Low-temperature highly selective water delignification based on geopolymer materials

Delignification pretreatment is the main source of high cost and high pollution in biomass processing. This paper reports on a simple cheap geopolymers-based highly selective and efficient pretreatment process for delignifi-cation under low-temperature water-cooking without discharging black liquor. The geopolymer with a SiO2/ Al2O3 ratio of 4.4 showed the largest number of acidic sites and highest catalytic activity. Under mild reaction conditions (mGeopolymer/mFiber = 1/4, 90 min and 90 degrees C), the delignification rates of woody (eucalyptus) and herbaceous (bagasse) biomass increased by up to 38.90% and 62.20%, respectively. Moreover, the low-alkali black liquor produced by the new water delignification process facilitates subsequent water treatment, elimi-nating the need for alkali recovery. This study confirms the immense application prospects of geopolymers for the highly selective delignification of most biomass fibre. This study will develop a low-temperature water -cooking process for the delignification of papermaking or biomass processing without wastewater discharge.

Automated summary

This paper presents a simple and cost-effective pretreatment process for delignification of biomass using geopolymers. The geopolymer with a SiO2/Al2O3 ratio of 4.4 exhibited the highest catalytic activity. Under mild reaction conditions, the delignification rates of woody and herbaceous biomass increased significantly. Furthermore, the low-alkali black liquor produced by this process eliminates the need for alkali recovery. This study demonstrates the potential application of geopolymers in selective delignification of biomass.