Surface modified layered double hydroxide/polyaniline nanocomposites: Synthesis, characterization and Pb2+ removal

In this study, Ca/Fe layered double hydroxide (LDH) with good accessible chemically active sites and with intercalate anions of citrate was prepared, and then 3-aminopropyl triethoxysilane as a silane coupling agent was used to modify the LDH surface. Then, in order to improve the thermal stability and removal efficiency toward bivalent Pb2+, polymer matrix nanocomposites (PMNCs) were fabricated by in situ polymerization of aniline in the presence of modified LDH. The as-synthesized PMNCs were characterized by XRD, FT-IR, TGA, TEM, and FE-SEM. Morphological studies revealed that modified LDH were dispersed homogeneously in polymer matrix without any aggregation. Finally, polyaniline (PANI) and synthesized PMNCs were used as adsorbents to removal of Pb2+ from aqueous solution. The effective parameters affecting metal adsorption including contact time, pH and initial concentration were studied and optimized. Also, the sorption kinetics and isotherm of these sorbents were investigated. The results revealed that the kinetic adsorption could be designated by a pseudo-first order model for the removal of Pb2+. Comparing the results of Langmuir and Freundlich equations showed that NC10 % with more adsorption capacity (q(max)) and adsorption constant (K-1) were more suitable adsorbent than NC5 % and PANI for removal Pb2+. The results of R-2 values show that the Langmuir model showed the best fit on the lead absorption data by PANI and the synthesized PMNCs.