physico 4.pdf

Physicochemical processes outline Definitions of these physicochemical processes Similarities and differences between them Advantages and disadvantages of these physicochemical processes Pharmaceutical applications of these process 1. Precipitation Definition Precipitation occurs throug...

Physicochemical processes outline Definitions of these physicochemical processes Similarities and differences between them Advantages and disadvantages of these physicochemical processes Pharmaceutical applications of these process 1. Precipitation Definition Precipitation occurs through a chemical reaction that forms an insoluble compound out of two or more soluble compounds Precipitation is the process of separation of the solids substance from a solution either by altering the substance to an insoluble form or by altering the solvent composition to lessen the solubility of the substance in it. Precipitate – is the solid formed when the precipitation reaction occurs in liquids Precipitant is a substance which causes a precipitate to form when it is added to a solution or a suspension, examples lime, caustic soda Supernatant is the remaining liquid above the precipitate Precipitation process Precipitation reactions occur when cations and anions of aqueous solutions combine to form an insoluble ionic solid, called a precipitate. The most important method for precipitation is by displacement reaction taking place in the solution, in which more metal displace the inactive or less active metal Temperature, pH, solvent, raw materials, additive, concentration and composition affects properties such as phase, composition, purity, particle size, surface area and pore size of the final product Advantages Helps in the creation of pure and homogenous material It is very sensitive technique Useful in determining whether a certain element is present in a solution. Very specific components can be removed, while not removing other substances Disadvantages Generation of large volume of salt containing solutions Necessity of product separation after precipitation Difficulty in maintaining a constant product quality throughout the whole precipitation process if the precipitation is carried out discontinuously Long reaction time Application üThe separation of metal ions in aqueous solution üThe analysis of metal ions in aqueous solution üRemoval of heavy metals in the industry üThe purification of some substances, eg. Water üPreparation of white lotion üUsed in diagnostic immunology eg. Detection of syphilis in patients  2. Lyophilisation /cryodesiccation/ freeze drying Definition This is a low temperature dehydration process which involves freezing the sample, lowering pressure, and removing the ice by sublimation Freeze drying can be described simply as: üFreeze – sample is completely frozen in a vial, flask or tray. üVacuum – sample is placed under a deep vacuum, well below the triple point of water. üDry – heat energy is added to the sample causing the ice to sublime. Advantages of Freeze drying Less damage to physical structure Can increase shelf-life (decomposition is minimized) No need to use preservatives Can reconstitute easily and quickly No risk of contamination Easy to transport Disadvantages Can cause structural deformation Long process time Sometimes require special storage conditions Expensive Materials are extremely hygroscopic Freeze drying equipment Applications of Freeze drying Ceramics – to create formable powder Food processing – for instant meals and soup, juices, cheese, yoghurt, meats, probiotics etc Dairy industry – high value proteins Nutraceuticals – aloe vera, shark cartilage etc Pharmaceuticals – proteins, enzymes, hormones, vaccines, biological products etc Research 3. Ignition / incineration