Background: The thyroid gland is a cornerstone of the endocrine system, regulating metabolism, growth, and development through its synthesis of thyroid hormones. The micronutrient iodine is an indispensable component of these hormones, and its availability is a critical determinant of thyroid health. Both deficiency and excess of iodine can lead to a spectrum of thyroid pathologies, representing a significant global health challenge.

Objective: This review aims to provide a comprehensive analysis of the intricate relationship between iodine and thyroid function. It synthesizes evidence on iodine metabolism, dietary requirements, the pathophysiology of iodine-related disorders, and the public health strategies implemented to mitigate them.

Methods: A systematic literature review was conducted, analyzing 56 seminal and contemporary research articles. The selected literature covers the foundational biochemistry of thyroid hormone synthesis, the epidemiology of iodine deficiency disorders (IDD), the neurodevelopmental consequences of iodine insufficiency, the impact of environmental and dietary goitrogens, and the global outcomes of salt iodization programs.

Results: The synthesis of the literature confirms that iodine uptake is a tightly regulated process involving the sodium-iodide symporter (NIS) and pendrin. Iodine deficiency is causally linked to hypothyroidism, goiter, and cretinism, with profound, irreversible effects on fetal and childhood neurodevelopment. Factors such as perchlorates, thiocyanates, and deficiencies in selenium and iron can exacerbate iodine-related disorders. While universal salt iodization has been a landmark public health success, challenges remain, including monitoring population iodine status, addressing deficiencies in vulnerable groups (e.g., pregnant women, vegans), and managing the risks of iodine-induced hyperthyroidism in previously deficient populations.

Conclusion: Maintaining optimal iodine nutrition is paramount for the prevention of thyroid pathologies. Effective and continuous monitoring of salt iodization programs and public education are essential to eradicate iodine deficiency disorders and ensure global thyroid health.

This study investigates the adsorption of Ag⁺ ions by polymer sorbents impregnated with organic ligands using IR spectroscopy. Comparative spectra recorded before and after adsorption show systematic shifts of characteristic vibrational bands, confirming coordination-driven complex formation between Ag⁺ and donor functional groups on the sorbent surface. Ligands such as MAB, DEDTK, and DADTFK bind within the polymer matrix and yield stable metal–ligand complexes; diagnostic changes are observed in bands assigned to N–H, C=N, and, for phosphorus-containing ligands, P=S and P–S modes. The polymer matrix exhibits the expected polystyrene signatures, against which new or shifted bands are benchmarked to infer interaction strength and site specificity. The results underscore the decisive role of ligand functionality in designing selective sorbents for silver ion separation and purification.

The influence of the medium’s acidity and temperature on the sorption of silver ions by impregnated polymer sorbents was investigated. The sorption process was studied in the pH range of 1–12 using PAD400, PAD600, and FK-based sorbents modified with chelating ligands such as MAB, Dtz, and DEDTK. The results demonstrated that the sorption efficiency strongly depends on the acidity of the solution, with maximum sorption observed at pH = 3. The kinetics of silver ion sorption were analyzed using pseudo-first-order, pseudo-second-order, and intra-particle diffusion models. Experimental data showed that the sorption process reaches equilibrium within 60 minutes. Comparison of the kinetic parameters revealed that the pseudo-second-order model best describes the sorption process for all sorbents, with correlation coefficients (R² > 0.99) and calculated equilibrium capacities (Qₑ,calc) consistent with experimental data (Qₑ,obs). These findings indicate that the rate-limiting step of the sorption process is the surface chemical reaction between the functional groups of the sorbent and silver ions.