Cr(VI) Removal on Fungal Biomass of Neurospora crassa: the Importance of Dissolved Organic Carbons Derived from the Biomass to Cr(VI) Reduction

Interactions of toxic D(VI) with renewable biomaterials are considered an important pathway for Cr(VI) removal in ecosystems. Biomaterials are susceptible to dissolution, and their dissolved derivatives may provide an alternative to surface-involved pathway for scavenging of Cr(VI) In this study, dissolved organic carbon (DOC) derived from Neurospora crassa biomass was investigated The proportion of Cr(VI) reduction by DOG to that on biomass was determined to evaluate the importance of DOC to Cr(VI) reduction A rapid increase in DOC concentration from 145 6 to 193 7 mg L-1 was observed when N. crassa-biomass was immersed in 0 01 M KCl solution at pH of 1-5, and polysaccharides, peptides, and glycoproteins with carboxyl, amide, and -NH functional groups, are the major compositions of DOC On reaction of 96 2 mu M Cr(VI) with N. crassa-biomass or DOC, it was estimated that DOC contributed similar to 53 8-59.5% of the total Cr(VI) reduction on biomass in the dark. Illumination enhanced Cr(VI) reduction via photo-oxidation of biomass/DOC under aeration conditions, which formed superoxide for Cr(VI) reduction At pH 1, photoinduced Cr(VI) reduction by DOG proceeded more rapidly than reduction on the biomass surface. However, at pH > 3, with a decrease in Cr(VI) reduction by DOC, photon-excited biomass may become an important electron source for Cr(VI) photoreduction.