question: Why do super dry rooms turn dust or particles into charged particles with electrostatic?
comment: Dust gets electrostatic charge when it bumps into other dust particles or surfaces due to airflow. However normally the humidity of the air allows them to discharge through the air at a low rate. However when there is low humidity the charges can build up to high levels.
passages: The third, and generally most common problem with high resistivity dust is increased electrical sparking. When the sparking rate exceeds the "set spark rate limit," the automatic controllers limit the operating voltage of the field. This causes reduced particle charging and reduced migration velocities toward the collection electrode. High resistivity can generally be reduced by doing the following:
  
  BULLET::::- Adjusting the temperature;
  
  BULLET::::- Increasing moisture content;
  
  BULLET::::- Adding conditioning agents to the gas stream;
  
  BULLET::::- Increasing the collection surface area; and
  
  BULLET::::- Using hot-side precipitators (occasionally and with foreknowledge of sodium depletion).
   Section::::Risks and counter-measures.:In the workplace.
  
  Means have to be provided to discharge static from carts which may carry volatile liquids, flammable gasses, or oxygen in hospitals. Even where only a small charge is produced, it can result in dust particles being attracted to the rubbed surface. In the case of textile manufacture this can lead to a permanent grimy mark where the cloth comes in contact with dust accumulations held by a static charge. Dust attraction may be reduced by treating insulating surfaces with an antistatic cleaning agent.
  
  Section::::Risks and counter-measures.:Damage to electronics.
   BULLET::::3. Submerging a whirling rotor in a liquid pool.
  
  These droplets collect particles by using one or more of several collection mechanisms such as impaction, direct interception, diffusion, electrostatic attraction, condensation, centrifugal force and gravity. However, impaction and diffusion are the main ones.
  
  Section::::Impaction.
   In recent years, some scrubber manufacturers have utilized other collection mechanisms such as electrostatic attraction and condensation to enhance particle collection without increasing power consumption. 
  
  In electrostatic attraction, particles are captured by first inducing a charge on them. Then, the charged particles are either attracted to each other, forming larger, easier-to-collect particles, or they are collected on a surface.
  
  Condensation of water vapor on particles promotes collection by adding mass to the particles. Other mechanisms such as gravity, centrifugal force, and direct interception slightly affect particle collection. 
  
  Section::::Bibliography.
   BULLET::::- A means of removing the collected particulates
  
  BULLET::::- A housing to enclose the precipitator zone
  
  The following factors affect the efficiency of electrostatic precipitators:
  
  BULLET::::- Larger collection-surface areas and lower gas-flow rates increase efficiency because of the increased time available for electrical activity to treat the dust particles.
  
  BULLET::::- An increase in the dust-particle migration velocity to the collecting electrodes increases efficiency. The migration velocity can be increased by:
  
  BULLET::::- Decreasing the gas viscosity
  
  BULLET::::- Increasing the gas temperature
  
  BULLET::::- Increasing the voltage field
  
  Section::::Electrostatic precipitators (ESP).:Types of precipitators.
  
  There are two main types of precipitators:
   Often, air showers are equipped with air ionizers to reduce static electricity, as large volumes of high-velocity air create electric charges. Since laboratory equipment, electronic measuring instruments and many hi-tech manufactured goods can often be damaged by electrostatic discharge, ionizers are essential in rendering material surfaces electrically neutral prior to entering the cleanroom.
  
  Section::::Safety.
   Particle collection in wet scrubbers
  
  Wet scrubbers capture relatively small dust particles with large liquid droplets. In most wet scrubbing systems, droplets produced are generally larger than 50 micrometres (in the 150 to 500 micrometres range). As a point of reference, human hair ranges in diameter from 50 to 100 micrometres. The size distribution of particles to be collected is source specific.br
   Tubular precipitators consist of cylindrical collection electrodes with discharge electrodes located on the axis of the cylinder. The contaminated gases flow around the discharge electrode and up through the inside of the cylinders. The charged particles are collected on the grounded walls of the cylinder. The collected dust is removed from the bottom of the cylinder.
  
  Tubular precipitators are often used for mist or fog collection or for adhesive, sticky, radioactive, or extremely toxic materials.
  
  Section::::Electrostatic precipitators (ESP).:Unit collectors.
   Section::::Post-treatment systems.
  
  High frequency vibrating screens are widely used in many industrial process, thus there will be high quantity of waste product released into the environment. It is important that these waste streams are treated, since the untreated waste will cause damage to the environment over a sustained period of time.
   Resistance affects electrical conditions in the dust layer by a potential electric field (voltage drop) being formed across the layer as negatively charged particles arrive at its surface and leak their electrical charges to the collection plate. At the metal surface of the electrically grounded collection plate, the voltage is zero, whereas at the outer surface of the dust layer, where new particles and ions are arriving, the electrostatic voltage caused by the gas ions can be quite high. The strength of this electric field depends on the resistance and thickness of the dust layer.
   The majority of electrostatic precipitators installed are the plate type. Particles are collected on flat, parallel surfaces that are 8 to 12 in. (20 to 30 cm) apart, with a series of discharge electrodes spaced along the centerline of two adjacent plates. The contaminated gases pass through the passage between the plates, and the particles become charged and adhere to the collection plates. Collected particles are usually removed by rapping the plates and deposited in bins or hoppers at the base of the precipitator.
  
  Section::::Electrostatic precipitators (ESP).:Types of precipitators.:Tubular precipitators.
   The exact composition of the dry piles is unknown, but it is known that they have been coated with molten sulphur for insulation and it is thought that they may be Zamboni piles.
  
  At one point this sort of device played an important role in distinguishing between two different theories of electrical action: the theory of contact tension (an obsolete scientific theory based on then-prevailing electrostatic principles) and the theory of chemical action.
   A Smart Dust research proposal was presented to DARPA written by Kristofer S. J. Pister, Joe Kahn, and Bernhard Boser, all from the University of California, Berkeley, in 1997. The proposal, to build wireless sensor nodes with a volume of one cubic millimeter, was selected for funding in 1998. The project led to a working mote smaller than a grain of rice, and larger "COTS Dust" devices kicked off the TinyOS effort at Berkeley.
   To collect the very fine particles a new technology is used in the field of "nano" spray drying. The reason is that common cyclone technology depends on the particle mass; particles smaller than 2 μm can’t be separated and instead exit the system along with the exhaust gas.
   Fugitive dust acquires an electronic charge when dispersed in the air. Spraying an oppositely charged water fog can be used to effectively control dust in an industrial setting. If so charged, less water is needed to cause the particulate matter to drop from the air. This method has been tested with many materials including silica flour, sulfur dioxide, and fly ash.
  
  Section::::See also.
  
  BULLET::::- Asian dust
  
  BULLET::::- Bull dust
  
  BULLET::::- Coal dust
  
  BULLET::::- Occupational dust exposure
  
  Section::::Further reading.
  
  BULLET::::- PM 10 and Fugitive Dust in the Southwest Ambient Impact, Sources and Remedies, US Environmental Protection Agency
   Section::::History.
  
  First observations of IRE effects go back to 1898. Nollet reported the first systematic observations of the appearance of red spots on animal and human skin that was exposed to electric sparks. However, its use for modern medicine began in 1982 with the seminal work of Neumann and colleagues. Pulsed electric fields were used to temporarily permeabilize cell membranes to deliver foreign DNA into cells. In the following decade, the combination of high-voltage pulsed electric fields with the chemotherapeutic drug bleomycin and with DNA yielded novel clinical applications: electrochemotherapy and gene electrotransfer, respectively.
  
  Section::::Mechanism.
   Section::::History.
  
  CCFT was originally invented by David Hallam to remove unpleasant odors from a nursing home where an ailing uncle was a resident. When the nursing staff noticed a dramatic decrease in the spread of infections, this led Hallam to further investigate CCFT. Hallam went on to develop the AirManager system, which uses a combination of CCFT and high airflow filtration (HAF), which filters any dust, pollen, airborne contaminants and resultant debris from the CCFT process down to 0.1 micrometres.
   "Electrokinesis" has also been observed in biology, where it was found to cause physical damage to neurons by inciting movement in their membranes. It is discussed in R.J.Elul's "Fixed charge in the cell membrane" (1967).
  
  Section::::Water electrokinetics.
   BULLET::::- Bleaching by the oxygen ions produced in the reaction chamber oxidizes dyes, cyanides, bacteria, viruses, biohazards, etc. Electron flooding of electrodes forced ions to be formed to carry charge into the water, thereby eliminating the polar effect of the water complex, allowing colloidal materials to precipitate and the current controlled ion transport between the electrodes creates an osmotic pressure that typically ruptures bacteria, cysts, and viruses.
   Since the cell membrane is not able to pass current (except in ion channels), it acts as an electrical capacitor. Subjecting membranes to a high-voltage electric field results in their temporary breakdown, resulting in pores that are large enough to allow macromolecules (such as DNA) to enter or leave the cell.
   The full life cycle of a nanomaterial should be considered when planning to control for dust exposure. Nanomaterial synthesis reactors, nanoparticle collection and handling, product fabrication with nanomaterials, product use, and product disposal are potential sources of dust exposure. 
  
  National Institute for Occupational Safety and Health recommends the use of high-efficiency particulate air (HEPA) filters on local exhaust ventilation, laboratory chemical hoods, lowflow enclosures, and any other containment enclosures as a best practice during the handling of engineered nanomaterials.
   If the voltage drop across the dust layer becomes too high, several adverse effects can occur. First, the high voltage drop reduces the voltage difference between the discharge electrode and collection electrode, and thereby reduces the electrostatic field strength used to drive the gas ion-charged particles over to the collected dust layer. As the dust layer builds up, and the electrical charges accumulate on the surface of the dust layer, the voltage difference between the discharge and collection electrodes decreases. The migration velocities of small particles are especially affected by the reduced electric field strength.
   Examples of non-ventilation engineering controls include placing equipment that may release nanomaterials in a separate room, and placing walk-off sticky mats at room exits. Antistatic devices can be used when handling nanomaterials to reduce their electrostatic charge, making them less likely to disperse or adhere to clothing. Standard dust control methods such as enclosures for conveyor systems, using a sealed system for bag filling, and water spray application are effective at reducing respirable dust concentrations.
  
  Section::::Hazard controls.:Administrative controls.
   Other non-ventilation engineering controls in general cover a range of control measures, such as guards and barricades, material treatment, or additives. One example is placing walk-off sticky mats at room exits. Antistatic devices can be used when handling nanomaterials to reduce their electrostatic charge, making them less likely to disperse or adhere to clothing. Water spray application is also an effective method for reducing respirable dust concentrations.
  
  Section::::External links.
  
  BULLET::::- Effective workplace safety and health management systems from the U.S. Occupational Safety and Health Administration
   Section::::Applications.
  
  Electrowetting is now used in a wide range of applications from modular to adjustable lenses, electronic displays (e-paper), electronic outdoor displays and switches for optical fibers. Electrowetting has recently been evoked for manipulating soft matter particularly, suppressing coffee stain effect. Furthermore, filters with Electrowetting functionality has been suggested for cleaning oil spills and separating oil-water mixtures.
  
  Section::::International meeting.
  
  An international meeting for electrowetting is held every two years. The most recent meeting was held on June 18 to 20, 2018, at the University of Twente, the Netherlands.
  