Enhanced Removal of Sulfonated Lignite from Oilfield Wastewater by Soft Colloidal Templated Porous Structure of MgAl-LDH

Mg/Al layered double hydroxides (LDH) with mesoporous and microstructures based on soft colloidal template were prepared by co-precipitation method, employing salicylic acid and the anionic surfactant cetyl trimethyl ammonium bromide as soft templates. N₂ adsorption–desorption isotherms, SEM and XRD, were employed to describe the morphology and structure of the samples, respectively. The results showed that structured MgAl-LDH with mesoporous and microstructures dispersed uniformly with increasing the average pore diameter and specific surface area of the samples. The absorption activity of obtained structured MgAl-LDH to sulfonated lignite containing in wastewater of oil field has been investigated. The prepared structured MgAl-LDH could adsorb SL and attain equilibrium in 60 min with better removal efficiency than MgAl-LDH. Due to its relatively special layered pore size distribution and large surface area, the adsorption capacity can reach 510.2 mg/g when the initial concentration is 600 mg/L and adsorbent dosage is 0.3 g/L at 308 K and pH 7.0. The adsorption process of sulfonated lignite is exothermic in nature and follows to the Langmuir adsorption isotherm model and the pseudo-second-order kinetic model.