Carbon functional materials (CFMs)
such as biochar and hydrochar
can be obtained from hundreds of biomass precursors varying from urban
sludge to agriculture wastes. They can be produced through tens of
synthesis methods and postsynthesis processing steps tuned at specific
conditions (e.g., temperature, time, and chemical concentrations).
To achieve a “rational design” platform for a system
with a high dimensional parameter space such as CFMs, we processed
10,975 scientific articles (from years 2000 to 2020) related to the
subject with automatic reading–interpreting–extracting
computational routines (namely, the a.RIX engine). The a.RIX engine
automatically recognized more than a hundred precursors, among which
wheat straw, rice husk, and rice straw were the most studied for CFM
synthesis and application in agriculture (e.g., as an amendment),
as fuel (energy generation), and as an adsorbent. Parameters related
to the CFMs’ synthesis conditions, such as carbonization temperature
and time, and parameters related to CFMs’ properties, such
as surface area and heavy metals adsorption capacity, can also be
extracted from the articles. Correlations between the CFM precursors
and synthesis conditions indicated very little statistical difference
between the carbonization temperature and time used for the CFMs’
synthesis from different precursors. Essentially, precursors are carbonized
at temperatures varying from 100 to 900 °C for 30 min to 6 h
using pyrolysis, hydrothermal carbonization, and gasification. When
focusing the analysis on just CFMs produced by pyrolysis (biochar),
we observed that peanut shells can produce materials with higher surface
areas than other precursors (P < 0.05). When performing
correlations between biochar synthesis conditions and their properties,
general trends can be confirmed: (i) the higher the carbonization
temperature, the lower the H/C and O/C ratios, and (ii) the increase
in the surface area can be achieved by preserving a high aromatic
degree (low H/C ratio) and a low oxidation level (low O/C ratio).
However, a deeper understanding of the relation between CFM synthesis/postsynthesis
methods and the resulting properties can only be achieved using clustering
algorithms (e.g., k-means) and complex network analysis.
The a.RIX engine groups articles describing optimized synthesis conditions
and CFM properties (e.g., low carbonization temperature, low carbonization
time, and large surface area and adsorption capacity) and automatically
recognizes the synthesis/postsynthesis steps used for these groups.
The program efficiently recognized that precursors such as peanut
shells can be converted into highly porous biochar by using experimental
routes such as “pyrolysis” → “activation”
→ “drying” → “ashing” →
“washing” → “filtration.” With
this approach, we show that a noncomputational review of scientific
articles for materials with a huge parameter space such as CFMs is
largely obsolete. Finally, taken together, the results provide a powerful
platform for data-oriented experimental design of CF...
