Advanced buffer materials for indoor air CO₂control in commercial buildings

Abstract

In this study, we evaluated solid sorbents for their ability to passively control indoor CO concentration in buildings or rooms with cyclic occupancy (eg, offices, bedrooms). Silica supported amines were identified as suitable candidates and systematically evaluated in the removal of CO from indoor air by equilibrium and dynamic techniques. In particular, sorbents with various amine loadings were synthesized using tetraethylenepentamine (TEPA), poly(ethyleneimine) (PEI) and a silane coupling agent 3-aminopropyltriethoxysilane (APS). TGA analysis indicates that TEPA impregnated silica not only displays a relatively high adsorption capacity when exposed to ppm level CO concentrations, but also is capable of desorbing the majority of CO by air flow (eg, by concentration gradient). In 10 L flow-through chamber experiments, TEPA-based sorbents reduced outlet CO by up to 5% at 50% RH and up to 93% of CO adsorbed over 8 hours was desorbed within 16 hours. In 8 m flow-through chamber experiments, 18 g of the sorbent powder spread over a 2 m area removed approximately 8% of CO injected. By extrapolating these results to real buildings, we estimate that meaningful reductions in the CO can be achieved, which may help reduce energy requirements for ventilation and/or improve air quality.

Performance of a CO 2 sorbent for indoor air cleaning applications: Effects of environmental conditions, sorbent aging, and adsorption of co‐occurring formaldehyde

“…The sorbent studied here could be part of the solution for occupant‐associated contaminants. Considering that the average amount of CO 2 emitted by a resting adult is 34 g/h, 22 the mass of sorbent required to prevent CO 2 concentration to increase beyond 1000 ppm is approximately 2 kg per person. This estimation assumes that the sorbent is placed in the return loop to defer an equivalent amount of outdoor air over four hours of daily operation in loading mode, with nighttime regeneration, as a peak reduction strategy.…”

“…Among technologies to capture CO 2 from air, amine‐functionalized materials are promising because of their high selectivity at low concentrations, 15 tolerance to moisture due to the chemical rather than physical nature of the sorbent‐adsorbate interaction, 16 and long‐term stability 15 . Amines can be coated onto different substrates, including zeolites, 17,18 silica, 15,19‐22 diatomaceous earth, 23 and activated carbon, 24 yielding capacities that are in most cases in the range 10‐100 mg CO 2 per g of sorbent. Two main mechanisms are postulated for the chemical interaction of CO 2 with surface‐functional primary or secondary amine groups on the solid sorbent material 19,25‐28 .…”

Nature-Based Solution for Reducing CO2 Levels in Museum Environments: A Phytoremediation Study for the Leonardo da Vinci’s “Last Supper”

“…In air-tight museum environments with limited ventilation, indoor CO 2 could be removed through adsorption, using sorption-type filters with activated carbons [14][15][16]. Nevertheless, these systems are not cost/effective, and some of them have a short lifespan or need a constant maintenance [17][18][19]. Eco-friendly and sustainable control measures are therefore needed for regulating CO 2 levels within air-tight museums.…”

CO2 Capture from Air Using Amine‐Functionalized Kaolin‐Based Zeolites

“…In particular, supported amine adsorbents, mainly aminosilica materials, have been shown as promising candidates for removing ultra‐low CO 2 concentration from air . In addition, with the aim of combining the advantages of supported amines and zeolites, several attempts have been undertaken to develop hybrid adsorbents by incorporating amine moieties into the framework of zeolites .…”