Facilitated transport of Hg(II) through novel activated composite membranes

Green synthesis of reduced graphene oxide/polyaniline composite and its application for salt rejection by polysulfone-based composite membranes

In this study, a novel, simple, and eco-friendly enzymatic-reaction-based approach to produce reduced graphene oxide/polyaniline (rGO/PANI) composite material was proposed. Glucose oxidase (GOx) was used as an effective catalyst producing hydrogen peroxide, in the presence of glucose, for the oxidative polymerization of aniline under ambient conditions. The prepared rGO/PANI composite was dispersed in polysulfone (PSf), and the mixed membranes were prepared by the phase inversion polymerization method. The morphology of membranes was investigated using scanning electron microscopy (SEM), atomic force microscopy (AFM), and contact angle (CA) techniques. The performance of membranes was studied in terms of salt rejection and pure water flux. The incorporation of rGO into the membrane matrix led to hydrophobic membrane surface with the enhanced macro-voids. On the contrary, the contact angle data revealed that the rGO/PANI-incorporated membrane surface is partly hydrophilic due to the PANI fibers in membrane, whereas SEM images showed the enhanced macro-voids. Membranes exhibited an improved salt rejection after rGO/PANI doping. The rGO/PANI-modified membrane loading exhibited a maximum of 82% NaCl rejection at an applied pressure of 10 bar. In addition, the results showed that the PSf-rGO/PANI composite membrane had the highest mean porosity and water flux.

Earliest Results in the Use of Activated Composite Membranes for the Transport of Silver Ions from Aqueous Solutions

This paper presents the results concerning the first use of activated composite membranes (ACMs) for the facilitated transport of silver ions containing di-(2-ethylhexyl)-dithiophosphoric acid (DTPA) as the carrier. DTPA was immobilized by interfacial polymerization in a dense layer that was deposited in a porous layer, which was prepared on a nonwoven fabric support by phase inversion. The influence of fundamental parameters affecting the transport of silver ion as the carrier concentration in the membrane phase and stripping agent variation of the stripping solution have been studied. In the optimal conditions, the amount of silver transported across the ACMs was greater than 50%, whereas if the content of the carrier is modified, more than the 90% of the initial silver is removed from the feed phase.

Transport of mercury through liquid membranes containing calixarene carriers

Now membranes are widely used in many industries, e.g, dairy, food and beverage, electronics, starch and sweetener, water and wastewater treatment, pharmaceutical, biotechnology, environmental and so on. In addition to these, liquid membranes have received much attention for developing new, selective and stable systems to improve or perform separation processes involving specific chemical reactions such as ionic species, non-metallic species, bioactive materials, etc. In this aspect, liquid membranes have advantages for high selectivity towards specific ionic species and specific molecular recognition. Liquid membranes have a relatively high efficiency, and as such, are being looked into for industrial applications. We briefly discuss the transport kinetics of mercury using calixarene derivative carriers in liquid membranes and demonstrate various investigations regarding selective transport of mercury in particular using of various calixarene derivatives as a carrier. The review however does not cover all of the different approaches to liquid membrane transport, mercury transport or mercury removal.