Purification of Laboratory Chemicals

Questions: 1. Identify and describe the five primary mechanisms of particle deposition and then identify and describe the two primary methods of integrated air sampling for particulates used in industrial hygiene.2. Identify and describe at least four of the critical factors used in determining acceptable exposure levels to particulate materials.3. Identify and discuss the five critical exposure factors regarding gases. vapors and solvents. Answers: 1. Primary mechanisms of particle deposition and two primary methods of integrated air sampling The removal of particles from an aerosol is particle deposition. Certain mechanisms are used for the deposition of particles. One such mechanism is inertial impaction. The impact of the particles is directly proportional to the dimensions of the aerosol. Other mechanisms include interception. According to Elimelech, Gregory Jia (2013), the particles that are not deposited by inertial impact are deposited by interception. Some particles respond to gravity and move towards the centre of the earth. These particles settle on the surface of the earth without a fixed shape or size. Most particles, which are airborne, are charged with positive or negative ions. Thus, the electrostatic charge of the particles will attract the opposite charge on the surface. The smaller particles, however, react to individual atoms of the gas. These random effects diffuse the particles. Ruzer Harley, (2012) stated that the diffusion of the particles depends upon the square of the diameter of the particle an d the velocity of the air. The deposition of the particles in the air is the result of any of the deposition mechanisms. As stated by Prodi et al. (2016), certain methods are considered for the sampling of the air particles. These sampling techniques are both short-term and long-term sampling. A short-term sampling includes gas-sampling bags. This system provides an economical means of collecting and transferring air samples to laboratories for analysing. This offers the short sampling of a full work shift. The most common application of this technique includes the use of a single analytical instrument. A long-term sampling includes adsorption. This is the most common form of air sampling. It is used to collect traces of insoluble or non-reactive solvents or vapour. The entire sample is removed and analysed at once. This is also considered as the standard method of sampling recovery. The properties of the adsorbent are determined by the nature of the surfaces. They are considered as either polar or nonpolar. 2. Critical factors to determine acceptable exposure levels The health problems that arise due to the inhalation of particulate matter is critically influenced by a number of factors. Some of the factors include chemical and biological composition. The chemical composition is considered as the primary factor for the toxicity of any materials. As observed by Gordon et al. (2014), the smoke emitted from vehicles in the United States is considered less poisonous than the smokes emitted from coal or tar. This is because the inhalation of such chemicals may cause anthrax, lung disease. According to Yang et al. (2013), Crystalline, structural, and isotopic form of particles prove as another dangerous factor that increases the exposure level. Silicon dioxide, commonly known as silica, is an example of such particles. The inhalation of the finest crystalline particles causes silica among the individuals. Among the organic particulate matter like smokes, molecules with identical chemical compositions have a toxic effect. The variation of the structure of the organic pharmaceutical chemicals creates an impact of the level of toxicity. The shape of the particles and size of the particles determine the level of toxicity. Most manufacturing industries in the United States use asbestos to emit particles. All the asbestos has different shapes and sizes. Thus, the particles emitted from this asbestos also have different shapes and sizes. If these are chemically analysed it will bring out the level of toxicity among all the particles. This results in a huge risk factor among the workers. However, as per Bose (2013), it is easy to determine the size of a moderate particle with the help of AED. Another factor that contributes to the exposure level is the health of the workers. Not all the workers in an industry are healthy. There are workers who suffer from already existing health problems and certain genetic diseases. Such workers are easily exposed to the toxic nature of the chemicals in the industry. Such exposures may cause incurable problems among the workers. For example, the over exposure of lead may have some adverse effects on the male body. 3. Critical exposure factors regarding gases, vapors and solvents According to Sinturel et al. (2013), the various factors result in the exposure of gases and harmful fumes. One such factor is the level of concentration of the fumes. It is important to know that the concentration level depends on the temperature of the atmosphere. It is important to maintain equilibrium between the liquid phase of a material and the gaseous phase. High level of concentration in the chemicals causes severe problems in the lungs. Similarly, the reaction caused between the fusion of two particles is a huge factor. The reaction can enhance or reduce the health hazard among the industrial workers in the United States. It is important to identify the components that have a diluted effect and concentrated effect. Based on these understandings, the industrialists need to cause the chemical reactions. Temperature and volatility affect the pressure of the vapour and creates an impact on the inhalation process. The vapor pressure of the chemical compounds is directly related to the temperature. The airborne concentration measures the volatility of the solvent. This volatility depends on upon the vapor pressure. This is another factor, which causes breathing problems and severely affects the lungs. According to Armarego Chai (2013), the United States based industries must follow certain guidelines regarding the exposure of toxic materials. These guidelines include the Personal Exposure Limit (PEL), Assigned Exposure Limit (AEL) and Threshold Limit Value (TLV). These guidelines define the level of exposure for a worker in his lifetime. The United States industry must follow these guidelines and ensure the safety of the workers. These guidelines are instrumental in protecting the workers from overexposure of harmful chemicals. The mode of use of the gases and vapors affects the health of the people. The industries of the United States must have a proper ventilation system so that the harmful fumes are removed from the chambers. The managers of the industry can compare the level of fumes exposed from using spray painting with that of rolling paint. References Armarego, W. L., Chai, C. L. L. (2013). Purification of laboratory chemicals. Massachusetts: Butterworth-Heinemann. Bose, A. (2013). Advances in particulate materials. Missouri: Elsevier. Elimelech, M., Gregory, J., Jia, X. (2013). Particle deposition and aggregation: measurement, modelling, and simulation. Massachusetts: Butterworth-Heinemann. Gordon, S. C., Butala, J. H., Carter, J. M., Elder, A., Gordon, T., Gray, G., West, J. (2014). Workshop report: strategies for setting occupational exposure limits for engineered nanomaterials. Regulatory Toxicology and Pharmacology, 68(3), 305-311. Prodi, A., Filon, F. L., Particles, N. S., Assessment, F. O. E. (2016). An Integrated Approach from Air Sampling to Skin and Surface Contamination. Nano Biomed. Eng, 8(2), 91-104. Ruzer, L. S., Harley, N. H. (2012). Aerosols handbook: measurement, dosimetry, and health effects. Florida: CRC press. Sinturel, C., Vayer, M., Morris, M., Hillmyer, M. A. (2013). Solvent vapor annealing of block polymer thin films. Macromolecules, 46(14), 5399-5415. Yang, F., Ding, J., Huang, W., Xie, W., Liu, W. (2013). Particle size-specific distributions and preliminary exposure assessments of organophosphate flame retardants in office air particulate matter. Environmental science technology, 48(1), 63-70.