TY - JOUR
T1 - Formation conditions and stability of a toxic tridecameric Al polymer under a soil environment
AU - Etou, Akira
AU - Bai, Shuqin
AU - Saito, Tomoyuki
AU - Noma, Hiroaki
AU - Okaue, Yoshihiro
AU - Yokoyama, Takushi
N1 - Funding Information:
This work was financially supported by a Grant-in-Aid from the Ministry of Education, Culture, Science, Sports, and Technology of Japan (18651014), and the Global COE Program, “Science for Future Molecular Systems” from the Ministry of Education, Culture, Science, Sports, and Technology of Japan. This work was also by financially supported from Kyushu University Interdisciplinary Programs in Education and Projects in Research Development. The measurement of 27 Al NMR was made at the Center of Advanced Instrumental Analysis, Kyushu University. The authors thank Mr. Takayasu Egashira and Mr. Hidetaka Yano for their contribution to this work in the first step.
PY - 2009/9/15
Y1 - 2009/9/15
N2 - It is important to study the formation conditions and the stability of the tridecameric Al polymer (Keggin-type Al13 polycation, [AlO4Al12(OH)24(H2O)12]7+, known as Al13) due to its strong toxicity to living organisms of a soil environment. In order to examine the pH range where toxic Al13 can exist in aqueous solution, 27Al NMR spectra for sample solutions containing Al3+ ions with various pH (pH 3.5-6.1) were measured. The results show that the peak due to Al13 (peak due to 4-coordinated Al around 63 ppm) appeared at pH 3.6-5.7 and the peak intensity was relatively high at pH 4.1-4.8, suggesting that Al13 can be formed at pH 3.6-5.7, while it can exist dominantly at pH 4.1-4.8. It was also found that Al13 can stably adsorb onto a chelate resin, Chelex 100, by weak electrostatic interaction. The Chelex 100, with iminodiacetate groups, served as a model compound for surfaces of microbes covered with carboxyl groups and for surfaces of soil particles covered with humic substances having many carboxyl groups. Additionally, decomposition of Al13 did not occur even after adsorption, and its pH stability range was wide compared to that in aqueous solution.
AB - It is important to study the formation conditions and the stability of the tridecameric Al polymer (Keggin-type Al13 polycation, [AlO4Al12(OH)24(H2O)12]7+, known as Al13) due to its strong toxicity to living organisms of a soil environment. In order to examine the pH range where toxic Al13 can exist in aqueous solution, 27Al NMR spectra for sample solutions containing Al3+ ions with various pH (pH 3.5-6.1) were measured. The results show that the peak due to Al13 (peak due to 4-coordinated Al around 63 ppm) appeared at pH 3.6-5.7 and the peak intensity was relatively high at pH 4.1-4.8, suggesting that Al13 can be formed at pH 3.6-5.7, while it can exist dominantly at pH 4.1-4.8. It was also found that Al13 can stably adsorb onto a chelate resin, Chelex 100, by weak electrostatic interaction. The Chelex 100, with iminodiacetate groups, served as a model compound for surfaces of microbes covered with carboxyl groups and for surfaces of soil particles covered with humic substances having many carboxyl groups. Additionally, decomposition of Al13 did not occur even after adsorption, and its pH stability range was wide compared to that in aqueous solution.
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U2 - 10.1016/j.jcis.2009.05.079
DO - 10.1016/j.jcis.2009.05.079
M3 - Article
C2 - 19580976
AN - SCOPUS:67650973426
SN - 0021-9797
VL - 337
SP - 606
EP - 609
JO - Journal of Colloid and Interface Science
JF - Journal of Colloid and Interface Science
IS - 2
ER -