The effect of varying battery voltage output on the emission rate of carbonyls released from e-cigarette smoke

Qu, Yao,Szulejko, Jan E.,Kim, Ki-Hyun,Jo, Sang-Hee Elsevier 2019 Microchemical journal Vol.145 No.-

<P><B>Abstract</B></P> <P>The effect of vaping voltage (range: 3.6 to 7.0 V) on the emission of carbonyl compounds (CC) from electronic cigarettes (ECs) was investigated in this study. Changes in the CC levels were compared between prior to (e–liquid samples) and after vaping (EC-aerosol samples) using a total of six different e-liquid samples. Three of them were lab-made binary e-liquid solutions (composed only of propylene glycol (PG) and vegetable glycerin (VG) at the following 3 mixing ratios: 7:3, 5:5, and 10:0), while the remaining three were retail e-liquid products. The CCs in aerosol samples were captured from 10 EC puffs on 2,4-dinitrophenylhydrazine (DNPH) cartridges (2 s puff duration with a 10 s interpuff interval). All six e-liquids analyzed prior to EC use contained formaldehyde (FA) and acetaldehyde (AA) in the range of 0.12–50.0 and 0.53–14.9 μg mL<SUP>−1</SUP>, respectively. As the vaping voltage increased from 3.6 to 7.0 V, their emission factors increased from 1.12 to 1.64 and from 1.30 to 2.02 (μg puff<SUP>−1</SUP>), respectively. Such patterns were also observed for other CCs. The 40-year cancer risk (CR) of FA and CA for a typical user (120 puffs day<SUP>−1</SUP>) was estimated to be 7.0 × 10<SUP>−4</SUP>–1.1 × 10<SUP>−3</SUP> and 3.2 × 10<SUP>−5</SUP>–1.4 × 10<SUP>−4</SUP>, respectively; these CR values increased by 1.2 and 1.7–2.0 times, respectively with an increase in vaping voltage (3.6–7.0 V). The CR due to FA exposure from the three tested retail e-liquids was estimated to be 2.6–56 times higher than that of traditional tobacco cigarettes. Therefore, the use of ECs may expose users to high levels of certain CCs (like FA and AA), which may increase the risk for cancer in humans.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Electronic cigarettes (e-cigarettes or ECs) are widely used around the world. </LI> <LI> Use of EC releases infamous pollutants (e.g., carbonyl compounds (CCs) - formaldehyde (FA)). </LI> <LI> A heating element is activated to vaporize the e-liquid to release various CCs like FA. </LI> <LI> Here, the effect of EC vaping voltage was investigated with regard to CC emission factors. </LI> <LI> Accordingly, we quantified CCs in two different phases (EC liquid vs. aerosolized samples). </LI> </UL> </P>

The effect of flavor content in e-liquids on e-cigarette emissions of carbonyl compounds

Qu, Yao,Kim, Ki-Hyun,Szulejko, Jan E. Elsevier 2018 Environmental research Vol.166 No.-

<P><B>Abstract</B></P> <P> <B>T</B>he effect of flavors on carbonyl compound (CC) emission factors (EF) from electronic cigarettes (ECs) vaping was investigated at the default vaping (voltage) setting in all experiments using a total of 21 lab-made e-liquid samples (five different types of retail flavorant bases: beverage/dessert/fruit/mint/tobacco). Each flavorant base was added to a separate unflavored base composed of a 1:1 mixture of propylene glycol/vegetable glycerol (PG/VG) at four levels (5/10/30/50% (v/v)). The e-liquid CC levels increased linearly with flavorant base content, 1.3–10.5 times (R<SUP>2</SUP>: 0.762–0.999). The vaping CC EFs increased linearly with flavorant base content (if ≥ 10%) from 1.0 to 92 times (R<SUP>2</SUP>: 0.431–0.998). For flavorant base content of 0%, 5%, and 10%, the EFs ranged from undetected to 0.11 μg puff<SUP>−1</SUP> (acetone). The 40-year cancer risk due to formaldehyde (70 kg EC user inhaling 5% flavorant base content e-liquid: 120 puffs day<SUP>−1</SUP>) is estimated to be 2.0E-06 (highest) compared to 1.0E-06 for the 1:1 PG:VG base. Most formaldehyde vaped from the fruit flavored e-liquid was the flavorant base. The CC concentrations in EC liquids (before vaping) were approximately linear with e-liquid flavorant base content. Retail e-liquid product information labels should be guided to provide a complete list of all ingredients, their concentrations, and carbonyl compound EFs.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Electronic cigarettes (e-cigarettes or ECs) are designed to deliver nicotine to a smoker. </LI> <LI> The flavorings in e-liquids were considered safe but raised concerns due to potential toxicity. </LI> <LI> In this study, we investigated the effects of flavor content on CC emissions from EC vaping. </LI> <LI> The CC amounts (before/during vaping) was estimated from the flavor content in the e-liquid. </LI> <LI> The effects of flavor content in e-liquids on vaping CC emissions warrant attention. </LI> </UL> </P>

Derivatization techniques for determination of carbonyls in air

Szulejko, Jan E.,Kim, Ki-Hyun Elsevier 2015 Trends in analytical chemistry Vol.64 No.-

<P><B>Abstract</B></P> <P>This review critically assesses the derivatization techniques employed in sampling and detection of carbonyl compounds in air. We explore the most common techniques reported for the collection of vapor- phase carbonyl compounds by focusing on the hydrazine-derivatization techniques developed with the aid of diverse sorptive media [solution (e.g., in impingers), solid sorbents, solid-phase extraction, solid-phase microextraction, and denuder, or other approaches]. We discuss the advantages and the disadvantages of each sampling and pretreatment option for key carbonyl compounds with reference to measurement data obtained under laboratory and field conditions.</P> <P><B>Highlights</B></P> <P> <UL> <LI> To quantify ambient carbonyls, derivatization is employed in sampling and detection. </LI> <LI> Common derivatization techniques have shortcomings as sources of bias. </LI> <LI> Up-to-date review of progress in derivatization for carbonyl compounds in air. </LI> </UL> </P>

Seeking the most powerful and practical real-world sorbents for gaseous benzene as a representative volatile organic compound based on performance metrics

Szulejko, Jan E.,Kim, Ki-Hyun,Parise, John Elsevier 2019 Separation and purification technology Vol.212 No.-

<P><B>Abstract</B></P> <P>To assess the best sorbents available in real-world treatment of airborne volatile organic compounds (VOCs), we explored four sorbent performance metrics (10% breakthrough volume, space velocity, regeneration cycles, and cost) against benzene, a representative VOC, using well-known sorbents in the partial pressure (P<SUB>benzene</SUB>) range 0.01 – 1 Pa. Accordingly, some common materials (e.g., activated carbons) outperformed novel materials like MOFs. The performance of MOFs was often exaggerated as data were generally collected under unrealistic P<SUB>benzene</SUB> (e.g., >5,000 Pa). The use of metrics appropriate to real-world conditions is thus critical for selecting sorbents.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Performance of sorbents in real-world treatment of VOC is important for AQM purposes. </LI> <LI> Metrics were selected as breakthrough volume, space velocity, regeneration cycles, and cost. </LI> <LI> Sorbent performance metrics were checked for benzene in the partial pressure 0.01–1 Pa. </LI> <LI> Some common materials (e.g., activated carbons) have the potential to outperform others. </LI> <LI> The use of metrics appropriate to real-world conditions is critical for selecting sorbents. </LI> </UL> </P>

Airborne volatile aromatic hydrocarbons at an urban monitoring station in Korea from 2013 to 2015

Khan, Azmatullah,Szulejko, Jan E.,Kim, Ki-Hyun,Brown, Richard J.C. Elsevier 2018 Journal of environmental management Vol.209 No.-

<P><B>Abstract</B></P> <P>The concentrations of C<SUB>6</SUB>-C<SUB>10</SUB> volatile aromatic hydrocarbons (AHCs) in air were measured at an urban air quality monitoring station in Jong-Ro, Seoul, Korea, between 2013 and 2015. Their temporal patterns (e.g., diurnal, intraweek, daily) were assessed individually and collectively as groups of benzene, toluene, ethylbenzene, styrene, and xylene (BTESX); total aliphatic hydrocarbon (TALHC: C<SUB>2</SUB>-C<SUB>12</SUB>); total aromatic hydrocarbon (TARHC: C<SUB>6</SUB>-C<SUB>10</SUB>); and total hydrocarbon (THC: C<SUB>2</SUB>-C<SUB>12</SUB>). The highest mean AHC concentrations over the 3-year study (in ppb (v/v)) were observed for toluene (6.0 ± 4.3), followed by the xylenes (1.5 ± 1.3), ethylbenzene (0.85 ± 0.93), benzene (0.73 ± 0.77), and styrene (0.16 ± 0.30) nL/L. The mean ppbC ((v/v), nL∙atm∙C/nL∙atm) values for BTESX, TALHC, TARHC, and THC were 65.8, 113, 77.7, and 191 ppbC, respectively. For most AHC species (e.g., toluene, styrene, and BTESX), only weak seasonal trends were observed in contrast to temporally varying species like nitric oxide (NO) (e.g., 26.3 ppb (January–February) vs. 8.5 ppb (July–August) during weekdays in 2013). Furthermore, toluene and NO concentrations were much higher (up to a factor 3) on weekdays than on Sunday for most weeks. This might reflect reduced anthropogenic activities on Sunday.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Toluene was the major BTESX. </LI> <LI> Propane was major hydrocarbon in all 56 hydrocarbons. </LI> <LI> Toluene and NO has strong correlation. </LI> <LI> Both toluene and NO showed much higher working day levels compare to Sunday. </LI> </UL> </P>

A comparison of figure of merit (FOM) for various materials in adsorptive removal of benzene under ambient temperature and pressure

Khan, Azmatullah,Szulejko, Jan E.,Kim, Ki-Hyun,Sammadar, Pallabi,Lee, Sang Soo,Yang, Xiao,Ok, Yong Sik Elsevier 2019 Environmental research Vol.168 No.-

<P><B>Abstract</B></P> <P>To effectively remove gaseous pollutants from air using sorbents, a thorough knowledge of the actual sorption performance is needed at ambient conditions rather than at unrealistically high-pressure conditions, as is commonly presented in the literature. To this end, the sorbent capacities of gaseous benzene were evaluated at a constant sorbent bed inlet pressure (50 ppm or ~5 Pa) in 1 atm of N<SUB>2</SUB>, room temperature (298 K), a fixed flow rate (50 mL min<SUP>−1</SUP>), and equal outlet sampling intervals (5 min). The benzene adsorption patterns were investigated against six sorbent types in a total of 17 different forms: 1- zeolite in five forms: beads (ZB), ground to 212 µm (ZG212), beads ground to 300 µm (ZG300), coarsely ground/washed zeolite (ZWc), and coarsely ground/washed/thermally treated zeolite (ZTc), 2- activated carbon in two forms: 212 µm (ACd212) and granular (ACdg), 3- Carbopack-X (CX), 4- Tenax TA (TA), 5- used black tea leaves of 150 or 300 µm in three forms: dry (TD150/TD300), wet (TW150/TW300), and wet dust (TWd), and 6- used ground coffee in either dry (CD) or wet forms (CW). Accordingly, the largest adsorption capacities at 5 Pa (e.g., >10 mg g<SUP>−1</SUP>) were observed for ACd212 (79.1) and ACdg (73.6). Moderate values (e.g., 5 < < 10 mg g<SUP>−1</SUP>) were obtained for ZG212 (7.98), CX (6.79), ZG300 (5.70), and ZB (5.58), while the remainder were far lower at < 5 mg g<SUP>−1</SUP> (e.g., tea leaves, ground coffee, TA, ZWc, and ZTc). The experimental benzene capacities of the tested sorbents were further assessed by the Langmuir, Henry's law, Freundlich, Dubinin-Radushkevich, and Elovich isotherm models. The linearized Langmuir adsorption isotherms of ACd212, ACdg, and CX showed the presence of more than one adsorption site (i.e., retrograde at the lowest pressures and two others at higher pressures). However, TA, zeolite, tea leaves, and ground coffee exhibited a type-V isotherm, wherein the sorption capacity continued to increase with loaded volume (i.e., multilayer adsorption). Thus, ACd212 has the best figure-of-merit based on a high 10% breakthrough volume (BTV) and low cost for real-world applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Activated carbon (ACd212) has retrograde isotherm. </LI> <LI> The ground sorbent has higher BTV compare to granular sorbent. </LI> <LI> The Langmuir adsorption isotherms identified more than one adsorption site. </LI> <LI> Tea leaves and ground coffee followed multilayer adsorption isotherm. </LI> <LI> The practicality of different sorbents is finally evaluated in terms of FOM. </LI> </UL> </P>

Air ionization as a control technology for off-gas emissions of volatile organic compounds

Kim, Ki-Hyun,Szulejko, Jan E.,Kumar, Pawan,Kwon, Eilhann E.,Adelodun, Adedeji A.,Reddy, Police Anil Kumar Elsevier Applied Science Publishers 2017 Environmental pollution Vol.225 No.-

<P><B>Abstract</B></P> <P>High energy electron-impact ionizers have found applications mainly in industry to reduce off-gas emissions from waste gas streams at low cost and high efficiency because of their ability to oxidize many airborne organic pollutants (<I>e.g</I>., volatile organic compounds (VOCs)) to CO<SUB>2</SUB> and H<SUB>2</SUB>O. Applications of air ionizers in indoor air quality management are limited due to poor removal efficiency and production of noxious side products, e.g., ozone (O<SUB>3</SUB>). In this paper, we provide a critical evaluation of the pollutant removal performance of air ionizing system through comprehensive review of the literature. In particular, we focus on removal of VOCs and odorants. We also discuss the generation of unwanted air ionization byproducts such as O<SUB>3</SUB>, NOx, and VOC oxidation intermediates that limit the use of air-ionizers in indoor air quality management.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Much research effort has been put to eliminate or reduce airborne pollutants. </LI> <LI> Destructive methods of VOCs commonly involve thermal oxidation with or without a catalyst. </LI> <LI> In this review, we provide insights into effective strategy for air quality remediation. </LI> <LI> To this end, we assessed the role of air ionization methods for the control of IAQ. </LI> <LI> We discuss future opportunities for air ionization techniques as reliable tools for controlling VOCs. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Chemisorption of hydrogen sulfide by metal-organic frameworks and covalent-organic polymers based on experimental/theoretical evaluation

Lee, Min-Hee,Vikrant, Kumar,Younis, Sherif A.,Szulejko, Jan E.,Kim, Ki-Hyun Elsevier 2020 JOURNAL OF CLEANER PRODUCTION Vol.250 No.-

<P><B>Abstract</B></P> <P>The rapid expansion of modern industrial productivity has led to the ever-increasing emissions of various hazardous gaseous pollutants. In order to efficiently treat gaseous odorants like hydrogen sulfide (H<SUB>2</SUB>S), it is important to accurately assess the sorptive performance under near ambient conditions [<1 Pa at 298 K]. To this end, the performance of H<SUB>2</SUB>S sorption was investigated at 1 Pa (∼10 ppm at 298 K) inlet stream partial pressure of H<SUB>2</SUB>S in 1 bar of N<SUB>2</SUB> using three metal-organic frameworks (MOFs: MOF-199, MOF-5, and UiO-66-NH<SUB>2</SUB>), two covalent-organic polymers (COPs: CBAP-1 (EDA) and CBAP-1 (DETA)), and two commercial sorbents (Carbopack-X and activated carbon [AC]). The 10% breakthrough volume (BTV10: L g<SUP>−1</SUP>)/corresponding adsorption capacity (mg g<SUP>−1</SUP>) confirmed a noticeable advantage of MOF-199 (3040/42) over all other tested materials (i.e., MOF-5 (94/1.3) >AC (3.5/0.049) > UiO-66-NH<SUB>2</SUB> (3.1/0.043) > CBAP-1 (EDA) (2.5/0.035) > CBAP-1 (DETA) (2/0.028) > Carbopack-X (1.9/0.026)). The overall results clearly confirm that MOF-199 is an excellent chemisorbent to effectively capture gaseous H<SUB>2</SUB>S via the formation of irreversible chemical bonds with Cu–Cu site bridge (i.e., Cu–S). However, a comparison between previous (theoretical) and present (experimental) data indicates substantial divergence in the partition coefficient (PC: mol kg<SUP>−1</SUP> Pa<SUP>−1</SUP>) data of MOF-199 (e.g., PC (at BTV5) = 16.0 (experiment) vs. PC = 7.5E-05 (simulation)). These divergences with the computed PC values are attributed to the fact that the crystal lattice of MOF-199 relaxes to a more thermodynamically stable structure under real-experimental conditions. In contrast, the assumption of frozen geometry of MOF-199 crystal lattice used for the theoretical simulation (by density functional theory) unrealistically underestimated the H<SUB>2</SUB>S adsorption capacity.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

The effect of diverse metal oxides in graphene composites on the adsorption isotherm of gaseous benzene

Khan, Azmatullah,Szulejko, Jan E.,Samaddar, Pallabi,Kim, Ki-Hyun,Eom, Wonsik,Ambade, Swapnil B.,Han, Tae Hee Elsevier 2019 Environmental research Vol.172 No.-

<P><B>Abstract</B></P> <P>The effective removal technique is necessary for the real world treatment of a hazardous pollutant (e.g., gaseous benzene). In an effort to develop such technique, the adsorption efficiency of benzene in a nitrogen stream (5 Pa (50 ppm) at 50 mL atm min<SUP>−1</SUP> flow rate and 298 K) was assessed against 10 different metal oxide/GO composite materials (i.e., 1: graphene oxide Co (GO-Co (OH)<SUB>2</SUB>), 2: graphene oxide Cu (GO-Cu(OH)<SUB>2</SUB>), 3: graphene oxide Mn (GO-MnO), 4: graphene oxide Ni (GO-Ni(OH)<SUB>2</SUB>), 5: graphene oxide Sn (GO-SnO<SUB>2</SUB>), 6: reduced graphene oxide Co (rGO-Co(OH)<SUB>2</SUB>), 7: reduced graphene oxide Cu (rGO-Cu(OH)<SUB>2</SUB>), 8: reduced graphene oxide Mn (rGO-MnO), 9: reduced graphene oxide Ni (rGO-Ni(OH)<SUB>2</SUB>), and 10: reduced graphene oxide Sn (rGO-SnO<SUB>2</SUB>)) in reference to their pristine forms of graphene oxide (GO) and reduced graphene oxide (rGO). The highest adsorption capacities (at 100% breakthrough) were observed as ~23 mg g<SUP>−1</SUP> for both GO-Ni(OH)<SUB>2</SUB> and rGO-SnO<SUB>2</SUB>, followed by GO (~19.1 mg g<SUP>−1</SUP>) and GO-Co(OH)<SUB>2</SUB> (~18.8 mg g<SUP>−1</SUP>). Therefore, the GO-Ni(OH)<SUB>2</SUB> and rGO-SnO<SUB>2</SUB> composites exhibited considerably high capacities to treat streams containing >5 Pa of benzene. However, the lowest adsorption capacity was found for GO-MnO (0.05 mg g<SUP>−1</SUP>). Alternately, if expressed in terms of the 10% breakthrough volume (BTV), the five aforementioned materials showed values of 0.50, 0.46, 0.40, 0.44, and 0.39 L g<SUP>−1</SUP>, respectively. The experimental data of target sorbents were fitted to linearized Langmuir, Freundlich, Elovich, and Dubinin-Radushkevich isotherm models. Accordingly, the non-linear Langmuir isotherm model revealed the presence of two or more distinct sorption profiles for several of the tested sorbents. Most of the sorbents showed type-III isotherm profiles where the sorption capacity proportional to the loaded volume.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The diverse forms of graphene-based composite with metal oxides were synthesized. </LI> <LI> The adsorption performance of these composites has been evaluated against benzene. </LI> <LI> Empirical isotherm models were employed to interpret the role of metal oxides in the adsorption. </LI> <LI> The possible mechanisms were explained by performance metrics over varying pressure regions. </LI> </UL> </P>

Recovery of nanomaterials from battery and electronic wastes: A new paradigm of environmental waste management

Dutta, Tanushree,Kim, Ki-Hyun,Deep, Akash,Szulejko, Jan E.,Vellingiri, Kowsalya,Kumar, Sandeep,Kwon, Eilhann E.,Yun, Seong-Taek Elsevier 2018 RENEWABLE & SUSTAINABLE ENERGY REVIEWS Vol.82 No.3

<P><B>Abstract</B></P> <P>Recycling battery and electronic wastes for the recovery of nanomaterials (NMs) has ushered in a new era in nanotechnology and environmental research. Essentially, NM recycling offers a two-way method of environmental remediation. The potential economic benefits of high-value NM end-products are conducive for industrial scale operations. Simultaneously, it reduces the industrial consumption of finite primary resources. The added benefits of abating environmental pollution (e.g., from VOCs, VFAs, SO<SUB>2</SUB>, NOx, and heavy metals) further contributes to the significance of ongoing research in this particular area. However, some challenges still persist due to the lack of motivation for recycling and the problem of the limited usability (or low stability) of many of the end-products. In this study, we aimed to evaluate different basic aspects of waste recycling in relation to NM recovery, along with other associated techniques. The utility of recovered NMs and potential options for NM recovery are described as highlighting features to help construct a future roadmap for this emerging scientific field. In addition, an assessment of the potential economic returns from recycling high-purity NMs is provided. Outcomes of this review may fuel further innovations for optimizing the current recycling methods for the efficient synthesis of commercial-grade, high purity NMs at minimal cost.</P>