Green mussel-inspired lignin magnetic nanoparticles with high adsorptive capacity and environmental friendliness for chromium(III) removal.

We report an ingenious technique to prepare magnetic alkaline lignin-dopamine nanoparticles (AL-DA/Fe3O4 NPs). Alkaline lignin, a kind of abundant waste from agriculture, pulping and bio-energy industry, was functionalized by the conjugation with DA molecules and nano-precipitation method. Benefiting from the three-dimensional network of lignin and mussel-inspired DA molecules, chromium(III) can be effectively removed by physisorption and chemisorption. The maximum Cr(III) adsorption capacity of AL-DA/Fe3O4 NPs was found to be 44.56 mg/g, which was among the highest of previously reported biomass-based Cr(III) adsorbents. Moreover, sensitive magnetic responsiveness (24.6 emu/g) of AL-DA/Fe3O4 NPs can be more helpful in recycling (over 90% recycled within 2 min) and multiple reusing. The preparation of this low-cost, high adsorptive capacity and good ecofriendly lignin-based nano-adsorbent is expected to become a sustainable technology to simultaneously achieve the wastewater reutilization from pulping and bio-energy industry and purification of other modern industries.