Porous lignin based poly (acrylic acid)/organo-montmorillonite nanocomposites: Swelling behaviors and rapid removal of Pb (II) ions

Publication date: 16 October 2017
Source:Polymer, Volume 128
Author(s): Yanli Ma, Ling Lv, Yuanru Guo, Yujie Fu, Qian Shao, Tingting Wu, Sijie Guo, Kai Sun, Xingkui Guo, Evan K. Wujcik, Zhanhu Guo
Lignin grafted N, N′-methylene-bisacrylamide (LM) was copolymerized with acrylic acid (AA) to fabricate lignin based poly (acrylic acid) (LBPAA) nanocomposites, and organo-montmorillonite (OrgMMT) was uniformly dispersed in LBPAA by ultrasonic method. The water absorbency in KCl solution was 302.9 g/g for LBPAA/OrgMMT (3 wt% OrgMMT, 43.65 wt% LM, and 53.35 wt% poly(acrylic acid) (PAA)), higher than PAA/OrgMMT (104.5736 g/g), and PAA (131.8 g/g). The Pb²⁺ adsorption for LBPAA/OrgMMT was demonstrated to be pH-dependent and followed Freundlich multilayer adsorption, with the removal following a pseudo-second-order kinetic model. The Pb²⁺ absorption capacity of LBPAA (PAA 48.50/48.50 LM)/OrgMMT (3 wt%) was 1.0803 mmol·g⁻¹, the highest among the composites. When the mole ratio of Na⁺ and Pb²⁺ was less than 0.21, the Pb²⁺ adsorption capacity of LBPAA/OrgMMT decreased slightly. The negative ΔG0 indicated that the Pb²⁺ adsorption process for composite hydrogel and PAA was spontaneous. XPS analysis data indicated that Pb²⁺ ions formed Pb-O bonds by hydroxyl groups and carboxyl groups for efficient lead ion adsorption. This study demonstrates that LBPAA/OrgMMT can be used as a water retention agent with salt tolerance and as an adsorbent for removing Pb²⁺ ions from industrial waste water.

Graphical abstract

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