Aerosol generation in public restrooms.

Aerosolized droplets play a central role in the transmission of various infectious diseases, including Legionnaire's disease, gastroenteritis-causing norovirus, and most recently COVID-19. Respiratory droplets are known to be the most prominent source of transmission for COVID-19; however, alternative routes may exist given the discovery of small numbers of viable viruses in urine and stool samples. Flushing biomatter can lead to the aerosolization of micro-organisms; thus, there is a likelihood that bioaerosols generated in public restrooms may pose a concern for the transmission of COVID-19, especially since these areas are relatively confined, experience heavy foot traffic, and may suffer from inadequate ventilation.

Stability of amine-functionalized CO adsorbents: a multifaceted puzzle.

This review focuses on important stability issues facing amine-functionalized CO2 adsorbents, including amine-grafted and amine-impregnated silicas, zeolites, metal-organic frameworks and carbons. During the past couple of decades, major advances were achieved in understanding and improving the performance of such materials, particularly in terms of CO2 adsorptive properties such as adsorption capacity, selectivity and kinetics. Nonetheless, to pave the way toward commercialization of adsorption-based CO2 capture technologies, in addition to other attributes, adsorbent materials should be stable over many thousands of adsorption-desorption cycles.

Insights into the Hydrothermal Stability of Triamine-Functionalized SBA-15 Silica for CO Adsorption.

The hydrothermal stability of triamine-grafted, large-pore SBA-15 CO adsorbents was studied by using steam stripping. Following two 3 h cycles of steam regeneration, lower CO uptakes, lower CO /N ratios, and slower adsorption kinetics were observed relative to fresh samples, particularly at the lowest adsorption temperature (25 °C). CO adsorption measurements for a selected sample exposed to 48 h of steam stripping depicted that after the initial loss during the first exposure to steam (3-6 h), the adsorptive properties stabilized.

The role of beaded activated carbon's surface oxygen groups on irreversible adsorption of organic vapors.

The objective of this study is to determine the contribution of surface oxygen groups to irreversible adsorption (aka heel formation) during cyclic adsorption/regeneration of organic vapors commonly found in industrial systems, including vehicle-painting operations. For this purpose, three chemically modified activated carbon samples, including two oxygen-deficient (hydrogen-treated and heat-treated) and one oxygen-rich sample (nitric acid-treated) were prepared. The samples were tested for 5 adsorption/regeneration cycles using a mixture of nine organic compounds.

The role of beaded activated carbon's pore size distribution on heel formation during cyclic adsorption/desorption of organic vapors.

The effect of activated carbon's pore size distribution (PSD) on heel formation during adsorption of organic vapors was investigated. Five commercially available beaded activated carbons (BAC) with varying PSDs (30-88% microporous) were investigated. Virgin samples had similar elemental compositions but different PSDs, which allowed for isolating the contribution of carbon's microporosity to heel formation.

Automotive Wastes.

A review of the literature from 2014 related to automotive wastes is presented. Topics include solid wastes from autobodies and tires as well as vehicle emissions to soil and air as a result of the use of conventional and alternative fuels. Potential toxicological and health risks related to automotive wastes are also discussed.

Two-dimensional modeling of volatile organic compounds adsorption onto beaded activated carbon.

A two-dimensional heterogeneous computational fluid dynamics model was developed and validated to study the mass, heat, and momentum transport in a fixed-bed cylindrical adsorber during the adsorption of volatile organic compounds (VOCs) from a gas stream onto a fixed bed of beaded activated carbon (BAC). Experimental validation tests revealed that the model predicted the breakthrough curves for the studied VOCs (acetone, benzene, toluene, and 1,2,4-trimethylbenzene) as well as the pressure drop and temperature during benzene adsorption with a mean relative absolute error of 2.6, 11.

Effect of the adsorbate kinetic diameter on the accuracy of the Dubinin-Radushkevich equation for modeling adsorption of organic vapors on activated carbon.

This paper investigates the effect of the kinetic diameter (KD) of the reference adsorbate on the accuracy of the Dubinin-Radushkevich (D-R) equation for predicting the adsorption isotherms of organic vapors on microporous activated carbon. Adsorption isotherms for 13 organic compounds on microporous beaded activated carbon were experimentally measured, and predicted using the D-R model and affinity coefficients. The affinity coefficients calculated based on molar volumes, molecular polarizabilities, and molecular parachors were used to predict the isotherms based on four reference compounds (4.

Adsorption and desorption of mixtures of organic vapors on beaded activated carbon.

In this study, adsorption and desorption of mixtures of organic compounds commonly emitted from automotive painting operations were experimentally studied. A mixture of two alkanes and a mixture of eight organic compounds were adsorbed onto beaded activated carbon (BAC) and then thermally desorbed under nitrogen. Following both adsorption and regeneration, samples of the BAC were chemically extracted.

Effect of adsorption and regeneration temperature on irreversible adsorption of organic vapors on beaded activated carbon.

This paper investigates the effect of adsorption and regeneration temperature on the irreversible adsorption of a mixture of organic compounds typically emitted from automobile painting operations. Adsorption of the organic vapors mixture onto microporous beaded activated carbon (BAC) and regeneration of the saturated BAC were completed under different conditions. Results indicated that increasing the adsorption temperature from 25 to 35 or 45 °C increased heel buildup on BAC by about 30% irrespective of the regeneration temperature due to chemisorption.