Innovative Methods To Extract Pollution Molecules From Air

Air pollution is a pressing issue that affects the health and safety of millions of people worldwide. It is caused by a range of human activities and natural sources, including the burning of fossil fuels, industrial processes, transportation, waste management, and natural disasters like wildfires and volcanic eruptions. To combat this issue, scientists have developed various methods to separate pollution molecules from the air, such as filtration, extraction, and chromatography. These techniques target different types of pollutants, including solid particles, gas particles, and solutes. Technological innovations, such as scrubbers and catalytic converters, are also employed to filter out harmful pollutants from exhaust gases. Additionally, advancements in environmental technology and a growing number of countries implementing waste management systems contribute to the fight against air pollution.

Filtration

Biofiltration is another filtration technique that uses biological processes to remove pollutants from the air. This method employs microbes, such as bacteria and fungi, to break down pollutants into non-toxic by-products. Biofiltration is particularly effective at removing VOCs, odours, and other contaminants from the air. It is a low-cost, energy-efficient, and straightforward technique that has gained popularity globally. However, it is important to note that natural sources of pollution, such as volcanoes, dust storms, and sea salt, cannot be treated with biofilters or any other filtration methods.

In industrial settings, filtration systems are used to trap particulate matter and harmful pollutants before they are released into the atmosphere. For example, scrubbers and catalytic converters are employed in exhaust gases to absorb, chemically change, or convert pollutants into less harmful substances. Additionally, electrostatic precipitators (ESPs) are used for ultra-fine dust filtration, although they may require higher air velocities depending on the dust density and level.

The choice of filtration method depends on the specific type of pollutant and its properties. Advancements in material science continue to improve filtration techniques, leading to better air quality management. For instance, researchers are applying molecular orbital theory to design filter materials that can selectively separate molecules like oxygen (O₂) and nitrogen (N₂). This approach utilizes the different responses of these gases to external magnetic fields to achieve more efficient separation.

Extraction

One way to separate gaseous molecules from the air is to use fractional distillation. This process involves cooling air to a temperature at which it liquefies, and then selectively distilling the components at their various boiling temperatures. For example, pure gases can be separated from air by first cooling the air until it liquefies, and then distilling the components at their various boiling temperatures. This method is known as cryogenic distillation and is often used to separate nitrogen and oxygen, and sometimes argon and other rare inert gases.

Another method of gas separation is membrane gas separation, which uses the different solubility of gases in water. For example, oxygen is more soluble than nitrogen in water, so if air is degassed from water, a stream of 35% oxygen can be obtained. Ceramic membranes can also be used to separate oxygen from nitrogen. These membranes can provide high-purity oxygen (90% or more) but require higher temperatures (800-900°C) to operate.

Technologies such as scrubbers and catalytic converters are also employed to filter gaseous pollutants effectively. Scrubbers can absorb or chemically change pollutants, while catalytic converters convert them to less harmful substances.

Chromatography

There are various types of chromatography techniques, including:

• Ion-exchange chromatography: This technique is based on electrostatic interactions between charged protein groups and solid support material (matrix). It is useful for separating macromolecules like nucleic acids and proteins.
• Paper chromatography: This technique is used to separate proteins and in studies related to protein synthesis.
• Gas-liquid chromatography: This technique is used to separate and observe alcohol, esters, lipids, and amino groups, as well as enzymatic interactions.
• Molecular sieve chromatography: This technique is used specifically for determining the molecular weights of proteins.
• Agarose-gel chromatography: This type of chromatography is used for the purification of RNA, DNA, and viruses.

Gas chromatography (GC) is one of the most widely used techniques for analyzing pollutants in the air. It is used to monitor and regulate the amount of volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs) in the air. GC can also help identify potential sources of contaminants and toxins, as well as monitor changes in pollution levels over time. Manufacturers use GC to ensure their products meet national safety guidelines and to provide consumers with adequate ventilation warnings.

Other chromatographic techniques, such as GC-mass spectrometry (GC-MS) and hydrophilic interaction liquid chromatography (HILIC), are also used to address urban air pollution. These techniques help to identify and classify organic compounds in the air, including those emitted by diesel vehicles, and to measure organosulfates, which are significant components of atmospheric aerosols.

Molecular orbital theory

Scientists employ various methods to separate pollution molecules from the air, including filtration, extraction, and chromatography. An interesting approach under exploration is filter-based separation using molecular orbital theory (MO theory).

MO theory provides a delocalized approach to bonding, where electrons are not viewed as being localized between the nuclei of bonded atoms but are instead delocalized throughout the entire molecule. This theory is based on a quantum mechanical model, where electrons in molecules are described in terms of molecular orbitals (MOs) rather than atomic orbitals (AOs). Molecular orbitals refer to the spatial distribution of electrons in a molecule, which is associated with a particular orbital energy.

The key difference between atomic and molecular orbitals is that in molecular orbitals, electrons can interact with more than one atomic nucleus simultaneously. This allows for a better understanding of the bonding and behavior of molecules, enabling researchers to design filter materials that can selectively separate molecules. For example, by applying MO theory, researchers can design filters that separate oxygen (O₂) from nitrogen (N₂) by exploiting their different responses to external magnetic fields.

MO theory also provides insights into the nature of resonance, the stability of substances with unpaired electrons, and the identification of effective semiconductors. It helps explain why some compounds are coloured while others are not and sheds light on the electrical conductivity of substances, differentiating between conductors, semiconductors, and insulators.

Technological innovations

Filtration

One of the most common methods used to separate pollution molecules from the air is filtration. This technique involves using filters with small pores to trap solid particulates such as dust, smoke, and other solid particles, while allowing clean air to pass through. Filtration systems can be used in various settings, including factories, to trap particulate matter before it escapes into the atmosphere.

Extraction

Extraction is another useful method for separating gaseous pollutants, solutes, and solids from the air. It is often employed to target specific types of pollutants.

Chromatography

Chromatography is a technique that separates the components of a mixture based on their interactions with a stationary phase and a mobile phase. Paper or thin-layer chromatography, for example, can be used to analyze air samples by separating individual pollutant gases based on their size or chemical properties.

Molecular Orbital Theory Applications

By applying molecular orbital theory, researchers can design selective filters that separate specific gases, such as oxygen (O₂) from nitrogen (N₂). This approach utilizes the different responses of gases to external magnetic fields to achieve efficient separation.

Scrubbers and Catalytic Converters

Technologies like scrubbers and catalytic converters are employed to filter out harmful pollutants from exhaust gases before they are released into the atmosphere. Scrubbers can absorb or chemically alter pollutants, while catalytic converters convert them into less harmful substances. These technologies are used in power plants and automobiles to reduce emissions.

Biofiltration

Biofiltration-based techniques have emerged as a promising solution for removing air pollutants. They facilitate the abatement of unsafe impurities from a polluted atmosphere. However, biofiltration requires occasional inspections and monitoring, especially during significant weather events, to ensure that excess water or snow does not lead to adverse gas streams.

Membrane-Based Separation Procedures (MBSPs)

MBSPs are well-known detachment technologies that have been successfully employed in water treatment processes. They utilize membranes made from various substances, such as polymers, ceramics, and zeolites, with specific filtering qualities determined by factors like pore size and membrane surface structure.

Ultraviolet (UV) Disinfection

UV disinfection technology is seeing increased popularity, particularly in hospitals and healthcare settings. Unlike other air cleaning technologies, UV does not capture particles or gases but instead inactivates airborne microbes.

Low-Cost Sensors

While they may not directly separate pollution molecules, low-cost sensors play an essential role in monitoring air quality. These sensors provide approximate information about the types and concentrations of pollutants, enabling individuals to take necessary protective measures for their health.

Frequently asked questions