Effect of pretreatment and biomass blending on bio-oil and biochar quality from two-step slow pyrolysis of rice straw

[Display omitted] •Rice straw was co-pyrolyzed with two crop residues before and after washing.•The removal efficiency was > 73% Na and > 42 % K after washing rice straw.•Co-pyrolysis of 60 min washed rice, and wheat straw (1:1 w/w) doubled levoglucosan.•Biochar samples obtained were potential fuel-source and soil amendment additives. This study investigated biomass blending and water washing to improve product quality from two-step pyrolysis of rice straw. Rice straw (RS) was mixed with groundnut shells (GNS) and wheat straw (WS) in different weight ratios. Blending RS with GNS/WS in a 1:1 ratio increased the total bio-oil yields by 7–9% and reduced the pyrolysis gas and char yields by 5–7% and