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High-performance capturing polar phenoxycarboxylic acids herbicides (PCAs) from water samples remains a great challenge because PCAs form salt easily and dissolve. Polyphenylene-based conjugated microporous polymers (PP-CMPs), a fascinating type of polymers, bear π-conjugation over 3D polyphenylene scaffolds, inherent micropore, and large surface area, which are essential for capturing trace PCAs in complex samples. This work developed a novel approach to quantify trace PCAs using PP-CMPs as an efficient dispersive solid-phase extraction (d-SPE) adsorbent. The developed method based on PP-CMPs achieved high sensitivity with limits of detection of 0.55–3.84 ng L−1, satisfactory correlation coefficients (≥ 0.9912), good linearity (50–10,000 ng L−1), and good precisions (2.0–9.0%). Moreover, this method was used for simultaneous monitoring of the amounts of five PCAs in environmental water samples with satisfactory spiked recoveries (86.9–101.3%). All these fact demonstrated that this new d-SPE technique based on PP-CMPs exhibited a promising potential for highly sensitive analysis of trace PCAs in complex samples.

Transformation of PAHs, i.e., anthracene, and production of environmentally persistent free radicals (EPFRs) on seven types of representative soils were investigated, focusing on the influences of soil characteristics and ambient conditions on these reactions. The transformation rate of anthracene exhibits the order of red earth > yellow earth > latosol ∼ fluvo-aquic soil > brown earth > chernozem > calcic brown soil, which is positively correlated with Fe content in soils. Afterwards, batch reactions on pure representatives of soil minerals, including Fe2O3, Fe3O4, FeOOH, and MnO2, demonstrate that anthracene is prone to mineral-promoted transformation. The presence of higher amount of organic carbon lower the transformation rate of anthracene, whereas the formed EPFRs can be stabilized for a longer time. Subsequent experiments associated with the influences of environmental conditions on mineral-promoted reactions suggest that both anthracene transformation and EPFRs generation readily occur under dry condition. Light irradiation not only promotes the formation of EPFRs, but also greatly accelerates the decay of EPFRs and the 1/e lifetime decreases from 5 to 20 d in dark to approximately 1 d. Meanwhile, the anoxic condition is favorable for the persistence of EPFRs. The obtained results suggested the potential environmental risks association with EPFRs in PAHs-contaminated soils.

The novel amino-functionalized magnetic covalent organic framework nanocomposites (Fe3O4@[NH2]-COFs) were fabricated at room temperature, which were explored as a magnetic adsorbent for magnetic solid-phase extraction (MSPE). On the basis of the hydrophobic surfaces of magnetic nanocomposites and introduction of primary amines into the COFs shell, Fe3O4@[NH2]-COFs displayed excellent enrichment capacity in “catching” ultratrace perfluoroalkyl acids (PFAAs) from water samples because of the synergistic combination of hydrophobic and electrostatic interactions between PFAAs and Fe3O4@[NH2]-COFs. Under the optimized pretreatment and instrumental parameters, the proposed pretreatment approach, which hybridized MSPE using Fe3O4@[NH2]-COFs and HPLC-MS/MS, displayed favorable linearity (10–10,000 ng L−1) with R2 (0.9990–0.9999), low limits of detection (0.05–0.38 ng L−1), and excellent repeatability (3.7–9.2%). Moreover, the established approach was successfully utilized to determine PFAAs in real water samples with spiked recoveries ranging from 72.1% to 115.4%. Results indicated that Fe3O4@[NH2]-COFs would be a potential alternative for MSPE of PFAAs at ultra-low levels.

The magnetic layered double hydroxide-based materials (MLDHs) with the metal composition of Mg(II)Al(III) were synthesized by different conditions as the adsorbent for removal of a phytohormone, indole-3-butyric acid (IBA). The morphological characteristics of MLDHs were studied through various characterization methods such as XRD, SEM, TEM, FTIR, BET, Zeta-potential and VSM. The adsorption results showed that the adsorption capacity of MLDH-1 synthesized by co-precipitation method with ammonia as the base source was the best (maximum 522.6 mg/g). The extent of adsorption in the pH range of 3.0–9.0 was observed to be no noticeable change. From the economical point of view, 1.0 g/L MLDH-1 composites were selected as optimum parameter. For a given adsorbent concentration (Cs), its kinetics and adsorption isotherm followed the pseudo-second-order and Liu isotherm model, respectively. The adsorbed sample can be easily magnetically separated and regenerated with NaNO3. The adsorption process was spontaneous and exothermic, including two path stages: surface adsorption of lamellar and interlayer anion exchange. The research makes a contribution to evaluating the ability of MLDHs in IBA removal and helping the public to understand the mechanism of adsorption process.

Food and environmental safety issues attributable to the polybrominated diphenyl ethers (PBDEs) are gaining increasing attention, and these urge us to establish a high-performance sample-handling technique. In this study, an outstanding adsorption performance with short adsorption time (10 min) was achieved for PBDEs using a novel synthesized dispersive solid-phase extraction adsorbent, a reticulated covalent organic framework with N/O functional groups (i.e., imine linkage, triazine, and methoxy) (TAPT-DMTA-COF). By conducting sufficient experimentation and theoretical simulation on adsorption mechanism, the halogen bond between electronegative N/O atoms of TAPT-DMTA-COF and the electropositive Br atoms of PBDEs were observed to play a more pivotal role than π-π, C-H…π interactions, and hydrophobic effects. Furthermore, the positive linear relation between calculated adsorption energy and Br content directly clarified that enrichment behavior of PBDEs can be attributed to halogen bonding. These data implied that integrated nanostructure (i.e., N/O functional groups and reticulated architecture) effectively enhanced adsorption capacity. In case of PBDE analysis, this approach achieved excellent results with low limits of detection (0.03-0.13 ng L-1). Finally, the promising potential applications of aforementioned method were verified by spiking water, fish, and milk samples with PBDEs; good PBDEs recoveries were obtained.

The abiotic transformation of polycyclic aromatic hydrocarbons (PAHs) is significantly impacted by soil components, especially inorganic redox species like iron oxides. In this study, the catalytic activities of three types of iron oxides in PAHs degradation without light irradiation were evaluated using a combination of experimental techniques. The results showed that α-Fe2O3 possessed the highest transformation rate for anthracene (ANT), with a reaction rate constant (Kobs) up to 0.28 d−1, followed by Fe3O4 (Kobs = 0.06 d−1) and α-FeOOH (Kobs = 0.06 d−1). X-ray photoelectron spectroscopy (XPS) characterization suggested that α-Fe2O3 had the highest oxygen vacancy concentration, which was conducive to the adsorption of O2 by α-Fe2O3, providing sufficient adsorbed oxygen species. Oxygen vacancy contributed to the exposure of Fe(III), and accordingly, more active sites were created that were responsible for ANT degradation. According to these results, two possible pathways for the degradation of PAHs on iron oxides can be concluded: (1) direct oxidation by Fe(III) and (2) oxidation by the O2•− generated onto oxygen vacancies. This study provides significant insights into the environmental fate of PAHs on iron oxides, and raises the possibility that iron oxides may be used as catalytic materials in the remediation PAHs-contaminated soil.

There is an increase in demand to develop simple, convenient, and low-cost approaches for rapid and label-free detection of antibiotics. Herein, we propose a new principle for the detection of kanamycin using the surface-anchored liquid crystal (LC) droplets. The optical images of the LC droplets uniformly change from four-clover, uniformly dark, and dark cross appearance gradually with the increase of surfactant concentration. The detection of kanamycin is fulfilled with the aid of a cationic surfactant cetyltrimethylammonium bromide (CTAB) and a kanamycin aptamer. The LC droplets show uniformly dark appearance and four-clover appearance in the presence of the aqueous solutions of CTAB and CTAB/aptamer complex, respectively. However, the specific binding of kanamycin to its aptamer can release the CTAB, which induces the uniformly dark appearance of the LC droplets. A portable device is built to measure the optical luminance of the LC droplets. This system can detect kanamycin with a concentration below 0.1 ng/mL (~0.17 nM) and also allows the detection of kanamycin in real samples such as milk and honey. Therefore, it is very promising in the development of new types of LC-based sensors by the surface-anchored LC droplets assisted with a portable optical device.

Trihalomethanes (THMs) are the primary toxic and carcinogenic byproducts during disinfection of drinking water. THMs have been frequently detected in water body and posed a huge threat to human health. Thus, analyzing the trace levels of THMs in an accurate and rapid method for water quality monitoring is important. In this paper, silver-based organic coordination networks (Ag-OCN) were fabricated with different diameters under mild pH condition. After modification with magnet, Fe3O4 @ Ag-OCN as extractant was applied to the magnetic solid-phase extraction of THMs from water samples. Gas chromatography-tandem mass spectrometry was used for sample quantification and detection. The magnetic extractant displayed good linearity in the range of 0.03–10 ug/L, low limits of detection (1.41–10.13 ng/L), and good reproducibility (relative standard deviations

Environmentally persistent free radicals (EPFRs) have been widely detected in superfund sites and atmospheric particles contaminated with organic contaminants, but the impacts of environmental factors such as light irradiation on the formation and evolution of EPFRs remain unclear. In the present study, in-situ irradiated Fourier transform infrared spectrometer and electron paramagnetic resonance were applied to probe the formation mechanisms of EPFRs during photo-transformation of polycyclic aromatic hydrocarbons (PAHs) on montmorillonite surface. EPFRs were only detected on Fe(III)-montmorillonite containing PAHs with relatively high electron-donating ability, such as anthracene (ANT), but not in the systems of Fe(III)-montmorillonite spiked with phenanthrene or Na(I)-montmorillonite. The 1/e lifetime of the EPFRs was much shorter under light irradiation (5.49 h) than in dark (30.3 h), suggesting that light irradiation facilitated the transformation of EPFRs. On the one hand, light irradiation promoted direct electron transfer from ANT to the mineral surface, accelerating the formation of PAHs-type radical cations. On the other hand, light irradiation induced the generation of reactive oxygen species, which facilitated the transformation from radical cations to oxygenic EPFRs, which finally led to ANT degradation. This work clarified the underlying mechanisms for EPFRs generation and evolution on clay minerals.

The degradation of azo dye C.I. Acid Red 14 (AR14) was investigated using cast iron in the absence and presence of low frequency ultrasound (59kHz). The effects of pH, amount of cast iron ([Fe](0)) and initial concentration of AR14 ([dye]) on the degradation of AR14 by cast iron combined with low frequency ultrasound had been assessed. The degradation followed the first-order kinetics model. The first-order rate constant of AR14 degradation by cast iron was 7.50 x 10(-2) min(-1) while that by US-cast iron was 2.58 x 10(-1) min(-1). A 3.4-fold increase in the reaction rate was observed in the presence of ultrasound compared with that of absence of ultrasound. This kinetic effect is quantitatively accounted for a simple kinetic model based on the reaction of Fe(II) from cast iron in aqueous solution with sonochemically produced H2O2 (Fenton's reaction). This latter effect illustrates a simple way of achieving a substantial improvement in the efficiency of sonochemical degradation reactions. It was found that for azo dye AR14, the rate of color decay was the first order with respect to the visible absorption of the dye. The destruction of the naphthalene rings in azo dyes was slower than that of color. A significant mineralization of AR14 was observed. (C) 2008 Elsevier B.V. All rights reserved.