Nanofiber membranes from the composite of cellulose acetate/polyvinylpyrrolidone were prepared using electrospinning technique. After treated with water and alcoholic KOH to remove partially polyvinylpyrrolidone and d...Nanofiber membranes from the composite of cellulose acetate/polyvinylpyrrolidone were prepared using electrospinning technique. After treated with water and alcoholic KOH to remove partially polyvinylpyrrolidone and deacetylate the cellulose acetate, the membranes were further functionalized with thiol groups using thioglycolic acid. Related materials were characterized using infrared and thermogravimetric analysis. And the results showed that the membranes were success of functionalisation. Then the nanofiber membranes were used in the sorption-desorption process. The effects of pH, contacting time and adsorption capacity of nanofiber membranes were studied against Cu（II）, Cd（II） and Pb（II） ions. And the maximum adsorption capacities of Pb （II）, Cu （II）, and Cd （II） ions were estimated at 30.96, 19.63, 34.70 mg g-1. Our results suggested that the adsorption be- haviour of metal ions could be described using Langmuir model. Their adsorption kinetics was in agreement with the model of pseudo-second order, suggesting chemical adsorption as the rate-limiting step of the adsorption mechanism. The durability of the thiol-functionalized cellulose nanofiber membranes was also evaluated by repetitive adsorption-desorption.展开更多
Metal acetylacetonates,a type of readily synthesized or commercially available metal complex,were demonstrated to be robust catalysts for the synthesis of oxazolidinone from CO_(2);aziridine under condition of atmosph...Metal acetylacetonates,a type of readily synthesized or commercially available metal complex,were demonstrated to be robust catalysts for the synthesis of oxazolidinone from CO_(2);aziridine under condition of atmospheric pressure and mild temperature,exhibiting high chemo- and regio-selectivity.Tetrabutylammonium halides were employed as cocatalysts in the reaction,and it was believed that the reaction activity was influenced by a balance of anions’ two abilities,namely their nucleophilicity in ring-opening of aziridines and their leaving capacity in ring-closing of intermediate carbamate salts to form oxazolidinones.Notably,higher nucleophilicity of these anions resulted in increased formation of dimers,which served as by-products of the reaction.The study of mechanism suggested that there should be an alternative pathway involving CO_(2) derivative acting as a nucleophile during the ring-opening process,and this pathway could not be ignored when conventional nucleophiles,such as tetrabutylammonium halides are absent.展开更多
基金the National Nature Science Foundation of China (21177049,51103063)the Program of Science and Technology of Zhejiang Province (2011C22096, 2011C37033)the Program for Science and Technology of Jiaxing (2011AY1027, 2011AY1007) for financial supports
文摘Nanofiber membranes from the composite of cellulose acetate/polyvinylpyrrolidone were prepared using electrospinning technique. After treated with water and alcoholic KOH to remove partially polyvinylpyrrolidone and deacetylate the cellulose acetate, the membranes were further functionalized with thiol groups using thioglycolic acid. Related materials were characterized using infrared and thermogravimetric analysis. And the results showed that the membranes were success of functionalisation. Then the nanofiber membranes were used in the sorption-desorption process. The effects of pH, contacting time and adsorption capacity of nanofiber membranes were studied against Cu（II）, Cd（II） and Pb（II） ions. And the maximum adsorption capacities of Pb （II）, Cu （II）, and Cd （II） ions were estimated at 30.96, 19.63, 34.70 mg g-1. Our results suggested that the adsorption be- haviour of metal ions could be described using Langmuir model. Their adsorption kinetics was in agreement with the model of pseudo-second order, suggesting chemical adsorption as the rate-limiting step of the adsorption mechanism. The durability of the thiol-functionalized cellulose nanofiber membranes was also evaluated by repetitive adsorption-desorption.
基金supported by the Program for Public Technology of Jiaxing Province,China (No.2023AD11041)the Natural Science Foundation of Zhejiang Province,China (No.LY22E020009)+1 种基金the National Undergraduate Training Programs for Innovation of China (No.202110354038)the Student Research Training Program of Jiaxing University,China (No.8517231462).
文摘Metal acetylacetonates,a type of readily synthesized or commercially available metal complex,were demonstrated to be robust catalysts for the synthesis of oxazolidinone from CO_(2);aziridine under condition of atmospheric pressure and mild temperature,exhibiting high chemo- and regio-selectivity.Tetrabutylammonium halides were employed as cocatalysts in the reaction,and it was believed that the reaction activity was influenced by a balance of anions’ two abilities,namely their nucleophilicity in ring-opening of aziridines and their leaving capacity in ring-closing of intermediate carbamate salts to form oxazolidinones.Notably,higher nucleophilicity of these anions resulted in increased formation of dimers,which served as by-products of the reaction.The study of mechanism suggested that there should be an alternative pathway involving CO_(2) derivative acting as a nucleophile during the ring-opening process,and this pathway could not be ignored when conventional nucleophiles,such as tetrabutylammonium halides are absent.
