NZ329832A

NZ329832A - Process of manufacturing activated carbon from a liquid source on a silicate carrier or similar material

Info

Publication number: NZ329832A
Application number: NZ329832A
Authority: NZ
Inventors: Thomas Anthony Hill
Original assignee: Thomas Anthony Hill
Priority date: 1998-02-24
Filing date: 1998-02-24
Publication date: 2000-11-24
Also published as: AU1836899A

Abstract

The method of producing activated carbon from a liquid source comprises: a) obtaining a suitable carbon containing substance; b) applying the carbon containing substance in liquid form to a suitable carrier and c) activating carbon from the carbon containing substance to produce activated carbon on and/or within the carrier.

Description

<div class="application article clearfix" id="description"> Patents Form No. 5 THE PATENTS ACT 1953 COMPLETE SPECIFICATION No: 329832 Date: 19 February 1999 ACTIVATED CARBON ON A CARRIER MATERIAL I, Thomas Anthony Hill, a New Zealand citizen, of 2001 Te Rapa Road, Hamilton, New Zealand, hereby declare this invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: -2- This invention relates to activated carbon substances and the preparation thereof. Background Art Activated carbon substances are often used in the purification of liquids and gases. They can be used to filter out impurities such as chlorine, pesticides, hydrogen sulphide, and organic materials which impart undesirable tastes and odours, etc. A problem in producing activated carbon filter products is that it can be difficult to achieve the desired level of impregnation of activated carbon on a carbon carrier. It is accordingly an object of at least one form of the invention to go at least some way towards addressing this problem, or to at least offer the public with a useful choice. Disclosure of Invention According to one aspect of the invention there is provided a method of producing activated carbon from a liquid source on a silicate carrier or some similar material. According to a more particular aspect of the invention there is provided a method of producing activated carbon, comprising the steps of: a) obtaining a suitable carbon containing substance, b) applying the carbon containing substance in liquid form to a suitable carrier, and c) activating carbon from the carbon containing substance to produce activated carbon on and/or within the carrier. Preferably the step of activating the carbon involves the use of heat to achieve activation. Preferably the carrier comprises a suitable silicate. Preferably the silicate comprises aluminium silicate, sodium silicate, or Ferro silicate. Desirably the carrier comprises pumice, which may or may not be in the form of granules. Preferably the step of activating the carbon from the carbon containing substance involves carbonisation and activation in a controlled gaseous atmosphere to regulate porosity characteristics of the activated carbon. Preferably the step of activating the carbon from the carbon containing substance involves carbonisation and activation in the presence of an impurity to regulate porosity characteristics of the activated carbon. Expediently the impurity comprises a suitable salt. Advantageously the impurity comprises calcium chloride or zinc chloride. Preferably the carrier is substantially in the form of granules which may or may not be porous in nature. Preferably the activated carbon on and/or within the carrier, together with the carrier, form a molecular filter. -4- In a preferred embodiment of the invention a molecular filter product may be formed by applying a suitable carbon containing substance in liquid form to a suitable carrier, and applying heat to the carbon containing substance and carrier so that the carbon containing substance is carbonised and converted to activated carbon on and/or within the carrier. Generally speaking, the process of activating carbon involves modifying or producing a carbon pore structure to enhance the adsorption characteristics of the carbon concerned. The use of a carbon containing substance in liquid form facilitates adsorption of the carbon containing substance with respect to the carrier. As will be appreciated by those skilled in the art, it can be difficult to achieve a good level of adsorption with a solid source of carbon. The carbon containing substance in liquid form may be applied to the carrier under vacuum conditions to enhance penetration. Examples of carbon containing substances in liquid form include sugars, starch, aromatic hydrocarbons, resins, carbohydrates, lignins, proteins, waste plastics, and waste or virgin oils. In particular, it has been found that sucrose and formaldehyde resin can be used with success. It should of-course be appreciated that there are many other useful carbon containing substances, and the particular substances mentioned herein are not intended to be limiting in any way. Examples of carriers include suitable silicates, for example aluminium silicate, sodium silicate, and Ferro silicate. It should however be appreciated that other carriers can be used, and the examples given herein should not be seen as limiting the scope of the invention. It has been found that modified pumice, sometimes referred to as "silicon sponge", can be used as a suitable carrier material. At the date of -5- patent modified pumice is available from Works Filter Systems Limited of Hamilton, New Zealand. In a preferred form of the present invention it is desirable to use a pumice carrier modified to specific density parameters. Controlling the density of the pumice enhances the ability of the eventual filter product to fluidize and settle in a layer. The process of producing the activated carbon may involve the use of suitable salts, for example calcium chloride and zinc chloride. Suitable salts, or indeed other impurities in the liquid carbon, can facilitate carbonisation and influence pore sizes achieved. The presence of calcium chloride or zinc chloride has been found to promote microporosity in at least a number of cases. The size and number of pores achieved in the filter product can be modified or controlled by controlling the activation atmosphere. Atmospheres such as steam, carbon dioxide, hydrogen, and nitrogen, or some mixtures thereof, may be used to influence activation. Example 1 - Activated Carbon from Phenol-Formaldehyde Three samples of dry pumice were soaked in 10%, 30% and 50% w/w Phenol-Formaldehyde resin to pumice for 2 hours. The resin contained 54-59% by weight of solids. The soaked pumice was then dried at 40 degrees Celsius for approximately one hour, giving free granules. Carbonisation was then carried out in a tunnel furnace at 650 degrees Celsius for 1.5 hours, using a nitrogen atmosphere. The carbon yield of each sample was determined by burning all of the carbon off the -6- pumice at 500 degrees Celsius in air, and comparing the final and initial weights. The results were as follows: Weight % resin Weight % carbon Weight % yield added to pumice on pumice of carbon 10 2.5 41 20 8.1 37 30 11.9 42 The activated carbon formed from Phenol-Formaldehyde was found to have pore sizes in the vicinity of 3.76 - 4.75 Angstrom units. Example 2 - Activated Carbon from Sucrose A 1:1 raw sugar to water solution was added to 20 grams of dry pumice in a beaker to give a 60.8% w/w sugar solution to pumice. After soaking for 24 hours the sugar solution was dried onto the pumice at 80 degrees Celsius until it did not run off. This took approximately 4 hours. The sugar was then carbonised on the pumice in a tunnel furnace at 800 degrees Celsius for 1.5 hours in a Nitrogen atmosphere. The activated carbon achieved was found to have inherent microporous properties. In the activation of carbon from sucrose it was found that activation in the presence of CC>2 gave rise to microporosity, for example a maximum micropore volume of approximately 0.03 ml/g pumice (0.3 ml/g carbon). With the use of catalyst impurities, for example metal salts such as iron chloride, sucrose carbon can be activated with CO2 at 820 degrees Celsius with mesopores and macropores. It was also found that by controlling the flow rate of CO2 the volume of mesopores and macropores can be controlled. High flow rates generally correspond with a reduced volume of mesopores and macropores due to high bulk burn-off. While some aspects of the invention have been described by way of example, it should be appreciated that modifications and improvements can occur without departing from the scope of the appended claims. </div>

Claims

<div class="application article clearfix printTableText" id="claims"> -8- WHAT I CLAIM IS:

1. A method of producing activated carbon, comprising the steps of: a) obtaining a suitable carbon containing substance, b) applying the carbon containing substance in liquid form to a suitable carrier, and c) activating carbon from the carbon containing substance to produce activated carbon on and/or within the carrier.

2. A method according to claim 1, wherein the step of activating the carbon involves the use of heat.

3. A method according to claim 1 or 2, wherein the carrier comprises a suitable silicate.

4. A method according to claim 1, 2 or 3, wherein the silicate comprises aluminium silicate, sodium silicate, or Ferro silicate.

5. A method according to any one of the preceding claims, wherein the carrier comprises pumice.

6. A method according to any one of the preceding claims, wherein the step of activating the carbon from the carbon containing substance involves use of a controlled gaseous atmosphere to regulate porosity characteristics of the activated carbon. -9- 229832

7. A method according to any one of the preceding claims, wherein the step of activating the carbon from the carbon containing substance involves use of an impurity to regulate porosity characteristics of the activated carbon.

8. A method according to claim 7, wherein the impurity comprises a suitable salt.

9. A method according to claim 7, wherein the impurity comprises calcium chloride or zinc chloride.

10. A method according to any one of the preceding claims, wherein the activated carbon on and/or within the carrier, together with the carrier, form a molecular filter.

11. A method according to any one of the preceding claims, wherein the carrier is substantially in the form of granules.

12. A method according to any one of the preceding claims, substantially as herein described.

13. An activated carbon / carrier combination formed in accordance with the method of any one of the preceding claims.

14. An activated carbon / carrier combination according to claim 13, substantially in the form of a molecular filter material. THOMAS ANTHONY HILL lniteaofprNTrty '3 OCT 2000 A.J. Pietras & Associates By His Authorised Attorney END </div>