Three-dimensional microspheric g-CN coupled by biochar: facile sodium alginate immobilization and excellent photocatalytic Cr() reduction

Photocatalysts comprising Broussonetia papyrifera biochar and g-C 3 N 4 loaded on sodium alginate were prepared and characterized in terms of reusability and photocatalytic Cr( vi ) reduction performance. The observed photocurrent responses as well as photoluminescence and UV-visible diffuse reflectance spectra showed that the best-performing catalyst featured the benefits of efficient photogenerated charge separation, superior electron conductance/transfer, and excellent light adsorption ability, which resulted in a higher photocatalytic Cr( vi ) reduction performance compared to that of pure g-C 3 N 4 powder. The prepared composite was shown to be reusable and well separable from the reaction mixture, thus being a promising material for the practical photocatalytic removal of Cr( vi ) from wastewater. The trapping experiment and XPS spectra of catalysts after reactions confirm that the decontamination of Cr( vi ) lies in the photocatalytic reduction of this species into low-toxicity Cr( iii ) by photoinduced electrons generated from g-C 3 N 4 , followed by the adsorption of Cr( iii ) on biochar or alginate with large specific areas. g-C 3 N 4 - Broussonetia papyrifera biochar-sodium alginate composites were prepared. Composite recyclability and activity for photocatalytic Cr( vi ) reduction and the origin of enhanced photocatalytic activity relative to that of g-C 3 N 4 were probed.