Poly(vinyl alcohol)/quaternized lignin composite absorbent: Synthesis, characterization and application for nitrate adsorption

摘要

A new poly(vinyl alcohol) (PVA)/quaternized lignin composite absorbent (PVA/QL) was synthesized from modified lignin and PVA, crosslinked by glutaraldehyde. As-prepared absorbent was characterized by IR, DSC, SEM BET, and DMA. Effects of shaking time, absorbent dose, initial pH, and temperature on NO3 ~- removal from aqueous solution by the absorbent were comprehensively investigated. The results show that the PVA/QL absorbent comprises quaternary ammonium groups in the form of ether bond. The composite absorbent exhibits remarkable network structure with large numbers of connected holes. The mechanical strength of the absorbent is enhanced by combining of PVA with modified lignin and crosslinkage of glutaraldehyde. The effect of pH on adsorption of NO_3 ~- is apparent and appropriate pH is 2.0. The adsorption process is endothermic, and determined to be consistent with the Langmuir isotherm. Furthermore, it is found that the quaternary ammonium structure and network structure in the surface of PVA/QL are the key factors to remove nitrate.