INTRODUCTION:

NO_x is a generic term for the mono-nitrogen oxides NO and NO₂ (nitric oxide and nitrogen dioxide). They are produced from the reaction of nitrogen and oxygen gases in the air during combustion, especially at high temperatures. In areas of high motor vehicle traffic, such as in large cities, the amount of nitrogen oxides emitted into the atmosphere as air pollution can be significant. NOx gasses are formed everywhere where there is combustion – like in an engine. In atmospheric chemistry, the term means the total concentration of NO and NO₂. NO_x react to form smog and acid rain. NO_x are also central to the formation of tropospheric ozone. Oxides of nitrogen react with volatile organic compounds (VOCs) in the presence of sunlight to form ozone. Ozone is a reactive and corrosive gas that contributes to many respiratory problems. NOx emissions themselves can damage respiratory systems and lower resistance to respiratory infection.^2,3,4,8,9,10

Fuller earths are natural clays and they are chiefly Magnesium Aluminium Silicates in the form of minerals Attapulgite and Montmorrillonite. When clay is heated and dried during this operation it develops structure.

Activated clays and fuller earths are useful in decolorizing, neutralizing, drying petroleum and transformer products like lubricating oils, transformer oils such as kerosene and gasoline as well as vegetable and animal oils. Bricks are soaked in water for 24 hours to increase its weight to almost one and a half time. This reveals the fact that bricks have a large number of pores. Taking this into account Brick powder is selected in this study of adsorption process. Bricks are also obtained from clay by heating and drying process. It develops the capacity to adsorb gases.^1,5,6,7

METHODS AND MATERIALS:

Selection of Adsorbent:

The present work, examines the possibility of using a well-known physicochemical method like adsorption for the removal of NOxfrom air. The initial screening studies have been carried by introducing a known amount of adsorbent into the aqueous solution of NOx. It was found that brick powder has large capacity to adsorb NOx. For the present studies adsorption techniques are selected because NOx gas is incombustible and it is present in very low concentrations. The experiments are carried with respect to to contact time, with respect to initial concentration of NOx and with respect to brick powder dosages.

Effect of Contact Time:

Contact time plays an important role in designing a system.. The initial (before adsorption) and final (after adsorption) concentration is determined at regular intervals of time i.e. 15, 30, 45, 60, 120 minutes. The results are given in TABLE 1 and FIG 1.

Effect of Initial NOx Concentration:

Different concentrations of NOx were studied, which consists of a fixed amount of adsorbent. The experiments are carried out with constant contact time and the contact time is fixed depending upon contact time experiments. The results are given in TABLE 2 and FIG 2.

Fig 1 Variation of contact time between NOx and Brick powder

Fig 2 Variation of aqs.solution of NO₂ concentration on brick powder

From the table, it is clear that the % removal decreases with increase in concentration. (9)

Effect of brick powder Dosages:

Definite concentration of NOx is studied with different amounts of adsorbent dosages i.e. 2 gms, 4gms, 6gms, 8gms respectively. The experiments are carried out with constant contact time of one hour. The results are given in TABLE 3 and FIG 3.

RESULTS AND DISCUSSIONS:

TABLE 1: VARIATION OF CONTACT TIME BETWEEN BRICK POWDER AND NOx

Amount Of Adsorbent: 1gm

Volume: 100ml

Concentration: 40 ppm

S.NO	Contact time (min)	Initial concentration(ppm)	Final concentration(ppm)	Gas adsorbed	%Removal
1.	0	40	40	-	-
2.	15	40	30	10	25
3.	30	40	29	11	27.5
4.	45	40	27	13	32.5
5.	60	40	25	15	37.5

From the table, it is evident that the %removal increases with increase in contact time. (9)

TABLE 2: VARIATION OF NOx GAS CONCENTRATION ON BRICK POWDER

Amount of adsorbent: 1 gm

Volume: 100 ml

Contact time: 60 mins

S.NO	Initial Conc. (ppm)	Final Conc. (ppm)	Amount Adsorbed	% Removal
1	1	0	1	100
2	2	0.5	1.5	75
3	3	1.5	1.5	50
4	4	2.2	1.8	45
5	5	2.9	2.1	42
6	6	3.6	2.4	40
7	7	4.4	2.6	37
8	8	5.3	2.7	34
9	9	6.7	2.3	25
10	10	8	2	20
11	20	17	3	15

TABLE 3: VARIATION OF ADSORBENT DOSAGE

Concentration: 40 ppm

Volume: 100 ml

Contact time: 60 mins

S.NO	Amount of brick powder introduced (gms)	Initial Conc. (ppm)	Final Conc. (ppm)	Absolute Amount of aqs. NO₂	% Removal
1	2	40	12	28	70
2	4	40	10	30	75
3	6	40	6	34	85
4	8	40	3	37	92.5

From the table, it is clear that the % removal increases with increase in adsorbent dosage. (9)

Fig 3 Variation of brick powder dosage

CONCLUSIONS:

Brick powder has a capacity to adsorb NO_2.. Physical forces or Vander Waal’s forces are binding NO₂molecules to the surface of the pulp. The percentage removal of NO₂molecules increased with the decrease in concentration, with the increase in adsorbent dosages and with the increase in contact time. This study provides an economic solution for cleaning up environmental pollutant NOx and it is recommended to use this adsorbent in industries.

REFERENCES:

1. Asheesh Kumar Yadav, et al., (2006). “Defluoridation of groundwater using brick powder as an adsorbent”. Journal of Hazardous materials, Vol. 128, Issues 2-3: 289-293.

2. Bovensman, H., et al. (1999), SCIAMACHY: Mission objectives and measurement modes, J. Atmos. Sci., 56, 127–150.

3. Burrows, J. P., et al. (1999), The Global Ozone Monitoring Experiment (GOME): Mission concept and first scientific results, J. Atmos. Sci., 56, 151– 175.

4. Crutzen, P. J. (1979), The role of NO and NO2 in the chemistry of the troposphere and stratosphere, Annu. Rev. Earth Planet. Sci., 7, 443– 472.

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6. Dakiky M, Khamis M, Manassra A; Mereb, M. (2002). “Selected adsorption of Cr (Vi) in industrial wastewater using low cost abundantly available adsorbent”. Advances in environmental research; 6 (4):533-540.

7. Mohamed Suhail, et al., (2010). “Trihalomethanes Removal from Drinking Water Using Low-cost Adsorbents”. ICTT Civil Engineering Papers. Source: http://hdl.handle.net/ 123456789/1044.

8. Mittal A. K. andVenkobachar. C., (1993). Journal of Environ Eng ASCE, 119, 366.

9. Zhe Ming NI, et al., (2004). “The Adsorption of NOxon Magnesium Aluminium Hydrotalcite”. Chinese Chemical Letters Vol. 15, No. 8: 989-992.

10. Zhang, W., Yahiro, H., Mmno, N and Iwamoto, M 1993, Eng Chem. Res. 9, 2337

Received on 19.12.2011 Modified on 02.01.2012

Asian J. Research Chem. 5(1): January 2012; Page 140-142