Biomedical Engineering Reference
In-Depth Information
Calculations of Eq. (2.33), using the experimental values of (H/C)
α
and acceptable values of the specific surface area (about 100-300
m
2
-1
) for the samples used in Ref. [94] also point to the possibility
of physical adsorption.
g
2.2.4.4
Polylayer Physical Adsorption in GNFs Initiated by
Monolayer Chemisorption
Sensational experimental data [12] (see Fig. 2.3, Chambers
)
on a GNF-based superadsorbent (see Maeland's review in Ref. [7])
were, firstly, presented at international conferences and, then,
published in scientific journals by a group of US researchers
(Rodriguez, Becker, and others) between 1996 and 1999. So far,
nobody has been able to reproduce the data described in Ref. [12],
but they are examined and cited in reviews and research papers
(see Refs. [7-11]). The researchers, who claim to have discovered
this superadsorbent [12], continued to not consider erroneous
their results [13]. The study [13] has been carried out together
with the other well-known US researchers and has been devoted to
hydrogen sorption by carbon materials.
As noted in Ref. [7], Becker “re-activated” the interest of scientific
community in 1972, by discovering “a new” graphite nanofiber. It
should be noted that in recent years, Becker and coworkers have
published a large series of fundamental papers and registered
patents in this field.
At the same time, discussing the hydrogen accumulation
problem, many researchers speak of
et al.
expectations, delusions, and
prospects
.
In such a context, we believe it is useful to analyse the data
reported in Ref. [12], both critically and constructively, employing
the novel analytical approaches developed in Refs. [10, 17-25, 97].
The anomalously high experimental values of the sorption capacity
of GNF samples (up to 40 wt% of hydrogen, (H/C)
, but also of
good luck, mistakes, and mystifications
≤ 8) presented
in Ref. [12] make this material a superadsorbent. The samples are
saturated with hydrogen at about 11 MPa and 298 K for 24 h.
Going to higher pressures and ageing the hydrogen-saturated
samples for
Σ
≥ 10 min, desorption of the larger adsorbate fraction
(about 75%) was achieved, corresponding to a release of about
33 wt% of hydrogen (process
τ
≤ 6). Subsequent thermal
desorption, heating the GNF samples up to 1223 K at the rate of
0.17 K s
α
X, (H/C)
αX
-1
, revealed the presence of two high-temperature TPD peaks
