Propagation and Separation of Charged Colloids by Cylindrical Passivated Gel Electrophoresis

A novel electrocatalytic approach for effective degradation of Rh-B in water using carbon nanotubes and agarose

Carbon nanotubes (CNTs)/agarose (AG) membrane on the ITO (indium tin oxide) conductive glass, with high efficiency of electrocatalytic degradation for rhodamine B (Rh-B) in water, was prepared using an easy and green method. The prepared CNTs/AG membrane was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectra (EDS), infrared spectroscopy (IR), and electrochemical impedance spectroscopy (EIS). The results revealed that CNTs were dispersed in the AG membrane. Additionally, the electrocatalytic activities for Rh-B were conducted on the electrochemical workstation with a three-electrode system. Both initial pH and potential played an important role in the process of electrocatalytic degradation. At pH 3 and potential reaching 4 V, the removal rate of Rh-B (10 mg/L) in water achieved 96% within 20 min. The stability of the prepared CNTs/AG membrane was also investigated. Besides, the toxicities of the main intermediates from the electrocatalytic degradation for Rh-B were calculated using the ECOSAR program and EPIWIN software, and results indicated that the toxicities of some intermediates were higher than those of the parent pollutant (Rh-B). These findings provided a light-spot to simplify the preparation of efficient working electrode and emphasized the possible potential risks from intermediates at the same time.

Micropore Geometry Manipulation by Macroscopic Deformation Based on Shape Memory Effect in Porous PLLA Membrane and its Enhanced Separation Performance

An effective strategy to tailor the microporous structures has been developed based on the shape memory effect in porous poly(l-lactic acid) membranes in which tiny crystals and amorphous matrix play the roles of shape-fixed phase and reversible-phase, respectively. Our results indicate that not only PLLA membranes but micropores exhibit shape memory properties. The proportional deformations on two scales have been achieved by uniaxial or biaxial tension, providing a facile way to manipulate continuously the size and the orientation degree of pores on microscale. The enhanced separation performance has been validated by taking polystyrene colloids with varying diameters as an example.

Influence of ionic constituents and electrical conductivity on the propagation of charged nanoscale objects in passivated gel electrophoresis

When determining the electric field E acting on charged objects in gel electrophoresis, the electrical conductivity of the buffer solution is often overlooked; E is typically calculated by dividing the applied voltage by a separation distance between electrodes. However, as a consequence of electrolytic reactions, which occur at the electrodes, gradients in the ionic content of the buffer solution and its conductivity can potentially develop over time, thereby impacting E and affecting propagation velocities of charged objects, v, directly. Here, we explore how the types and concentrations of ionic constituents of the buffer solution, which largely control its conductivity, when used in passivated gel electrophoresis (P-gelEP), can influence E, thereby altering v of charged nanospheres propagating through large-pore gels. We measure the conductivity of the buffer solution in the center of the gel region near propagating bands of nanospheres, and we show that predictions of E based on conductivity closely correlate with v. We also explore P-gelEP involving two different types of passivation agents: nonionic polyethylene glycol (PEG) and anionic sodium dodecyl sulfate (SDS). Our observations indicate that using a conductivity model to determine E from the local current density and the conductivity where spheres are propagating can lead to a better estimate than the standard approach of a voltage divided by a separation. Moreover, this conductivity model also provides a starting point for interpreting the complex behavior created by amphiphilic ionic passivation agents, such as SDS, on propagating nanospheres used in some P-gelEP experiments.