Degradation of Levofloxacin by a green zero-valent iron-loaded carbon composite activating peroxydisulfate system: Reactivity, products and mechanism.

In this study, a green zero-valent iron-loaded carbon composite (ZVI-SCG) was synthesized using coffee grounds and FeCl3 solution through two-steps method, and the synthesized ZVI-SCG was used in the activation of peroxydisulfate (PDS) to degrade Levofloxacin (LEX). Results revealed that ZVI-SCG exhibited a great potential for LEX removal by adsorption and catalytic degradation in the ZVI-SCG/PDS system, and 99% of LEX was removed in the ZVI-SCG/PDS system within 60 min. ZVI-SCG/PDS system showed a high reactivity toward LEX degradation under realistic environmental conditions. Also, the ZVI-SCG/PDS system could effectively degrade several quinolone antibiotics including gatifloxacin, ciprofloxacin and LEX in single and simultaneous removal modes. A potential reaction mechanism of LEX degradation by ZVI-SCG/PDS system was proposed, SO4•-, HO•, O2•- and 1O2 involved in radical and non-radical pathways took part in catalytic degradation of LEX by ZVI-SCG/PDS system, but HO• might be the main reactive species for LEX degradation. The possible degradation pathway of LEX was also proposed based on the identified ten intermediate products, LEX degradation was successfully achieved through decarboxylation, opening ring and hydroxylation processes. The potential toxicity of LEX and its oxidation products decreased significantly after treatment. This study provides a promising strategy of water treatment for the antibiotics-containing wastewater.

The preparation of a flexible AuNP modified carbon cloth electrode and its application in electrochemical detection of Hg(ii) by continuous flow in environmental water.

In this article, a carbon cloth composite electrode modified with gold nanoparticles (AuNPs) was prepared by a facile in situ electrodeposition method and applied to the detection of mercury ions in water. With the optimized electrochemical detection conditions and methods, the limit of detection (LOD) was 0.6 µg L-1 with the linearity ranging from 2 to 200 µg L-1 by the SWSV detection method, and the electrode showed good repeatability after many cycles. Based on this detection method, a continuous flow electrochemical detection system was constructed and applied to the detection of Hg ions in environmental water samples. The standard addition experimental results of two real water samples with an addition level of 10 and 50 µg L-1 showed that the recoveries were between 92.4% and 108.9% with RSDs from 2.01% to 3.22%. These results showed the same performance as that of the ZAAS mercury detection method (recovery: 94-102.4%, RSD 2.09-5.4%). Compared with other electrode materials, a shorter detection time, a wider linear range and high stability with a similar LOD can be achieved by a continuous flow detection method by using the composite electrode. The established continuous flow electrochemical detection system would have promising application in online and real-time detection of heavy metals in environmental water.

Fabrication of Metal-Organic Framework MOF-177 Coatings on Stainless Steel Fibers for Head-Space Solid-Phase Microextraction of Phenols.

Direct head-space solid-phase microextraction (HS-SPME) of phenols in water is usually difficult due to its polarity and solubility in aqueous matrix. Herein we report the fabrication of metal-organic framework MOF-177 coated stainless steel fiber for the HS-SPME of phenols (2-methylolphenol, 4-methylolphenol, 2,4-dimethylolphenol, 2,4-dichlorphenol, and 3-methyl-4-chlorophenol) in environmental water samples prior to the gas chromatography-mass spectrometry detection. Several parameters affecting the extraction efficiency were optimized in the experiment, including extraction temperature and time, the pH value and salt addition. The results indicated that the coated fiber gave low detection limits (0.015-0.043 µg L-1) and good repeatability with the RSD ranging from 2.8% to 5.5% for phenols. The recoveries are between 84.5%-98.6% with the spiked level of 10 µg L-1 for the real water samples. The established method may afford a kind of potential enrichment material and a reference method for the analysis of methylphenols in water samples.

[Distribution Characteristics of Heavy Metals in Environmental Samples Around Electroplating Factories and the Health Risk Assessment].

This study aimed to investigate the pollution degree and human health risk of heavy metals in soil and air samples around electroplating factories. Soil, air and waste gas samples were collected to measure 8 heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb and Zn) in two electroplating factories, located in Baiyun district of Guangzhou city. Geoaccumulation index and USEPA Risk Assessment Guidance for Superfund (RAGS) were respectively carried out. Results showed that concentrations of Hg and Pb in waste gas and Cr in air samples were higher than limits of the corresponding quality standards, and concentrations of Cd, Hg and Zn in soil samples reached the moderate pollution level. The HQ and HI of exposure by heavy metals in air and soil samples were both lower than 1, indicating that there was no non-carcinogen risk. CRAs and CRCr in soil samples were beyond the maximum acceptable level of carcinogen risk (10(-4)), and the contribution rate of CRCr to TCR was over 81%. CRCr, CRNi and TCR in air samples were in range of 10(-6) - 10(-4), indicating there was possibly carcinogen risk but was acceptable risk. CR values for children were higher than adults in soils, but were higher for adults in air samples. Correlation analysis revealed that concentrations of heavy metals in soils were significantly correlated with these in waste gas samples, and PCA data showed pollution sources of Cd, Hg and Zn in soils were different from other metals.

[Characteristics of speciation and evaluation of ecological risk of heavy metals in sewage sludge of Guangzhou].

Contents of heavy metals in different sewage sludges were analyzed and the speciation distribution and bioavailability of heavy metals were investigated, and the risk assessment code (RAC) and toxicity characteristic leaching procedure for solid waste were used to evaluate the potential ecological risk and leaching toxicity risk of heavy metals in sludge samples, respectively. The results showed that contents of Cu, Cr, Pb and Zn were high and presented a great difference by different sources in sewage sludges. Most of heavy metals existed in non-residual fractions and percentages of the mobile fraction (acid soluble fraction) of heavy metals in acidic sludge were higher. According to the results of single extraction, 1 mol x L(-1) NaOAc solution (pH 5.0) and 0.02 mol x L(-1) EDTA + 0.5 mol x L(-1) NH4OAc solution (pH 4.6) were suitable for evaluating bioavailable heavy metals in acidic and alkaline sludge, respectively. Percentages of bioavailable heavy metals were higher with the stronger of sludge acidity. The mobile ability of heavy metals resulted in the high ecological risk of sludge samples, and the bioavailability of heavy metals caused acidic sludges with a very high ecological risk but alkaline sludges with the middle ecological risk. Leaching toxicity risk was very high in sludge samples except domestic sewage sludge. After the removal of bioavailable heavy metals, leaching toxicity risk of sludge samples was still high in spite of its decrease; however, part type of sludges could be implemented landfill disposal.

A two-dimensional network containing an -Mn-O-C-O-Mn- chain: poly[diaqua[1,2-bis(pyridin-4-yl)ethylene][µ3-3-carboxy-5-(carboxylatomethoxy)benzoato]manganese(II)].

In the title compound, [Mn(C10H6O7)(C12H10N2)(H2O)2]n or [Mn(HOABDC)(bpe)(H2O)2]n [H3OABDC is 5-(carboxymethoxy)isophthalic acid and bpe is 1,2-bis(pyridin-4-yl)ethylene], each Mn(II) cation is at the centre of a distorted octahedron formed by three carboxylate O atoms from three different HOABDC(2-) ligands, one pyridyl N atom from the terminal bpe ligand and two water molecules. The flexible oxyacetate group bound to a methylene C atom of the HOABDC(2-) ligand links the Mn(II) centres into -Mn-O-C-O-Mn- chains, and the carboxylate group bound directly to the benzene ring extends the chains into two-dimensional layers which lie parallel to the (010) plane and present herringbone patterns. Intermolecular O-H...N and C-H...O hydrogen bonds connect the layers into a three-dimensional supramolecular structure.

A fourfold interpenetrating diamondoid three-dimensional coordination polymer: poly[[[µ2-1,2-bis(pyridin-4-yl)ethene-κ2N:N'](µ2-5-hydroxyisophthalato-κ2O1:O3)zinc(II)] 1,2-bis(pyridin-4-yl)ethene hemisolvate].

In the title compound, {[Zn(C8H4O5)(C12H10N2)]·0.5C12H10N2}n or {[Zn(HO-BDC)(bpe)]·0.5bpe}n [HO-H2BDC is 5-hydroxyisophthalic acid and bpe is 1,2-bis(pyridin-4-yl)ethene], the asymmetric unit contains a Zn(II) atom, one HO-BDC ligand, one coordinated bpe ligand and half a noncoordinating bpe molecule with crystallographic inversion symmetry. Each Zn(II) centre is four-coordinated by two O atoms from two distinct HO-BDC ligands and two N atoms from two different bpe ligands in a ZnO2N2 coordination environment. The three-dimensional topology of the title compound corresponds to a fourfold interpenetrating diamondoid coordination polymer network, with the uncoordinated bpe ligands located in the cavities, hydrogen bonded to the main network via the hydroxy group of the HO-H2BDC ligand.

Synthesis and optical properties of europium-complex-doped inorganic/organic hybrid materials built from oxo-hydroxo organotin nano building blocks.

Hybrid materials doped with novel europium complexes were synthesized using PMMA-co-Sn(12)Clusters (copolymers from oxohydroxo-organotin dimethacrylate and methylmethacrylate) as the matrix material. Two types of hybrid materials were obtained: the physically doped product, PMMA-co-Sn(12)Cluster/Eu(TTA)(3)phen, and the grafted product, PMMA-co-Sn(12)Cluster-co-[EuAA(TTA)(2)phen] (TTA = 2-thenoyltrifluoroacetone, phen = phenanthroline and AA = acrylic acid). The hybrid materials exhibited characteristic luminescence of the Eu(3+) ions, and also showed relative especial optical properties compared with samples just using PMMA as the matrix material. The PMMA-co-Sn(12)Cluster matrix exhibited a high physical doping quantity of [Eu(TTA)(3)phen], which can be attributed to the special structure of this kind of hybrid material. GPC (gel-permeation chromatography), TGA (thermogravimetric analysis), SEM, (1)H NMR, ICP (inductively coupled plasma), (119)Sn NMR, FTIR, and diffuse reflectance techniques were employed to characterize the structures and properties of these hybrid materials.