Controllable preparation of calcined magnesium-aluminum layered metal hydroxides for adsorption of glyphosate

In this study, magnesium-aluminum layered double hydroxides (LDHs-MgAl) were controllable synthesized via coprecipitation and calcined at 400°C (LDHs-400-MgAl) for adsorption of glyphosate (Gly) from wastewater. The experiments showed that LDHs-400-MgAl exhibits outstanding adsorption capacities and stability within the range of pH 3.0 to 10.0. Particularly, LDHs-400-MgAl displayed excellent equilibrium and maximum adsorption capacities, measuring 192.31   mg/g and 259.85   mg/g respectively at 25°C compared with other adsorbents. Importantly, even in solutions containing diverse anions such as NO - 3 , CO 2- 3 , SO 2- 4 , and Cl - with concentrations as high as 0.1   mol/L, LDHs-400-MgAl exhibited exceptional anti-interference capability. Moreover, the adsorption process of Gly with LDHs-400-MgAl is in accordance with the pseudo-second-order kinetic model and Langmuir model, simultaneously showing the spontaneous and endothermic thermodynamics. According to the characterization analysis such as XRD, FTIR, SEM-EDS, TEM, TG-DSC, and zeta potential, the adsorption mechanism of Gly by LDHs-400-MgAl is mainly attributed to the combined effect of electrostatic attraction, surface coordination, ion exchange and ion intercalation. In addition, LDHs-400-MgAl can be reused after 0.075   mol/L Na 2 CO 3 regeneration. Consequently, LDHs-400-MgAl has good adsorption capacity, selectivity, a broad pH range, and considerable scalability potential, enabling the effective removal of Gly from complex water environments.