A New Fluoride Chemodosimeter Based on 3-Ether-Substituted 1, 8-Naphthalimide Derivatives.

We developed a new chromogenic and fluorescent "off-on" 1, 8-naphthalimide-derivated chemosensor 1 based on an F--triggered desilylation reaction. It showed significant variations in UV/visible absorption (510 nm) and fluorescence emission wavelength (580 nm) for selective detection of fluorides in THF/H2O system (v/v, 50:50). Moreover, chemodosimeter 1-loaded test strips were successfully fabricated todetect fluorides efficiently.

A CH-Controlled Colorimetric Probe Based on Anthracene Carboximide for Near-Infrared Cyanide Detection.

A chemical sensor that can induce near-infrared red-shifted response represents a promising strategy for the design and development of anion probes. In this work, novel CH-controlled colorimetric probe 3 based on anthracene carboximide was developed for near-infrared detection of cyanide. Probe 3 consisted of CHCN binding site to anthracene carboximide fluorophore, and showed a significant visual change from yellow-green (535 nm) to deep violet (825 nm) with a larger redshift (≈ 290 nm) and fluorescence quenching at 480 nm and 520 nm upon interacting with cyanide. Job curves determined 1:1 binding stoichiometry of probe 3 with cyanide. Additonally, probe 3 detected cyanide ion conveniently in aqueous solution and could be reused after trifluoroacetic acid treatment. Colorimetric test paper was used to detect cyanide in aqueous solutions. The C-H deprotonation sensing mechanism was confirmed by 1H NMR titration. The near-infrared detection of cyanide by CH-controlled probes was founded for the first time.

Cyanide Ion-Promoted Nucleophilic Displacement of Aromatic Nitro Groups: A Mild, One-Pot, Transition Metal-Free Synthesis of Nitrile-Containing Naphthalimide Aryl Ether Derivatives.

Herein we report the novel synthesis of nitrile-containing naphthalimide aryl ether derivatives via transition metal-free cyanide ion-promoted nucleophilic displacement of nitronaphthalimide with alcohols or phenols. The transformation involves a one-pot reaction, which is operationally simple and mild and bereft of transition metal catalysts. This work provides a novel route for the preparation of diaryl ether derivatives.

Effects of alkali-treated agricultural residues on nitrate removal and N2O reduction of denitrification in unsaturated soil.

Lignocellulosic agricultural residues were utilized as denitrification carbon substrates to improve the purification capacity of unsaturated soil and alleviate nitrate pollution of groundwater. In this study, corncob and wheat straw were treated by calcium hydroxide to improve biodegradability and enhance denitrification potential. Calcium hydroxide treatment decreased the contents of lignin (i.e., from 16.7 wt% to 15.2 wt% in corncob and from 21.9 wt% to 20.6 wt% in wheat straw), increased potential biodegradable carbon by 4.4-5.3 times, reached complete nitrate removal 7-14 days earlier and decreased N2O/(N2O+N2) ratios by 85-99%. The results provide an insight into the application of alkali-treated agricultural residues as denitrification carbon sources to alleviate nitrate transport to groundwater and reduce potential greenhouse effect.

All-inorganic perovskite CsPb(Br/I)3 nanorods for optoelectronic application.

Halide perovskites have attracted great attention in recent years as promising materials for optoelectronic devices, especially inorganic perovskites like CsPbX3 (X = I, Br, Cl). Herein, CsPb(Br/I)3 nanorods with a photoluminescence (PL) spectrum located at 610 nm have been obtained by a facile hot-injection method, and the UV-vis absorption spectrum further revealed that the bandgap absorption is around 1.98 eV. Furthermore, the photoelectric response of the CsPb(Br/I)3 nanorods showed a relatively short rise-time (0.68 s) and decay-time (0.66 s), and the on/off photocurrent ratio of the CsPb(Br/I)3 nanorod based photodetector was up to 10(3).

Distinct kinetics and mechanisms of mZVI particles aging in saline and fresh groundwater: H2 evolution and surface passivation.

Application of microscale zero-valent iron (mZVI) is a promising technology for in-situ contaminated groundwater remediation; however, its longevity is negatively impacted by surface passivation, especially in saline groundwater. In this study, the aging behavior of mZVI particles was investigated in three media (milli-Q water, fresh groundwater and saline groundwater) using batch experiments to evaluate their potential corrosion and passivation performance under different field conditions. The results indicated that mZVI was reactive for 0-7 days of exposure to water and then gradually lost H2-generating capacity over the next hundred days in all of the tested media. In comparison, mZVI in saline groundwater exhibited the fastest corrosion rate during the early phase (0-7 d), followed by the sharpest kinetic constant decline in the latter phases. The SEM-EDS and XPS analyses demonstrated that in the saline groundwater, a thin and compact oxide film was immediately formed on the surface and significantly shielded the iron reactive site. Nevertheless, in fresh groundwater and milli-Q water, a passive layer composed of loosely and unevenly distributed precipitates slowly formed, with abundant reactive sites available to support continuous iron corrosion. These findings provide insight into the molecular-scale mechanism that governs mZVI passivation and provide implications for long-term mZVI application in saline contaminated groundwater.

Remediation of trichloroethylene-contaminated groundwater by three modifier-coated microscale zero-valent iron.

Building a microscale zero-valent iron (mZVI) reaction zone is a promising in situ remediation technology for restoring groundwater contaminated by trichloroethylene (TCE). In order to determine a suitable modifier that could not only overcome gravity sedimentation of mZVI but also improve its remediation efficiency for TCE, the three biopolymers xanthan gum (XG), guargum (GG), and carboxymethyl cellulose (CMC) were employed to coat mZVI for surface modification. The suspension stability of the modified mZVI and its TCE removal efficiency were systematically investigated. The result indicated that XG as a shear-thinning fluid showed the most remarkable efficiency of preventing mZVI from gravity sedimentation and enhancing the TCE removal efficiency by mZVI. In a 480-h experiment, the presence of XG (3 g L(-1)) increased the TCE removal efficiency by 31.85 %, whereas GG (3 g L(-1)) and CMC (3 g L(-1)) merely increased by 15.61 and 9.69 % respectively. The pH value, Eh value, and concentration of ferrous ion as functions of the reaction time were recorded in all the reaction systems, which indicated that XG worked best in buffering the pH value of the solution and inhibiting surface passivation of mZVI.

Transport and retention of xanthan gum-stabilized microscale zero-valent iron particles in saturated porous media.

Microscale zero valent iron (mZVI) is a promising material for in-situ contaminated groundwater remediation. However, its usefulness has been usually inhibited by mZVI particles' low mobility in saturated porous media for sedimentation and deposition. In our study, laboratory experiments, including sedimentation studies, rheological measurements and transport tests, were conducted to investigate the feasibility of xanthan gum (XG) being used as a coating agent for mZVI particle stabilization. In addition, the effects of XG concentration, flow rate, grain diameter and water chemistry on XG-coated mZVI (XG-mZVI) particle mobility were explored by analyzing its breakthrough curves and retention profiles. It was demonstrated that XG worked efficiently to enhance the suspension stability and mobility of mZVI particles through the porous media as a shear thinning fluid, especially at a higher concentration level (3 g/L). The results of the column study showed that the mobility of XG-mZVI particles increased with an increasing flow rate and larger grain diameter. At the highest flow rate (2.30 × 10(-3) m/s) within the coarsest porous media (0.8-1.2 mm), 86.52% of the XG-mZVI flowed through the column. At the lowest flow rate (0.97 × 10(-4) m/s) within the finest porous media (0.3-0.6 mm), the retention was dramatically strengthened, with only 48.22% of the particles flowing through the column. The XG-mZVI particles appeared to be easily trapped at the beginning of the column especially at a low flow rate. In terms of two representative water chemistry parameters (ion strength and pH value), no significant influence on XG-mZVI particle mobility was observed. The experimental results suggested that straining was the primary mechanism of XG-mZVI retention under saturated condition. Given the above results, the specific site-related conditions should be taken into consideration for the design of a successful delivery system to achieve a compromise between maximizing the radius of influence of the injection and minimizing the injection pressure.

Mechanism insights into enhanced trichloroethylene removal using xanthan gum-modified microscale zero-valent iron particles.

This report focuses on the enhancement in trichloroethylene (TCE) removal from contaminated groundwater using xanthan gum (XG)-modified, microscale, zero-valent iron (mZVI). Compared with bare mZVI, XG-coated mZVI increased the TCE removal efficiency by 30.37% over a 480-h experimental period. Because the TCE removal is attributed to both sorption and reduction processes, the contributions from sorption and reduction were separately investigated to determine the mechanism of XG on TCE removal using mZVI. The results showed that the TCE sorption capacity of mZVI was lower in the presence of XG, whereas the TCE reduction capacity was significantly increased. The FTIR spectra confirmed that XG, which is rich in hydrophilic functional groups, was adsorbed onto the iron surface through intermolecular hydrogen bonds, which competitively repelled the sorption and mass transfer of TCE toward reactive sites. The variations in the pH, Eh, and Fe(2+) concentration as functions of the reaction time were recorded and indicated that XG buffered the solution pH, inhibited surface passivation, and promoted TCE reduction by mZVI. Overall, the XG-modified mZVI was considered to be potentially effective for the in-situ remediation of TCE contaminated groundwater due to its high stability and dechlorination reactivity.