water samples with mean recoveries in the range of 82.6–118.4% at three spiked levels and the relative standard deviations less than 10.7%. The results indicated that our developed method had great potential in enrichment and detection of trace polycyclic aromatic hydrocarbons in real aqueous samples.

Fabrication of nickel-tagged magnetic imprinted polymeric network for the selective extraction of Ni(II) from the real aqueous samples.

A new nickel ion, magnetic imprinted polymer was fabricated through the precipitation polymerization process, using amine-functionalized silica-capped iron oxide particles as a core material, and 4-vinyl pyridine as complexing agent methacrylic acid as functional monomer. The resulted magnetic adsorbent was employed to eliminate toxic Ni2+ ions from industrial wastewater. The different parameters were optimized, such as pH, shaking speed, and adsorbent dose, to obtain the maximum adsorption capacity. The synthesized material showed high selectivity coefficient for Ni+2 ions in the presence of other competitive ions and followed pseudo-second-order kinetics and Langmuir isotherm. A good adsorption capacity of 158.73 mg g-1 was obtained at optimized pH 6 in the concentration of 5 mg L-1 nickel ions aqueous solution. The limit of detection, quantification, and the percent relative standard deviation was found to be 0.58, 1.93, and 3.4%. This proves the excellent performance of prepared magnetic Ni(II) ion-imprinted polymer for selective detoxification of Ni2+ ions from real aqueous samples. Due to tunable magnetic properties, the prepared MMIPs are highly selective and sensitive and highly porous in nature; due to excellent magnetic properties, there is no need for centrifugation. Just use external magnetic field, it has good reusability. Showing preparation of Ni (II) imprinted magnetic polymer.

Inkjet-printed paper-based sensor array for highly accurate pH sensing

In this work, a novel paper-based colorimetric sensor array was developed by inkjet printing method with polyethylene glycol (PEG) immobilization system. Eight commercially available pH indicators with sequential pH segments in nearly whole pH range were dissolved in nine mixed inks to fabricate the 3 × 3 sensor array on mixed cellulose ester (MCE) paper. Based on homogeneous deposition of inkjet printing, the eight pH indicators were sufficiently immobilized on MCE paper with the assistance of PEG-400, which guaranteed pH detection of aqueous samples on sensor array without hydrophobic barriers. Besides, the indicating range of each indicator obtained an extension through the addition of PEG 400, which remarkably enriched the distinguishable capability of sensor array and benefited for high resolution of pH detection. As such, the as-fabricated paper-based sensor array exhibited an excellent discrimination ability in pH range of 1.00–13.60 with a high resolution of 0.20 pH unit, not only for standard pH buffer solutions but for real aqueous samples.

Selective colorimetric sensing of sub-nanomolar Hg2+ based on its significantly enhancing peroxidase mimics of silver/copper nanoclusters.

A simple colorimetric sensing strategy for Hg2+ ions was developed using silver/copper nanoclusters (Ag/Cu NCs) with excellent selectivity and sensitivity. Bimetallic Ag/Cu NCs were synthesized by using glutathione (GSH) as a template and sodium borohydride as a reducing agent. It was found that the peroxidase-like activity of Ag/Cu NCs was significantly enhanced in the presence of Hg2+. Therefore, a colorimetric method based on catalysis was developed to detect Hg2+ with a linear concentration range of 0.1-700 nM and a detection limit of 0.05 nM (S/N = 3). The common species have no effect on Hg2+ ion detection. Furthermore, this method is applicable to accurately detect Hg2+ in real aqueous samples and is reproducible. Therefore, owing to the merits of sensitivity, selectivity, rapid response and visual read-out, it can be promising in the development of a portable Hg2+ analyzer for on-site detection.