Coagulation characteristics of humic acid modified with glucosamine or taurine |
| |
Authors: | Terashima Motoki Tanaka Shunitz Fukushima Masami |
| |
Institution: | Research Institute for Humanity and Nature, RIHN, 457-4 Motoyama Kamigamo, Kyoto 603-8047, Japan. TerashimaM@chikyu.ac.jp |
| |
Abstract: | To suppress the coagulation of humic acid (HA) in aqueous solutions, HA was modified with hydrophilic amines, such as glucosamine or taurine. These amines were attached to carboxyl groups in HA via amide bond formation. The degree of modification (R(m)) was estimated to be 21-38%. Infrared spectra of the modified HAs were also consistent with the presence of amide bonds. Acid-base titration showed that the average acid-dissociation constant (pK(app)) of the HA samples was increased by the modification. The Ca(2+) binding capacity of HA decreased with an increase in R(m) value. Critical pH or Ca(2+) concentration, at which HA coagulation occurs, was increased as the result of the modification. These critical points for taurine-HA were higher than those for glucosamine-HA. This is mainly due to electrostatic repulsion by sulfonate groups in taurine. These results indicate that the coagulation of HA is suppressed by modifying the molecules with glucosamine or taurine. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
|