Hollow Co3S4 polyhedron decorated with interlayer-expanded MoS2 nanosheets for efficient tetracycline removal from aqueous solution

In this study, hollow Co3S4 polyhedron decorated with interlayer-expanded MoS2 nanosheets (Co3S4-MoS2) was devised and applied to absorb tetracycline (TC) from aqueous solution. The adsorption performances and mechanisms were systematically explored. The experimental results indicated that the adsorption kinetics well-fitted the pseudo-second-order kinetics model and the adsorption isotherms followed the Langmuir model. In terms of Langmuir model, the maximum adsorption capacity of Co3S4-MoS2 was achieved with a record-high value of 1667.14 mg/g at 308 K, which was much higher than that of other reported adsorbents. The excellent adsorption performance of the adsorbent toward TC was presented under a wide pH range (3.0–8.0) and was enhanced by the addition of salinity. The high adsorption capacity of Co3S4-MoS2 depended on the combined effects of multi-affinities including π-π interaction, hydrophobic effect, surface complexation and hydrogen bonding. These results suggested that Co3S4-MoS2 was a high-efficiency adsorbent for treating wastewater that contains TC and provided new insights into the design of other hollow metal sulfides nanomaterials to treat antibiotic-containing wastewater.