Clarification Flashcards
describe processes that involve the removal or separation of a solid from a fluid / or a fluid from a fluid
clarification
term that encompasses both liquids and gases
fluid
achieved using either filtration or centrifugation techniques
clarification
What are the two main reasons for clarification?
- remove unwanted solid particles from either a liquid product or from air
- collect the solid as the product itself (e.g., after crystallization)
types of clarification
- filtration
- centrifugation
types of filtration
- solid/fluid filtration (solid/liquid or solid/gas filtration)
- fluid/fluid filtration
separation of an insoluble solid from a fluid by means of a porous medium that restrains the solid but allows fluid to pass
solid/fluid filtration
most common type of filtration during manufacture of pharmaceuticals
solid/fluid filtration
types of solid/fluid filtration
solid/liquid and solid/gas filtration
removal of immiscible oils or liquid by passing them through an appropriate filter
fluid/fluid filtration
mechanisms of filtration
- straining/sieving
- impingement
- attractive forces
- autofiltration
what mechanism of filtration:
If the pores in the filter medium through which the fluid is flowing are smaller than the material that is required to be removed, the material will be retained
Straining/Sieving
Use of ________ include the removal of bacteria and fibers from parenteral preparations
membrane filters
Filtration occurs on the surface of the filter in this case, and therefore the filter can be very thin. Filter media of this type is referred to _________
MEMBRANE FILTER
[true or false]
Potassium permanganate may be filtered with regular filter paper
false
Paper cannot be used for filtering because permanganate ion reacts with it to form additional manganese dioxide
what mechanism of filtration:
As flowing fluid approaches and passes an object, the fluid flow pattern is disturbed.
Impingement
In impingement, suspended solids, may, however, have sufficient momentum that they do not follow the fluid path but impinge on the filter fiber and are retained, owing to __________ between particles and the fiber
attractive forces
example of an object that disturbs flow pattern in impingement
filter fiber
what mechanism of filtration:
Electrostatic and other surface forces may exert sufficient force on the particles to attract and retain them on the filter medium
Attractive Forces
what mechanism of filtration:
Air can be freed from dust particles is an electrostatic precipitator by passing the air between highly charged surfaces, which attract the dust particles
Attractive Forces
what mechanism of filtration:
filtered material ( termed as filter cake) acts as its own filter medium.
Autofiltration
Mechanism is used by metafilter
Autofiltration
Autofiltration is the Mechanism is used by ________
metafilter
Factors affecting the rate of filtration
- Area available for filtration
- Pressure difference across the filter bed
- Viscosity of the fluid passing through the filter
- Thickness of the filter medium and any deposited cake
to increase filtration rate: (increase/decrease) area available for filtration must
increase
to increase filtration rate: (increase/decrease) pressure difference across
the filter cake
increase
to increase filtration rate: (increase/decrease) filtrate viscosity
decrease
to increase filtration rate: (increase/decrease) thickness of the filter cake
decrease
to increase filtration rate: (increase/decrease) permeability of the cake
increase
[true or false]
Ideally the equipment chosen should allow a slow filtration rate to minimize production costs, be cheap to buy and run, be easily cleaned and resistant to corrosion, and be capable of filtering large volumes of products before the filter needs stripping down for cleaning or replacing
false
fast filtration rate
Product-related factors that should be considered when selecting a filter for a particular process
- Chemical nature of the products
- Volume to be filtered and the filtration rate
required - Operating pressure needed
- Amount of material to be removed
- Degree of filtration required
- Product viscosity and filtration temperature
Industrial Filtration Equipment
Filters for _______ products may be classified by the method used to drive the filtrate through the filter medium
liquid
Industrial Filtration Equipment
Filters can be organized into what 3 classes
Gravity, vacuum and pressure filters
Gravity filters that rely solely on gravity only generate (high/low) operating pressures
low
use of Gravity filters on a large scale is _______
limited
Simple and cheap, and are frequently used in laboratory, where volumes are small and a low filtration rate is relatively unimportant
Gravity Filters
Vacuum Filters are also called
Rotary vacuum filters
Continuous in operation
Vacuum Filters
has a system for removing the cake so that it can be rum for long periods handling concentrated slurries
Vacuum Filters
Automatic and continuous in operation, so that labor costs are very low
Advantages of Rotary Vacuum Filters
Rotary Vacuum Filters have (small/large) capacity
large
Variation of the speed of rotation enables the cake thickness to be controlled
Advantages of Rotary Vacuum Filters
in Rotary Vacuum Filters, solids that form an impenetrable cake the thickness may be limited to _______; solids are coarse, forming a porous cake, the thickness may be _________
less than 5mm; 100 mm or more
Complex piece of equipment with many moving parts and is very expensive . In addition to the filter itself, ancillary equipment such as vacuum pumps, slurry receivers and traps, slurry pumps and agitators are required
Disadvantages of the Rotary Vacuum Filters
Complex piece of equipment with many moving parts and is very expensive . In addition to the filter itself, ancillary equipment such as vacuum pumps, slurry receivers and traps, slurry pumps and agitators are required
Disadvantages of the Rotary Vacuum Filters
pressure difference is limited to 1 bar and hot filtrates may boil
Disadvantages of the Rotary Vacuum Filters
Cake tends to crack because of the air drawn through by the vacuum system, so that washing and drying are not efficient
Disadvantages of the Rotary Vacuum Filters
only for straightforward slurries, being less satisfactory if the solids form an impermeable cake or will not separate cleanly from the cloth
Disadvantages of the Rotary Vacuum Filters
Rotary Filters are most suitable for continuous operation on a large quantities of slurry, especially of the slurry contains considerable amounts of solids, that is, in the range of _______%
15-30%
Rotary Filters are most suitable for continuous operation on a (small/large) quantities of slurry
large
used in Collection of calcium carbonate, magnesium carbonate and starch
Rotary Filters
used in the separation of the mycelia from the fermentation liquor in the manufacture of antibiotics
Rotary Filters
Metafilters, cartridge filters, cross-flow microfiltration are under what filter class
Pressure Filters
Feed the products to the filter at a pressure greater than that which would arise from gravity alone
Pressure Filters
Most common type of filter used on the processing of pharmaceutical products
Pressure Filters
Consists of a grooved drainage rod on which is packed a series of metal rings. These rings, usually of stainless steel, are about 15 mm inside diameter, 22 mm outside diameter and 0.8 mm in thickness, with a number of semicircular projections on one surface
Metafilters
Strainer for coarse particles, but for finer particles abed of a suitable material is first build up over the rings. The pack of rings, serves essentially as a base on which the true filter medium is supported
Metafilters
Possesses considerable strength and high pressures can be used with no danger of bursting
Advantages of the Metafilters
As there is no filter medium as such, the running costs are low and it is very economical
Advantages of the Metafilters
Can be made from materials (such as stainless steel) that can provide excellent resistance to corrosion and avoid contamination of the product
Advantages of the Metafilters
By selecting of a suitable grade of material to form the filter bed it is possible to remove very fine particles; in fact, it is possible to sterilize a liquid using this filter
Advantages of the Metafilters
Used almost exclusively for clarifying liquids where contaminant level is low
Metafilters
permits the use of high pressures (up to 15 bar), making the method suitable for viscous liquid
Metafilters
Clarifying syrups, injection solutions, insulin liquors
Metafilters
Commonly used in the preparation of pharmaceutical products, as they possess a very large filtration area in a small unit and are easy and relatively cheap to operate
Cartridge Filters
Consist of cylindrical cartridge containing highly pleated material (PTFE or nylon) or string wound material (wound like a ball of string)
Cartridge Filters
fits in a metal supporting cylinder and the product is pumped under pressure into one end of the cylinder surrounding the filter cartridge. The filtrate is forced through the filter cartridge from the periphery to the inner hollow core, from where it exits through the other end of the support cylinder
Cartridge Filters
Disposable and good for applications where there is low contamination levels
Cartridge Filters
Membrane is consist of polysulphone, acrylonitrile or polyamide, is laid down within fiber which forms a rigid porous outer support
Cross-Flow Microfiltration
Lumen of each fiber is small, typically 1-2 micrometer – but a large number of them can be contained in a surrounding shell to form a cartridge which have an effective filtration area of over 2 m2
Cross-Flow Microfiltration
Used for fractionation of biological products by first using a filter of pore size sufficient to let all the wanted molecules through, and then passing the permeate through a filter which will retain the required molecules while passing smaller unwanted molecules
Cross-Flow Microfiltration
Blood plasma can be processed to remove alcohol and water and prepare concentrated purified water.
Cross-Flow Microfiltration
The process has been suggested for the recovery of antibiotics from fermentation media
Cross-Flow Microfiltration
Centrifugal force can be used either to provide the driving force for the filtration process or to replace the gravitational force in sedimentation processes
Centrifugation
are often used in the laboratory to separate solid material from liquid, the solid typically forming a plug at the bottom of the test tube at the end of the process
Centrifuges
Perforated basket centrifuges and tubular bowl centrifuges
Centrifugation