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Activation of lignin by demethylation for improving the reactivity has attracted extensive attentions. However, it still faces many challenges, such as the unsatisfied increase of hydroxyl content and the undesired cracking of linear linkages. Here, the efficient demethylations for significantly increasing the hydroxyl content and protecting the structure of industrial lignin were explored using lewis acid as modification reagent. As BBr 3 was used, the phenolic hydroxyl content (Ar-OH) was increased by 80.65 %, but the lignin structure might be destroyed. About 75 % of the β- O -4 linkages could be fortunately retained by using AlCl 3. This method could also be used for the demethylation of alkaline poplar lignin with up to 171.67 % increase of Ar-OH (from 1.80 to 4.89 mmol/g). After activation, the antioxidant properties were improved 4.64-fold and 2.58-fold for 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals, respectively. This work would provide a theory guidance for activation of lignin and facilitate its high-value application. • The phenolic hydroxyl content of the activated alkaline poplar lignin increases by 171.67 %. • The lignin activated by AlCl 3 retains most of its macromolecular structure. • The reaction time and the demethylation reagent are the key reasons for controlling the activation process. • The activated lignin shows significantly increased antioxidant properties for DPPH and ABTS+. [ABSTRACT FROM AUTHOR]

Development of lignin-derived carbon adsorbents with ultrahigh phosphate adsorption activity and rapid adsorption kinetics is of great importance, yet limited success has been achieved. Herein, we develop a CeO 2 functionalized N-doped lignin-derived biochar (Ce@NLC) via a cooperative modification strategy for effective and fast phosphate capture. The novel modification strategy not only contributes greatly to the loading of well-dispersed CeO 2 nanoparticles with a smaller size, but also significantly increases the relative concentration of Ce(III) species on Ce@NLC. Consequently, an enhanced capture capacity for phosphate (196.85 mg g−1) as well as extremely rapid adsorption kinetics were achieved in a wide operating pH range (2–10). Interestingly, Ce@NLC exhibited a strong phosphate adsorption activity at even low-concentration phosphorus-containing water. The removal efficiency and final P concentration reached 99.87% and 2.59 μg P L−1 within 1 min at the phosphate concentration of 2 mg P L−1. Experiments and characterization indicated that Ce(III) species plays a predominant role for the phosphate capture, and ligand exchange, together with electrostatic attraction, are the main adsorption mechanism. This work develops not only an efficient carbon-based adsorbent for phosphate capture, but also promotes the high-value application of industrial lignin. Nitrogen-doped lignin-derived biochar with enriched loading of CeO 2 nanoparticles for highly efficient and rapid phosphate capture. [Display omitted] • Ce@NLC with smaller and Ce(III)-enriched CeO 2 nanoparticles is developed. • The maximum phosphate capture capacity of Ce@NLC reaches 196.85 mg g−1. • Ce@NLC exhibits a rapid phosphate capture in wide operating pH range (2–10). • Ce@NLC possesses strong adsorption activity at even a low phosphate concentration. [ABSTRACT FROM AUTHOR]

The use of lignin carbon as an adsorbent for the adsorption of phosphates from wastewater is a promising technology. However, most lignin carbon-based adsorbents still suffer from low adsorption efficiency and poor selectivity. Herein, a novel FeLaO 3 -modified sulfomethylated lignin (SL) biochar adsorbent (FLO@CSL) was prepared for phosphate removal. The development of this adsorbent took into consideration the strong affinity of lanthanum (La) and iron (Fe) (hydro) oxides for phosphate and the excellent carrier properties of lignin-based biochar. As the core of FLO@CSL, FeLaO 3 active sites are highly dispersed on the surface of SL biochar. Besides, doping of Fe(III) not only imparts magnetic properties to FLO@CSL, thereby effectively improving the separation efficiency of the adsorbent, but also enhances the phosphate adsorption performance. Performance studies revealed that FLO@CSL exhibits remarkable adsorption selectivity and substantial phosphate-adsorption capacity. Notably, the maximum adsorption capacity was found to be 137.14 mg P g−1. Phosphate adsorption on the FLO@CSL surfaces proceeds via chemisorption in a single layer, and ligand exchange plays an important role in determining the adsorption behaviour. Because of its exceptional selectivity, remarkable adsorption capacity and outstanding magnetic separation efficiency, FLO@CSL is a highly promising adsorbent material for effectively treating phosphates in wastewater. • FeLaO 3 active sites have a high dispersion on the surface of sulfonylmethylated lignin biochar. • The maximum phosphate capture capacity of FLO@CSL 1:1 reaches 137.14 mg P g−1. • FLO@CSL 1:1 has an excellent magnetic separation performance. • Satisfactory phosphate selectivity was maintained in ions-affected adsorption. [ABSTRACT FROM AUTHOR]