Voltammetric behavior and determination of 17 beta-estradiol at multi-wall carbon nanotube-Nafion modified glassy carbon electrode.

For the purpose of low cost and sensitive electrochemical detection of 17 beta-estradiol (E2), a multi-wall carbon nanotube (MWNT)-Nafion modified electrode was fabricated. The MWNT modified electrode shows enhancement for the anodic peak current of E2 compared with the value obtained using a bare electrode. The anodic peak current measured by square wave voltammetry after 5 min open-circuit accumulation was proportional to the concentration of E2 over the range of 2.5 x 10(-7) to 10 10(-6) M, and a detection limit of 1 x 10(-8) M was obtained.     

Affinity-based elimination of aromatic VOCs by highly crystalline multi-walled carbon nanotubes

Carbon nanotubes (CNTs) are capable of adsorbing pollutant chemicals. Their adsorptive capacities and adsorbing mechanisms, however, are not fully understood. As-grown CNTs often contain both crystalline and amorphous carbon, and the ratio of carbon types can affect adsorption. In this study, highly crystalline multi-walled carbon nanotubes (HC-MWCNTs) were used as the adsorbent for volatile organic compounds (VOCs) in contaminated air samples. Air containing 23 added VOCs (1,1-dichloroethylene, dichloromethane, trans-1,2-dichloroethylene, cis-1,2-dichloroethylene, chloroform, 1,1,1-trichloroethane, carbon tetrachloride, 1,2-dichloroethane, benzene, trichloroethylene, 1,2-dichloropropane, bromodichloromethane, cis-1,3-dichloropropene, toluene, trans-1,3-dichloropropene, 1,1,2-trichloroethane, tetrachloroethylene, dibromochloromethane, m-xylene, p-xylene, o-xylene, bromoform, and p-dichlorobenzene) was used for model samples. Adsorptive experiments were carried out by passing the air samples through a cartridge packed with HC-MWCNTs. Initial results showing high selectivity and high affinity for adsorbing aromatic VOCs (benzene, toluene, m-xylene, p-xylene, o-xylene, and p-dichlorobenzene) have provided new insight into the adsorption mechanisms. Data suggest that the HC-MWCNTs, unlike conventional carbon materials, adsorb aromatic compounds according to Fukui's frontier theory, which is based on the interactions between the HOMO and LUMO of the aromatic VOCs and those of the HC-MWCNTs.     

Encapsulation of multi-walled carbon nanotubes (MWCNTs) in Ba(2+)-alginate to form coated micro-beads and their application to the pre-concentration/elimination of dibenzo-p-dioxin, dibenzofuran, and biphenyl from contaminated water

We report preliminary data on the first use of multi-walled carbon nanotubes as adsorbents for the pre-concentration/elimination of dibenzo-p-dioxin, dibenzofuran and biphenyl from contaminated water.