Preparation Of Molybdenum Diselenide Based Nanomaterials With Adsorption Performance

The adsorption method has became the most widely used organic wastewater treatment method in industry due to its advantages of simple operation,low secondary pollution,economical and environmental protection and so on.The adsorbent is the core element of the adsorption method,so develop the high-performance adsorbents is of great significance.In the thesis,the ultrathin MoSe2 and the composites of MoSe2/rGO were prepared by hydrothermal method,and all exhibited excellent piezoelectric adsorption characteristics under the action of ultrasound,which is the application of two-dimensional transition metal chalcogenides(TMDs)in the field of adsorption provide theoretical basis and technical support.The ultrathin MoSe2 were first prepared by hydrothermal method using a series of analytical testing techniques to study the effect of hydrothermal time on the composition structure and adsorption properties of MoSe2.The results showed that when the hydrothermal time was 24 h,the obtained MoSe2 materials have uniform morphology,thin lamellar structure and large interlayer spacing.Under ultrasonic action,the adsorption rate of malachite green can reach 85%within 5 s,which is much larger than that under stirring(38%).Accordingly,the adsorption mechanism with piezoelectric effect is proposed.The electron separation and transfer ability of MoSe2 under ultrasonication was further improved.MoSe2/rGO composites were prepared by hydrothermal method after introducting the graphene.The effects of different amounts of graphene on the crystal structure,phase state and adsorption properties of the samples were investigated.It showed that the MoSe2/rGO synthesized by adding 5 mL GO dispersion was uniform in size and best in dispersion.The rate of adsorption for MoSe2/rGO on MG can reach 90%after ultrasonic 5 s and 100%desorption can be achieved after adding 400 mL ethanol as desorption agent.Compared with ultrathin MoSe2,the piezoelectric induction charge on the surface of MoSe2 is successfully dredged to rGO,which effectively improves the adsorption performance of adsorbent.The adsorption kinetics,adsorption isothermal model and adsorption thermodynamics of ultrathin MoSe2 and MoSe2/rGO composites were investigated.It can be seen that the adsorption process of MG by MoSe2 and MoSe2/rGO follows the quasi-second-order rate equation(the correlation parameters R2 are 0.9999).The equilibrium adsorption capacity of MoSe2 and MoSe2/rGO to MG are 208.3 mg g-1 and 232.0 mg g-1.Moreover,the adsorption of MG by both MoSe2 and MoSe2/rGO is spontaneous process,and increasing temperature is beneficial to adsorption.After comparing the adsorption properties of MoSe2 and MoSe2/rGO for different adsorbates(methine blue,rhodamine B(RhB)and tetracycline hydrochloride(TC)),it proved that the surface induced charge generated by piezoelectric effect was beneficial to the process of adsorption and the adsorption mechanism was by a process of ?-? adsorption.