Claims:1. Regenerated Bleaching Clay comprising 40-80 wt.% Silica and 10-30% Alumina, wherein the Silica and Alumina is obtained from Spent Bleaching Clay.

Wherein the composition of Regenerated Bleaching Clay gives the better surface adsorptive properties for the bleaching and purification of Edible and Non-Edible Oil.

2. A method for preparing a Regenerated Bleaching Clay comprising the following steps.
a. Take the Spent Bleaching Clay having 4-25% oil as an initial raw material.

b. Extract the trapped oil in Auto Clave at 200-500°C and inbuild pressure 10-40kg/Cm2 for a period of 0.5-2.5 hrs.

c. Separate the liquid and solid by filter press.

d. Collect the liquid mass which is mixture of Oil and water, separate it in cyclone separator.

e. Take the solid cake coming from filter press, expose to the thermal treatment in the temperature range of 200-800°C.

f. Optionally we can treat the thermally activated SBC with 1-10 wt. % Sulphuric acid having a concentration of 50-98%.

g. Grind the activated mass in the rage of 24 – 30µ.
, Description:FIELD OF INVENTION:

The present invention relates to the composition, preparation and regeneration of Spent Bleaching Clay adsorbent for the Purification of Edible & Waste oil. Waste Oil may be from Edible oil, Non-Edible Oil, Aromatic Hydrocarbon, Aliphatic Hydrocarbon, Mineral Oil, Lubricating Oil, Transformer Oil, Cutting Oil and Petroleum waxes.

BACKGROUND OF INVENTION AND PRIOR ART:
Clay minerals are ubiquitous on earth and are well known for the adsorbent and catalyst in oil segments. Regeneration and Reuses of Spent Adsorbent is done by various methods. The invention focusses on extraction of oil and regeneration of spent adsorbent by Autoclaving technique with water without using any oil, esters, ethers, ketones, heptane’s and alcohol to extract the oil.
To make the Spent Adsorbent reusable, it should possess good surface area and active sites. These surface properties can be achieved by doing certain processing. Oil is removed and, the oil extracted clay is activated thermally and chemically to get the porosity and active sites. The activated adsorbent is used to purify the oils using same process normally use with virgin adsorbent. The spent Bleaching Earth was taken and regenerated by the above-mentioned technique. The regenerated Bleaching Earth was giving the efficiency of 75-95% against the virgin Bleaching Earth. The other physical parameters of the regenerated Bleaching Earth like Particle size, pH, bulk density and fineness are adjusted more or less same as of virgin Bleaching Earth.

PRIOR ART:
Different sources of Adsorbent like Clay minerals (Bentonite, Attapulgite, Bauxite etc.), Activated Charcoal (Animal Charcoal, Wooden Charcoal, husk charcoal etc.), Silica (Silica hydrogel, precipitated Silica etc.) based Adsorbent are being used for the purification of Edible and non-Edible oil since long back. After one time used these adsorbents become spent and most of the time it is being dumped in land filling. These spent adsorbents contain some oil percentage which creates the hazardous and pollution to land and water bodies by increasing the COD. Regeneration and Reuses of Spent Adsorbent is done by various methods. Most of the methods are involved to extract the oil and dumped the spent adsorbent without regeneration. Unlike the other oil extraction techniques, no oil, esters, ethers, ketones, heptane’s and alcohol are used to extract the oil, instead water is used to extract the oil under sub-critical temperature. The remaining separated water can be reuse/recycled.

OBJECT OF THE INVENTION:

It is an object of the invention to make clay adsorbent by regenerating the Spent Bleaching Clay which can remove the maximum unwanted impurities like chlorophyll, Carotenoids and color bodies from Edible & Non-Edible Oil.

Another object of the present invention is to avoid the pollution and reuse these spent Adsorbent by regenerating.

Yet another object of the present invention is to improve the Bleaching Efficiency of Regenerated Spent Clays.

Yet another object of the present invention is to improve the efficiency for reducing the Acid Value, Free Fatty Acid content, Soap Content, Phosphorus content and Peroxide value in Edible Oil against the virgin Bleaching Earth.
Yet another object of the present invention is to purify the Non-Edible oil like Used Lubricating Oil and Used Transformer Oil from Regenerated Bleaching Clay.

Yet another object of the present invention is to provide the method of preparing Regenerated Bleaching Clay from Spent Bleaching Clay.

SUMMARY OF THE INVENTION:
The invention provides a process for the preparation of Regenerated Spent Bleaching Clay. The Spent Bleaching Clay (SBC) is charged into the Autoclave containing water. The Oil is extracted in the temperature range of 200 – 500°C, at an inbuilt pressure of 10-40 kg/cm2 for 0.5 – 2.5 hrs. Oil, water and clay are separated through Filter press and mixture of oil and water are again separated in a cyclone separator. The extracted Clay material is dried and activated thermally in the temperature range of 200-800°C for 0.5-3.0 hrs. Optionally, the thermally activated SBC can be treated with 1- 10 wt% of Sulphuric acid having a concentration of 50-98%. A very fine powder up to 200 mesh is obtained with the help of Pulverizer. The oil is bleached by adding 0.5-1.5% Regenerated SBC at 100 – 120°C for 0.2-2.0 hrs. The quality parameter is analyzed as per the standard norms and method.

DESCRIPTION OF INVENTION:

The process of the invention is described with the help of the accompanying drawings, in which:
Figure 1 illustrates the SEM images of Spent Bleaching Clay Before Oil Extraction
Figure 2 illustrates the SEM images of Spent Bleaching Clay After Oil Extraction
Figure 3 illustrate the SEM images of Regenerated Bleaching Clay After Thermal Activation
Figure 4 illustrate the BET Surface Area Graph of Regenerated Bleaching Clay

The current invention envisages a clay based adsorbent and a method for its preparation. In the present invention, the Clay Adsorbent is a Regenerated Bleaching Clay(RBC) which has got a similar performance, efficiency and properties as of the virgin Bleaching Clay. This RBC can be used for the purification or Bleaching of Edible oil as well as some Non-Edible oil.

The process for the preparation of the composite material is also described below.

There are several unwanted impurities like Chlorophyll, Carotenoids, phosphorus, Free fatty acids, Sodium salt of fatty acids (soap) etc. are present in the edible oil. To remove these impurities, edible oil is treated with the Bleaching Earth. This treated Bleaching Earth after filtration is known as Spent Bleaching Clay (SBC). During the treatment, some percentage of oil is also being adsorbed/absorbed along with the impurities, which is not fully removed at the filtration stage. SBC containing 4-25 wt.% oil is taken as an initial raw material for the regeneration studies. The whole regeneration process is comprised of mainly three step i.e. Extraction, Recovery and Regeneration.

To make the SBC reusable, the first step is to remove the trapped oil. Trapped oil can be extracted in two ways, first- by making azeotrope with water at sub critical temperature and second by extracting with some soluble non-polar solvents at low temperature. The oil is extracted with water at sub critical temperature.

To carry out the Extraction process, the raw material containing 4-25 wt.% oil is fed to the Autoclave, where it is mixed with proportionate amount of water. The mixture mass is heated at 200-500°C for 0.5-2.5 hrs. At subcritical temperature water evaporates and creates inbuilt pressure (10-40kg/cm2). The high temperature and pressure helps to leach the trapped oil from clay, leached oil comes into the water phase which can be separated at later stage. Pores which were occupied by the oil and other trapped material, become free after leaching the oil.

The next step is to recover and separate the oil, water and clay material form the mixture. To separate the solid-liquid from the mixture the Filter press technique is adopted. Solid and liquid material are collected separately and forwarded for further processing.

Oil and water are immiscible to each other so it can be separated easily in cone separator. But due to the subcritical temperature some parts of the oils forms emulsion with water which further can be separated with the help of centrifugation or can be extracted with known non-polar solvents. In the Regeneration step, the oil extracted clay material is subjected to the Stationary/Rotary furnace at 200-800°C for 0.5-3.0 hrs. Thermal treatment will helps to remove the surface/trapped moisture and makes the pore free. Some of the oil which was not separated at filtration stage and was absorb/adsorbed by the clay material, will be converted into carbon. This generated carbon on the surface of the clay makes the material lighter and porous with high surface area (refer the experiments) which in results enhance the color removal efficiency in oil purification. To enhance the surface property and make the site more active optionally, dilute sulphuric acid in the range of 0-10 wt.% is also added. The regenerated material are mixed and grinned into the size range of 40-90 microns.

This Regenerated Bleaching Clay is used to bleach the Edible oil like Soybean Oil, Cottonseed Oil, Rice Bran Oil, Palm Oil and Castor Oil. To remove the unwanted impurities, RBC is dosed in to the oil in the range of 1.0 -3.0 wt. %. RBC treated oil is analyzed as per the standard norms and compared with the oil treated with the fresh Bleaching Earth. Bleaching efficiency lies in the range of 65-95% against the virgin Bleaching Earth depending upon the type of impurity level in the Raw Oil. Due to the presence of carbon, SBC gives the 10-50% better efficiency to remove the other impurities like Free Fatty Acid (FFA), Soap, Phosphorus and Acid Value.

Non-Edible used Oil like Lubricating Oil, Insulating Oil, Cutting Oil and Paraffin wax contains some impurities like color bodies, Dissolve gases, Acids, Water, Metal and Nonmetal compounds. To reuse these used oil, it has to be passed through some Adsorbents which can remove the above said impurities. As per the prior art and literature, Alumina based Adsorbent, Clay based Adsorbent and Silica based Adsorbent are used to remove these impurities. RBC as an alternate environment friendly Adsorbent is used to remove the above impurities. The efficiency against the fresh Adsorbent is 65-95% irrespective to the process parameter and dosing.

The Regeneration of Spent Bleaching Clay (SBC) significantly changes some of the specific properties of interest. In the Spent Bleaching Clay, some oil and unwanted impurities like Chlorophyll, Carotenoids, phosphorus, soap are trapped into the pores and surface of the clay which further agglomerate the clay particle (Refer Image 1). This trapped oil and impurities, blocks the pores of clay and does not allow the further adsorption of Oil impurities. To make the SBC reusable, this trapped impurity and oil must be removed. When the SBC is heated along with the water at sub critical temperature, oil forms an azeotrope with water at high temperature and pressure which helps to take out the oil and other adsorbed impurity from pores and surface. This extraction helps to makes the clay particle deagglomerate (Refer Image 2), which further confirms that most of the trapped oil and other impurities has been removed from the pores and surface. Still some of the oil and volatile matter are there on the surface of the SBC, which further must be removed.

To make the surface free from volatile matter and make the clay porous, it is exposed to the thermal treatment, which helps to remove the volatile matter and converts the remaining trace oil into the carbon. After heat treatment structure of clay become flattered and porous (Refer Image 3) which helps to enhance the surface area. To make the RBC more active and efficient, it is activated chemically with sulphuric acid. The increment in surface area further confirms by the BET graph (Refer Image 4).

The RBC obtained in accordance with the process of the present disclosure find extensive applications including in the purification of Petroleum and Non-Edible Oil, but not limited to their uses in Edible Oil, used Lubricating Oil and Used Insulating Oil.