Variable for the synthesis of the Iron oxide/hydroxide used in this study is the pH with time. pH conditions are 4.0, 6.0, 8.0, 10.0, 12.0, 14.0, and the reaction time was adjusted to 1hour and 24 hours. Synthesis results, Goethite is mainly generated in the low pH and Magnetite is systhesized at a high pH. The range of pH 6.0-12.0 includes the Lepidocrocite. In the case of samples synthesized in pH 4.0 and 6.0 mainly consisting of Goethite, The crystallinity of Goethite is higher as the reaction time increases and tends to increase when pH in high in the same reaction time.
In the form of synthesis iron oxide/hydroxide are composed of circular or flat-type particles, the particle size tends to increase from about 10nm to about 200nm as pH condition and the reaction time increase. The specific surface area increases when pH is low and the reaction time is short. Samples that were collected after making them react in pH 4.0 and 6.0 for an hour and 24 hours had higher specific surface area than samples synthesized under other conditions of pH and reaction time.
The result about adsorption experiments of synthetic iron oxide/hydroxide about heavy metal solutions, arsenic was removed first in most of the samples regardless of the concentration of the initial heavy metal solution. In particular, The removal ratio is the highest when the reaction time is 1hour and pH is 6.0. The other heavy metals represent a very low adsorption ratio at the most of the synthesis iron oxide/hydroxide.
Re-elution experiment results, Re-elution ratio of arsenic is very low, but lead is re-eluted more than 30%. This indicates that arsenic can''t be re-eluted because it is stably adsorbed in crystal structure, but lead is easily re-elupted because it is attached to the surface. The optimum synthesis conditions for selectively removing arsenic from mixed heavy metal solutions are pH 6.0, the reaction time 1hour. The iron oxide/hydroxide synthesized under those conditions are judged that there can be used as adsorbent for removing arsenic