Method for determining volatile phosphorus in carbon

• US 4,843,015 A
• Filed: 11/05/1987
• Issued: 06/27/1989
• Est. Priority Date: 11/05/1987
• Status: Expired due to Term

• Current Assignee: Wastvaco Corporation
• Original Assignee: Westvaco Corporation (Meadwestvaco Corporation)
• Inventors: Flowe, Robert C., Sarathy, Aravamuthan P., Grubbs, John R. Jr.
• Primary Examiner(s): Richman, Barry S.
• Assistant Examiner(s): ALEXANDER, LYLE
• Application Number:
  US07/116,973
• Time in Patent Office: 600 Days
• Field of Search: 436/103-105, 436/38, 436/155, 436/164, 436/167, 436/181, 436/177, 422/78, 422/80, 422/130
• US Class Current: 436/103
• CPC Class Codes: G01N 21/78 producing a change of colour
• CPC Class Codes: G01N 25/14 by using distillation, extraction, sublimation, condensation, freezing, or crystallisation G01N25/02 takes precedence
• CPC Class Codes: Y10T 436/16 Phosphorus containing

Abstract

A method and apparatus for determining the phosphorus content which can be volatilized in a solid carbon sample. The sample is heated in the presence of steam to produce a vaporous steam containing volatile phosphorus. Next, the vaporous stream is passed through a zinc oxide layer whereby the voliatle phosphorus is retained. A colored solution is formed upon adding to the zinc oxide layer a vanadate-molybdate reagent. Finnally, the intensity of the colored solution is determined by a spectrophotometer; and the phosphorus content is determined by comparison with a standard intensity graph.

Claims

1. A method for determining the volatile phosphorus content in a solid sorbent comprising the steps of:

heating the solid sorbent and liberating the phosphorus contained therein in gaseous form;

passing the liberated gases through a zinc oxide layer and retaining the volatile phosphorus therein;

forming a colored solution comprising the zinc oxide layer and a vanadate-molybdate reagent;

determining the intensity of the colored solution by means of a spectrophotometer; and

determining the content of phosphorus by comparison with a standard intensity graph.

2. A method according to claim 1 wherein the zinc oxide layer comprises granulated or powdered zinc oxide.

3. A method according to claim 1 wherein the liberated phosphorus is retained in the zinc oxide layer by reacting with zinc oxide to form zinc orthophosphate.

4. A method according to claim 3 wherein the vanadate-molybdate reagent is prepared from ammonium vanadate and ammonium molybdate.

5. A method according to claim 1 wherein the solid sorbent is carbon which is heated to an elevated temperature.

6. A method according to claim 5 wherein the elevated temperature is at least about 1500°

F.

7. A method according to claim 5 wherein steam is employed to liberate the volatile phosphorus from the carbon.

8. A method according to claim 5 wherein the carbon used is a wood-based carbon which is heated in the presence of steam.

9. A method according to claim 8 wherein said steam is passed through the carbon.

10. A method for determining the phosphorus content in a solid phosphorus-containing carbon sample which comprises the steps of:

(a) preparing a combustion reactor comprising an open ended elongated tube having arranged therein a plurality of separated beds, the beds comprising, in an individual array, a weighed solid phosphorus-containing carbon sample, granulated quartz, and zinc oxide;

(b) heating the combustion reactor;

(c) concurrently with step (b) passing steam through the reactor for a period of time sufficient to regenerate the carbon sample;

(d) cooling the combustion reactor and collecting the zinc oxide;

(e) contacting the zinc oxide with a standard solution comprising molybdate and vanadate ions to obtain a colored solution;

(f) measuring the intensity of the colored solution; and

(g) comparing the measured color intensity to a standard to determine the phosphorus content in the solid carbon sample.

11. A method according to claim 10 wherein the solid carbon sample is obtained from a large mass of regeneratable carbon in an amount of about 5 to 10 grams.

12. A method according to claim 10 wherein the combustion reactor is heated to a temperature above about 1575°

F.

13. A method according to claim 10 wherein condensate water from the steam is collected and weighed to obtain amount of steam recovered.

14. A method according to claim 10 wherein an inert gas is passed through the combustion reactor prior to the passage of steam.

15. A method according to claim 14 wherein the inert gas is nitrogen.

16. Apparatus for determining the volatile phosphorus content of a solid comprising:

means for heating a solid and liberating the phosphorus contained therein in gaseous form;

means for passing the liberated gases through a zinc oxide layer;

means for forming a colored solution comprising the zinc oxide layer and a vanadate-molybdate reagent;

spectrophotometric means for determining the intensity of the colored solution by means of a spectrophotometer; and

means for determining the content of phosphorus in the solution by comparison with a standard intensity graph.

17. The apparatus according to claim 16 comprising an elongated vessel containing therein said heating means and said liberated gases passing means wherein said passing means is spaced from said heating means so that zinc oxide layer is not in contact with a solid sample positioned within said heating means.

18. The apparatus according to claim 17 wherein the heating means comprises a jacket furnace which surrounds a vessel.

19. The apparatus according to claim 17 wherein a layer of granulated quartz is positioned between the heating means and zinc oxide layer.