Activated carbon aerogel derived from banana rachis, an easily
accessible agricultural waste, features a unique interconnected network
structure that is ideal for water purification. This study investigated the
preparation of activated carbon aerogel from banana rachis through four
distinct processes: nitro-oxidation, lignin impregnation, carbonization, and
CO 2 activation. The goal is to have a lightweight aerogel, maintain a high
specific surface area and compressive strength while effectively removing
Methylene Blue (MB) dye from water. Initially, the native banana rachis
aerogel has a specific surface area of 494.67 m²/g, 96.6% porosity, and a
compressive strength of 0.47 MPa. The nitro-oxidation process enhances the
aerogel properties by removing components such as lignin and hemicellulose
from the cell wall, resulting in a higher specific surface area of 884.61
m²/g and a porosity of 98%, with a compressive strength of 0.51 MPa. During
this process, primary hydroxyl groups at the 6C position on the cellulose
surface are oxidized to carboxylic groups. Then, 5 wt.% lignin extracted from
coir pith was impregnated into the nitro-oxidized aerogel (NOA) to prevent
structural collapse during carbonization. Finally, the carbonization,
followed by activation, was conducted at 700°C on the lignin-impregnated NOA,
exhibited only slight shrinkage along the cross-section. The structural
properties of the activated carbon aerogel are impressive, revealing a
porosity of 97.6% and a specific surface area of 1519.6 m²/g. The aerogel
also displayed good compressive strength at 0.35 MPa, emphasizing its
lightweights and robustness. The purification efficiency is discussed when
purifying a solution containing 100 mg of Methylene Blue in one liter of
water. These unique structural characteristics and the purification
effectiveness of activated carbon
aerogels derived from banana farming waste offer a new perspective on water
purification, highlighting their
intriguing cellular structure and potential for regeneration and
reusability.