THE BEHAVIOR OF SOLUBLE METALS ELUTED FROM Ni/Fe-BASED ALLOY REACTORS AFTER HIGH-TEMPERATURE AND HIGH-PRESSURE WATER PROCESS

M. Faisal (Department of Chemical Engineering, Faculty of Engineering, Syiah Kuala University, Jl. Syech Abdurrauf No. 7, Darussalam-Banda Aceh 23111, Indonesia)
Hiroyuki Daimon (Department of Environmental and Life Science, Toyohashi University of Technology, Toyohashi, Aichi 441-8580, Japan)
Koichi Fujie (Graduate School of Environment and Information Sciences Yokohama National University, Yokohama, 24-8501 Japan)

Reaktor
Volume 14, Nomor 1, April 2012

The behavior of heavy metals eluted from the wall of Ni/Fe-based alloy reactors after high-temperature and high-pressure water reaction were studied at temperatures ranging from 250 to 400oC. For this purpose, water and cysteic acid were heated in two reactor materials which are SUS 316 and Inconel 625. Under the tested conditions, the erratic behaviors of soluble metals eluted from the wall of Ni/Fe-based alloy in high temperature water were observed. Results showed that metals could be eluted even at a short contact time. The presence of air also promotes elution at sub-critical conditions. At sub-critical conditions, a significant amount of Cr was extracted from SUS 316, while only traces of Ni, Fe, Mo and Mn were eluted. In contrast, Ni was removed in significant amounts compared to Cr when Inconel 625 was tested. It was observed that eluted metals tend to increased under acidic conditions and most of those metals were over the limit of WHO guideline for drinking water. The results are significant both on the viewpoint of environmental regulation on disposal of wastes containing heavy metals, toxicity of resulting product and catalytic effect on a particular reaction.