| Summary: | The presence of lignin hampers the utilization of hemicelluloses in the pre-hydrolysis liquor (PHL) from the kraft-based dissolving pulp production process. In this paper, a novel process for removing lignin from PHL was proposed by effectively recycling catalysts of BiOCl/BiOBr. During the whole process, BiOCl and BiOBr were not only adsorbents for removing lignin, but also photocatalysts for degrading lignin. The results showed that BiOCl and BiOBr treatments caused 36.3% and 33.9% lignin removal, respectively, at the optimized conditions, and the losses of hemicellulose-derived saccharides (HDS) were both 0.1%. The catalysts could be regenerated by simple photocatalytic treatment and obtain considerable CO and CO<sub>2</sub>. After 15 h of illumination, 49.9 μmol CO and 553.0 μmol CO<sub>2</sub> were produced by BiOCl, and 38.7 μmol CO and 484.3 μmol CO<sub>2</sub> were produced by BiOBr. Therefore, both BiOCl and BiOBr exhibit excellent adsorption and photocatalytic properties for lignin removal from pre-hydrolysis.
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