an9b01083_si_001.pdf (943.04 kB)
Lignin-Based Magnesium Hydroxide Nanocomposite. Synthesis and Application for the Removal of Potentially Toxic Metals from Aqueous Solution
journal contribution
posted on 2019-08-23, 18:40 authored by Nikolai Ponomarev, Olga Pastushok, Eveliina Repo, Bhairavi Doshi, Mika SillanpääThe
pollution of water by potentially toxic metals or so-called
heavy metals is the most severe form of environmental impact. Nanocomposites
are considered promising materials for the removal of potentially
toxic metals from aqueous solution through adsorption or ion exchange.
To produce high-performance adsorbent for the removal of Ni2+, Cd2+, and Pb2+, lignin–Mg(OH)2 nanocomposite (LH-MH) was developed utilizing hydrolytic
lignin waste with possible regeneration after metal uptake. The LH-MH
was prepared using hydrolytic lignin, magnesium chloride, and NaOH
solution by a thermally assisted method. The structure was studied
using X-ray diffraction, transmission electron microscopy, and scanning
electron microscopy, while chemical composition was evaluated by Fourier
transform infrared spectroscopy, thermogravimetric analysis/differential
thermogravimetry, and energy-dispersive X-ray spectroscopy mapping.
Adsorption was described by the Langmuir and Sips models, whereas
kinetics was elucidated by pseudo-first-order and pseudo-second-order
models. The obtained material demonstrated a nanocomposite structure
indicating well-distributed nano-Mg(OH)2 onto the lignin
polymer matrix. The nanocomposite demonstrated superior removal of
Ni2+, Cd2+, and Pb2+. The mechanism
of adsorption was investigated indicating ion exchange between toxic
metals and Mg2+. The obtained adsorbent was successfully
regenerated using combined treatment by HCl–MgCl2–NaOH.