为了提高海藻酸钠(SA)对疏水性农药的负载量和释药缓释作用,将其与月桂醇通过偶联酯化反应进行疏水改性,对改性后的海藻酸钠进行红外光谱、核磁共振表征分析,结果证明月桂醇侧链成功接枝到海藻酸钠分子骨架上。将月桂醇改性海藻酸钠(DA...为了提高海藻酸钠(SA)对疏水性农药的负载量和释药缓释作用,将其与月桂醇通过偶联酯化反应进行疏水改性,对改性后的海藻酸钠进行红外光谱、核磁共振表征分析,结果证明月桂醇侧链成功接枝到海藻酸钠分子骨架上。将月桂醇改性海藻酸钠(DA)和十六烷基三甲基溴化铵(CTAB)与层状双金属氢氧化物(LDH)纳米颗粒进行复配,其Zeta电位分别为+44.9 m V和-33.2 m V,同时其粒径分别增大到93.3 nm和659.8 nm。结果表明带负电的月桂醇改性海藻酸钠吸附在层状双金属氢氧化物颗粒表面可以阻碍颗粒间的相互聚集,在分散体系中表现出了良好的稳定性能。高速剪切下制备稳定Pickering乳液,对疏水性农药氯氟氰菊酯进行了释药试验,表明改性后的海藻酸钠与LDH颗粒制备Pickering乳液对氯氟氰菊酯具有较好的药物缓释作用。展开更多
该文采用Pickering双乳液法,以硝磺草酮为模板分子、甲基丙烯酸甲酯为功能单体、木质素为稳定粒子制备分子印迹聚合物,并对其进行傅里叶红外光谱、扫描电镜、X射线衍射与接触角表征,同时探究了该聚合物对硝磺草酮的静态吸附、动态吸附...该文采用Pickering双乳液法,以硝磺草酮为模板分子、甲基丙烯酸甲酯为功能单体、木质素为稳定粒子制备分子印迹聚合物,并对其进行傅里叶红外光谱、扫描电镜、X射线衍射与接触角表征,同时探究了该聚合物对硝磺草酮的静态吸附、动态吸附和选择性吸附。Scatchard分析表明:合成的聚合物对硝磺草酮的结合方式有两种,最大表观吸附量(Q_(max))和平衡离解常数(Kd)分别为Q_(max1)=32.31 mg/g,K_(d1)=116.28 mg/L;Q_(max2)=89.99 mg/g,K_(d2)=413.22 mg/L。动力学测定结果显示:该聚合物对硝磺草酮的吸附符合准二级动力学模型。将制备得到的分子印迹聚合物作为基质固相分散的分散剂萃取分离玉米中的硝磺草酮。最佳萃取条件为分子印迹聚合物与样品的质量比3∶2;研磨时间10 min,淋洗剂2 mL 20%甲醇水溶液,洗脱剂5 mL 5%乙酸乙腈。最佳条件下,硝磺草酮的检出限为0.018μg/g,回收率为97.0%~98.4%,相对标准偏差(RSD)为0.70%~5.6%。该研究分析时间短、有机溶剂用量少,且提高了选择性和分析效率。展开更多
Pickering emulsions have been widely used for biphasic catalysis in the past decade.However,it remains a great challenge to achieve simple product collection and enzyme recovery.Poly(N-isopropylacrylamide)(PNIPAM)-bas...Pickering emulsions have been widely used for biphasic catalysis in the past decade.However,it remains a great challenge to achieve simple product collection and enzyme recovery.Poly(N-isopropylacrylamide)(PNIPAM)-based microgels can endow Pickering emulsions with stimuli-responsiveness,while most microgelstabilized emulsions are oil-in-water(O/W)type and not ideal for interfacial catalysis.Besides,altering temperature or pH value for demulsification is time-and energy-consuming and may cause irreversible deactivation of enzymes.In this work,inverse water-in-oil(W/O)Pickering emulsions were formed using hexanoic acidswollen microgels as the sole emulsifiers.When lipase was added in the water phase,stable oil-in-water-in-oil(O/W/O)Pickering double emulsions could be formed through one-step emulsification,owing to the synergistic effect of the hydrophobic microgels and hydrophilic lipase at the interface.Compared with other biphasic systems,such double emulsion systems represent a desirable platform for highly efficient biodiesel production because of the ultra-high interfacial areas and fast mass transport between two phases.More importantly,the switchable transition between hydrophobicity/hydrophilicity of microgels is controlled by the catalytic reaction.Therefore,double emulsions demulsify spontaneously when substrates are used up without the need for energy input or loss of enzymatic activity,enabling the facile collection of products and demonstrating the excellent recyclability of the biphasic catalysis system.展开更多
文摘为了提高海藻酸钠(SA)对疏水性农药的负载量和释药缓释作用,将其与月桂醇通过偶联酯化反应进行疏水改性,对改性后的海藻酸钠进行红外光谱、核磁共振表征分析,结果证明月桂醇侧链成功接枝到海藻酸钠分子骨架上。将月桂醇改性海藻酸钠(DA)和十六烷基三甲基溴化铵(CTAB)与层状双金属氢氧化物(LDH)纳米颗粒进行复配,其Zeta电位分别为+44.9 m V和-33.2 m V,同时其粒径分别增大到93.3 nm和659.8 nm。结果表明带负电的月桂醇改性海藻酸钠吸附在层状双金属氢氧化物颗粒表面可以阻碍颗粒间的相互聚集,在分散体系中表现出了良好的稳定性能。高速剪切下制备稳定Pickering乳液,对疏水性农药氯氟氰菊酯进行了释药试验,表明改性后的海藻酸钠与LDH颗粒制备Pickering乳液对氯氟氰菊酯具有较好的药物缓释作用。
文摘该文采用Pickering双乳液法,以硝磺草酮为模板分子、甲基丙烯酸甲酯为功能单体、木质素为稳定粒子制备分子印迹聚合物,并对其进行傅里叶红外光谱、扫描电镜、X射线衍射与接触角表征,同时探究了该聚合物对硝磺草酮的静态吸附、动态吸附和选择性吸附。Scatchard分析表明:合成的聚合物对硝磺草酮的结合方式有两种,最大表观吸附量(Q_(max))和平衡离解常数(Kd)分别为Q_(max1)=32.31 mg/g,K_(d1)=116.28 mg/L;Q_(max2)=89.99 mg/g,K_(d2)=413.22 mg/L。动力学测定结果显示:该聚合物对硝磺草酮的吸附符合准二级动力学模型。将制备得到的分子印迹聚合物作为基质固相分散的分散剂萃取分离玉米中的硝磺草酮。最佳萃取条件为分子印迹聚合物与样品的质量比3∶2;研磨时间10 min,淋洗剂2 mL 20%甲醇水溶液,洗脱剂5 mL 5%乙酸乙腈。最佳条件下,硝磺草酮的检出限为0.018μg/g,回收率为97.0%~98.4%,相对标准偏差(RSD)为0.70%~5.6%。该研究分析时间短、有机溶剂用量少,且提高了选择性和分析效率。
基金Hong Kong Special Administrative Region(HKSAR)General Research Fund of The Chinese University of Hong Kong,Grant/Award Numbers:CUHK14304619,2130642National Natural Science Foundation of China,Grant/Award Number:32172347Natural Science Foundation of Guangdong Province,Grant/Award Number:2021A1515011000。
文摘Pickering emulsions have been widely used for biphasic catalysis in the past decade.However,it remains a great challenge to achieve simple product collection and enzyme recovery.Poly(N-isopropylacrylamide)(PNIPAM)-based microgels can endow Pickering emulsions with stimuli-responsiveness,while most microgelstabilized emulsions are oil-in-water(O/W)type and not ideal for interfacial catalysis.Besides,altering temperature or pH value for demulsification is time-and energy-consuming and may cause irreversible deactivation of enzymes.In this work,inverse water-in-oil(W/O)Pickering emulsions were formed using hexanoic acidswollen microgels as the sole emulsifiers.When lipase was added in the water phase,stable oil-in-water-in-oil(O/W/O)Pickering double emulsions could be formed through one-step emulsification,owing to the synergistic effect of the hydrophobic microgels and hydrophilic lipase at the interface.Compared with other biphasic systems,such double emulsion systems represent a desirable platform for highly efficient biodiesel production because of the ultra-high interfacial areas and fast mass transport between two phases.More importantly,the switchable transition between hydrophobicity/hydrophilicity of microgels is controlled by the catalytic reaction.Therefore,double emulsions demulsify spontaneously when substrates are used up without the need for energy input or loss of enzymatic activity,enabling the facile collection of products and demonstrating the excellent recyclability of the biphasic catalysis system.
