Two various materials, copper and aluminum doped cobalt ferrite nanoparticles (NPs) were fabricated for investigating their effects of addition amounts on hydrogen (H2) synthesis and process stability. CoCu0.2Fe1.8O4NPs enhanced H2 production more than CoAl0.2Fe1.8O4 NPs under same condition. The highest H2 yield of 212.25 ml/g glucose was found at optimal dosage of 300 mg/L CoCu0.2Fe1.8O4 NPs, revealing the increases of 43.17% and 6.67% compared with the control without NPs and 300 mg/L CoAl0.2Fe1.8O4 NPs groups, respectively. NPs level of more than 400 mg/L inhibited H2 generation. Further investigations illustrated that CoCu0.2Fe1.8O4 NPs were mainly distributed on extracellular polymer substance while CoAl0.2Fe1.8O4 NPs were mostly enriched on cell membrane, which facilitated electron transfer behavior. Community structure composition demonstrated that CoCu0.2Fe1.8O4 and CoAl0.2Fe1.8O4 separately caused a 9.67% and 9.03% increase in Clostridium sensu stricto 1 compared with the control reactor without NPs exposure.
Keywords: Al- and Cu- doped cobalt ferrite nanoparticles; Dark fermentation; Hydrogen production; Microbial community composition; Process stability.
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