Nano-diamond particles functionalized with single/double-arm amide–thiourea ligands for adsorption of metal ions

• Published in: Journal of colloid and interface science 2016-05, Vol.469, p.109-119
• Main Authors: Zhao, Xiaosheng, Zhang, Shuang, Bai, Chiyao, Li, Bo, Li, Yang, Wang, Lei, Wen, Rui, Zhang, Meicheng, Ma, Lijian, Li, Shoujian
• Format: Article
• Language: English
• Subjects: Adsorbents; Adsorption; Amide–thiourea; Ligands; Metal ions; Nanodiamond; Nanostructure; Neodymium; Selectivity; Spatial configuration; Uranium
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2016.02.017

[Display omitted] •Nanodiamond-based adsorbents for separation of uranium were synthesized firstly.•The adsorbents were composed with single or double arms of amide thiourea chains.•Comparative studies were carried out on adsorption behaviors of the adsorbents.•Single-armed adsorbent exhibited higher selectivity for uranium.•The mechanism basing on spatial configuration and chelate ability was proposed. Separation efficiency of solid-phase extractant is greatly subjected to the spatial configurations of functional ligands attached to the matrix, which has not been studied efficiently till now. In order to further understand the relationship between spatial configurations of the attached functional ligand and the adsorption ability of the extractant, two novel molecules (single-armed ligand, SA and double-armed ligand, DA) with identical coordination unit (amide–thiourea) but different spatial configurations (single/double arms) were designed and synthesized. The corresponding extractants, ND-SA and ND-DA were obtained by modification of nanodiamond (ND) with SA and DA and both the extractants displayed good chemical and thermal stabilities. The batch adsorption experiments showed that ND-SA and ND-DA possess large adsorption capacities (∼200mgg−1), very fast adsorption kinetics (reaching equilibrium within 2min) and excellent selectivities (up to 82% and 72%, respectively) for uranium. The study of the possible mechanism indicated that ND-DA tends to utilize its tweezer-like double arms to “clamp” metal ions and the stronger chelate interaction could to some extent weaken the coordination selectivity of attached DA ligand. In contrast, single-armed adsorbent ND-SA unexpectedly exhibited better adsorption selectivity for uranium than ND-DA owing to its more flexible spatial configuration and moderate complexing ability.