In recent years, the efficacy and cost-efrfectiveness of 99

In recent years, the efficacy and cost-effectiveness of catalytic nanoparticles to the water treatment sector for the room-
temperature, aqueous-phase catalytic breakdown (to benign species) of a large list of carcinogenic and recalcitrant halogenated
hydrocarbon and heavy metal groundwater pollutants (often via sub-surface injection) has been well – documented. For a given
mass of catalyst particles the total effective catalytic surface area (on which breakdown reactions occur) is inversely proportional
to the average size of the catalytic pellets themselves. So the Surface Area - to - Mass ratio of a ‘charge’ of these micro- or nano-
sized catalyst particles in any fixed ‘reactor’ volume is approximately 4 – 8 orders of magnitude greater than that for ordinary-
sized (~10E-2 m diameter) catalysts. The effect is to make feasible for the first time, the complete catalytic breakdown of very
dilute (e.g. ppb / ppm in water) pollutants into their benign constituent species at very high reaction rates, which has many
process engineering ramifications, but for the water remediation industry, translates most obviously to the potential for complete
contaminant breakdown (99.999 % conversions yielding below 0.1ppb discharge levels) at high-throughputs (MGD levels
attainable), opening up, for the first time, the possibility of a whole new genre of treatment options via micro- and nano-catalysis
which, under the right circumstances, hold the potential of, for instance, replacing RO/UF membrane systems at a tiny fraction of
the capital and operating cost.

Hence, these micro- and nano-catalysts have as yet found little real-world ex-situ remediation use, and recently members of the
water treatment community clarified the last remaining major obstacle to this effort: the very attribute which makes these nano-
catalyst particles so effective – their small size – creates the problem which has thus far prevented their use: Due to the small size
of these FBNPs (mean effective diameters of ~20 to 200 nm), there has been no way to cost-effectively immobilize large
quantities of FBNPs in a column through which polluted water may pass (and come into intimate contact with the FBNPs to
facilitate catalysis) without entraining the nanoparticles themselves in it’s flow stream.

However, due to the failure of all the previous brilliant-yet-performance-challenged immobilization technologies to provide ample
exposure of these nanocatalysts to reaction-matrix (polluted inlet) streams without requiring NF-like pressure drops, huge reaction
vessels, and other technical (hence economic) drawbacks, the only way to fully exploit the kinetics unique to these materials
(arising from their aforementioned SA-Mass ratios) has been to use them in-situ. Hence, any remediation achieved by these
particles must then be followed by expensive (often membrane) processes to remove the catalytic particles themselves from the
remediated solution, financially defeating the very purpose of using them in the first place.

High-Efficiency Nano-Catalyst Immobilization (HENCI) reactors were developed in Q4 2004. They readily immobilize micro-and
nano-catalysts in continuous-flow reactors at FBNP packing densities ~3 generations greater than, and without the technical (and
resulting financial) drawbacks (including high energy requirements, pressure drops and/or residence times) of membrane
impregnation, nano-cage structures, resin-fixation, and related unprofitable immobilization technologies. HENCI immobilization
achieves more intimate contact between the reactant matrix (aqueous or not) and these micro-or nano-sized catalytic particles -
and hence better mass transport in the reaction vessel - than can be achieved with most in-situ (rolled- or shaken-bottle)
experiments, without actually allowing the particles to go into solution. As a result, these new catalyst particles can finally be cost-
effectively deployed ex-situ (in flow-through reactors, emulating a ‘packed-bed’) to remediate a host of at least 38 significant and
recalcitrant chlorinated hydrocarbon pollutants. Because HENCI technology overcomes the mass- and momentum-transport
limitations inherent in other immobilization strategies, the observed reaction rate constants (kobs, hr-1) unique to these ultra-small
particles but previously achievable only in-situ can now be realized in a flow-through column, translating to ultra-low residence
times required to achieve ultra-high conversions (e.g. 99.99 to 99.99999%) of even the most dilute contaminants (down to single-
digit 10ppb) in an inlet stream. The difference is, that with HENCI, the product stream contains no nanoparticles to be removed.
Of course, HENCI-facilitated micro- and nano-catalyses preserve the most important aspect of catalytic breakdown remediation:
recalcitrant pollutants are chemically converted into benign species instead of merely being separated into a concentrated mass.
Moreover, HENCI reactors operate at ambient pressure and temperature, feature low capital and very low operating costs
require no chemicals, very little power, little maintenance, have an indefinite lifespan, and can be scaled, configured, and
transported easily for varying applications.