*2.1. Materials*

The guinea grass (GG) samples were harvested in an outdoor field (8◦7 14" N; 5◦4 56" E) within the Landmark University premises in June 2020. The grasses (of about 1–1.5 m tall) were initially air dried for 2 weeks and then oven dried at 70 ◦C for 24 h for ease of pulverization. The sample was pulverized in a ball mill and sieved into 0.6 and 1.18 mm particle sizes with the aid of a mechanical sieve. The 0.6 mm screened particles were used for chemical and TGA characterization. The cellulose (Whatman CF1, Maidstone, England), xylan from corn (TCI America, Portland, OR, USA), softwood kraft lignin (Indulin AT, Meadwestvaco, Charleston, SC, USA), and hardwood organosolv lignin (Lignovate LLC, Fayetteville, AR, USA) were used as received.
