Selective adsorption of anions on hydrotalcite-like compounds derived from drinking water treatment residuals.

Most drinking water treatment residuals (DWTRs) with rich metal resources are landfilled directly without treatment, which results in wasted Al/Fe resources. This work proposes a new method of preparing Mg-Al-Fe Hydrotalcite-like compounds (MAF-HTCLs) by recycling DWTRs as the raw material to selectively adsorb anions in the waste water. In this study, MAF-HTCLs were prepared by the coprecipitation method with recycled DWTRs. The characterizations and adsorption of MAF-HTCLs were studied for the selective adsorption of P, Cr, F, and Br. The adsorption capacity was increasing as the value of pH decreased. For kinetic adsorption, the pseudo-second-order model fit better, and two isotherm models (the Langmuir and Freundlich models) described the isotherm results well. According to the Langmuir model, the maximum adsorption capacities of P, Cr, F, and Br were 55.2, 34.9, 16.84, and 13.9 mg/g, respectively. Based on the results of characterizations before and after adsorption, adsorption mechanisms of Cr, F, and Br were proposed, including physicochemical adsorption, surface complexation, and ion exchange, in which ion exchange was dominant. Finally, we determined that the selective adsorption mechanisms of P on MAF-HTCLs included strong ion exchange and surface chemical precipitation by analyzing the results of X-ray photoelectron spectroscopy.

The Naturally Evolved EPSPS From Goosegrass Confers High Glyphosate Resistance to Rice.

Glyphosate-resistant crops developed by the CP4-EPSPS gene from Agrobacterium have been planted on a massive scale globally, which benefits from the high efficiency and broad spectrum of glyphosate in weed control. Some glyphosate-resistant (GR) genes from microbes have been reported, which might raise biosafety concerns. Most of them were obtained through a hygromycin-HPT transformation system. Here we reported the plant source with 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene from goosegrass endowed rice with high resistance to glyphosate. The integrations and inheritability of the transgenes in the rice genome were investigated within two generations. The EiEPSPS transgenic plants displayed similar growth and development to wild type under no glyphosate selection pressure but better reproductive performance under lower glyphosate selection pressure. Furthermore, we reconstructed a binary vector pCEiEPSPS and established the whole stage glyphosate selection using the vector. The Glyphosate-pCEiEPSPS selection system showed a significantly higher transformation efficiency compared with the hygromycin-HPT transformation system. Our results provided a promising alternative gene resource to the development of GR plants and also extended the plant transformation toolbox.

A New Strategy for Enantioselective Construction of Multisubstituted Five-Membered Oxygen Heterocycles via a Domino Michael/Hemiketalization Reaction.

A new highly enantioselective domino Michael/hemiketalization reaction of α-hydroxyacetophenone with ß,γ-unsaturated α-keto esters for the synthesis of 2,2,4,5-tetrasubstituted chiral tetrahydrofurans is reported. With 2 mol % intramolecular dinuclear zinc-AzePhenol complex prepared in situ from the reaction of multidentate semi-azacrown ether ligand with ZnEt2 , the corresponding anti-multisubstituted tetrahydrofuran products were obtained in up to 90 % yields, and 98 % enantiomeric excess (ee) at 0 °C for 45 min. Moreover, the products were easily converted to 2,3,5-trisubstituted 2,3-dihydrofurans without any loss in optical activity.

Highly enantioselective catalytic system for asymmetric copolymerization of carbon dioxide and cyclohexene oxide.

A new ligand can be easily prepared, and its intramolecular dinuclear zinc complexes act as a high performance catalyst for the asymmetric alternating copolymerization of cyclohexene oxide and CO2 under very mild conditions (1 atm CO2 , room temperature), affording completely alternating polycarbonates with up to 93.8 % enantiomeric excess (ee) and 98 % yield. A high Mn value of 28 600 and a relatively narrow polydispersity (Mw /Mn ratio) of 1.43 were also achieved.