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.