Adsorption of Pb2+ and Cu2+ on anionic surfactant-templated amino-functionalized mesoporous silicas

Abstract

Amino-functionalized mesoporous silicas (AFMS) were synthesized using the anionic surfactant N-lauroylsarcosine sodium (Sar-Na) as template and 3-aminopropyltrimethoxysilane (APTMS) as co-structure directing agent (CSDA). Orthogonal experiments were applied to optimize the synthesis of AFMS with high amino loading, high surface area, and large pore size. The synthesized AFMS were characterized by FT-IR, TG-DTA, XRD, N2 adsorption–desorption, and TEM techniques. The removal of Cu2+ or Pb2+ from aqueous solutions by the synthesized AFMS was investigated in detail. The pH value of an aqueous solution containing Cu2+ or Pb2+, adsorption temperature, and the dosage of the used AFMS affect the removal efficiency of Cu2+ or Pb2+ greatly. The unary adsorption isotherms of Cu2+ and Pb2+ on the optimized AFMS adsorbent are well described by the Sips isotherm model, in which the adsorption capacities are 2.18 and 4.74mmol/g for Cu2+ and Pb2+, respectively, under the optimized conditions, much higher than the literature data. Furthermore, the AFMS adsorbent shows a good stability, confirmed by adsorption–regeneration cycles. Based on these excellent properties, the application in the removal of Cu2+ and Pb2+ from wastewater is anticipated.