Manganese silicate/MoS2 composite material with high adsorption capacity for the selectively removing Cs+ from aqueous solution over a wide pH

Abstract

The wastewater generated by nuclear power plants contains a large number of radioactive substances, including 134Cs and 137Cs, which pose significant threats to human health and the environment. It is crucial to remove these radioactive substances from the nuclear waste. A significant challenge we encounter is the effective and selective extraction of cesium ions from wastewater. The wastewater is typically rich in competition ions and spans a wide pH range. In this report, we report a novel manganese silicate/MoS2 composite material with high adsorption capacity for selectively removing Cs+ from aqueous solutions with competition ions. Adsorption behaviors of cesium ions were investigated for composite ratio, adsorbent dosage, contact time, pH and competitive cations. Optimal conditions for the adsorption of cesium ions from aqueous solutions were achieved using a composite ratio of manganese silicate to MoS2 at 9:1, an adsorbent concentration of 1.0 g L−1, and a pH of 8 for a duration of 1 h. While the impact of K+ and Na+ is minimal at lower concentrations, it becomes more pronounced with increasing concentrations. The composite material demonstrates effective performance over the pH range of 2.0–12.0. Experimental data fitted with the pseudo-second-order kinetics and the Langmuir isotherm model suggests a single-layer chemical adsorption process, resulting in a remarkable adsorption capacity of 78.99 mg g−1. Microscopic analysis reveals the synergistic effect of manganese silicate and MoS2. The manganese silicate provides efficient active sites for selective Cs+ adsorption, while MoS2 allows the highly dispersed surface for manganese silicate. This work reveals new insights into the design and synthesis of high-performance Cs+ adsorption materials for application in the treatment of nuclear wastewater.