Facile preparation of biosurfactant-functionalized Ti2CTX MXene nanosheets with an enhanced adsorption performance for Pb(II) ions

The aim of this study is to improve the adsorption performance for Pb(II) ions of a novel two-dimensional Ti2CTX MXene. Three biosurfactants, chitosan (CS, a cationic surfactant), lignosulfonate (LS, an anionic surfactant) and enzymatic hydrolysis lignin (EHL, a non-ionic surfactant), were used to functionalize the Ti2CTX nanosheets. The samples were characterized by using Field-emission scanning electron microscopy, Fourier infrared spectroscopy, X-ray diffraction and Nitrogen adsorption-desorption isotherms, their adsorption performances for Pb(II) ions were investigated by bath adsorption experiments under various adsorption conditions including different types of biosurfactants, pH value, initial Pb(II) ions concentration, adsorbent concentration, contact time and adsorption temperature. Results revealed that the non-ionic surfactant EHL prevents Ti2CTX nanosheets from restacking and introduces active functional groups so that the adsorption performances of the EHL-functionalized Ti2CTX nanosheets are promoted. The EHL-functionalized Ti2CTX displayed a maximum adsorption capacity of 232.9 mg g−1 for Pb(II) ions. Moreover, reaction kinetics, isotherms and thermodynamics studies were analyzed to describe the adsorption behaviors, and the experimental data were fitted well with pseudo-second order model and Frendlich isotherm. The results showed that the biosurfactants-functionalized Ti2CTX shows improved adsorption performances in removal of Pb(II) ions and has great potential as an environmental adsorption material.