MoS_(2)/壳聚糖复合微粒的制备及其对水体中Pb(Ⅱ)的吸附性能与吸附机制

Preparation of W-MoS_(2)/CS beads and high-efficiency adsorption performance and mechanisms of Pb(Ⅱ)in aquatic systems

以MoS_(2)及壳聚糖(CS)为原料制备W-MoS_(2)/CS复合微粒,分析MoS_(2)掺杂对复合微粒形貌及孔隙结构的影响,考察吸附过程中溶液pH值、初始浓度、吸附时间及共存离子等因素对Pb(Ⅱ)的吸附容量的影响.结果表明:W-MoS_(2)纳米花被均匀掺杂进CS凝胶内后,起到了一定的固定、粘合凝胶结构的作用,使得复合微粒结构更坚实,表面更粗糙,并且保持了良好的孔隙结构.随着pH值在4~7范围内增加,复合材料对Pb(Ⅱ)的吸附量持续增大,在pH=7时达到最大值.W-MoS_(2)/CS复合微粒吸附速率在30 min前先急剧升高,最后在120 min左右达到吸附平衡.实验中W-MoS_(2)/CS复合微粒对Pb(Ⅱ)的吸附更符合Langmiur模型,表明吸附过程以单层吸附为主,并且W-MoS_(2)/CS-2(50 mg MoS_(2))复合微粒的理论最大吸附容量为663.7 mg/g,优于大多数碳基和硫功能化的纳米材料.同时研究发现复合微粒在复杂离子共存的条件下依然对Pb(II)表现出极强的选择性,并且经过6个吸附再生循环后,W-MoS_(2)/CS复合微粒的吸附性能仍保持稳定,具有很好的重复使用性和再生能力.W-MoS_(2)/CS复合微粒的设计拓展了壳聚糖基材料在水处理领域的应用范围.

In this study,W-MoS_(2)/CS beads were produced by W-MoS_(2) nano-flower and chitosan(CS),the effect of MoS_(2) inserting on the morphology and pore structure of composite beads was analyzed,and the adsorption capacity of Pb(Ⅱ)onto W-MoS_(2)/CS beads were examined by several variables like the pH of the solution,adsorption time,the initial concentration of Pb(Ⅱ)and coexistence of metal ions during the adsorption process.The results show that:W-MoS_(2) nanoflowers inserted into the CS gel played a role in fixing and bonding the gel structure,which making the inner structure of beads more solid and the surface of the beads more rough.The W-MoS_(2)/CS beads maintain good pore structure.As the pH value increases in the range of 4~7,the adsorption capacity of composite beads for Pb(Ⅱ)increased first and then decreased,reaching a maximum at pH of 7.The adsorption rate of W-MoS_(2)/CS beads increased sharply before 30 minutes,and finally reached adsorption equilibrium about 120 minutes.The adsorption of Pb(Ⅱ)by W-MoS_(2)/CS was well described by the Langmuir isotherm model,which is a typical monolayer adsorption,and the theoretical maximum adsorption capacity of W-MoS_(2)/CS-2(50 mg MoS_(2))reached up to 663.7 mg/g,which is much higher than most carbon-based and sulfur-functionalized nanomaterials.At the same time,it is found that the W-MoS_(2)/CS exhibited super selectivity to Pb(Ⅱ)under the conditions of the coexistence of metal ions.And after 5 regeneration cycles,the adsorption performance of the W-MoS_(2)/CS remained stable,reflecting the excellent reusability of.The design of W-MoS_(2)/CS expands the application range of chitosan-based materials in the field of water treatment.