Performance and mechanism of amphiphilic polymeric chelator for enhanced removal of high concentrations of Cu(II) from wastewater.

An amphiphilic polymeric chelator (APC16-g-SX) grafted with sodium xanthate (SX) groups was successfully prepared for the efficient removal of high concentrations of Cu(II) from wastewater. The ordinary polymeric chelator (PAM-g-SX) based on linear polyacrylamide (PAM) was also prepared for comparative studies. The polymeric chelators were characterized by Fourier transform infrared spectroscopy (FT-IR), solid-state nuclear magnetic resonance (13C-NMR), gel permeation chromatography (GPC), elemental analyzer, and scanning electron microscope (SEM). The chelating performance of these polymeric chelators was investigated, and the mechanism of APC16-g-SX for enhanced removal of Cu(II) from wastewater was proposed based on fluorescence spectroscopy, cryo-scanning electron microscope (Cryo-SEM), energy-dispersive spectrometer (EDS), and X-ray photoelectron spectroscopy (XPS) tests. The results show that as the initial Cu(II) concentration in the wastewater increases, APC16-g-SX shows more excellent chelating performance than ordinary PAM-g-SX. For the wastewater with an initial Cu(II) concentration of 200 mg/L, the removal rate of Cu(II) was 99.82% and 89.34% for both 500 mg/L APC16-g-SX and PAM-g-SX, respectively. The pH of the system has a very great influence on the chelating performance of the polymeric chelators, and the increase in pH of the system helps to improve the chelating performance. The results of EDS and XPS tests also show that N, O, and S atoms in APC16-g-SX were involved in the chelation of Cu(II). The mechanism of enhanced removal of Cu(II) by APC16-g-SX can be attributed to the spatial network structure constructed by the self-association of hydrophobic groups that enhances the utilization of chelation sites.

Preparation of Amphiphilic Chitosan-Loaded Bentonite Adsorbent and Its Performance in Removing Organic Matter from Coking Wastewater.

An amphiphilic chitosan-loaded bentonite adsorbent (C18CTS-BT) was prepared for the efficient removal of organic matter from coking wastewater. The structure and surface morphology of adsorbents were characterized by FT-IR, XRD, and SEM. The removal of those organics by C18CTS-BT was investigated by comparing the adsorption performances of C18CTS-BT with bentonite (BT) and chitosan-loaded bentonite (CTS-BT). The results showed that compared with BT and CTS-BT, C18CTS-BT showed the performance advantages of having a low dosage, wide pH range, and short adsorption equilibrium time. The optimized treatment process was as follows: the adsorbent dosage was 1.5 g·L-1, the adsorption time was 60 min, and the pH of the system was 7.0. The chemical oxygen demand (COD) of the coking wastewater treated with BT, CTS-BT, and C18CTS-BT decreased from 342 mg·L-1 in the raw water to 264 mg·L-1, 218 mg·L-1, and 146 mg·L-1, corresponding to COD removal rates of 22.81%, 36.26%, and 57.31%, respectively. The results of GC-MS analysis also confirmed that C18CTS-BT could remove most of the organic compounds in coking wastewater, especially long-chain alkanes and their derivatives. The hydrophobic modification of the adsorbent material can effectively improve the removal performance of organic compounds from coking wastewater.

A New Benzyl Phenethanolamine-ß-Cyclodextrin Bonded Phase: Chiral Chromatography Performance and Application for LC-MS/MS Analysis of Pesticide Enantiomers in Fruits and Vegetables.

BACKGROUND: At present, the research on achiral drug and pesticide residue detection methods is still the mainstay at home and abroad, and there is still a lack of systematic research on the enantiomeric analysis of chiral drugs and pesticides. OBJECTIVE: In order to prepare a novel chiral stationary phase, whose "multi-mode" chiral separation chromatographic performance and its utility was verified. METHOD: An S-(-)-2-benzylamino-1-phenylethanol mono-derivative ß-cyclodextrin bonded stationary phase (BzCSP) was prepared based on the "thiol-ene" addition reaction. The chiral compounds including four types of chiral compounds were used as "probes," and their chiral chromatographic properties were evaluated. Furthermore, a new LC-MS/MS method for the determination of the enantiomeric residues of three chiral pesticides in five kinds of fruits and vegetables was established. RESULTS: The study found that the novel stationary phase was suitable for a variety of chromatographic modes (normal phase mode, reversed-phase mode, polar organic mode). The resolutions of hexaconazole (Hex), tebuconazole (Teb), and triticonazole (Trit) enantiomers could be up to 2.31, 1.68, and 1.48, respectively, within 30 min under reversed-phase chromatography. Based on the optimal chromatographic and mass spectrum conditions, a new LC-MS/MS quantitative method for the Hex, Teb, and Trit enantiomers was established by multi-reaction positive ion monitoring (MRM). The detection limits (LODs) of enantiomers were less than 0.89 µg/kg for Hex, 0.93 µg/kg for Teb, and 0.93 µg/kg for Trit, and the averaged recoveries of enantiomers were in the range of 75.8-106.3% for Hex, 77.4-116.3% for Teb, and 78.7-113.4% for Trit. The method had good reproducibility with the RSDs (<5%) for intraday and (<7%) for interday. CONCLUSIONS: The established method had the characteristics of good selectivity, high sensitivity, strong resistance to matrix interference, and good reproducibility. It is indicated that the stationary phase prepared by the "thiol-ene" addition reaction is a new type of multi-mode stationary phase, which has a good development value. HIGHLIGHTS: The study reported a new method for the rapid preparation of a rare "multi-mode" chiral stationary phase BzCSP based on the "thiol-ene" addition reaction and verified the practicability of BzCSP including good selectivity, high sensitivity, strong resistance to matrix interference, and good reproducibility.