Effects of different substrates on the adsorption behavior of supported-adsorbents: A case study of MoS₂ for Ag⁺ adsorption

Supported-adsorbents growing on the substrate in situ are equipped with the advantages of high adsorption capacity, excellent regeneration performance, and adaptability to complex wastewater. However, the effects of substrate on the adsorption properties of supported-adsorbent are rarely considered, which will hinder its development and scale-up applications. In this study, the influences of different substrates (Ti, Mo, W, CC) on the Ag⁺ adsorption behavior of supported-MoS₂ adsorbents were investigated. The adsorption kinetics, adsorption mechanism, and the renewability of these supported-MoS₂ were compared orderly. As a result, MoS₂ grown on a tungsten substrate (MoS₂-W) exhibits a remarkable adsorption capacity for Ag⁺ (1.98 mg cm^-2 and 598.80 mg g^-1), which is 6.38-33 times more than the other three supported-MoS₂. Moreover, the MoS₂-W also possesses an ultrahigh distribution coefficient (24.80 mL cm^-2) for Ag⁺, and the selection coefficient can reach 1984. XRD and electrochemical characterization analysis indicated that Ag⁺ adsorption performance of supported-MoS₂ is positively correlated with the degree of its amorphous structure. Substrate W with the terrific electrical properties which may facilitate the disordered growth of MoS₂, resulting in more active sites exposed, and endow MoS₂-W with outstanding Ag⁺ capture performance. Finally, the supported-MoS₂ retains a high removal efficiency of Ag⁺ after 5 cycles of adsorption and desorption. This study provides a novel perspective for promoting the practical application of supported-sorbents to recycle heavy metals.