수용액중의 아닐린의 오존처리 및 생성부산물

유명호, 전성균, 양종규, 이성식

동아대학교 화학공학과

*양산대학 산업안전과

**부산정보대학 환경화학계열

Removal of Aniline and Subsequent Formation of By-Product

in Aqueous Solution During Ozonation

Myung-Ho YU, Sung-Kyun JEON*, Jong-Gyu YANG**, Sung-Sik LEE

Dept. of Chemical Engineering, Dong-A University

*Dept. of Industrial Safety, YangSan College

**Dept. of Envir. & Chemi., Pusan College of Information Technology

E-mail : sslee@seunghak.donga.ac.kr

INTRODUCTION

Ozonation has attracted attention as a potential treatment for various organic compounds in water and as part of an advanced wastewater treatment process during the last few decades.

However relatively little is known of the identity of by-products formed by the interaction of ozone with water.

The objective of this study is to investigate the removal of aniline and subsequent formation of disinfection by-products(DBPs) in aqueous solution by the ozonation.

EXPERIMENTAL

Figure 1 shows the ozone contactor used in this study. It was made entirely of acryl bench contactor with an effective volume of 20 L and was water-jacketed to keep solution temperature at 25℃ for all experiments.

Experimental procedures and techniques have been described in detail elsewhere1). The feed concentration of ozone was about 2 ppm at 10 psi(= 0.7 atm). Ozone contact with aniline solution lasted 1∼60min. At desired time intervals, aniline of a 20 ml solution was withdrawn from the sampling ports which was located at the middle of contactor. Samples were first filterated using the GF/C filter(1□m) and were analyzed for decomposition of aniline. The total organic carbon(TOC) was analyzed by the TOC analyzer (Sievers model TOC-800). The nitrate concentration was analyzed by a ion chromatography (Waters model ILC-1). The concentrations of ozone in the aqueous phases were determined by the Indigo blue method2).

The concentration of the aniline and DBPs were measured using a HP GC 5890 plus equipped with a mass detector(MSD).

Fig. 1. Experimental apparatus of               ozone contactor.

RESULT AND DISCUSSION

Color and TOC

Figure 2 shows the experimental results of aniline color changes with the ozone contact time. It was shown that the color of aniline solution becomes darker and the number of by-products particle was increased with the ozone contact time.

Figure 3 shows the TOC increased with ozone contact time and it was found that the aniline molecule can be destroyed and sequentially degraded and formed into some molecule during ozonation.

Fig. 2. Changes of color for           contact time.

Fig. 3. Changes TOC concentration of

Aniline for contact time.

Nitrate

The nitrogen-containing organic intermediates were postulated to be very refractory to the ozone molecule or OH attack possibly because of the slow and sequential oxidation of the nitrogen-containing species3).

(1)

The simplified decomposition pathway of aniline by ozonation in an aqueous solution is suggested as follow two models

(2-a)

(2-b)

Figure 4 shows the nitrate concentration was nearly constant during ozonation and it can be shown that the behavior of aniline decomposition by ozonation was not consistent with the model (2-a).

Fig. 4. Changed NO3--N concentration

for contact time.

Disinfection By-Products(DBPs)

Figure 5 shows the GC/MSD chart which was analyzed by SCAN mode.

The major ozonation by-products were identified nitrosobenzene, isothiocyanato- cycylohexane and 1-methyl-1H-pyrrolo[2,3-b]pyridine.

On the basis of the experimental results, the decomposition of aniline by ozonation is consistent with the model (2-b) and is proposed pathway as shown in Figure 6.

Fig. 5. GC/MSD chart for ozone contact time, 30min.

Fig. 6. DBPs identified by GC/MSD         for the ozonation of aniline         and propsed decomposotion         pathway of aniline in aqueous         solution by ozonation.

CONCLUSION

Ozonation has been shown to be feasible for achieving a high degree of aniline decomposition in aqueous solution.

The decomposition pathway of aniline by ozone was proposed. The major by-products of aniline by ozonation are nitrosobezene, isothiocyanato-cycylohexane and 1-methyl-1H- pyrrolo[2,3-b]pyridine.

LITERATURE CITED

1) Y. Ku, W. Wang, and Y. S. Shen, "Ozonation of Monocrotophos in Aqueous Solution", Ind. Eng. Chem. Res., 37, 367(1998).

2) J. Hoigne, and H. Bader, "Determination of Ozone in Water by the Indigo Method: A Submitted Method", Ozone Sci. Eng., 4, 169(1982).

3) K. H. Buchel, Chemistry of Pesticides, John Wiley, New York, 1983.