Enhanced buffer capacity of fermentation broth and biohydrogen production from corn stalk with Na2HPO4/NaH2PO4

The remarkable buffer capacity of buffer solution can significantly improve the biohydrogen production yield and energy conversion efficiency. In the present study, the effect of buffer solution Na2HPO4/NaH2PO4 on buffer capacity of fermentation broth and photo-fermentation biohydrogen production (PFHP) was studied. Gas characteristics, fermentation broth properties, and kinetic parameters in PFHP were investigated. With the in-crease in pH values (5-7) of buffer solution Na2HPO4/NaH2PO4, firstly hydrogen yield increased and then de-creased. Maximum energy conversion efficiency 9.84%, hydrogen yield 132.69 mL/g corn stalk, and hydrogen content 53.88% were achieved at pH value of 6. The results of one-way ANOVA showed that pH values of fermentation broth and cumulative hydrogen production were strongly affected by pH values of buffer solution. Buffer solution Na2HPO4/NaH2PO4 retarded the decrease of pH value of photo-fermentation broth, and sig-nificantly improved the PFHP.