Treatment of barium-contaminated wastewaters using adsorption: a review

Barium-containing wastewaters are produced on a large scale by various industries, including electronics, pigment, and ceramics manufacturing. They are also generated by the nuclear industry, where barium chloride is used to precipitate and remove Ra-226. Improper disposal of these wastes can potentially cause various adverse effects on the biosphere because the metal can be toxic to humans and other life forms, depending on the dosage. Therefore, choosing the best available treatment technology that is economically achievable is essential to ensure the safety of both the environment and human health. Among the various methods available for this purpose, adsorption is considered one of the most promising because it offers benefits like low cost, simple design, and high efficiency. This review discusses the use of adsorption for decontaminating industrial wastewaters containing barium. It highlights the adsorptive performance of various materials and explores key factors influencing adsorption, including optimal pH, contact time, and the impact of competing species. The adsorption capacities of various adsorbents ranged from less than 5 mg/g to over 500 mg/g. Adsorption mechanisms such as ion exchange and complexation were described. Surface modifications have been found to significantly improve the performance of some adsorbents. Similarly, nanotechnology has enabled the design of materials with enhanced properties, such as increased surface area and porosity, as well as the ability to be functionalized. Nature-derived adsorbents, in turn, offer the advantages of high environmental compatibility and wide availability, although some of these exhibited poor adsorptive performances. Finally, suggestions for future work include the incorporation of the adsorbents into macrostructures to facilitate their removal after adsorption.