The increasing use of nuclear technologies has resulted in growing environmental concerns due to uranium (VI) contamination in surface and groundwater. U(VI) forms are highly soluble and mobile under natural conditions, making their removal from aqueous systems both urgent and challenging. Developing low-cost and efficient sorbents for uranium removal is therefore essential.

Organoclays based on natural minerals modified with quaternary ammonium salts represent a promising class of sorbents. In this work, montmorillonite—a naturally occurring layered clay mineral—was modified with cationic surfactants to enhance its affinity for uranium ions. Specifically, tetramethylammonium chloride (С1), dodecylammonium chloride (С12), tetradecylammonium chloride (С14), and hexadecyltrimethylammonium chloride (С16) were used to functionalize the clay surface.

The modification involved ion exchange, where native cations were replaced by alkylammonium groups, resulting in a positively charged surface favorable for the sorption of anionic or weakly hydrated uranyl complexes.

Modification was conducted in several steps: conversion to the Na form followed by treatment with ammonium salts under varying conditions. The effects of temperature, solvent type, solid-to-liquid ratio, and contact time were optimized. Sorption experiments revealed that the modified materials exhibited significantly higher U(VI) uptake than unmodified montmorillonite, especially at pH values between 5 and 9. Adsorption isotherms at pH 6 showed a clear increase in capacity with longer alkyl chains of the modifying agent.

The study highlights that surface modification plays a critical role in tailoring clay minerals for selective uranium binding. Given their availability, low cost, and enhanced sorption performance, organomontmorillonite sorbents are promising candidates for use in environmental remediation technologies targeting uranium-contaminated water.