Desiccants & Adsorbents

Introduction

Silica gel sachets are very common nowadays. If we purchase any product, its packaging is sure to contain a silica gel sachet. Normally people throw away these silica gel sachets as they feel that they are of no use. This is where people are wrong as there are multiple uses of the Silica gel sachet around the house. The adsorbing properties of Silica gel can put to various uses.

Silica gel is basically a desiccant, which attracts water vapour using a process known as adsorption. This adsorption quality is very useful in removing moisture from certain areas and thus avoiding the ill-effects caused by excessive moisture, mostly in closed spaces.

Best Ways to use Silica Gel Sachets

While there are many ways to reuse Silica Gel sachets, given below are some of the main ones:

Keeps Gym Bags Fresh Smelling: Gym bags usually contain used clothes and tend to smell after some time. Keeping a Silica gel sachet in the gym bag will make a lot of difference. The Silica gel sachet will remove the vapour from the bag and in this process, destroy the odour-generating bacteria. Silica Gel sachets can also be placed in sports shoes to remove bad odours.

Protect Mobile Phones from Water Damage: If by mistake your cell phone falls into water and is soaking wet, there is a good chance it will not function properly again. This is where the role of a Silica gel sachet becomes important. Place the wet phone in a Ziploc bag full of Silica Gel sachets and leave it for some days. Later, when you take the phone out, you will be surprised to see that the phone is good as new.

Keeps Make-up Bag Dry: Another use of Silica Gel sachets is in keeping one's make-up bag dry. The Silica Gel will absorb a lot of vapour- nearly 20%-40% of its weight comprises of humidity. When the Silica Gel absorbs the humidity, then the make-up bag will be dry and will not smell bad after a period of time.

Understanding Oxygen Absorbers

Oxygen Absorbers are small sachets containing iron powder, which absorb the oxygen present in the surroundings. Oxygen absorbers are mainly used in the food packaging industry to increase the shelf life of packed food products. This is done by bringing down the levels of oxygen in the closed space with the use of the oxygen absorber. When the oxygen levels come down, it prevents the growth of fungi, mold and other micro-organisms in the food product. In this manner, oxygen absorbers ensure that the packed food items do not get spoilt and stay fresh for a longer period of time.

With the use of oxygen absorbers, the shelf life of all kinds of food- refrigerated, dried and frozen are extended as the oxygen absorber creates a hermetic seal around the food product thus keeping it safe from fungi, mold among others.

Benefits of Using Oxygen Absorbers

There are many benefits of placing oxygen absorbers in the packages containing food items. They are as follows:

1) Free from various damages: Packages containing oxygen absorbers will be free from various damages caused by oxygen, moisture and corrosion. Oxygen absorbers make the environment inside the closed space conducive for the food products.

2) Safeguards against aerobic pathogens, molds: The most important use of oxygen absorbers is prevention of the growth of aerobic pathogens and micro-organisms like molds and fungi. The oxygen absorbers remove all the oxygen from the surroundings so there is no scope for the fungus to grow.

3) Protects against insects: The presence of lesser oxygen will automatically lower the instances of insects entering the packages.

4) Reduces the need for additives: The use of oxygen absorbers drastically reduces the need for additives like BHA, BHT, sulfur dioxide, sorbates, benzoates among others.

5) Fatty food won't turn rancid: If one keeps oxygen absorbers in food packages then any fatty and oily food present will not turn rancid as there is no oxygen present in the closed space. Any oxygen coming out of the fatty food will be sucked in by the oxygen absorbers.

Silica Gel as a High-Capacity Desiccant

A widely used desiccant, Silica Gel, is manufactured from Silicon Dioxide in the form of hard granules or beads. The main characteristic of Silica Gel is that it has many interlocking same-sized pores. These pores increase the surface area of the Silica Gel, thus making it a top-grade desiccant. When substances pass through a bed of Silica Gel then the water molecules present in them will stick to the Silica Gel crystals because they contain a lower vapour pressure when compared to their surroundings. If the air outside has more humidity than the Silica Gel adsorption rate will also be higher. The adsorption will continue till equilibrium is reached and the desiccant can adsorb no more.

Silica Gel in Column Chromatography

Column Chromatography is an analytical method widely used to separate and purify both solids and liquid mixtures. It consists of both a stationary phase and mobile phase. While the stationary phase is solid, the mobile phase usually used is liquid. The solids used in column chromatography include Silica Gel, Alumina, Calcium Carbonate, Calcium Phosphate, Magnesia and starch. Of these, Silica Gel is the most widely used as it has high adsorption capacity.

The column Chromatography process works on the principle of adsorption. The different components of the mixture will adsorb at different levels and then later individually separated. The rate at which the adsorption takes place depends on the functioning of the adsorbent and the polarity of the solvent.

Re-use of Silica Gel in Column Chromatography/

Once the chromatography process is over, the different constituents of the mixture will have separated and will form different columns. They are then individually removed and then used for different purposes. The solid phase or Silica Gel would be completely saturated once the chromatography is over. The major benefit of using Silica Gel is that it can be reactivated and used multiple number of times. Silica Gel can be reactivated/regenerated by simply heating. Once it is heated, all the water present in the desiccant will evaporate and it is ready to use once again.

Silica Gel used in column chromatography can also be regenerated using this process. However, experts say that it is better not to reuse the reactivated Silica Gel as it may lead to the formation of byproducts. Also, the regenerated Silica Gel is usually colored and this may adversely affect the next column chromatography cycle. It will not be that much effective as the original Silica Gel and will turn out to be more aggressive/acidic. Due to this high level of acidity, Acetal are often split into aldehydes.  

What is Indicating Silica Gel?

While there are many moisture absorbers available in the market, Silica Gel is the most widely used one. A variant of Silica Dioxide (SiO2), silica gel is made up of many same-sized pores, thus giving the desiccant a large surface area. It is this feature, which helps silica gel in absorbing and storing water vapour for a long period of time.

The main advantage of using Silica Gel is that 40% of its total weight can be moisture and it will not swell up because of the absorbed humidity. This is the reason why silica gel is widely used in closed containers and packages. It can bring down the humidity levels by around 40% until it gets completely soaked. The temperatures at which Silica Gel works the best are 70-90ºF and 16-32ºC.

Silica Gel is mostly available in two forms- colorless and indicating. The indicating Silica Gel usually contains blue crystals of cobalt chloride, which is the main mositure indicator. As more and more humidity is adsorbed in, the cobalt chloride crystals will first turn light blue and then pink to indicate the changes. When the Silica Gel desiccant has reached its saturation point and cannot adsorb any more moisture, the cobalt chloride will turn white and will not undergo any more changes.

Ways to Reuse Indicating Silica Gel Crystals

When one is using Indicating Silica Gel crystals on a regular basis, it is highly important to do a thorough check on them. The only regular inspection will let you know if there are changes required. This depends on factors like the humidity in the atmosphere, the quality of your plastic storage and how many times it is exposed to the open. This will give one an idea whether the silica gels are working effectively or needs to be replaced.

Indicating Silica Gel can be reused after all its moisture has been removed. This can be done in the following ways:

1) Dry out in the Sun: One can directly dry out the Silica Gel beads under the direct sun. Spread them on a dark surface directly under the sun for a completely dry day. This is the most easiest and convenient method.

The system of adsorptive is normally based on the lead and lag design and they utilize the different columns. This design also allows people in order to run the column as well as to satisfy the full saturation while performing a change out. The lag column becomes the saturation repeating whereas the designed mainly utilize people in order to accommodate the needs of water system where this may be either smaller or larger. The Arsenic as well as Fluoride is strongly preferred component this used for the alumina also to derive the removal process. Moreover, some of the impurities are interfaced along with the absorption this leads to remove the capacities. The fluoride adsorption as well as bicarbonate ions is found in the alumina to have the interfering effects. Moreover the treatability equilibrium is used on the specific site, especially to treat the recommended usage. The arsenic removal always prefers the ball size of 1 to 3 mm.

Operation And Start Up:

The most common form of desiccant we see in our daily lives is the silica gel sachet present in many items that we purchase. A granular and permeable type of silicon dioxide, silica gel is usually syntheticallly manufactured from sodium silicate. Its average pore size of 2.4 nanometers helps in its function as a desiccant.

Usually available as granules or beads, silica gels are packed in a small (2 x 3 cm) paper packet. Silica gel sachets are kept alongside packed products because they adsorb moisture better and thus prevent the products from getting spoiled or turning rancid. The high specific surface area of the silica gel is what aids the desiccant in adsorbing water in a fast manner. Silica gel removes humidity by adsorption, wherin the water moves onto its numerous openings.

Most people are under the impression that silica gels have only use in the packaging industry for preserving items. That is far from true. The tiny desiccant packets you get whenever you make a new purchase are more useful than you think. Read on to find their other uses so that next time you will think twice before throwing away the silica gels.

1) Keep the bad smell away: Silica gels are very useful in keeping foul smells away from bags and containers. Placing some silica gel in your gym bag/travel bag prevents the growth of bacteria in it. Silica gel also proves useful if you are a collector of old books as it helps remove any bad smell of the books.

2) It can save your wet cellphone: Suppose your mobile falls into water accidentally and you have no clue how to bring it back to its original state, then all you need to do is remove the battery and put it along with the phone in an airtight container filled with silica gel sachets. Leave it for the night and when you switch on the phone in the morning, it will be back to normal.

3) Keeps your camera lens fog streak free: Placing a silica gel packet in your camera bag will prevent fog streaks from forming in your camera lens. This method works very well for underwater camera lenses.

4) Prevents tarnishing of silver jewellery: The silica gels also works against the tarnishing/coroding of silver jewellery. Place a desiccant packet in the jewellery box to lessen the harmful effects of tarnishing.

5) Preserves your photos, video tapes and files: One can also use silica gel to preserve old photographs, video and audio tapes and other important documents. There are two ways of doing this- One, place silica gel sachets inside your storage containers and second, tape desiccant packets behind photographs in photo frames.

Mainly used in the food industry, oxygen absorbers are small pouches containing an iron powder. These packets are safe to keep on top of the food as they are made of a material, which allows entry to oxygen and moisture but prevents the iron powder from leaking out. Oxygen absorbers are popularly used in preserving the shelf life of dairy products like milk, cheese among others.

Food oxygen absorbers work by removing or reducing the amount of oxygen present in any packaged product. Different types of oxygen absorbers are present in the market for preserving a wide range of products. What are the advantages of adding an oxygen absorber for food product? It acts against color change in food products, prevents the oil present in food from turning rancid and stops oxygen-requiring microorganisms from growing inside the food. This helps keep the food product fresh for a longer period of time.

The major user of the oxygen absorbers is the food industry. Food oxygen absorbers are used to safeguard products like nuts, snacks, spices and seasonings and whole fat dry foods. They are also used to preserve items like processed, smoked and cured meats as well as flour and grains. In addition to the food industry, oxygen absorbers are needed to preserve pharmaceuticals and vitamins. The healthcare industry also uses oxygen absorbers to safeguard medical diagnostic units.

The working of the oxygen absorber is explained as follows:

Ordinary packaging cannot fully absorb the oxygen from packed products so there are chances that the food may turn stale. Food oxygen absorbers take in all the oxygen from the packet and therefore do not allow aerobic bacteria and fungi to grow. Thus, the food product remains fresh for a longer period of time. Industry experts say that the major advantage of using oxygen absorbers is that the food products need not be compressed or squeezed and are intact in one piece. This works out well for high-value fragile products.

Orange silica gel is the methyl violet because this had orange color. This gel uses for the moisture absorption at the industrial level. There is nothing side effects in the environment and also very safe for the health because the organic nature presents and this is non toxic. The orange silica gel beads will absorb 40% moisture of weight in the water vapor. When this gel becomes moisture free, then orange beads color turns to the dark green into black. This orange beads available in two to five millimeter, three to five millimeter and four to eight millimeter. This gel desiccant is largely used in the silica gel breather transformer application in the power transformer industry. The power industries breather used to control the moisture. The moisture, making for heating and also cooling of the machines& it also helps to prevent from the moisture in the breather silica used to absorb the moisture amount. This silica gel orange is the moisture absorbing content and it is used where the products required to protect from the humidity and also moisture.

Applications, Industrial Use And Features:

The Activated Alumina used to the right filters mainly for the cleanliness where they require the proper conditions. In the system the component of the Activated Alumina requires the cleanliness level and this used to set the different sensitive component. Adsorption is one of the surface process and this available on the surface areas especially the activated alumina. Moreover the molecules are mostly absorbed by the liquid as well as gas phase and this used to remain the alumina as activated. Well the adsorption will take place on the both dynamic as well as static conditions but the adsorption capacity of the static is measured only by the capacity of the equilibrium this state the relative humidity as constant. The adsorbents are used in most of the applications and all take place only the dynamic conditions because the activated alumina stands remain standard to operate but the equilibrium capacity varies based on the design condition. Meanwhile, the regeneration of alumina is highly done after the absorbent and deserve is taken and this brings back later in order to activate.

Process Of Oil Generation: