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The pollution of water by potentially toxic metals or socalled 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 Ni 2+ , Cd 2+ , and Pb 2+ , 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 Ni 2+ , Cd 2+ , and Pb 2+ . The mechanism of adsorption was investigated indicating ion exchange between toxic metals and Mg 2+ . The obtained adsorbent was successfully regenerated using combined treatment by HCl−MgCl 2 −NaOH.

Due to growing demand, the performance of traditional active carbon is insufficient. An innovative solution is superactive carbon with an ultra-high surface area as high as 3000 m2 g−1. However, this material is very costly due to the considerable amount of alkali used in its manufacturing. To obtain superactive carbon from lignin, KOH and KCl were used simultaneously. The method was thoroughly studied to describe the mechanism of pore origin and control the pore size. Because of synergy between KOH and KCl, superactive carbon with an ultra-high surface area (2938 ± 42 m2 g−1) was obtained at essentially diminished KOH consumption (1 g g−1) in contrast to previously reported methods. The process was optimised using the response surface method. The pore size can be tuned by varying the amount of KOH and temperature. Observed synergy enabled reduced alkali consumption, overcoming the barrier to widespread implementation of superactive carbon.

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