Carbon dots-loaded cellulose nanofibrils hydrogel incorporating Bi 2 O 3 /BiOCOOH for effective adsorption and photocatalytic degradation of lignin.

A novel photocatalytic adsorbent, a cellulose nanofibrils based hydrogel incorporating carbon dots and Bi2 O3 /BiOCOOH (designated as CCHBi), was developed to address lignin pollution. CCHBi exhibited an adsorption capacity of 435.0 mg/g, 8.9 times greater than that of commercial activated carbon. This enhanced adsorption performance was attributed to the 3D porous structure constructed using cellulose nanofibrils (CNs), which increased the specific surface area and provided additional sorption sites. Adsorption and photocatalytic experiments showed that CCHBi had a photocatalytic degradation rate constant of 0.0140 min-1 , 3.1 times higher than that of Bi2 O3 /BiOCOOH. The superior photocatalytic performance of CCHBi was due to the Z-scheme photocatalytic system constructed by carbon dots-loaded cellulose nanofibrils and Bi2 O3 /BiOCOOH, which facilitated the separation of photoinduced charge carriers. Additionally, the stability of CCHBi was confirmed through consecutive cycles of adsorption and photocatalysis, maintaining a removal efficiency of 85 % after ten cycles. The enhanced stability was due to the 3D porous structure constructed by CNs, which safeguarded the Bi2 O3 /BiOCOOH. This study validates the potential of CCHBi for high-performance lignin removal and promotes the application of CNs in developing new photocatalytic adsorbents.