Delignified wood aerogels functionalized with Ag nanoparticles for efficient catalytic reduction of 4-nitrophenol and dyes

Abstract

Wood, a versatile, low-cost, and biodegradable material, holds great promise for water purification applications. However, its inherently low surface area and limited porosity present significant challenges. To overcome these limitations, we developed porous wood aerogels through delignification followed by in-situ functionalization with silver nanoparticles (AgNPs). The impact of delignification on crystallinity, surface functional groups, and morphology of the wood aerogels was thoroughly investigated and AgNPs preparation conditions were optimized using ICP-OES. Structural and chemical modifications were further analyzed using FTIR, XRD, XPS, and SEM, revealing preserved cellulose crystallinity and uniform AgNPs distribution. These AgNPs/wood aerogels demonstrated exceptional efficiency as filter materials, achieving over 90 % reduction of 4-nitrophenol at a flow rate of 2 mL/min, significantly outperforming non-delignified AgNPs/wood aerogels, which sustained only 0.5 mL/min. The aerogel also effectively degraded cationic (methylene blue) and anionic (Congo red) dyes, demonstrating its versatility for water treatment. Stability tests showed the material maintained over 90 % catalytic efficiency for 20 cycles without significant structural deterioration, as confirmed by post-reaction XRD, XPS, ICP-OES and SEM analyses. Applicability in real water samples was demonstrated using river, lake, and tap water, and a catalytic reduction mechanism was proposed.