Iminodisuccinic acid (IDHA) as an effective biodegradable complexing agent in the adsorption process of La(III), Nd(III) and Ho(III) ions

Abstract

Environmental pollution and the continued depletion of many deposits have made the recycling of used materials an urgent need. An important aspect of this topic is the development of alternative compounds with a more favourable environmental profile compared to those currently in use. Indeed, when designing such processes, the negative human impact on the environment should be mitigated as much as possible. This paper presents the results of a study on the application of biodegradable complexing agent iminodisuccinic acid (IDHA) for the recovery of La(III), Nd(III) and Ho(III) by adsorption (single-component systems, static and dynamic methods) using various types of ion exchangers. The results obtained allow to determine the optimal process conditions and show that the chelating ion exchanger Purolite S957 has the highest adsorption capacity related to the La(III) complexes (142.29 mg/g), while the Nd(III) and Ho(III) complexes adsorb with the highest efficiency (161.04 mg/g for Nd(III) and 201.74 mg/g for Ho(III)) in the cation exchanger Lewatit SP112. According to the desorption studies the adsorbents are characterized by a large regeneration capability. This paper also presents the characterization of the physicochemical properties of the applied ion exchangers and the analysis of the binary systems (Ln(III)-IDHA) to determine the overall stability constants of the complexes using the potentiometric methods. Biodegradable IDHA was used to this aim.