In this work, the adsorption of lignocelluloses from spent liquor (SL) of neutral sulfite semi chemical (NSSC) pulping process on bentonite was investigated. It was observed that 0.26 g/g of lignin and 0.27 g/g of hemicelluloses from SL were adsorbed on bentonite under the conditions of 50 degrees C, 100 rpm and 40 g/g SL/bentonite after 3 h of treatment. The adsorptions of lignin and hemicellulose were increased to 1.8 g/g and 0.45 g/g, respectively, via adding 15 mg/g of polydiallyldimethylammonium chloride (PDADMAC) in the system of SL/bentonite. The turbidity and COD removals were improved from 69% to 93% and from 25% to 38% by adding PDADMAC to the SL/bentonite system, respectively. The increase in the heating value of bentonite (from 0 to 15.4 MJ/kg) confirmed the adsorption of lignocelluloses. The modified bentonite can be used as filler in corrugated medium paper production or as fuel. (C) 2014 Elsevier Ltd. All rights reserved.