Title of Invention

CHEMICAL DENITRIFICATION OF WATER BY HYDROXYLAMINE HYDROCHLORIDE

Abstract In the present invention, nitrate was reduced using hydroxylamine hydrochloride since the byproducts are gaseous and there won"t be any residue left after the treatment of the water. The reduction was carried out in a glass container which can be maintained at the required temperature provided with stirrer. Nitrate contaminated water was taken and then calculated amount of hydroxylamine hydrochloride was added. Then the content of the flask was stirred for 20-30 minutes and was maintained at a temperature of 40 - 70 °C. Then the content of the flask was analyzed for residual nitrate and was found that the concentration was far below permissible limit. The reduction was almost 90% for nitrate at any concentration.
Full Text STATEMENT OF INVENTION:
The present invention discloses a simple technique for chemical denitrification of water using hydroxylamine hydrochloride. The hydroxylamine hydrochloride in less than 0.05% (w/v) is added to 100 mL water having 100 ppm nitrate and is heated to a temperature of 40 - 70 °C for 20-35 minutes. The nitrate is reduced to 10 ppm which is much below the permissible limit.
BACKGROUND OF INVENTION WITH RESPECT TO PRIOR ART:
Several nitrate removal methods like ion exchange, reverse osmosis, electrodialysis, catalytic hydrogenation and biological denitrification, adsorption etc. can be used to remove nitrates from drinking water. The use of biological reactor seems to be the most promising technique in the treatment of high nitrate concentration. However, maintaining biological processes at their optimum conditions is difficult, and the problems of contamination by dead-bacteria have to be solved to make such processes safety enough to utilize in drinking water treatment. On the other hand, adsorption is a very feasible process but there aren't many adsorbent available for removal of nitrate since nitrate is very selective towards adsorption. The above methods are not very much in use either because of complex technology or high cost. To overcome these difficulties, nowadays researchers are working on chemical reduction methods. Few chemical methods described below are also available by using zero-valent metals like iron (Fe°), aluminum (Al°) and magnesium (Mg°) has been studied intensively. In aqueous system at acidic pH, Fe° is oxidized to ferrous ion (Fe2+) and nitrate ion is reduced to ammonia or nitrogen gas. At pH above 10.5, Al° also reduces nitrate to ammonium ion and is oxidized to Al3+ ion. In acidic medium, Mg° is oxidized to magnesium ion (Mg2+) and nitrate ion is reduced to ammonium ion or nitrogen gas.
However, challenges like high dose requirement, long reaction time, and presence of anaerobic condition and rapid deactivation of metal surfaces due to hydroxide precipitation were observed. Low efficiency, ineffectiveness, and increase health concern

about residual Al3 + salt in water are problems with aluminum powder. Thus there is a need to develop a cheap and readily available reducing agent, which can reduce nitrate effectively in a wide range of concentrations under ambient temperature and pressure in aerobic condition, within short reaction time and at moderate dose.
OBJECT OF THE INVENTOR:
The objective of the invention is to develop a cost effective, user friendly, easy to handle, can be applied to water and waste water containing nitrate in any concentration for process for reduction of nitrate. The reduction of nitrate is a challenging job as the nitrate salt is highly soluble in water. Since nitrate is normally found in ground water and consumption of which causes a lot of health hazards to both man and animals, it was aimed to remove nitrate from ground water/waste water at the site of utilization.
SUMMARY OF INVENTION:
In the present invention, nitrate was reduced using hydroxylamine hydrochloride since the byproducts are gaseous and there won't be any residue left after the treatment of the water. The reduction was carried out in a glass container which can be maintained at the required temperature provided with stirrer. Nitrate contaminated water was taken and then calculated amount of hydroxylamine hydrochloride was added. Then the content of the flask was stirred for 20-30 minutes and was maintained at a temperature of 40 - 70 °C. Then the content of the flask was analyzed for residual nitrate and was found that the concentration was far below permissible limit. The reduction was almost 90% for nitrate at any concentration.
DETAILED DESCRIPTION:
Hydroxylamine hydrochloride was procured from Merck and was added to nitrate contaminated of different nitrate concentration. Hydroxylamine hydrochloride is soluble in aqueous medium producing hydroxylamine ion ([NH3OH]+) and chloride ion. Hydroxylamine ion is responsible for the reduction of nitrate.

2NH3OH+ + 2NO3→ N2O + 3H2O + 2HNO2
Nitrite so produced is reduced to nitrous oxide as per equation
NH3OH+ + NO2→ N2O + 2H2O
The overall nitrate reduction process is given by equation 4 NH3OH+ + 2 NO3→ 2N2O + 5H2O + 2H+
Alternatively it may be considered that hydroxylammonium chloride react with nitrate ion to produce hydroxylammonium nitrate (HAN) which decomposes readily under ambient condition to produce N2O and N2 in the ratio of 2:1 to 4:1. However in presence of iron, this ratio has been determined to be 36:1
[NH3OH]Cl + NO3→ [NH3OH] NO3 + C1"
2[NH3OH] NO3→ N2O + 3H2O + 2HNO2
[NH3OH] NO3 + HNO2 → N2O + 2H2O + 2HNO3
4[NH3OH] NO3 → 3N2O + 7H2O + 2HNO3
5[NH3OH] NO3 → 3N2 + 8H2O + 4HNO3
Stoichiometric Equations suggest that 2-5 mol of hydroxylamine hydrochloride will be necessary for reduction of each mol of nitrate, depending on the extent of nitrate reduction to nitrous oxide/ nitrogen gas. However, the actual hydroxylamine hydrochloride dose may be slightly higher than theoretical requirement.
Example 1
10L of 100 ppm nitrate containing water was taken in a container and 3g of hydroxylamine hydrochloride was added and was stirred for 30 minutes. The temperature was maintained at 50 °C. After 30 minutes, the water was tested for residual nitrate. It was observed that the concentration of nitrate was 10 ppm and the permissible limit is 45 ppm. So, concentration of nitrate was far below permissible limit.

Example 2
50L of nitrate containing water with nitrate concentration of 150 ppm was taken in a container and 20g of hydroxylamine hydrochloride was added and was stirred for 30 minutes. The temperature was maintained at 50 °C. After 30 minutes the water was tested for residual nitrate. It was observed that the concentration of nitrate was 16 ppm and the permissible limit is 45 ppm. So, concentration of nitrate was far below permissible limit.
Example 3
100L of nitrate containing water with nitrate concentration of 300 ppm was taken in a container and 35g of hydroxylamine hydrochloride was added and was stirred for 30 minutes. The temperature was maintained at 50 °C. After 30 minutes the water was tested for residual nitrate. It was observed that the concentration of nitrate was 30 ppm and the permissible limit is 45 ppm. So, concentration of nitrate was far below permissible limit.
We claim:
1. A process for reduction of nitrate from nitrate containing water comprising the steps of
addition of 0.05% (w/v) hydroxylamine hydrochloride. Then the water is heated to a temperature of 40-70 °C for 20-35 minutes with stirring to achieve the reduction of nitrate to a level much below the permissible limit.
2. A process according to claim 1, the hydroxylamine hydrochloride in less than 0.05%
(w/v) is added for reduction of nitrate from 100 ppm to a level much below the
permissible limit.
3. A process according to claim 1, the process is done in two stages; addition of hydroxylamine hydrochloride and heating and stirring causes reduction of nitrate.
4. A process according to claim 1, after addition of required amount of hydroxylamine
hydrochloride is heated to a temperature of 40 - 70 °C for 20 - 35 minutes with constant stirring.
5. A process according to claim 1, no other treatment process is required for reduction of
nitrate.

6. A process according to claim 1, the nitrate is reduced to 10 ppm which is much below the permissible limit. (Permissible Limit in drinking water-45ppm IS 10500:1991 and Guidelines for Drinking Water Quality Third Edition Vol. I Recommendations WHO Geneva 2004. )

In the present invention, nitrate was reduced using hydroxylamine hydrochloride since the byproducts are gaseous and there won't be any residue left after the treatment of the water. The reduction was carried out in a glass container which can be maintained at the required temperature provided with stirrer. Nitrate contaminated water was taken and then calculated amount of hydroxylamine hydrochloride was added. Then the content of the flask was stirred for 20-30 minutes and was maintained at a temperature of 40 - 70 °C. Then the content of the flask was analyzed for residual nitrate and was found that the concentration was far below permissible limit. The reduction was almost 90% for nitrate at any concentration.

Documents:

883 KOL 2009 Search Report.pdf

883-KOL-2009-(19-09-2012)-ABSTRACT-1.1.pdf

883-KOL-2009-(19-09-2012)-ABSTRACT.pdf

883-KOL-2009-(19-09-2012)-CLAIMS-1.1.pdf

883-KOL-2009-(19-09-2012)-CLAIMS.pdf

883-KOL-2009-(19-09-2012)-CORRESPONDENCE.pdf

883-KOL-2009-(19-09-2012)-DESCRIPTION (COMPLETE)-1.1.pdf

883-KOL-2009-(19-09-2012)-DESCRIPTION (COMPLETE).pdf

883-KOL-2009-(19-09-2012)-FORM 2-1.1.pdf

883-KOL-2009-(19-09-2012)-FORM-1.pdf

883-KOL-2009-(19-09-2012)-FORM-13.pdf

883-KOL-2009-(19-09-2012)-FORM-2.pdf

883-KOL-2009-(19-09-2012)-FORM-3.pdf

883-KOL-2009-(19-09-2012)-FORM-5.pdf

883-KOL-2009-(19-09-2012)-OTHERS.pdf

883-KOL-2009-(19-09-2012)-SPECIFICATION.pdf

883-kol-2009-abstract.pdf

883-kol-2009-claims.pdf

883-kol-2009-description (complete).pdf

883-kol-2009-form 1.pdf

883-kol-2009-form 18.pdf

883-kol-2009-form 2.pdf

883-kol-2009-form 3.pdf

883-kol-2009-specification.pdf


Patent Number 255341
Indian Patent Application Number 883/KOL/2009
PG Journal Number 07/2013
Publication Date 15-Feb-2013
Grant Date 13-Feb-2013
Date of Filing 19-Jun-2009
Name of Patentee NATIONAL INSTITUTE OF TECHNOLOGY
Applicant Address NATIONAL INSTITUTE OF TECHNOLOGY ROURKELA - 769 008 DIST: SUNDARGARH
Inventors:
# Inventor's Name Inventor's Address
1 MAHAMUDAR ISLAM NATIONAL INSTITUTE OF TECHNOLOGY ROURKELA - 769 008 DIST: SUNDARGARH
2 DR. RAJ KISHORE PATEL NATIONAL INSTITUTE OF TECHNOLOGY ROURKELA - 769 008 DIST: SUNDARGARH
PCT International Classification Number C02F
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA