Development of an engineering model for nickel loading onto an iminodiacetic resin for resin-in-pulp applications: Part I—Method development and discussion of rate limiting factors

This paper describes modifications made to the pH-stat procedure to allow for maintaining constant nickel concentrations as well as constant pH over the course of a batch ion exchange loading test. This method allows for a near continuous monitoring of loading rate and produces data that can be analyzed assuming infinite solution volume conditions. It has been shown to have good repeatability and negligible interference from the sodium introduced as sodium hydroxide for the case of nickel loading onto an iminodiacetic acid resin at pH 4. Data from a series of experiments for the loading of nickel, cobalt, and copper onto an iminodiacetic chelating resin in the hydrogen form are presented. From this work it can be seen that film diffusion only contributes at the very beginning of the tests. For the majority of the data both intraparticle diffusion and the ion exchange reaction are contributing to the overall rate of loading.