(562at) Physico-Chemical Activation of Biochar Using Acoustic Treatment and Amine Functionalization for Efficient CO2 Adsorption | AIChE

(562at) Physico-Chemical Activation of Biochar Using Acoustic Treatment and Amine Functionalization for Efficient CO2 Adsorption


Chatterjee, R. - Presenter, University of Mississippi
Sajjadi, B., University of Mississippi
Chen, W. Y., University of Mississippi
Mattern, D., University of Mississippi

For the last few decades, the emission of green-house gases especially
CO2, raises serious concerns since it is the major contributor to
global warming and climate change. Biochars, produced
from pyrolysis of woody biomasses, have highly porous structure with high
surface area that makes them potential CO2 adsorbents. The previous studies
of our group suggested that CO2 could be chemically fixed on biochar through reductive photocarboxylation
under ambient conditions that can be considered an effective way to capture CO2.
These studies have also suggested that ultrasound irradiation can exfoliate the
biochar structure, create new pores, and open the
blocked pores, thus enhancing the biochar’s chemical
functionalization efficiency and subsequent CO2 capture. Besides,
the biochar surface consists of reactive oxygen
functional groups (such as -COOH, C=O, -OH) that are susceptible to amine
functionalization. Amination is the technique to
incorporate nitrogen functionality (such as amine) to biochar
structure that has important applications in CO2 capture. The amine has a strong affinity for acidic CO2
due to its basic nature and can react through acid-base interaction and boost
adsorption efficiency significantly. Thus, the present study aims to maximize
the CO2 capture capacity of biochar by improving
its carbonaceous structure through physical activation with low-frequency
ultrasound and chemical functionalization using amines. The initial studies
were conducted with pine-wood derived commercial biochar
activated physically for 30 s under ultrasonic irradiation and then
functionalized chemically with individual and blended 1°, 2º and 3° amines (diethanolamine (DEA), monoethanolamine
(MEA), polyethylenimine (PEI),  piperazine (PZ) and
tetraethylenepentamime (TEPA)) subjecting to two
different groups of activating agents (N-(3-dimethylaminopropyl-N’-ethylcarbodiimide
hydrochloride)-HOBt (hydroxybenzotriazole
and KOH). The work was further extended to investigate
the role of different biomass origin on CO2 capture employing
Miscanthus, Switchgrass, Corn Stover,
Sugarcane Bagasse, Sorghum, Wheat Straw, Rice Straw and Rice Husk as different
biomass sources. The ultrasono-blended amination study revealed that biochar
samples activated with EDC-HOBt-TEPA, EDC-HOBt-TEPA-MEA, KOH-MEA possess maximum adsorption
capacities 2.04, 1.91 and 1.62 mmol/g respectively at
0.10 atm. CO2 partial pressure and 70 °C compared with raw biochar (0.3 mmol/g). Comparing
these results with subsequent biomass origin study, it was obtained that biochars prepared in-house from Miscanthus
has highest possible adsorption capacity of 2.53 mmol/g
(under similar experimental conditions as before) due
to its increased specific surface area, high carbon and low ash content.

* For presentation at the 2019 AIChE
Annual Meeting, Orlando, FL,
Nov 10-15, 2019