Air Treatment Research Articles

Exploration of Jaboticaba (Plinia cauliflora.) Cultivation in Bengkulu: Conservation in an Optimized Environment

Jaboticaba (Plinia cauliflora) is a plant with numerous benefits. The destruction of its natural habitat and illegal logging in areas where Jaboticaba grows have led to concerns about population decline. Therefore, serious conservation efforts are necessary to protect this plant. This research aims to plant and conserve Jaboticaba in an optimal environment in Bengkulu. To maintain the viability of jaboticaba populations, it is essential to protect their natural habitat and implement conservation efforts. The methods used included seedling preparation, jaboticaba planting, and treatment and observation of soil conditions, air, light, and height gain. The results indicated that Jaboticaba can grow in areas with soil pH 5.5; 50% soil moisture, 28℃ air temperature, 69% air humidity, and 900 µmol/m²/s light intensity. The study employed an experimental approach to investigate the growth of Jaboticaba. The growth of Jaboticaba from 15 cm to 30 cm was promoted within the study period through continuous care, including watering and fertilization. The study results indicate that environmental factors play an important role in the growth of Jaboticaba. Therefore, protecting its natural habitat in Bengkulu, Indonesia is crucial for environmental sustainability and human health. Jaboticaba holds high ecological, economic, and health values. The study's findings regarding the cultivation, environmental requirements, and urgency of conservation are enlightening for safeguarding this species for future generations.

UV-C Light Intervention as a Barrier against Airborne Transmission of SARS-CoV-2.

SARS-CoV-2 continues to impact human health globally, with airborne transmission being a significant mode of transmission. In addition to tools like vaccination and testing, countermeasures that reduce viral spread in indoor settings are critical. This study aims to assess the efficacy of UV-C light, utilizing the Violett sterilization device, as a countermeasure against airborne transmission of SARS-CoV-2 in the highly susceptible Golden Syrian hamster model. Two cohorts of naïve hamsters were subjected to airborne transmission from experimentally infected hamsters; one cohort was exposed to air treated with UV-C sterilization, while the other cohort was exposed to untreated air. Treatment of air with UV-C light prevented the airborne transmission of SARS-CoV-2 from the experimentally exposed hamster to naïve hamsters. Notably, this protection was sustained over a multi-day exposure period during peak viral shedding by hamsters. These findings demonstrate the efficacy of the UV-C light to mitigate against airborne SARS-CoV-2 transmission. As variants continue to emerge, UV-C light holds promise as a tool for reducing infections in diverse indoor settings, ranging from healthcare facilities to households. This study reinforces the urgency of implementing innovative methods to reduce airborne disease transmission and safeguard public health against emerging biological threats.

Plasma‐assisted surface engineering for value added in starch bioplastics: A study on enhanced surface properties and natural dye immobilization

AbstractThis study examines the enhancement of starch‐based bioplastic sheets for immobilizing natural dyes (ND) using plasma processes. The effects of poly(vinyl alcohol) (PVA) as a binder for ND were also assessed. Starch substrates were treated with air plasma, air plus 1,7‐octadiene (OD) plasma, and air plus 2‐methy‐2‐oxazoline (Ox) plasma before immobilizing curcumin and telang NDs, followed by an OD overcoating. Surface morphology, wettability, chemical composition, tensile strength, and surface charge were analyzed. Results showed improved wettability and dye immobilization, particularly for telang with a PVA binder and plasma treatment. OD overcoating prevented dye leaching. Air plasma reduced, while OD plasma maintained the starch's negative charge. XPS analysis indicated increased oxygen and nitrogen presence after air plasma and enhanced aliphatic carbon from OD overcoating. Tensile strength was largely unaffected, but elongation at break was reduced, especially after air and OD plasma treatment.

Liquid air filtration and continuous monitoring: Customized indoor air quality

Air treatment in environmental air conditioning systems exposes the system to gases, contaminants, and often biological pollutants that cannot be solved by traditional mechanical filtration, motivating decision-makers to diagnose challenges and develop innovative strategies to mitigate the problem. More and more, in environments with high turnover of people (e.g., hospitals, hotels and shopping centers), fresh air ventilations are avoided and replaced by closed windows air purifier solutions to account for undesirable saturation of the atmosphere and the presence of pollutants such as PM10, PM2.5, PM1.0, nitrogen, and carbon oxides. The consensus is that polluting gases render the most efficient traditional filters ineffective. The ANSI/ASHRAE 62.1 and EN13779 standards reveal the absence of air treatment technologies that use the wet route in air conditioning systems. This work discusses the liquid air multi-venturi centrifugation technology of hydrodynamic precipitator purifiers in association with the synchronized and continuous monitoring of parameters (PM10, PM2.5, PM1.0, CO2) in the external urban environment and internal environments of a shopping center. It evaluates the performance of the wet route for the physical-chemical and biological treatment of air. Efficiency for retaining particulate matter in a single step without disposable filter reached levels above F9 (85-95% PM2.5), with a reduction of 82.4% for CO2. Wet route technology extends the air conditioner’s life, reducing external air flows and energy consumption by up to 13%, making IAQ a manageable and customizable variable. Among the conclusion of the investigation, the authors believe that the migration of industrial pollutant control technologies, such as liquid filtration promoted by gas scrubbers and hydrodynamic precipitators, should be considered as a first choice option due to the high efficiency achieved in the three types of pollutants to be controlled. That is micrometric particulate matter such as anthropogenic PM1.0 capable of reaching the lung alveoli, chemicals such as carbon dioxide and nitrogen, and biological assets such as viruses and bacteria that showed the vulnerability of HVAC-R systems during the COVID pandemic that rendered windowless corporate buildings unusable.

The effects of water, substrate, and intermediate adsorption on the photocatalytic decomposition of air pollutants over nano-TiO2 photocatalysts.

The photocatalytic performance of nano-TiO2 photocatalysts in air pollutant degradation greatly depends on the adsorption of water, substrates, and intermediates. Especially under excessive humidity, substrate concentration, and intermediate concentration, the competitive adsorption of water, substrates, and intermediates can seriously inhibit the photocatalytic performance. In the past few years, extensive studies have been performed to investigate the influence of humidity, substrate concentration, and intermediates on the photocatalytic performance of TiO2, and significant advances have been made in the area. However, to the best of our knowledge, there is no review focusing on the effects of water, substrate, and intermediate adsorption to date. A comprehensive understanding of their mechanisms is key to overcoming the limited application of nano-TiO2 photocatalysts in the photocatalytic decomposition of air pollutants. In this review, the progress in experimental and theoretical fields, including a recent combination of photocatalytic experiments and adsorption and photocatalytic simulations by density functional theory (DFT), to explore the impact of adsorption of various reaction components on nano-TiO2 photocatalysts is comprehensively summarized. Additionally, the mechanism and broad perspective of the impact of their adsorption on the photocatalytic activity of TiO2 in air treatment are also critically discussed. Finally, several solutions are proposed to resolve the current problems related to environmental factors. In general, this review contributes a comprehensive perspective of water, substrate, and intermediate adsorption toward boosting the photocatalytic application of TiO2 nanomaterials.

Ditopic ligand effects on solution structure and redox chemistry in discrete [Cu12S6] clusters with labile Cu-S bonds.

Copper chalcogenide nanoclusters (Cu-S/Se/Te NCs) are a broad and diverse class of atomically precise nanomaterials that have historically been studied for potential applications in luminescent devices and sensors, and for their beautiful, mineral-like crystal structures. By the "cluster-surface" analogy, Cu-S/Se NCs are prime candidates for the development of nanoscale multimetallic catalysts with atomic precision. However, the majority of studies conducted to date have focused exclusively on their solid-state structures and physical properties, leaving open questions as to their solution stability, dynamics, and reactivity. Herein, we report the first detailed interrogation of solution structure, dynamics, electrochemistry, and decomposition of Cu-S NCs. Specifically, we report the detailed NMR spectroscopy, diffusion-ordered spectroscopy, MALDI mass spectrometry, electrochemical and stoichiometric redox reactivity studies, and DFT studies of a series of [Cu12S6] clusters with labile Cu-S bonds supported by monodentate phosphines and ditopic bis(diphenylphosphino)alkane ligands PPh2R (R = Et, -(CH2)5-, -(CH2)8-). We find that the ligand binding topology dictates the extent of speciation in solution, with complete stability being afforded by the longer octane chelate in dppo (1,8-bis(diphenylphosphino)octane) according to 1H and DOSY NMR and MALDI-MS studies. Furthermore, a combined electrochemical and computational investigation of [Cu12S6(dppo)4] reveals that the intact [Cu12S6] core undergoes a quasireversible one-electron oxidation at mild applied potentials ([Cu12S6]0/+: -0.50 V vs. Fc0/+). In contrast, prolonged air exposure or treatment with chemical oxidants results in cluster degradation with S atom extrusion as phosphine sulfide byproducts. This work adds critical new dimensions to the stabilization and study of atomically precise metal chalcogenide NCs with labile M-S/Se bonds, and demonstrates both progress and challenges in controlling the solution behaviour and redox chemistry of phosphine-supported copper chalcogenide nanoclusters.

Harnessing plasma-generated reactive species for the synthesis of different phases of molybdenum oxide to study adsorption and photocatalytic activity.

This study employs plasma-liquid interaction technique to synthesize different phases of molybdenum oxide using air and argon as plasma-forming gases. In situ plasma-generated nitrogen species primarily NO3-/NO2- and hydrogen species (H+) facilitate the reduction of the molybdenum precursor anion (Mo7O24-). The reduced Mo species subsequently reacts with reactive oxygen species, forming MoO6 octahedra, which is the building block of a molybdenum oxide crystal. Varied concentrations of NO3-/NO2- and H+ species in air and argon plasma treatment significantly influence the growth process. Air plasma synthesis yields hexagonal molybdenum oxide microrods, which upon calcination changes its phase to orthorhombic 2D layered structure. Moreover, the argon plasma synthesized sample exhibits a mixed phase of hexagonal and orthorhombic molybdenum oxide due to the heavy argon ion bombardment, inducing material porosity and surface oxygen vacancies. The mixed-phase material exhibits superior adsorption and photo-degradation towards cationic dye compared to the other two phases. The higher photocatalytic performance may be responsible for the extended lifetime of the photo-generated charge carriers possessed by the mixed-phase material. Radical scavenging tests have identified holes and hydroxyl radicals as the key reactive species that take part in the photo-degradation process.

УСТОЙЧИВОСТЬ ЯБЛОНИ К ВЫСОКОТЕМПЕРАТУРНОМУ СТРЕССУ

Under unstable climatic conditions, the resistance of apple trees to high temperatures is an important varietal trait. The aim of the research is to identify heat resistance indicators of different apple varieties in a heat chamber for dry air treatment. The heat treatment of the varieties Antonovka Obyknovennaya, Lobo, Rozhdestvenskoe, Bolotovskoe, Kandil Orlovskiy, Imrus was carried out in a heat chamber at the temperature of +38°С and air humidity of 40% for 90 days. For the heat treatment, 2-year-old apple plants were used. Higher heat resistance was observed in the Lobo variety compared to the other varieties studied. The apple varieties were characterized by medium (Lobo, Rozhdestvenskoe) and high (Bolotovskoe, Imrus, Antonovka Obyknovennaya, Kandil Orlovskiy) water content, high water losses after a simulated heat shock, increased (Kandil Orlovskiy) and high (Bolotovskoe, Imrus, Antonovka Obyknovennaya, Lobo, Rozhdestvenskoe) wa- ter deficit, high degree of restoration of leaf water content. The proposed heat resistance coefficient was characterized by a strong degree of association with water loss (r = –0.97) and a moderate degree of association with water content restoration (r = 0.65). Apple plants had a high survival rate after thermotherapy, which was 92.3%.

UVC-Mirror for effective pathogens inactivation in air ducts

Improving the air quality of indoor environments (IAQ) is of utmost importance to safeguard public health as people spend about 80–90% of their time indoor. Efficient Ultraviolet germicidal irradiation (UVGI) system represents a strategic and sustainable solution to protect from recurrent and new airborne pathogens. Here, we present a new approach to design highly efficient UVGI systems, which can be installed in existing Air Treatment Units (ATU) plants with minimal effort. The increased efficiency relies on the concept of an optical cavity, thanks to its shape and source position. The internal volume consists of a highly reflective cavity illuminated with UV-C lamps. Optical simulations permitted the variation of the parameters to maximize the internal irradiance and, thus, the performance. The sanitation efficacy of the system was assessed on a full-scale pilot system. Tests were carried out under normal operating conditions against various microorganisms showed an inactivation rate of > 99%. The benefits of such systems are triple and encompass economic, environmental, and societal aspects. Since the system requires little energy to operate, its application for air disinfection may yield significant energy savings and ensure a balance between energy sustainability and good IAQ.

Effectiveness of Pregnane Glycoside Compound Extracts from Sansevieria Trifasciata Laurentii and Sansevieria Trifasciata Plants in Reducing Carbon Monoxide Gas

This study aimed to evaluate the effectiveness of pregnane glycoside compound extracts obtained from the Sansevieria trifasciata Laurentii plant in reducing carbon monoxide (CO) emissions. The extraction method uses solvent extraction techniques with organic solvents to isolate active compounds from the plant. After extraction, the pregnane glycoside compound was tested at various concentrations to determine its effectiveness in reducing CO gas concentrations. Tests were carried out using tools that allow real-time gas monitoring. The results of this study show that the pregnane glycoside compound extract from the Sansevieria trifasciata Laurentii and Sansevieria trifasciata plants can reduce carbon monoxide gas with significant effectiveness. This research contributes to the development of natural solutions for reducing air pollution caused by CO gas and can develop plant-based air treatment technology.

Structure and wear characteristics of cast iron after laser surface modification

The paper presents the results of studies of macro- and microstructure of alloyed chromium-vanadium cast iron after laser treatment (LT) in air using a continuous laser source with a variation in its power from 60 to 100 W and scanning speed of the laser beam varying from 5 to 17 mm/s. Metallography and durometry methods were used to determine composition and structure of the laser exposure zones (LEZ). It is shown that LT with a slight melting of the surface leads to a significant increase in microhardness in LEZ. In this case, martensite is the main structure in the near-surface layer of LEZ in the melting zone, and ledeburite structure prevails in the quenching zone. For the studied LT modes, LEZ depth is 220 – 310 μm. At the same time, microhardness is more than 2.5 – 4.2 times higher than microhardness of the base metal and reaches 820 HV0.1, that is a significant factor in increasing the wear resistance of the material. On the contrary, no significant structural changes were found in the case of LT without melting the surface. In order to identify the role of LT in wear of cast iron, sliding friction tests were carried out according to the “disk – finger” scheme at a pressure in the contact zone of 12.5 MPa and indenter rotation speed of 580 rpm. According to the test data, a significant decrease in linear wear and the wear intensity after the surface melting was found. The wear intensity is reduced by more than 100 times, and linear wear – by more than 50 times. The characteristics of LEZ surface cause a decrease in the friction coefficient by 30 % relative to the untreated surface.

On-site measurement and optimization of energy efficiency of the cascading desiccant wheel deep dehumidification systems in the lithium-ion battery manufacturing factory

The desiccant wheel deep dehumidification system in the lithium-ion battery manufacturing factory is significantly energy intensive, which substantially treats the process air from the ambient to the supply air state with a dew point temperature below −20 °C. On-site measurements were conducted in this study to investigate the actual performance of the deep dehumidification systems. The air treatment process and energy consumption during the operation were continuously monitored. The results reveal that the coefficient of performance of the dehumidification process of the systems ranges from 0.54 to 0.63 under basic winter conditions and ranges from 1.15 to 1.25 under basic summer conditions. The deep dehumidification processes of the systems are divided into multiple stages, and with the deepening of the process air humidity ratio from above 6 g/kg to below 0.3 g/kg, the partial energy efficiency of the treatment stages decreases. The efficient operational strategies are further elaborated for the improvement of the deep dehumidification system, including the proper match between the dehumidification gradient and the dehumidification stages, and the appropriate use of outlet process air with low humidity ratio as the regeneration air. The energy consumption of the cascading desiccant wheel dehumidification system can be reduced by lowering the cooling temperature of the cooling coil to undertake more latent load in the preliminary dehumidification stage. The effect of the bypass air state as the regeneration air is revealed, and the energy efficiency of the system is enhanced by up to 32 % by applying appropriate bypass air. This study offers guidance for the future design of the cascading desiccant wheel deep dehumidification system in similar applications.

Pengolahan Air Limbah dengan Metode Koagulasi Flokulasi pada Industri Kimia

Utilities are one of the supporting processes in a factory, consisting of units providing water, steam, electricity, fuel procurement, compressed air, and wastewater treatment. Wastewater from industrial processes contains: toxic pollutants, organic and inorganic materials, also other industrial materials are toxic, mutagenic, and carcinogenic, so treatment is needed to overcome this. Wastewater treatment can use coagulation and flocculation methods. Coagulation is the process of adding chemicals to the water that causes the separation of particles to destabilize the particles and allow them to adhere to other particles (to remove) in the following process. Factors that can affect the success of the coagulation process include the type of coagulant used, coagulant dose, moving process, and pH. Meanwhile, flocculation removes water turbidity by collecting small particles into larger particles with the addition of chemical flocculants. The flocculants are divided into two, perikinetic flocculation and optokinetic flocculation. This article aims to determine the effectiveness of wastewater treatment in the chemical industry using the coagulation-flocculation method. The coagulation-flocculation process can reduce pollution of the aquatic environment so as not to aggravate cases of environmental pollution.

Evaluasi Aspek Teknis Kualitas Air Membran Ultrafiltrasi dalam Pengolahan Air Minum (Studi Kasus: IPA Krian Perumda Air Minum Sidoarjo)

The Sidoarjo Regional Public Company (Perumda) is a regionally owned business entity that participates in managing and providing clean water which will be distributed to the people of Sidoarjo Regency. The Sidoarjo Drinking Water Company, especially the Krian IPA, uses the main channel to supply raw water from the Mangetan Canal which passes through seven sluice gates to irrigate 17,583 Ha of rice fields. The series of air treatment installations at Perumda Air Minum Sidoarjo are coagulation units, flocculation units, sedimentation units and ultrafiltration membranes. However, not all technology can be implemented optimally due to considerations of costs and Perumda personnel. The problem is that the ultrafiltration membrane unit at Perumda Air Minum Sidoarjo is not activated. Therefore, the aim of the research is to determine the ineffectiveness of ultrafiltration membranes at Perumda Air Minum Sidoarjo in terms of technical aspects, namely the quality of water resulting from membrane processing in 2016-2020. The results of the research on the technical aspect, namely data on water quality parameters for turbidity and color for 2016-2020, have complied with Minister of Health Regulation Number 2 of 2023 for drinking water quality standards, the rejection percentage for turbidity parameters was 69.39%. - 95.48%; the percentage of color parameter rejection was 43.60% - 61.6% with the resulting flux value decreasing.

Zeolite A with waste material: Morphological effect of laser treatments in air

The goal of this work is to investigate the action of femtosecond (fs) laser treatment performed under atmospheric conditions on morphology of zeolite A (LTA topology) synthesized with the addition of a waste material rich in iron such as red mud (RMFe-LTA) or introducing nanomagnetite (NMFe-LTA) during the hydrothermal synthesis. Both zeolite samples were analyzed by Scanning Electron Microscopy (SEM) technique. LTA zeolite formed using pure sources was assumed as reference. The results confirm that the presence of iron has a significant influence on laser-matter interactions affecting the morphology of the final treated synthetic material. Comparing to our previous data performed in vacuum conditions, these new results indicate that zeolite structure is generally preserved by fs laser treatment under atmospheric conditions although the presence of the Fe oxides distributed on the zeolite surfaces due to the use of red mud or in the form of nanomagnetite at specific locations, determines clear changes in treated zeolite morphology. However, the best performing results in terms of homogeneity of treatment and potential improvement of hydrophilic surface properties take places on zeolite formed with the addition of waste material (RMFe-LTA).

Physico-chemical surface modification of the natural leather using gliding arc discharge: An in-depth analysis of improving surface and mechanical properties

Leather, a widely used material in various industries, presents challenges in terms of dye uptake, hydrophilicity, and environmental concerns associated with chemical wet processing. In this context, non-thermal plasma technology offers a promising alternative for leather surface modification. In this study, the gliding arc, with air and water vapor plasmas, was used for the surface modification of natural leather for the first time. The influence of the treatment time and also the plasma gas chemistry on the surface chemical bonding, surface morphology, wettability, water absorption time and absorption capacity, color, and mechanical properties of the leather were investigated. The results showed that in the water vapor gliding arc discharge, the produced active oxygen and hydroxyl species can effectively react with the functional groups and break the relatively weak hydrocarbon CH bonds in the chemical composition of the natural leather. SEM images showed increased pore depth and diameter on the leather surface after air and water vapor plasma treatment with mean diameters of 76 μm and 92 μm, respectively. The tensile stress-strain curves illustrated that despite small cracks were created on the plasma treated samples, the elongation at break (ultimate strain) increased from 83.7 % to 88.5 % and 91.8 % for the samples treated with the air and the water vapor plasmas for 5 min, respectively. The water contact angle decreased from 96° to 55° and 48° after only 5-second treatment with the air and the water vapor plasmas, respectively. The same trend was also observed for the water absorption time and the absorption capacity of the treated samples. Also, the color analysis showed that the color change in the plasma treated samples was not detected by the unaided eye. It was also found that water vapor plasma has a better influence on the physico-chemical properties of the leather.

Integrated metabolomics and transcriptomics analysis reveals γ-aminobutyric acid enhances the ozone tolerance of wheat by accumulation of flavonoids

Wheat is susceptible to atmospheric ozone (O3) pollution, thus the increasing O3 is a serious threat to wheat production. γ-aminobutyric acid (GABA) is found to play key roles in the tolerance of plants to stress. However, few studies elaborated the function of GABA in response of wheat to O3. Here, we incorporated metabolome and transcriptome data to provide a more comprehensive insight on the role of GABA in enhancing the O3-tolerance of wheat. In our study, there were 31, 23, and 32 differentially accumulated flavonoids in the carbon-filtered air with GABA, elevated O3 with or without GABA treatments compared to the carbon-filtered air treatment, respectively. Elevated O3 triggered the accumulation of dihydroflavone, flavonols, and flavanols. Exogenous GABA enhanced dihydroflavone and dihydroflavonol, and also altered the expression of genes encoding some key enzymes in the flavonoid synthesis pathway. Additionally, GABA stimulated proline accumulation and antioxidant enzyme activities under elevated O3, resulting in the less accumulation of H2O2 and malondialdehyde. Consequently, GABA alleviated the grain yield loss from 19.6% to 9.6% induced by elevated O3. Our study provided comprehensive insight into the role of GABA in the alleviating the detrimental effects of elevated O3 on wheat, and a new avenue to mitigate O3 damage to the productivity of crops.

High temperature AlN thin film ultrasonic transducers with dual mode wave excitation

AlN thin film ultrasonic transducers with dual mode wave (transverse and longitudinal) excitation were deposited by reactive RF magnetron sputtering technique. The transducers deposited at radial distances of 0 and 50 mm in the sample plane exhibited well-developed straight and inclined columnar structures with dominating (002) and (103) X-ray diffraction peaks, respectively. The transducers deposited at radial distances of 0, 30, and 50 mm demonstrated excitation of longitudinal, transverse, and longitudinal-transverse waves, respectively. Short term heat treatment was conducted in air within a temperature range of 20–900 °C to investigate the high temperature ultrasonic response. Temperature dependencies of the time-of-flight and pulse-echo amplitude were analyzed. Long term heat treatment in air at 700 °C for 192 h revealed a degradation of ultrasonic response due to the oxidation of the AlN layer.

Impedance of nanocomposite SiO2(Si)&FexOy(Fe) thin films containing Si and Fe nanoinclusions

In this study, electrical properties at alternating current of the nanocomposite films containing silicon and iron inclusions in amorphous SiO x matrix are presented. The composite SiO 2 (Si)&Fe x O y (Fe) films were obtained using the ion-plasma co-sputtering of Si and Fe targets in oxygen containing atmosphere (Ar + O 2 ) followed by temperature annealing. It was revealed the predominance of the inductive contribution over the capacitive one in the reactive part of the admittance (impedance) at low frequencies (f < 1 MHz) both after annealing in air and nitrogen atmosphere. The frequency dependences of the admittance after heat treatment in air have the minima that shift to the region of high frequencies with increasing the annealing temperature. In the case of low- frequency dependence, the phase shift angle passes into the region of positive values, which indicates the predominance of the inductive contribution to the admittance at these frequencies. The dependence of the conductivity real part at the alternating current frequency does not change significantly up to ~20 kHz. Starting from the frequency higher than ~20 KHz and up to ~1 MHz, the exponent in the frequency dependence of the conductivity lies within the limits m ~ 0.49…0.52.

Antimicrobial activity of ZnO-Ag-MWCNTs nanocomposites prepared by a simple impregnation–calcination method

Zinc oxide (ZnO) nanorods and ZnO nanostructures composited with silver (Ag) and multi-walled carbon nanotubes (MWCNTs) have been synthesized by a simple impregnation–calcination method and have been shown to be suitable for use as antimicrobial agents. The preparation method used for composite materials is very simple, time-effective, and can be used for large-scale production. Several analytical techniques, including X-ray diffraction (XRD), scanning electron spectroscopy (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM) and Fourier transmission infrared spectroscopy (FTIR), have been used to characterize the prepared ZnO-Ag-MWCNT composite materials. The effects on structural, morphological, and antimicrobial properties of (ZnO)100-x (Ag)x nanocomposites at various weight ratios (x = 0, 5, 10, 30, and 50 wt%) have been investigated. The antimicrobial properties of ZnO composited with Ag nanoparticles and MWCNTs towards both gram-positive and gram-negative bacteria species were studied. The effect of raw MWCNTs and MWCNTs composited with ZnO and Ag on the cell morphology and chemical composition of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) was studied by SEM and EDS, respectively. It was found that composite materials made of ZnO-Ag-MWCNTs exhibit greater antibacterial activities toward the microorganisms E. coli and S. aureus than ZnO-Ag, which could be beneficial for efficient antimicrobial agents in water and air treatment applications.