Simultaneous Extraction and Concentration in Carbon Nanotube Immobilized Hollow Fiber Membranes

Carbon Nanotube Based Groundwater Remediation: The Case of Trichloroethylene

Adsorption of chlorinated organic contaminants (COCs) on carbon nanotubes (CNTs) has been gaining ground as a remedial platform for groundwater treatment. Applications depend on our mechanistic understanding of COC adsorption on CNTs. This paper lays out the nature of competing interactions at play in hybrid, membrane, and pure CNT based systems and presents results with the perspective of existing gaps in design strategies. First, current remediation approaches to trichloroethylene (TCE), the most ubiquitous of the COCs, is presented along with examination of forces contributing to adsorption of analogous contaminants at the molecular level. Second, we present results on TCE adsorption and remediation on pure and hybrid CNT systems with a stress on the specific nature of substrate and molecular architecture that would contribute to competitive adsorption. The delineation of intermolecular interactions that contribute to efficient remediation is needed for custom, scalable field design of purification systems for a wide range of contaminants.

A physical entrapment method for the preparation of carbon nanotube reinforced macroporous adsorption resin with enhanced selective extraction performance

In this paper, we demonstrate a novel carbon nanotube (CNT) reinforced macroporous adsorption resin (MAR) for the first time. The CNTs were dispersed in water via sonication, and then in situ physically entrapped in the pores of MAR by capillary forces and sonication. The resulting CNT reinforced MAR (CNT-MAR) was proved by transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM), and subsequently applied to extract a mixture of 8 types, 14 natural products. For comparison, the extraction efficiency of original MAR without CNTs was also evaluated. After extraction, the supernatants were detected via high-performance liquid chromatography (HPLC). The results indicated that the introduction of carbon nanotubes (CNTs) into the pores of MAR can significantly improve the adsorptive selectivity of MAR for natural products. The original MAR without CNTs has almost the same adsorption capacity for selectively extracting 3 types of natural products (phenols, alkaloids and anthraquinones). However, the CNT-MAR only could selectively extract anthraquinones and the adsorption capacity for three anthraquinone natural products is 1.46-1.83 times higher than that of unmodified MAR. In order to achieve the highest extraction efficiency of CNT-MAR for anthraquinone natural products, the main extraction parameters such as the extraction time and the pH value were also optimized. The CNT-MAR demonstrated an excellent ability to extract anthraquinone natural products with high selectivity and adsorption capacity. Due to its low cost, easy preparation and use, and operational characteristics, it shows great potential for selective extraction of natural products.

Novel sorption-based methodologies for static microextraction analysis: A review on SBSE and related techniques

Stir bar sorptive extraction (SBSE) became a well-established analytical technique in the last years, for which hundreds of applications in almost all types of scientific fields can be found in the literature. In spite of the great enrichment capacity and outstanding performance to operate at the ultra-trace level, this remarkable static sorption-based method is already not quite effective for some complex systems, in particular to monitor the large group of polar organic compounds. This review aims to cover the state-of-the-art in SBSE, as well as supplying a discussion of the analytical potential of the novel adsorptive microextraction techniques, as complementary enrichment approaches, by explaining the main principles and providing technical know-how for the beginners.

Water desalination using carbon-nanotube-enhanced membrane distillation

Carbon nanotube (CNT) enhanced membrane distillation is presented for water desalination. It is demonstrated that the immobilization of the CNTs in the pores of a hydrophobic membrane favorably alters the water-membrane interactions to promote vapor permeability while preventing liquid penetration into the membrane pores. For a salt concentration of 34 000 mg L(-1) and at 80 °C, the nanotube incorporation led to 1.85 and 15 times increase in flux and salt reduction, respectively.