Methods for Removal of Radioactive Compounds from Aqueous Solution: a Review

 Radioactive compounds in water and wastewater have raised global concerns. Numerous epidemiological studies have shown that these substances can endanger the health of humans and animals. These contaminants must be removed before entering the natural cycle due to their carcinogenic properties. This study investigated the processes of removing radioactive compounds from water and wastewater.

 For this purpose, related articles were selected from Scopus, PubMed, and Web of Science databases. Overall, 89 articles were retrieved, and ultimately 11 articles were reviewed after removing duplicates and deleting unrelated studies. Experimental conditions, including pH, temperature, initial concentration, adsorbent dose, ionic strength, and contact time, as well as adsorbent regeneration and adsorption/recovery capacity, were extracted from these studies. 

 Almost all adsorption experiments were performed at room temperature and showed that higher temperature leads to higher adsorption rates. More than 45% of studies determined the optimum pH at the 6-7 range. In addition, increasing the initial concentration improves the adsorption capacity while reducing metal ion recovery. Most articles (44%) used of Langmuir equation to model isotherm studies. In addition, about 41% of them described the adsorption kinetics with a pseudo-second-order model and suggested chemical adsorption as a velocity-limiting step. 

 As discussed in this review, decontamination of such wastewater is much more challenging than handling conventional industrial and municipal wastewater. However, further studies concerning well-designed large-scale studies are needed to strengthen the evidence.