Papers by Keyword: Aerosol

Abstract: It is well known that adding the appropriate amount of Ag to semiconductor materials can enhance photocatalytic performance. In our previous study, the addition of Ag nanoparticles to ZnO enhanced the photocatalytic activity. The best photocatalytic performance was obtained when Ag content was 5 wt%. However, the effect of a carrier gas flow rate has not been investigated. The objective of this study is to investigate the effect of carrier gas flow rate on the morphology of the ZnO-Ag nanocomposites as well as the photocatalytic activity of the produced nanocomposites. ZnO-Ag nanocomposite was fabricated by a one-step process using flame pyrolysis and the produced nanocomposites were characterized by a scanning electron microscope (SEM) and X-Ray Diffraction (XRD) analysis. The photocatalytic performance was evaluated by measuring the degradation of methylene blue under UV light irradiation. SEM images indicated that the morphology of ZnO-Ag nanocomposites has a spherical shape with a particle diameter of around 65 nm. Moreover, increasing the flow rate will increase the particle size of the produced nanocomposites. The photocatalytic test was determined based on the rate constant of MB degradation efficiency under UV light irradiation, where the photocatalytic activity decreased when the carrier gas increased. Finally, the produced nanocomposites were also tested several times (recycling test), where photocatalytic performance showed that the degradation value of methylene blue for each recycle did not vary much with the variable before being recycled.

Abstract: Aerosol measurement is used in a variety of fields such as nanotechnology, materials science, pollution monitoring, air quality measurements, combustion and engine exhaust analysis, inhalation toxicology, and medical studies. One of the most prevalent methods for aerosol measurement is to use electrical mobility. An electrical mobility spectrometer (EMS) is used to measure aerosol particles size distribution ranging from 10 – 1000 nanometers, under the influence of an electric field. The accuracy of this distribution is influenced by flow conditions, the geometry of the EMS, the electric field, and the number of electrode rings. In this work, a multi-channel EMS is studied using computational fluid dynamics to numerically simulate the flow pattern, electric field and particle trajectories in the device. We found that neglecting the effect of the electric field on particles outside the sizing region generates an oversimplified model leading to high particle loss to the flow guide. In order to reduce the number of particle losses and obtaining a more realistic particle distribution we proposed a modification to the electrode electric potential which effectively reduces the particle loss. The applied modification has quintupled the number of particles which are classified by the EMS.

Abstract: An airflow control system is one of important parts in the scanning mobility particle sizers system (SMPS) used in the field of aerosol and air filtration. In this paper, the air flow control system that consists of an air filter, a blower, an air flow sensor, a controller, and a computer are reported. A flow rate adjustment was performed by varying the rotation speed of the blower using a pulse width modulation (PWM) technique. The air flow sensor capable of measuring flow rate up to 20 liters / min was used to measure the air flow rate. In order to keep at a certain value of the flow rate, a proportional-integral-derivative (PID) control action was employed in which PID controller were manually tune. The results showed that the desired value of flow rate was quickly achieved with little overshoot was observed in the system output.

Abstract: The paper discusses approaches to compositional build-up of high strength alkali activated cements made using water glass as alkaline activator represented by commercial products in a form of powder and liquid. The purpose was to study the influence of fineness of ground granulated blast-furnace slags, admixtures and additives, compatible with alkali activated cements, water glass and mode of manufacturing technology in order to reach high compressive strength (≥ 80 MPa at standard age (28 days)) and early strength (≥ 20 MPa after 3 h of hardening in normal conditions).

Abstract: Ground-based solar photometer measurements were utilized in the ambiance of Universiti Sains Malaysia (USM) Penang and Universiti Teknologi MARA (UiTM) Penang during September-November 2013 with a specific end goal to portray the characteristics of the local atmospheric environment. This both sites were established as being component of the collaborative work of the Seven South East Asian Studies (7SEAS) regional aerosol measurement project. This study concentrates on the Angstrom exponent (α), that is the gradient of the logarithm of the aerosol optical depth (AOD) against the logarithm of the wavelength as well as being commonly used to characterize the wavelength reliance of AOD and to furnish some critical data on the aerosol size distribution. In most situations fine mode aerosols appear to be the predominant category with marginally substantial contributions of coarse mode particles resulting from the particle growing, blending processes with other aerosol types, precipitation factors and relative distance to the seashore.

Abstract: The vertical distribution of aerosol extinction coefficients, and relativity between aerosol and BC the within summer planetary boundary layer (PBL) over the observation site are shown in this paper. The data indicates that the aerosol is almost trapped within PBL and troposphere layer is rather stable and the main composition of aerosol in Beijing is BC. The multi-layer structure of the aerosol distribution is obvious.

Abstract: The review focuses on the progresses of air microbes in indoor environment, including their sources, sorts, influence of human body health, spread regulation and spatiotemporal distribution characteristics. Most airborne microorganisms attached to the dust particles, which is present in the air in the form of aerosol .The distribution of microbe is related with indoor environment condition in the air. The factor which influences it to distribute mainly includes temperature, degree of humidity, wind velocity and weather condition etc. Air microbe is bred easily in ventilation and air conditioning system. The growth of microbe has a tremendous relation with the ventilation and air condition. The distribution of microorganisms in different regions, different buildings and different ventilation system is different from each other.

Abstract: Based on the OPAC (Optical Properties of Aerosols and Clouds) database, the impact of 8 typical aerosol types on the skylight polarization sensitive is researched. By combining the impact of cloud, the correction between aerosol and the polarization sensitive spectral of insects is analyzed. It can predict the polarization properties of different areas and provide the theoretical basis for the application of bionic micro-nanopolarization sensor.

Abstract: We address the problem of estimating the particle distribution in the suspension flow near solid walls which is of considerable interested in science and technology. The present paper focuses on the methodology that can be used to study the dynamics of moving particles. A statistical-mechanics based analytical model is developed for the particle concentration distributions (Eulerian approach). The performance of this approach is compared with a standard force balance model on moving particles that treats particles as a discrete phase (Lagrangian approach). The attractive properties of these approaches are demonstrated in the simulation of a gas-solid suspension flow above solid surfaces with a rebound effect. Results shows that our model can effectively predict particle concentration distributions and both approaches are complementary descriptions for simulating aerosol flows.

Abstract: The vertical distribution of aerosol extinction coefficients within winter planetary boundary layer (WPBL) over the observation site are shown in this paper, and the heights of PBL are discussed. The data indicates that the aerosol over the measurement site is almost trapped within PBL and troposphere layer and is rather stable, and the multi-layer structure of the aerosol distribution is obvious.