Study of adsorption behavior using activated carbon for removal of colored impurities from 30% caprolactam solution produced by means of SNIA-toluene-technology

Hongtao Zhang; Ping Yu; Zhen Yuan; Yunbai Luo

Korean Journal of Chemical Engineering, Vol.23, No.3, 455-463, May, 2006

Hongtao Zhang, Ping Yu, Zhen Yuan, and Yunbai Luo^†

College of Chemistry and Molecular Science, Wuhan University, Wuhan 430072, China

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We studied the adsorption removal of the colored impurities from caprolactam solution by granular activated carbons. It was observed that removal was favored at lower pH (pH 3.84 or below) and higher temperature. The effects of concentration, dosage of activated carbons, contact time have been also reported. Uptake of colored impurities was very rapid in the first 100 minutes and reached equilibrium after 24 h. The batch adsorption kinetics was found to follow the pseudo-second-order model and the rate constants of adsorption for all these kinetic models have been calculated. Three isotherm expressions Langmuir, Freundlich and Trinomial were shown to fit with the experimental results successfully. The mass transfer coefficient β and the effective diffusion coefficient in aqueous phase Deff was calculated under a temperature 35-80 °C. The value of the mean free energy of adsorption E signifies that the adsorption of colored impurities onto activated carbon has a physical nature.

Keywords:Colored Impurities;Caprolactam Solution;Activated Carbon;Adsorption Kinetics;Diffusion

[References]

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[1] Czerwinski W, Wiejcka M, Malikowska H, Dyjas S, J. Chromatogr., 208(1), 27 (1981)

[2] Guenter E, Gert L, Claus S, J. Chromatogr., 508(1), 149 (1990)

[3] Jodra LG, Romero A, Garcia-Ochoa F, Aracil J, J. Appl. Polym. Sci., 26(10), 3271 (1981)

[4] Jodra LG, Romero A, Garcia-Ochoa F, Aracil J, Ind. Eng. Chem. Prod. Res. Dev., 20(3), 562 (1981)

[5] Agudo JAG, Cubero MTG, Sep. Purif. Technol., 29, 199 (2002)

[6] Kim SH, Bidkar A, Ngo HH, Vigneswaran S, Moon H, Korean J. Chem. Eng., 18(2), 163 (2001)

[7] Kim SJ, Kim TY, Kim SJ, Cho SY, Korean J. Chem. Eng., 19(6), 1050 (2002)

[8] Kim SJ, Shim WG, Kim TY, Moon H, Kim SJ, Cho SY, Korean J. Chem. Eng., 19(6), 967 (2002)

[9] Kim TY, Kim SJ, Cho SY, Korean J. Chem. Eng., 18(5), 755 (2001)

[10] Kontoyannis GG, Bouropoulos NC, Koutsoukos PG, Analyst, 120(2), 347 (1995)

[11] Malik PK, J. Hazard. Mater., 113, 83 (2004)

[12] McKay G, Allen JS, McConvey IF, Otterburn MS, J. Colloid Interface Sci., 80(2), 323 (1981)

[13] McKay G, Chem. Eng. J., 81(1-3), 213 (2001)

[14] Sarkar M, Acharya PK, Bhattacharya B, J. Colloid Interface Sci., 266(1), 28 (2003)

[15] Namasivayam C, Kavitha D, Dyes Pigment., 54, 47 (2002)

[16] Pendleton P, Wu SH, J. Colloid Interface Sci., 266(2), 245 (2003)

[17] Singh TS, Pant KK, Sep. Purif. Technol., 36, 139 (2004)