Question Statement:
Which of the following statements regarding the thermal pyrolysis of agricultural crop residues (paddy straw, cotton stalks) is/are CORRECT?
Options:
- (A) Fast pyrolysis ($450\text{--}550^\circ\text{C}$ with rapid heating rate and vapor residence time lt; 2\text{ s}$) maximizes the yield of liquid bio-oil (up to $60\text{--}70\%$)
- (B) Slow pyrolysis (carbonization) at low heating rates and long vapor residence times maximizes the yield of solid biochar
- (C) Biochar application to agricultural soils improves soil water retention capacity and cation exchange capacity (CEC)
- (D) Raw crude bio-oil has a pH of $7.5\text{--}8.5$ and is completely miscible with petroleum diesel