Influence of solution pH and background electrolytes on heavy metals ion adsorption by activated carbons from aqueous solutions

CARBON

4 7 ( 20 0 9 ) 2 3 0 1–23 0 2

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journal homepage: www.elsevier.com/locate/carbon

Tanso 237 — Abstracts Electron microscope studies on the disintegration of core/shell polymer structure during heat treatment in carbon nanotube preparation by a polymer blend technique a

a

a

b

Terukazu Sandou , Asao Oya , Chiemi Ida , Noriko Yoshizawa , Jun-ichi Ozakia a

Graduate School of Engineering, Gunma University, 1-5-1 Tenjin-cho,

Kiryu, Gunma 376-8515, Japan b

National Institute of Advance Industrial Science and Technology

(AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan

The adsorption of cadmium and zinc ions, IIb family heavy metals, from aqueous solutions onto two activated carbons of different surface nature, one with acidic functional groups prepared by concentrated nitric acid oxidation (oxidized carbon) at 95 °C and the other with no acidic functional groups treated at 1000 °C in helium flow (out-gassed carbon), was investigated to clarify the influence of background electrolyte on the adsorption performance. The cadmium uptake onto oxidized carbon was found to be decreased by the coexistence of NaCl, because Na+

The polymer blend technique has been revealed to give a poor

occupied adsorption sites for cadmium. For the out-gassed car-

yield in the preparation of carbon nanotubes (CNTs) by spinning

bon, the cadmium uptake was increased at low pH due to the for-

three-layered core/shell polymer particles with different thermal

mation of complex anions of CdCl3 and CdCl4 , but zinc uptake

decomposition properties. In order to elucidate the reason for the

was not changed at any pH, because chloride anions could not

2

low yields on this method, we carried out the present study on

make a complex with zinc ions. Under the coexistence of NaNO3,

using three-layered core/shell particles, (core) PMMA/PAN-

the increase in cadmium uptake to the out-gassed carbon was not

PMAA/PMMA (shell), with electron microscope techniques. The

observed because the complex is no longer formed with nitrate

core/shell structure did not disintegrate in the stabilization and

anions for cadmium. For simultaneous adsorption of cadmium

carbonization processes. The influence of the copolymer compo-

and zinc ions onto the out-gassed carbon under the coexistence

sition of the carbon precursor polymer (CPP), PAN-PMAA, on the

of NaCl, only cadmium could be adsorbed at low pH as expected.

deformation of the core/shell structures was studied. When the

The results suggest that the separation of these IIb family ions

concentration of PMAA in the PAN-PMAA copolymer is 3 mol%,

may be achieved using out-gassed carbon.

the core/shell structure was retained, but when the concentration

TANSO 2009 (No. 237) 61–6.

of PMAA was increased to 7.5 mol%, the core/shell structure disintegrated. By using a copolymer with 4 mol% PMAA, a hollow

doi:10.1016/j.carbon.2009.04.006

cigar-like nano-structured carbon was formed. This can be considered to be an indication for the formation of a CNT. Thus, the copolymer composition was found to be an important parameter for the preparation of CNTs by the polymer blend technique. The results obtained indicate the possibility of obtaining CNTs by properly tuning the copolymer composition of the CPP. TANSO 2009 (No. 237) 57–60.

Analysis of surface structure of carbon materials by using temperature-programmed desorption method Hideyuki Takagi National Institute of Advanced Industrial Science and Technology, Energy Technology Research Institute, Energy Storage Materials Group,

doi:10.1016/j.carbon.2009.04.005

16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan Temperature-programmed desorption (TPD) is useful for ana-

Influence of solution pH and background electrolytes on heavy metals ion adsorption by activated carbons from aqueous solutions Kazuya Yoshiharaa, Masami Aikawab, Motoi Machidaa,c a

Graduate School of Engineering, Chiba University, 1-33 Yayoi-cho,

Inage-ku, Chiba 263-8522, Japan b

Faculty of Science, Kisarazu National College of Technology, 2-11-1

Kiyomidai-higashi, Kisarazu, Chiba 292-0041, Japan c

Safety and Health Organization, Chiba University, 1-33 Yayoi-cho,

Inage-ku, Chiba 263-8522, Japan

doi:10.1016/S0008-6223(09)00213-9

lyzing the surface structure, i.e. oxygen-containing functional groups, of carbon materials. This review introduces the analysis of the activated carbon fiber sample by the TPD method, and discusses changes in the functional groups caused by the oxidation treatment, and the relationship with the porosity parameters estimated from the nitrogen adsorption isotherm. In addition, the structures of single-walled carbon nanotube (SWCNT) samples treated with nitric acid and then heated in either an inert gas or a hydrogen flow were evaluated by the TPD method. Subsequent, heat treatment of the acid-treated SWCNT sample is effective for increasing nitrogen or hydrogen adsorption due to the