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The capture of radioactive iodine is an inevitable requirement in nuclear industry for environmental protection. Metal-organic frameworks (MOFs) are a new generation of sorbents that have wide applications for iodine adsorption and recovery. Although the loading of MOFs on wood can avoid the drawbacks of the powder form of MOFs in implementation, the dense structure of wood results in the lower loading, even after delignification, which limits the adsorption capacity. Herein, a hierarchically porous UiO-66-NH 2 @WCA composite was fabricated by in-situ synthesis of UiO-66-NH 2 in wood-derived cellulose aerogel (WCA) that was further removed hemicellulose from delignified wood. UiO-66-NH 2 @WCA exhibited a high loading (36 wt%) of UiO-66-NH 2 crystals and a high adsorption capacity of 704 mg/g for iodine vapor and 248 mg/g for iodine aqueous solution. The adsorption behavior in iodine aqueous solution was well predicted by the Freundlich isotherm and pseudo-second-order kinetic model. The adsorption capacity of UiO-66-NH 2 @WCA was highest in solution when the pH was 6, while the ionic strength had little effect. The hydroxyl groups on the WCA matrix had a charge transfer effect with iodine, providing additional sites for iodine capture. Furthermore, a packed column system was applied to demonstrate the excellent recyclability and potential for practical application., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The capture of radioactive iodine has recently attracted much attention due to the release of radioactive iodine during nuclear waste disposal and disasters. Exploring highly efficient, sustainable, and eco-friendly materials for capturing radioactive iodine has great significance in developing safe nuclear energy. We reported highly efficient, natural, lignin-based, electrospun nanofibers (LNFs) for reversible radioiodine capture. Abundant iodine adsorption sites, such as functional groups and the interaction between the intermolecular forces exist in LNFs. The capacity of the LNFs for the saturated adsorption of iodine was found to be 220 mg·g -1 , which is higher than that of the majority of bio-based adsorbents studied. Moreover, the LNFs exhibited an excellent recycling behavior, and their absorption capacity remained at 84.72% after 10 recycles. Therefore, the results imply that the lignin-based nanofibers can act as a natural, sustainable and eco-friendly packed material for the purification columns in industrial applications. The results demonstrate that the novel, nanostructured, natural biomass, as an ideal candidate has the potential for practical nuclear wastewater purification., (Copyright © 2022 Elsevier B.V. All rights reserved.)

This paper introduces a convenient approach for determining iodate in iodized salt by headspace gas chromatography (HS-GC). The analytical technique can measure the generated carbon dioxide from the redox reaction between iodate and sodium oxalate in the presence of strong acid. The formed carbon dioxide from this reaction in a closed vial is measured by GC. It was observed that the redox reaction in the vial was completed in 40 min at 95 °C. The results indicated that this analytical technique is precise (RSD ≤ 2.69%) and accurate (relative errors ≤ 7.21%). The present approach is fast and simple, providing a robust avenue to the routine estimation of iodate in iodized salt in a wide variety of applications from processing to quality monitoring., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Molecular iodine has been introduced into the alkali lignin (AL) solutions to adjust the π-π aggregation, and the effect of lignin-iodine complexes on the aggregation and assembly characteristics of AL have been investigated by using fluorescence, UV-vis spectroscopy, light scattering, and viscometric techniques. Results show that AL form π-π aggregates (i.e., J-aggregates) in THF driven by the π-π interaction of the aromatic groups in AL, and the π-π aggregates undergo disaggregation in THF-I(2) media because of the formation of lignin-iodine charge-transfer complexes. By using iodine as a probe to investigate the aggregation behaviors and assembly characteristics, it is estimated that about 18 mol % aromatic groups of AL form π-π aggregates in AL molecular aggregates. When molecular iodine is introduced into the AL solutions, lignin-iodine complexes occur with charge-transfer transition from HOMO of the aromatic groups of AL to the LUMO of iodine. The formation of lignin-iodine complexes reduces the affinity of the aromatic groups approaching each other due to the electrostatic repulsion and then eliminates the π-π interaction of the aromatic groups. The disaggregation of the π-π aggregates brings a dissociation behavior of AL chains and a pronounced molecular expansion. This dissociation behavior and molecular expansion of AL in the dipping solutions induce a decrease in the adsorbed amount and an increase in the adsorption rate, when AL is transferred from the dipping solution to the self-assembled adsorbed films. Consequently, the adsorption behavior of AL can be controlled by adjusting the π-π aggregation. Above observations give insight into the occurrence of J-aggregation of the aromatic groups in the AL molecular aggregates and the disaggregation mechanism of AL aggregates induced by the lignin-iodine complexes for the first time. The understanding can provide an academic instruction in the efficient utilization of the alkali lignin from the waste liquor and also leads to further development in expanding functionalities of the aromatic compounds through manipulation of the π-π aggregation.

The surface and total charge density of industrially manufactured hardwood and softwood grade kraft lignocellulosic fibers can mainly be attributed to carboxylic acid functionalities as determined from topochemical adsorption of a cationic polymer (methyl glycol chitosan) and the use of conductometric titration. These charge density measurement methods have led to a powerful and accurate photometric method for the quantitative analysis of surface charge. The method is based on directly monitoring the iodide ion, the counterion of the chitosan polymer, which is released upon electroneutralization between a chitosan cationic site and an anionic site at the fiber surface, thereby directly providing the concentration of surface charge. The stoichiometry for the chitosan adsorption onto the fiber surfaces is unity despite pulp types and adsorption quantity of cationic polymer. Given the high charge density of the chitosan molecule and the determined physical charge density limitations for its distribution onto the surface of pulps, a new and heretofore unused concept referred to as the subsurface was posited to adequately describe the surface charge determination after the adsorption of cationic polymer on the fibers. More specifically, within the subsurface of the suspended fibers in solution, carboxylates (COO-) were neutralized by the cationic sites of chitosan. The COO- sites in the subsurface can electrically attract positive sites of the cationic polymer, resulting in the complete release of counterions. To account for the charge density measurements, the charge measurement of the fibers includes not only nominal topochemical surface charges but also charges below this surface (subsurface)., (Copyright 2004 Elsevier Inc.)