Air Purification

Air decontamination is always a prime concern to society as the air to be inhaled should be free of contaminants so that living beings can get ample amount of energy to wheel their lives. Rapid urbanization causes drastic contamination in air that can create several life-threatening disorders. In this scenario, ultrahigh detection along with quick estimation of air pollutants has become an urgent need to the society. Nanotechnology enabled enzyme mimicking materials known as nanozymes, demonstrates elevated purification efficiency, sterilizability and low wind resistance. These materials when used in air-filter can work as a soldier to combat with air pollution. Incorporation of latest technology viz. Internet of Things (IoT), cloud computing, etc., brings a new flavor in air refinement. In this present work, several nanozymes are surveyed with high efficiency in air filtration. Single atom nanozymes have established themselves as proficient candidates in air decontamination. The im...

Gold catalysts, with different particle sizes ranging from 19 to 556 Å, and supported on SBA-15 mesoporous silica, were prepared by using deposition-precipitation, co-precipitation, and impregnation methods. All samples were characterised by TEM, EXAFS, XPS, XRD, CFR (Continuous Flow Reactor), and TPR. The sample which proved to have the highest activity was characterised by TAP (Temporal Analysis of Products) as well. XPS, wide-angle XRD, EXAFS, and H2-TPR measurements and data analysis confirmed that gold was present as Au0 only on all samples. The size of the Au nanoparticle was determined from TEM measurements and confirmed through wide-angle XRD measurements. EXAFS measurements showed that as the Au-Au coordination number decreased the Au-Au bond length decreased. TEM data analysis revealed a dispersion range from 58% (for the smallest particle size) to 2% (for the highest particle size). For Au particles’ sized lower that 60 Å, the Au dispersion was determined using a literatu...

There is growing interest in air quality and air purification, due to current high pollution levels, their effects on human health, and implications for urban economies. Since the improvement of air quality carries important economic value, air-related benefits have been evaluated monetarily from two perspectives: the first relates to air quality improvements, while the second values air purification as an ecosystem function. This research opted for the second perspective, given that the study area (two Colombian municipalities) does not suffer from poor air quality conditions, but stakeholders prioritized this function as highly important to them. Contingent valuation methods were applied in order to identify the population’s probability of willingness to maintain the air purification function. Although individuals (n = 245) attribute a yearly monetary value of USD 1.5 million to air purification, it was found that, despite the high level of social importance that respondents assig...

This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

The bimetallic core-shell nanostructures of galvanic metals have gained considerable scientific interest in improving the TiO 2 photocatalysis under solar radiations over the monometallic analogues. In the present research work, Pd@Au core-shell supported TiO 2 nanostructures were synthesized via galvanic replacement reaction and were examined for their catalytic/ photocatalytic hydrogenation. Three different types of bimetallic Pd@Au nanostructure were synthesized by varying Pd:Au weight ratio i.e. (1:1), (1:2) and (1:3). DLS measurements revealed that with increasing Au weight ratio, the hydrodynamic size increases from 126 to 157 nm. The optical studies showed a considerable blue shift in the absorption band of Au nanoparticles from 529 to 518 nm in the case of Pd@Au (1:1). The co-existence of absorption characteristic of Pd and Au suggests the successful synthesis of bimetallic nanostructure. STEM and EDS mapping further confirmed the formation of Pd@Au nanostructure with inner Pd core and outer Au shell. Bimetallic Pd@Au nanocatalyst displayed superior activity and selectivity towards hydrogenation of cinnamaldehyde in comparison to monometallic analogues. However, when Pd@Au nanostructures were impregnated on the surface of TiO 2, a significant improvement in the hydrogenation reaction was observed under solar radiations relative to catalytic conditions. The photocatalytic performance of Pd@Au-TiO 2 was found to be varied as a function of shell thickness and the optimized APT-2 (Pd 1 @Au 2 -TiO 2 ) photocatalyst exhibited higher rate constant (2.3 × 10 -1 h -1) for cinnamaldehyde hydrogenation. Hence, the plasmonic Pd@Au-TiO 2 hetero-junction could be a promising greener photocatalyst for selective hydrogenation of unsaturated carbonyls for large scale industrial applications.

The bimetallic core-shell nanostructures of galvanic metals have gained considerable scientific interest in improving the TiO 2 photocatalysis under solar radiations over the monometallic analogues. In the present research work, Pd@Au core-shell supported TiO 2 nanostructures were synthesized via galvanic replacement reaction and were examined for their catalytic/ photocatalytic hydrogenation. Three different types of bimetallic Pd@Au nanostructure were synthesized by varying Pd:Au weight ratio i.e. (1:1), (1:2) and (1:3). DLS measurements revealed that with increasing Au weight ratio, the hydrodynamic size increases from 126 to 157 nm. The optical studies showed a considerable blue shift in the absorption band of Au nanoparticles from 529 to 518 nm in the case of Pd@Au (1:1). The co-existence of absorption characteristic of Pd and Au suggests the successful synthesis of bimetallic nanostructure. STEM and EDS mapping further confirmed the formation of Pd@Au nanostructure with inner Pd core and outer Au shell. Bimetallic Pd@Au nanocatalyst displayed superior activity and selectivity towards hydrogenation of cinnamaldehyde in comparison to monometallic analogues. However, when Pd@Au nanostructures were impregnated on the surface of TiO 2, a significant improvement in the hydrogenation reaction was observed under solar radiations relative to catalytic conditions. The photocatalytic performance of Pd@Au-TiO 2 was found to be varied as a function of shell thickness and the optimized APT-2 (Pd 1 @Au 2 -TiO 2 ) photocatalyst exhibited higher rate constant (2.3 × 10 -1 h -1) for cinnamaldehyde hydrogenation. Hence, the plasmonic Pd@Au-TiO 2 hetero-junction could be a promising greener photocatalyst for selective hydrogenation of unsaturated carbonyls for large scale industrial applications.

Background: Bimetallic nanocomposites have currently gained significant importance for enhanced catalytic applications relative to monometallic analogues. The synergistic interactions modified electronic and optical properties in the bimetallic (M1@M2) structural morphology e.g., coreshell /alloy nanostructures resulting in a better co-catalytic performance for TiO 2 photocatalysis. Objective: Hence, this article discusses the preparation, characterization, and co-catalytic activity of different bimetallic nanostructures namely, Cu@Zn, Pd@Au, Au@Ag, and Ag@Cu, etc. Method: These bimetallic co-catalysts deposited on TiO 2 possess the ability to absorb visible light due to surface plasmonic absorption and are also expected to display the new properties due to synergy between two distinct metals. As a result, they reveal the highest level of activity than the monometal deposited TiO 2 . Result: Their optical absorption, emission, charge carrier dynamics, and surface structural morphology are explained for the improved photocatalytic activity of M1@M2 loaded TiO 2 for the hydrogenation of certain organic compounds e.g., quinoline, crotonaldehyde, and 1,3-dinitrobenzene, etc. under UV/ visible light irradiation. It was revealed that the use of bimetallic core@shell co-catalyst for hydrogenation of important industrial organics by M1@M2-TiO 2 nanocomposite demonstrates beneficial reactivity in many instances relative to conventional transition metal catalysts.

Homogeneously dispersed Au-Ag alloyed nanostructures varying from spherical (6-8 nm) to rod shape (aspect ratio ∼15-20 nm) were synthesized within the channels of amine modified mesoporous SBA-15 using post modification. Formation of alloy nanostructures for varying Au-Ag loadings have been supported by XPS and elemental mapping studies. Furthermore, changes in the surface/electronic properties of mesocomposites as a function of increased bimetallic Au:Ag loading have been elucidated with the help of XRD, BET, TEM and XPS studies respectively. It was found that synergism owing to electronic interplay between Au and Ag species concurrently improved the catalytic activity of bimetallic nanocomposites. Among the various monometallic and bimetallic mesocomposites, Au-Ag (5:1)/m-SBA-15 nanocomposites exhibited the best catalytic activity (k = 2.12 × 10 -2 min -1 and 3.99 × 10 -2 min -1 ) for the selective reduction of nitrobenzene to aniline and p-nitroacetophenone to p-aminoacetophenone respectively.

Bimetallic Pd@Ni nanostructure exhibited enhanced co-catalytic activity for the selective hydrogenation of benzaldehyde compare to their monometallic counterparts. Impregnation of these mono/bimetallic nanostructures on mesoporous TiO 2 leads to several surface modifications. The bimetallic PNT-3 (Pd 3 @Ni 1 /mTiO 2 ) exhibited large surface area (212 m 2 g À1 ), and low recombination rate of the charge carriers (e À -h + ). The hydrogenation reaction was analyzed under controlled experiments. It was observed that under UV-light irradiations and saturated hydrogen atmosphere the bimetallic PNT-3 photocatalyst display higher rate constant k = 5.31 Â10 À1 h À1 owing to reduction in the barrier height which leads to efficiently transfer of electron at bimetallic/mTiO 2 interface.

The redox properties of ceria make it suitable as a catalyst or support in oxidation reactions. Ceria-supported transition metal nanoparticles or isolated single atoms provide a metal-support interface that reduces the energy cost to remove interfacial oxygen atoms, providing active oxygen species that can participate in Mars van Krevelen oxidation processes. CO oxidation is a key probe reaction to test the reducibility of ceria-supported catalysts and is also practically important in the elimination of CO at relatively low temperatures in various applications. Preferential oxidation of CO (PROX) in excess H2 controls the CO concentration to ultra-low levels to prevent poisoning of hydrogen oxidation electrocatalysts. The reactivity of catalysts in CO oxidation and selectivity towards CO over H2 in PROX is dependent on the type and dispersion of metal species, the structural and chemical properties of CeO2, and the synthetic preparation methods of the catalysts. In this review, we summarize recently published works on catalytic CO oxidation and PROX reactions on ceria-supported metal nanoparticles and single atoms. We summarize the reactivity on different supported metals, and on different CeO2 surfaces with the same metal. We summarize the most likely reaction mechanisms as suggested by density functional theory calculations. The factors contributing to selectivity towards CO oxidation in PROX reactions on various supported metals are also discussed.

Global air pollution presents a pressing concern impacting human well-being. The growing emphasis on indoor air quality (IAQ) and heightened demands for enhanced home comfort have fueled interest in innovative solutions. This research introduces a comprehensive system integrating real-time monitoring, air purification, and cooling technologies using sensors, filters, Ultraviolet light, and a Peltier Module. Effectively eliminating indoor pollutants like dust and microparticles, the device is equipped to detect smoke, methane, LPG, and carbon monoxide, while monitoring temperature and humidity. Post-purification, the air undergoes partial chilling for improved interior temperatures. Operated through a manual remote control and the 'BLYNK I. O. T. ' Android application, The system enables remote operation over long distances, extending its functionality to operate seamlessly through the internet. Assessments indicate a temperature decrease of 5.7 ⁰C in real-time monitoring accuracy. Furthermore, the project incorporates automated control functions for the cooling system, humidifier activation, and alarm notifications, responding from the output of the sensors. This holistic approach showcases the potential for future advancements in IAQ solutions and Heating, Ventilation, and Air Conditioning (HVAC) technologies.

Diesel soot oxidation is a typical gas (O 2)-solid (soot)-solid (catalyst) three-phase oxidation, which requires both high contact efficiency between the three-phase substances and excellent intrinsic catalytic activity of catalysts. We proposed a new strategy for improving the catalytic performances of Ag/HZSM-5 catalyst for diesel soot oxidation via synergistically regulating both active species and support of catalyst. One is constructing hierarchical pore structure on HZSM-5 (denoted as Z) support by lye treatment with various concentration (0.1 M, 0.2 M and 0.5 M); the other is incorporating alkali-metal (K or Cs) into the Ag/Z catalyst to form the bimetallic catalysts. Internally, the bimetallic catalysts Ag-K/Z-0.1 M and Ag-Cs/Z-0.1 M exhibited the superior catalytic activities. The CO 2 selectivity reached 98.6% and 95.6% for Ag-K/Z-0.1 M and Ag-Cs/Z-0.1 M, respectively. In addition, Ag-Cs/Z-0.1 M obtained excellent stability, maintaining almost 100% activity without any recession after 10 cycles. Moreover, both bimetallic catalysts exhibited excellent sulfur and water resistance. The physicochemical properties of the bimetallic catalyst systems were investigated by SEM, N 2 adsorption-desorption, XRD, XPS, O 2-TPD, etc. The linear relationship between metallic silver and active oxygen content, and their correlation with catalysts activities have been discussed. Finally, possible dual synergistic effects in the bimetallic systems have been proposed.

Air decontamination is always a prime concern to society as the air to be inhaled should be free of contaminants so that living beings can get ample amount of energy to wheel their lives. Rapid urbanization causes drastic contamination in air that can create several life-threatening disorders. In this scenario, ultrahigh detection along with quick estimation of air pollutants has become an urgent need to the society. Nanotechnology enabled enzyme mimicking materials known as nanozymes, demonstrates elevated purification efficiency, sterilizability and low wind resistance. These materials when used in air-filter can work as a soldier to combat with air pollution. Incorporation of latest technology viz. Internet of Things (IoT), cloud computing, etc., brings a new flavor in air refinement. In this present work, several nanozymes are surveyed with high efficiency in air filtration. Single atom nanozymes have established themselves as proficient candidates in air decontamination. The im...

A series of Au-Pd/TiO 2 catalysts were synthesized in different weight % using sol-immobilization method. Of the range studied 1%Pd/TiO 2 catalyst achieved 86.4% conversion of phenol to CO 2 in a standard batch-slurry system utilizing UV. However under recycle or continuous operation Pd leaching from catalyst surface led to gradual deactivation. Au-Pd nanoparticles supported on TiO 2 P25 were stable and recyclable, here Au species were found to help to anchor Pd species on TiO 2 , and no observable Pd leaching occurred. Utilizing UV, 1%Pd/TiO 2 showed faster rate of phenol degradation in comparison to Au-Pd/TiO 2 , while 1%Au/TiO 2 and 0.5%Au-0.5%Pd/TiO 2 showed faster phenol degradation rates under visible light. The TiO 2 P25 support was also found to be active, stable and recyclable in phenol degradation utilizing UV; and was hence considered suitable for continuous operation. However poor oxygen mass transfer led to the formation and lay-down of polymeric species when using a Trickle bed approach. Operation in the Taylor flow regime was demonstrated to increase oxygen saturation and significantly reduced deactivation. Hence continuous photocatalytic degradation of phenol could be achieved using TiO 2 under Taylor Flow conditions.

Immobilization of photocatalysts in porous materials is an approach to significantly minimize the hazards of manipulation and recovery of nanoparticles. Inorganic materials, such as zeolites, are proposed as promising materials for photocatalyst immobilization mainly due to their photochemical stability. In this work, a green synthesis method is proposed to combine TiO2-based photocatalysts with commercial ZY zeolite. Moreover, a preliminary analysis of their performance as photocatalysts for the abatement of organic pollutants in waters was performed. Our results show that the physical mixture of TiO2 and zeolite maintains photocatalytic activity. Meanwhile, composites fabricated by doping TiO2–zeolite Y materials with silver and palladium nanoparticles do not contribute to improving the photocatalytic activity beyond that of TiO2.

Due to the environmental problems caused by the steadily increasing usage of fossil fuels, the interest for renewable sources of energy has amplified significantly. Among several possibilities, hydrogen gas is considered to be one of the most promising fuels for the future. If formed from water via photocatalysis it is a desirable, convenient and green improvement in the field of energy. During this work, we have tried to contribute to this important field. 4wt.% Au/TiO 2 synthesized by deposition-precipitation with urea was the main photocatalysts used in this project. Other noble metal-loaded (Pt and Ag) titanium dioxide materials were synthesized by deposition precipitation with urea and other methods such as sol gel and sol immobilization. These catalytic systems were studied and their activity compared for hydrogen production from water/methanol mixtures. Sets of monometallic Au, Ag, Pt and bimetallic Au-Pt and Au-Ag supported titanium dioxide were synthesized and tested. Au/TiO 2 photocatalysts synthesized by deposition precipitation with urea were the best in terms of hydrogen production compared to other photocatalysts. In the evaluation of possible sacrificial molecules, isopropanol was less efficient than methanol. Through the formation of bimetallic Ag-Au/TiO 2 and Pt-Au/TiO 2 catalysts, the hydrogen production could be further improved. Finally, Ir supported −Al 2 O 3 was investigated for the first time as a heterogeneous catalyst for hydrogen production by photocatalytic dehydrogenation of aqueous p-formaldehyde and photoreduction of carbon dioxide. First, completing a master's thesis in a foreign country while being a wife, a mother, is so difficult, it was a long trip full of obstacles and barriers. I want to thank my gad for a group of great people in my life helped make such a success possible. I am deeply grateful to them for making my dream of graduation a reality. For as long as I live, I will be thankful for having them in my life I would also like to take this opportunity to thank the sponsor of my scholarship King Abdullah, who passed away during the time I was studying, for offering the scholarship program which granted me the opportunity to be here. Acknowledgment and thanks are expressed to Saudi Cultural Bureau in Canada for their support, assistance and encouragement. Many thanks go to my supervisor, Dr. Sandro Gambarotta. I am very fortunate that he accepted to supervise my thesis. I would like to thank him for his continuous support, his valuables insights, his unlimited patience. I would also like to thank all my lab mates who have helped guide my project, I am very grateful to Dr. Nick Alderman Dr. Virginie Peneau, Camilo Viasus, Dr,Indira Thapa, Jacob Sommers, Laura Hull. I appreciate their skill and knowledge in interaction with students in the lab, presentation seminar and their assistance with the preparation of this thesis. Thank you to Dr. Dr. Glenn A. Facey for trining and helping me with NMR analysis. Also, many thanks go to Dr. Yun Liu for your training and help with my TEM and EDS needs. I would also like to express my deepest gratitude to my awesome parents, Safia & Ali; without them in my life I wouldn't be who I am. Their love, care, encouragement, and support have always reached me, wherever I was. "Thank you" will not be enough, even if I said it to them every second of the rest of my life. v Moreover, I dedicate this thesis to my soul mate and the love of my life, my husband, Maeed Thank you for holding my hand from the beginning of my study abroad until I reached this stage of prosperity. Thank you for your love, support, motivation, understanding and cooperation. I really appreciate your endless efforts to share responsibility with me to help me reach my goals. I also dedicate this thesis to the best things that ever happened to me, my lovely kids, Hamed & Hind. You are my precious inspiration. When I see your smile, when I hold you, when I hug you, I feel that I have the whole world in my hands. Without you in my life I would not think about the future and I would not be encouraged to make it brighter by completing such work. I would like to express my genuine thanks to all my siblings (Sharifa, Hasan, Layla, Huda, Hind, and cutest little brother Hassan). Even though you are far away, your encouragements reach my heart. I am so grateful to have you in my life, and I hope to be a part of your accomplishments as well. I would like to thank my friends in Canada who have eased the difficulty of being far away from home by providing me with love, laughter, cheer, and help, in sickness and in health. Throughout this long journey, you have been like sisters to me, especially, Muneerah and Hessa.

guidance and support, but more specifically, for her understanding when I decided to change to the Master's program. It was her understanding and comfort, that gave me the strength and determination to make one of the most important decisions in my career, and for that, I will be forever grateful. It has been a great honor to be part of the Walton Research Group. Each and every one of the group members have helped me at some point in these (almost) two years, either by training me in different equipment or by providing counsel and guidance throughout my research project. For that and so many other reasons, I would like to deeply appreciate all the former and current group members

This paper demonstrates the use of functionalized meso-silica materials (MCM-41 or SBA-15) as adsorbents for formaldehyde (H 2 CO) vapor from contaminated air. Additionally new green nanosilica (GNs) materials were prepared via a bioinspired synthesis route and were assessed for removal of H 2 CO from contaminated indoor air. These exciting new materials were prepared via rapid, 15 min, environmentally friendly synthesis routes avoiding any secondary pollution. They provided an excellent platform for functionalization and extraction of H 2 CO demonstrating similar performance to the conventional meso-silica materials. To the authors' knowledge this is the first reported practical application of this material type. Prior to trapping, all materials were functionalized with amino-propyl groups which led to chemisorption of H 2 CO; removing it permanently from air. No retention of H 2 CO was achieved with nonfunctionalized material and it was observed that best extraction performance required a dynamic adsorption setup when compared to passive application. These results demonstrate the first application of GNs as potential adsorbents and functionalized meso-silica for use in remediation of air pollution in indoor air.

Bimetallic Au-Pd alloy nanoparticles (NPs) dispersed on nanohybrid three-dimensionally ordered macroporous (3DOM) La 0.6 Sr 0.4 MnO 3 (LSMO) perovskite catalysts were fabricated via the L-lysine-mediated colloidal crystal-templating and reduction routes. The obtained AuPd/3DOM LSMO samples possess a nanovoid-like 3DOM construction with well-dispersed Au-Pd alloy NPs (2.05-2.35 nm in size) on the internal walls of the macropores. The Au-Pd alloy presence favored catalytic activity for methane combustion. The 3DOM LSMO support exhibits three key attributes: (i) a large surface area (32.0-33.8 m 2 /g) which aids high dispersion of the noble metal NPs on the support surface; (ii) abundant Brønsted acid sites which facilitate reactant adsorption and activation; and (iii) thermal stability. The AuPd/3DOM LSMO has been synthesized with the beneficial properties, including a richness of adsorbed oxygen species, increased oxidized noble metal species, low-temperature reducibility, and strong noble metal-3DOM LSMO interaction, all contributing to provide enhanced activity and a structure with high thermal and hydrothermal stability. In-situ diffuse reflectance infrared Fourier transform spectroscopy studies revealed that including Au in the bimetallic system accelerated the reaction rate and altered the reaction pathway for methane oxidation by enriching the adsorbed oxygen species and decreasing the bonding strength between the reaction intermediates and the Pd atoms.

Bimetallic Au-Pd alloy nanoparticles (NPs) dispersed on nanohybrid three-dimensionally ordered macroporous (3DOM) La 0.6 Sr 0.4 MnO 3 (LSMO) perovskite catalysts were fabricated via the L-lysine-mediated colloidal crystal-templating and reduction routes. The obtained AuPd/3DOM LSMO samples possess a nanovoid-like 3DOM construction with well-dispersed Au-Pd alloy NPs (2.05-2.35 nm in size) on the internal walls of the macropores. The Au-Pd alloy presence favored catalytic activity for methane combustion. The 3DOM LSMO support exhibits three key attributes: (i) a large surface area (32.0-33.8 m 2 /g) which aids high dispersion of the noble metal NPs on the support surface; (ii) abundant Brønsted acid sites which facilitate reactant adsorption and activation; and (iii) thermal stability. The AuPd/3DOM LSMO has been synthesized with the beneficial properties, including a richness of adsorbed oxygen species, increased oxidized noble metal species, low-temperature reducibility, and strong noble metal-3DOM LSMO interaction, all contributing to provide enhanced activity and a structure with high thermal and hydrothermal stability. In-situ diffuse reflectance infrared Fourier transform spectroscopy studies revealed that including Au in the bimetallic system accelerated the reaction rate and altered the reaction pathway for methane oxidation by enriching the adsorbed oxygen species and decreasing the bonding strength between the reaction intermediates and the Pd atoms.

Bu çalışmada içinde oturan insan olan bir odanın havasının temizlenmesinde kullanılan taşınabilir hava temizle cihazının performansı incelenmiştir. Cihazın temiz hava besleme menfezinden farklı üfleme açıları ve üfleme hızlarının cihazın temizleme performansına etkisi araştırılmıştır. Bu kapsamda temiz hava dağıtım oranı (CADR) ve hava yaşı parametreleri kullanılmıştır. Yapılan analizler ve hesaplamalar çerçevesinde temizlenmiş havanın farklı açı ve hızlarda üflenmesi cihaz performansını etkilediği tespit edilmiştir. Oda içerisinde ortalama hava yaşı üfleme hızı ile ters orantılı olduğu görülmüştür. Üfleme hızı arttıkça ortalama hava yaşında yarı yarıya azalma meydana gelmektedir. Temiz hava dağıtım oranı ve hava yaşı değerleri karşılaştırılarak en uygun üfleme hız ve açıları belirlenmiştir.

The air purifier industry has seen a growth in terms of demand and sales lately. All credit goes to massive industrialization in developing countries such as India and China. As a result, a lot of research has been focused into the various methods of purifying air. The most harmful of the pollutants are PM 2.5 particulates and NOx emissions. The aim has been to bring down the costs without compromising on efficiency as efficient air purification is an expensive deal. This article presents a study of the current scenario of the problems of air pollution. Severity of the issues have been highlighted. A compilation of the most common and significant methods of purifying air such as those employing the use of HEPA filters, electrostatic smoke precipitators, activated carbon and UV light has been presented and their use in air purifiers manufactured by OEMs has been mentioned. Some of the most modern methods of purifying air such as those using transparent PAN filters, photochemical mate...

This study focuses on the purification and monitoring of indoor air pollution aided with UV light radiation intended for laboratory and lecture rooms in Bataan Peninsula State University. The developed air recirculation prototype utilizes Arduino integrated development environment (IDE) software with two air quality sensors namely, BME680 and PMS5003, which send signals to relay to control the purification and monitoring operations. As a monitoring device, the prototype is capable of displaying real time air quality measurements as well as pollutant concentrations. The measured data control the purification process which activates only at acceptable range of indoor air quality (IAQ) allowing the prototype to conserve energy. Two approaches on monitoring accuracy were done with respect to the distance of prototype sensors to the air quality tester. While for the effectiveness of purification process, a five-minute recalibration speed on smoke tests were conducted. This study aimed to...

Nowadays, there is a significant interest in the development of environment friendly catalysts for alcohols oxidation. Aiming to produce improved catalytic materials, here, the synthesis of new TiO 2-MoO 3 nanocomposites, using distinct approaches is described. The samples were obtained by hydrothermal treatment of a molybdenum oxide precursor in the presence of TiO 2 using a step-by-step procedure (sample TM3) or using a one-pot approach (sample PTM3). Depending on the synthesis route, distinct morphologies, surface area and optical properties for the prepared samples, were obtained. The photocatalytic activity of the nanocomposite samples was evaluated for benzyl alcohol oxidation, under visible and UV-visible radiation. The results indicate that both materials are catalytic, presenting high selectivity for benzaldehyde production. Using UV-vis radiation, the best photocatalyst was PTM3 with 98% selectivity and under visible irradiation was TM3 with 99% of selectivity, with this performance being better than the one presented by either TiO 2 or MoO 3 separately.

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Tasit ici isitma, havalandirma ve iklimlendirme (HVAC) kanallarinda zamanla havada bulunan zehirli atiklar, sigara dumani, toz partikulleri havadaki nemle birlikte evaporatorde kendini birakmaktadir. Olusan kotu kokularin nedenlerinin en basinda evaporatorde ve havalandirma kanallari ic yuzeylerinde ureyen mikro organizmalardan ileri gelmektedir. Bu sorunun giderilmesinde klima kanallari icerisine sikilan pahali ve cevreye zararli dezenfektan maddelerin kullanimi yaygindir. Ancak cogu zaman bu yontemlerde yetersiz kalmaktadir. Baska bir yontem ise klima sisteminin tamamen sokulmesi ve koku kaynagi olan parcalarin fiziksel olarak temizlenmesidir. Bu yontem oldukca iscilik gerektiren ve pahali bir cozumdur. Bu calismada, arac ici (HVAC) kanallarinda hijyenin saglanmasinda, cevreye ve insan sagligina zararli kimyasallar kullanilmadan sicak buharli bir dezenfekte sistemi tasarimi ve calisma ozelliklerinden bahsedilmistir.

The thermocatalytic, photocatalytic and photothermo-catalytic oxidation of some volatile organic compounds (VOCs), 2-propanol, ethanol and toluene, was investigated over brookite TiO2-CeO2 composites. The multi-catalytic approach based on the synergistic effect between solar photocatalysis and thermocatalysis led to the considerable decrease in the conversion temperatures of the organic compounds. In particular, in the photothermo-catalytic runs, for the most active samples (TiO2-3 wt% CeO2 and TiO2-5 wt% CeO2), the temperature at which 90% of VOC conversion occurred was about 60 °C, 40 °C and 20 °C lower than in the thermocatalytic tests for 2-propanol, ethanol and toluene, respectively. Furthermore, the addition of cerium oxide to brookite TiO2 favored the total oxidation to CO2 already in the photocatalytic tests at room temperature. The presence of small amounts of cerium oxide allowed to obtain efficient brookite-based composites facilitating the space charge separation and inc...

Bimetallic Pt−Pd catalysts supported on ceria have been prepared by mechanochemical synthesis and tested for lean methane oxidation in dry and wet atmosphere. Results show that the addition of platinum has a negative effect on transient light-off activity, but for Pd/Pt molar ratios between 1:1 and 8:1 an improvement during time-on-stream experiments in wet conditions is observed. The bimetallic samples undergo a complex restructuring during operation, starting from the alloying of Pt and Pd and resulting in the formation of unprecedented "mushroom-like" structures consisting of PdO bases with Pt heads as revealed by high-resolution transmission electron microscopy (HRTEM) analysis. On milled samples, these structures are well-defined and observed at the interface between palladium and ceria, whereas those on the impregnated catalyst appear less ordered and are located randomly on the surface of ceria and of large PdPt clusters. The milled catalyst prepared by first milling Pd metal and ceria followed by the addition of Pt shows better performances compared to a conventional impregnated sample and also to a sample obtained by inverting the Pd−Pt milling order. This has been ascribed to the intimate contact between Pd and CeO 2 generated at the nanoscale during the milling process.

Objective Finely resolved PM2.5 exposure measurements at the level of individual participants or over a targeted geographic area can be challenging due to the cost, size and weight of the monitoring equipment. We propose re-purposing the low-cost, portable and lightweight Shinyei PPD42NS particle counter as a particle counting device. Previous field deployment of this sensor suggests that it captures trends in ambient PM2.5 concentrations, but important characteristics of the sensor response have yet to be determined. Laboratory testing was undertaken in order to characterize performance. Methods The Shinyei sensors, in-line with a TSI Aerosol Particle Sizer (APS) model 3321, tracked particle decay within an aerosol exposure chamber. Test atmospheres were composed of monodisperse polystyrene spheres with diameters of 0.75, 1, 2 3 and 6 um as well as a polydisperse atmosphere of ASHRAE test dust #1. Results Two-minute block averages of the sensor response provide a measurement with low random error, within sensor, for particles in the 0.75-6μm range with a limit of detection of 1 μg/ m3. The response slope of the sensors is idiomatic, and each sensor requires a unique response curve. A linear model captures the sensor response for concentrations below 50 μg/m3 and for concentrations above 50 μg/m 3 a non-linear function captures the response and saturates at 800 μg/m 3. The Limit of Detection (LOD) is 1 μg/m 3. The response time is on the order of minutes, making it appropriate for tracking short-term changes in concentration. Conclusions When paired with prior evaluation, these sensors are appropriate for use as ambient particle counters for low and medium concentrations of respirable particles (< 100 ug/m 3). Multiple sensors deployed over a spatial grid would provide valuable spatio-temporal variability in

Objective Finely resolved PM2.5 exposure measurements at the level of individual participants or over a targeted geographic area can be challenging due to the cost, size and weight of the monitoring equipment. We propose re-purposing the low-cost, portable and lightweight Shinyei PPD42NS particle counter as a particle counting device. Previous field deployment of this sensor suggests that it captures trends in ambient PM2.5 concentrations, but important characteristics of the sensor response have yet to be determined. Laboratory testing was undertaken in order to characterize performance. Methods The Shinyei sensors, in-line with a TSI Aerosol Particle Sizer (APS) model 3321, tracked particle decay within an aerosol exposure chamber. Test atmospheres were composed of monodisperse polystyrene spheres with diameters of 0.75, 1, 2 3 and 6 um as well as a polydisperse atmosphere of ASHRAE test dust #1. Results Two-minute block averages of the sensor response provide a measurement with low random error, within sensor, for particles in the 0.75-6μm range with a limit of detection of 1 μg/ m3. The response slope of the sensors is idiomatic, and each sensor requires a unique response curve. A linear model captures the sensor response for concentrations below 50 μg/m3 and for concentrations above 50 μg/m 3 a non-linear function captures the response and saturates at 800 μg/m 3. The Limit of Detection (LOD) is 1 μg/m 3. The response time is on the order of minutes, making it appropriate for tracking short-term changes in concentration. Conclusions When paired with prior evaluation, these sensors are appropriate for use as ambient particle counters for low and medium concentrations of respirable particles (< 100 ug/m 3). Multiple sensors deployed over a spatial grid would provide valuable spatio-temporal variability in

In this study, 0.1-4 wt.% Pd-loaded catalysts were synthesized via thermal decomposition of palladium (II) acetylacetonate (Pd(acac)2) at 210-310 °C or its photodecomposition under UV-LED irradiation using anatase TiO2 as a support. The catalysts were characterized by X-ray fluorescence, TEM, XPS, and CO chemisorption analyses and tested for CO oxidation at room temperature in a batch reactor both in the absence and presence of UV-LED irradiation. The effects of the Pd(acac)2 decomposition method and Pd content on the dark catalytic and photocatalytic activities were studied. Decomposition of Pd(acac)2 occurred with the formation of the metallic (Pd 0) and oxidized (PdO) forms of palladium on the TiO2 surface for both employed methods. The photodecomposition resulted in an increased amount of metallic palladium. All of the synthesized Pd/TiO2 catalysts completely oxidized CO to CO2 at room temperature. UV-LED irradiation with a total irradiance of 10.4 mW/cm 2 in the UVA region increased the rate of CO oxidation by up to 5 times compared to dark catalytic oxidation. Photodecomposition of Pd(acac)2 resulted in a higher activity of the Pd/TiO2 catalysts compared to the thermal decomposition method. The rate of CO oxidation under UV irradiation and under dark conditions monotonically increased as the Pd content increased due to the stability of high dispersion of Pd particles even with a high Pd content. The maximum value of the photonic efficiency was estimated to be 5.9%. CeO2, SiO2, and Al2O3 were also employed for the deposition of Pd to investigate the effect of a semiconducting support. For the CeO2-based catalyst, the activity under UV irradiation was higher than in the dark, but this effect was much lower compared to that of catalysts based on TiO2. By contrast, no substantial difference in the CO oxidation rate in the absence and presence of UV irradiation was observed for the non-semiconducting supports, SiO2 and Al2O3, confirming the photocatalytic oxidation of carbon monoxide for the TiO2-and CeO2-based catalysts.

The Pd nanoparticles were deposited on the TiO 2 surface via the thermal decomposition of palladium acetylacetonate (Pd(acac) 2). The catalytic activity of Pd/TiO 2 catalysts was investigated in the CO oxidation under ambient conditions both in the absence and presence of UV-LED irradiation. The effect of additional UV pretreatment of the catalyst on the activity in CO oxidation was also studied. The rate of CO oxidation under UV irradiation was 3.5 times higher than the rate of dark catalytic oxidation. The dark catalytic and photocatalytic oxidation rates were monotonically increased as the Pd content was increased up to 2 wt.%. A small size and narrow size distribution of Pd nanoparticles on the TiO 2 surface were the reasons for a high activity in CO oxidation. Al 2 O 3 and SiO 2 were also employed for the Pd deposition to investigate the effect of semiconducting support. Pd/TiO 2 had much higher CO oxidation rate under UV irradiation than the Pd/Al 2 O 3 and Pd/SiO 2 catalysts, which do not have photocatalytic activity. It indicates that in the case of the Pd/TiO 2 catalysts UV light energy can be used instead of thermal energy to increase the rate of CO oxidation.

Indoor air pollution has become a threat to human health. People spend much time inside different buildings with heavily polluted indoor air. Human and non-human activities release numerous and diverse pollutants into close environments. Biological pollutants are responsible for numerous respiratory diseases with a broad range of severity (allergies, infectious diseases, cancer). The World Health Organization remarks on the increased number of chronic and acute diseases related to indoor air pollution and urges the development of sustainable technologies for indoor air purification. Although adsorption or UV-assisted techniques exist, there are risks and limitations in their use and practical applications. Lately, some research studies show that photocatalysis is a feasible technique to eliminate indoor air pollutants, increasing indoor air quality and human wellness. Our research group is interested in periodic monitoring of indoor air to offer photocatalytic systems with optimal properties for remediation of the site (indoor air) under study. We aim to have an inventory of air pollutants (qualitative and quantitative analysis) by periodically monitoring its quality. After, we can develop a photocatalytic system for the remediation of the site. We have demonstrated the efficiency of different photocatalytic systems (TiO2-Cu 2+ , Ag@TiO2-Cu 2+ , ZnO-Cu 2+) for hospitals' indoor air disinfection. Our studies show the high disinfection capacity of the materials and their biocompatibility.

The air purifier industry has seen a growth in terms of demand and sales lately. All credit goes to massive industrialization in developing countries such as India and China. As a result, a lot of research has been focused into the various methods of purifying air. The most harmful of the pollutants are PM 2.5 particulates and NOx emissions. The aim has been to bring down the costs without compromising on efficiency as efficient air purification is an expensive deal. This article presents a study of the current scenario of the problems of air pollution. Severity of the issues have been highlighted. A compilation of the most common and significant methods of purifying air such as those employing the use of HEPA filters, electrostatic smoke precipitators, activated carbon and UV light has been presented and their use in air purifiers manufactured by OEMs has been mentioned. Some of the most modern methods of purifying air such as those using transparent PAN filters, photochemical mate...

This study demonstrated that a laboratory-scale recirculation closed-loop reactor can be an efficient technique for the determination of the Clean Air Delivery Rate (CADR) of PhotoCatalytic Oxidation (PCO) air purification devices. The recirculation closed-loop reactor was modeled by associating equations related to two ideal reactors: one is a perfectly mixed reservoir and the other is a plug flow system corresponding to the PCO device itself. Based on the assumption that the ratio between the residence time in the PCO device and the residence time in the reservoir τ P /τ R tends to 0, the model highlights that a lab closed-loop reactor can be a suitable technique for the determination of the efficiency of PCO devices. Moreover, if the single-pass removal efficiency is lower than 5% of the treated flow rate, the decrease in the pollutant concentration over time can be characterized by a first-order decay model in which the time constant is proportional to the CADR. The limits of the model are examined and reported in terms of operating conditions (experiment duration, ratio of residence times, and flow rate ranges).

Catalysis by gold has been continuously developing and recently one of the main subjects of interest in this area has been bimetallic catalysts containing gold [1]. This study is focused on gold-silver catalysts which have not been frequently studied. It was expected that the addition of silver to gold would increase the activity of the catalyst in oxidation processes because oxygen is effectively chemisorbed on silver species. The choice of zinc oxide as a support for metals was made taking into account strong metal-support interaction properties of ZnO which allows modification of electronic and catalytic properties of metals, and thus permits tuning their activity. The AuAg-ZnO catalysts were used in propene oxidation. The aim of this study was on the effect of silver and the treatment with hydrogen on the surface and catalytic properties of these bimetallic systems. Two kinds of ZnO were used as supports for gold and silver – commercial ZnO(C) (Aldrich – BET surface area = 10 m ...

These reactions also occurred with a very good selectivity to the targeted products. These performances are in line with the basicity of these catalysts demonstrated from CO2 chemisorption measurements. The effect of the nano-size and the interaction of the nano-particles with the graphene are also important to achieve this high activity.

Carbon (Vulcan XC-72)-supported bimetallic Pd–Ir catalysts with different Pd/Ir proportions (5–50 mol% Ir, 2 wt% Pd) were prepared by “water-in-oil” microemulsion method (w/o) using solutions of low (0.02 M, L series) and high concentration (0.2 M, H series) of the metals precursors (PdCl2 and IrCl3). The bimetallic particles were examined in terms of nanoscale phase properties (extent of Pd–Ir alloying, phase separation), surface composition (Pd and Ir fractions) and electrocatalytic performance for the formic acid oxidation reaction. Structural characterization was performed using XRD, SEM and HRTEM techniques. Electrochemical characterization allowed estimating the PdH formation ability and the surface composition of Pd–Ir particles what was confirmed by XPS data. The Pd–Ir nanoparticles of similar average size (ca. 4 nm), close to that of Ir (3.8 nm) and below that of Pd (6.2 nm) were formed regardless of the Pd/Ir proportion and the concentration of the metals precursors in the...

The photocatalytic process using semiconductor nanomaterials is considered to be the most advanced technologies for air purification. The pollutants present in the air are particularly harmful compared to soil and water pollutants. The air pollutants are of two types including particulate matters (PM) and gas-phase pollutants. Both types of pollutants have been identified to be the main sources of air pollution. For first kind of air pollutants (PM), the source control, physical treatments including electrostatic precipitation, wet scrubbing, and filtration were found highly effective strategies [1-4]. On the other hand, photocatalysis is very efficient technique for the removal of gaseous pollutants Therefore, in the proceeding sections, we will focus on basic photocatalysis mechanism and reactions of gaseous pollutants including variety of volatile organic compounds (VOCs), NO x , SO x , CO, ozone, and odors. 3.1.1 Photocatalytic Oxidation of VOCs Recently, the photocatalytic oxidation (PCO) is an advanced and widely used technique in the remediation of VOCs. Volatile organic compounds have various hazardous effects on human health and environment. The most detected indoor and outdoor VOCs come from aromatics, aldehydes, and halocarbons. For the better evaluation of photocatalysts performance, formaldehyde, trichloroethylene (TCE), toluene, and benzene were generally used in photocatalytic degradation studies [5-8]. The photocatalytic oxidation for VOCs degradation is not simple process because it has to deal with variety of hydrocarbons which are volatile at room temperature or particular conditions [9]. The basic degradation mechanism for VOCs is shown in Fig. 3.1, where upon light illumination of appropriate wavelength (λ ≥ E g), electrons transfer from valence band of semiconductor (e.g., TiO 2) to its conduction band and

TiO 2 was surface modified with silver, gold, palladium and platinum ion clusters to improve its photocatalytic activity. The effect of metal content and kind of dopant used during preparation procedure on the photoactivity were investigated. in toluene removal which was used as a model volatile organic compound. Toluene, at the concentration of about 100 ppm, was irradiated over noble metal modified TiO 2 using light-emitting diodes (LEDs) in four subsequent cycles.

h i g h l i g h t s CuOeZnOeAl 2 O 3 catalysts are synthesized by a co-precipitation method. The prepared catalysts are evaluated in carbon monoxide preferential oxidation (CO-PROX). The increment in CuO loading improves the activity of CuOeZnOeAl 2 O 3 catalysts. 50%CuOe3%ZnOe47%Al 2 O 3 shows the highest activity with a CO conversion of 88.9% at 125 C.

Bimetallic catalysts have attracted extensive attention for a wide range of applications in energy production and environmental remediation due to their tunable chemical/physical properties. These properties are mainly governed by a number of parameters such as compositions of the bimetallic systems, their preparation method, and their morphostructure. In this regard, numerous efforts have been made to develop ''designer'' bimetallic catalysts with specific nanostructures and surface properties as a result of recent advances in the area of materials chemistry. The present review highlights a detailed overview of the development of nickel-based bimetallic catalysts for energy and environmental applications. Starting from a materials science perspective in order to obtain controlled morphologies and surface properties, with a focus on the fundamental understanding of these bimetallic systems to make a correlation with their catalytic behaviors, a detailed account is provided on the utilization of these systems in the catalytic reactions related to energy production and environmental remediation. We include the entire library of nickelbased bimetallic catalysts for both chemical and electrochemical processes such as catalytic reforming, dehydrogenation, hydrogenation, electrocatalysis and many other reactions. Broader context To address the increasing energy demand while mitigating environmental concerns, numerous research efforts have been devoted to finding the most sustainable routes of energy production. Catalysis can offer attractive solutions to such processes, with the possibility of designing highly effective advanced catalytic systems as the basis of future industrial implementation. Bimetallic catalysts emerged as materials of a new category, which often show electronic and chemical properties different from their monometallic counterparts, thus offering an opportunity to design new catalysts with enhanced selectivity, activity, and stability. Since the infancy of bimetallic catalysts in the 1960's, an enormous number of catalysts have been explored, most of which were based on having noble metals as the main components. However, the industrial application of these noble metal catalysts is limited by their exceptionally high prices and low availability, which has turned the attention towards more abundant transition metal-based catalysts. Nickel is the most widely used element among the transition metal-based catalysts and has the highest ability to form bimetallic systems with other metals. As a result, the library of bimetallic Ni catalysts has been enriched very rapidly in the last decade. This review provides an overview of the recent progress in the design of bimetallic nickel-based catalysts for use in energy production and environmental remediation. Design aspects of the catalysts and the fundamental understanding of their catalytic properties are also critically discussed.