Alkali chlorides-induced phase separation of acetonitrile–water mixtures studied by small-angle neutron scattering

✍ Scribed by Toshiyuki Takamuku; Yasukuni Noguchi; Eiichi Yoshikawa; Tomomi Kawaguchi; Masaru Matsugami; Toshiya Otomo

• Publisher: Elsevier Science
• Year: 2007
• Tongue: English
• Weight: 757 KB
• Volume: 131-132
• Category: Article
• ISSN: 0167-7322
• DOI: 10.1016/j.molliq.2006.08.048

✦ Synopsis

Alkali chlorides (MCl, M = Li + , Na + , and K + ) -induced phase separation of acetonitrile-water mixtures at 298 K has been investigated. Phase diagrams of acetonitrile-H 2 O-MCl systems have shown that phase separation of the mixtures occurs at lower salt concentration in the order of NaCl b KCl b LiCl. Phase separation of acetonitrile-D 2 O-MCl systems takes place in the same order as the acetonitrile-H 2 O-MCl ones, but the D 2 O systems are separated at lower concentration of each salt than the H 2 O systems. To clarify phase separation of acetonitrile-water-MCl mixtures at a mesoscopic scale, small-angle neutron scattering (SANS) experiments have been made on acetonitrile-D 2 O-MCl mixtures before phase separation as a function of salt concentration. The SANS results in terms of the Ornstein-Zernike correlation length have suggested that D 2 O clusters are more easily evolved with increasing salt concentration in the order of NaCl N KCl N LiCl, which is in agreement with the order of phase separation. Based on the present results, mechanisms of LiCl-, NaCl-, and KCl-induced phase separation of acetonitrile-water mixtures have been discussed.