Solid absorbents made with polyethylenimine (PEI), which is loaded on different porous substrates, are promising for postcombustion carbon dioxide capture. Herein, theoretical studies of polyamine applications, including PEI for carbon dioxide capture, are reviewed and the development of experimental work on carbon dioxide capture by using PEI summarized. The mechanisms of carbon dioxide capture are discussed at different reaction sites of the polyamines, such as primary, secondary, and tertiary amine groups. Experimental achievements in carbon dioxide capture are investigated by the incorporation of PEI with different support materials, such as mesoporous silica; nanotubes; membranes; and other materials, such as alumina, zeolite, resin, metal–organic frameworks, and glass fibers, through impregnation, grafting, and synthesis. The excellent carbon dioxide capture capacity and great stability of PEI‐impregnated nanomaterials highlight PEI as one of the greatest candidates for carbon dioxide capture from flue gas or air.
Biodegradable natural surfactants obtained from plants
can be an attractive alternative to synthetic surfactants
in
the remediation of contaminated soils. In this
research,
a plant-based surfactant obtained from the fruit pericarp
of
Sapindus mukurossi, a tree generally grown in
tropical
regions of Asia, is tested. A simple and economical
method
for the preparation of the surfactant is developed.
An
empirical formula for the surfactant was determined to be
(C26H31O10)
n
.
The aqueous solubilities of hexachlorobenzene
(HCB) and naphthalene in the natural surfactant solutions
were found to vary linearly with the concentration of the
surfactant showing trends comparable to that of typical
com
mercial surfactants. Natural surfactant solutions were
also employed for flushing HCB from one-dimensional soil
columns. HCB recoveries after 12 pore volumes of
flushing
with 0.5 and 1% natural surfactant solutions were 20 and
100
times more than that recovered by water flooding.
These
promising results warrant further research to establish
the
usefulness of plant-based surfactants for soil washing
applications.
The last decade witnessed a quantum increase in wind energy contribution to the U.S. renewable electricity mix. Although the overall environmental impact of wind energy is miniscule in comparison to fossil-fuel energy, the early stages of the wind energy life cycle have potential for a higher environmental impact. This study attempts to quantify the relative contribution of individual stages toward life cycle impacts by conducting a life cycle assessment with SimaPro ® and the Impact 2002+ impact assessment method. A comparative analysis of individual stages at three locations, onshore, shallow-water, and deep-water, in Texas and the gulf coast indicates that material extraction/processing would be the dominant stage with an average impact contribution of 72% for onshore, 58% for shallow-water, and 82% for deep-water across the 15 midpoint impact categories. The payback times for CO 2 and energy consumption range from 6 to 14 and 6 to 17 months, respectively, with onshore farms having shorter payback times. The greenhouse gas emissions (GHG) were in the range of 5-7 gCO 2 eq/kWh for the onshore location, 6-9 CO 2 eq/kWh for the shallow-water location, and 6-8 CO 2 eq/kWh for the deep-water location. A sensitivity analysis of the material extraction/processing stage to the electricity sourcing stage indicates that replacement of lignite coal with natural gas or wind would lead to marginal improvements in midpoint impact categories.
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