How the adsorptive action of nano-tea is generated

Qy Yuan Qu Lai

Tea, with its strong adsorptivity, can adsorb moisture in the air as well as the liquid substances with peculiar smell in the water vapor. So that tea can be processed into deodoriferant, fishy odor removing agent and metal and waste gas adsorbent to be used in the course of waste water treatment. The mechanism of tea in absorbing water and variants and its applications has drawn great attention of the people. The tea produced by us is a specific manifestation.

Matter has adsorptive power because the molecules at the boundary of two phases stand in a specific state. There is a strong attracting power between the molecules in a matter phase, the magnitude of which depends on the summation of the gravitation of chemical bond between adjacent molecules in a material phase and Van der waal's attraction force between molecules (Vander waal's attraction force includes the gravitation between the dipole moments of polar molecules, the action between polar molecules and non- polar molecule and the attracting force between non-polar molecules, and usually has no direction and saturation).The attractive powers acting on the molecules at the boundary between two phases are different, and if the combined force of the attracting power of the boundary molecules of the attracting phase is directed to the interior of the phase, the surface of the phase shows a extracting capacity, which can attract the molecules in another phase in contact with it, indicating a adsorptive power. In the course of adsorption, the number of adsorbates enlarges with the increase of the surface of adsorbent. Therefore, in order to reach a greater adsorptive efficiency, it is essential to maximize the surface of adsorbent. Nano-tea is small in size of particles but greatly enlarged in size of surfaces, with the total surface area of 1 gram nano-tea standing at about several ten m2, and thus has a strong adsorptive power. In other words, only the matter that has a great surface, can has a great adsorptive action. The physical adsorption is selective in its direction in the interior of matter, and varies with temperature and pressure, that is to say, under increased temperature and pressure, the adsorption can be released, and under normal and low temperature, the physical action is the strongest.

The variant adsorption action of tea is expressed in physical form under normal and low temperature and in chemical form under high temperature, and depends on the unit surface of tea, the greater the unit surface, the greater the adsorptive power. In accordance with this principle, we have adopted nano-technology to increase the surface area of tea by a large margin. The surface of tea varies in hole sizes, hole distribution and porosity, and thus tea has different adsorptive action. Generally speaking, the tea prepared with tender leaves has much more and smaller surfaces and inner holes and thus stronger adsorption, while the tea prepared with old leaves has less and lager surfaces and inner holes, and thus weaker adsorption. Therefore, we have adopted the first grade tender leaves to produce nano-tea.

Adsorption is a phenomenon that the molecules or atoms of a phase object are adsorbed on the surface of another phase object. According to the principle of Van der waal's attraction force, due to the imbalance of action exerted by surrounding molecules or atoms on those on the surface of a solid, there are strain and energy on the surface of the solid. This means the action of a solid towards space is not saturated and surplus valences are available. These valences make the molecules or atoms of the solid combined with those in the space in a special form and keep the whole system in a stable state, and thus generating a phenomenon of adsorption. The object that adsorbs is called adsorbent, and the object that is adsorbed is called adsorbate. Tea is a soft and multi-porosity solid, and as common solids, enjoys a adsorptive power, and adsorb sweet smell as well as various kinks of peculiar smell, which are composed of molecules or atoms.

The adsorbability of tea is decided by its botanical and biochemical characteristics. The spongy tissue of tea is well developed, and the tender leaves of tea have a high concentration of water. Therefore, the dried tea, with high porosity, is a soft and multi-holes structure, manifested not only in its outside shape, but also in its complicate inner surface, with many small holes running through the entire leave and connecting the outside. With the inner surfaces of a great number of hole channels added up, the total effective area of a leave is very large, and the "hovering valence" has a large attractive power, and these decide the characteristics of tea in adsorption of variants.

The excellent adsorption of tea is related with the chemical substances in leaves of tea. The leave of tea contains considerable soft colloid and chemical components, such as palmitinic acid of fatty group, terpenes and dibutyl phthalate, which belong to high boiling point substances and can adsorb and fix variants. Therefore, nano-tea can deprive the activity of viruses following adsorb them. In addition, these matters have a great number of molecules and complicate structure, and with their great acting force and strong adsorptive power, are also within the range in which Waal 's attraction force generates adsorption.

According to the natural difference of binding power between the molecules or atoms of a solid and that of the air, the solid adsorption can be divided into physical adsorption and chemical adsorption. The former is formed relying on the attraction between common molecules, such as Waal 's attraction force and surplus valence force, and easier to adsorb variants, while the later needs specific conditions, for example, chemical valence should be formed between adsorbate and adsorbent, with the old valence broken and a new valence formed. This needs an activating course and a certain activating energy, both requiring a high temperature condition. Under normal temperature, the chemical adsorption of tea is rather small, and therefore, the adsorption of tea mainly depends physical adsorption under normal temperature.

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