An optimal conversion cascading of distinct lignocelluloses to maximize bioethanol productivity and bio-adsorption capacities of Cd2+/Cr(VI) and red/blue dyes selective for complete biomass recycling.

Although agriculture and forestry provide enormous lignocellulose resources, it remains to explore a novel technology for efficient biomass conversion into renewable bioethanol followed with complete recycling for valuable bioproduction with zero- waste release. As classic chemical (acid and alkali) pretreatments could cause chemical waste liberation, this study performed optimal pretreatments with hot-FeCl3 for sequentially enhancing biomass enzymatic saccharification in three bioenergy crops, which led to achieving hexoses yields raised by 4-7 times compared to the controls. By employing engineered yeast strain for xylose co-fermentation, the highest bioethanol yield was achieved at 18 % (% dry matter) in Miscanthus sample. The remaining enzyme-undigestible residue was thermal-chemically converted into high-porosity biochar capable of upgraded organic dyes adsorption. The yeast-fermentation residue of wheat was further incubated with classic oxidative chemicals for desirable biosorbent assembly with the highest Cd2+ adsorption capacity (25 mg/g), whereas the fermentation residue of Eucalyptus was mixed with its pretreatment liquid to generate another optimal biosorbent for maximum Cr(VI) adsorption (20 mg/g) among all biosorbents (7-13 mg/g) examined to date. A novel hypothetic model is thus proposed about how distinct lignocelluloses are convertible and selectable for high-yield bioethanol and high-performance bioproducts, providing insights into the optimal lignocellulose utilization under green-like processes.