OPEN ACCESS
The performance of carbons produced from the cold-pressed cake of Raphanus sativus (L. var.), a residue from the biodiesel industry, was evaluated for the adsorption of methylene blue (MB) from synthetic aqueous solutions. The study has focused on the following three topics: (i) physical and textural characterization of the carbon, (ii) batch investigation of equilibrium and kinetics of MB adsorption at room temperature, and (iii) analysis of MB adsorption mechanism onto such carbonaceous structures. Regarding the fi rst topic, carbon was characterized using several methods such as Brunauer–Emmett–Teller (BET), Barrett–Joyner–Halenda (BJH), scanning electron microscopy (SEM), and Raman spectroscopy. A microporous carbon was found thus indicating that MB adsorption may occur predominantly at the surface of the carbon. Regarding the second topic, equilibrium tests revealed that Langmuir-based maximum MB uptake capacity was 19.8 mg g–1 and that MB kinetics onto carbon was best described by a pseudo second-order model. Data fi tting analysis confi rmed that MB adsorption onto such carbons was predominantly superfi cial. And fi nally, regarding the third topic, MB adsorption may probably occur by bonding of monomer MB through the central nitrogen atom of its molecule and through sulfur atom while MB bonding through amino nitrogen atom does not seem probable. The study reveals that carbons made of R. sativus are suitable materials for the removal of dyes from aqueous solutions, mainly if fi ner fraction of carbons is used, because MB adsorption was found to be predominantly superfi cial
adsorption equilibrium, adsorption kinetics, methylene blue, Raman spectroscopy
[1] Banat, I.M., Nigam, P., Singh, D. & Marchant, R., Microbial decolorization of textile- dyecontaining effl uents: A review, Bioresource technology, 58, pp. 217–227, 1996. doi: http:// dx.doi.org/10.1016/S0960-8524(96)00113-7
[2] Slokar, Y.M. & Le Marechal, M.A., Methods of decoloration of textile wastewaters, Dyes Pigments, 37, pp. 335–356, 1998. doi: http://dx.doi.org/10.1016/S0143-7208(97)00075-2
[3] Robinson, T., Mcmullan, G., Marchant, R. & Nigam, P., Remediation of dyes in textile e ffl uent: a critical review on current treatment technologies with a proposed alternative, Bioresource technology, 77, pp. 247–255, 2001. doi: http://dx.doi.org/10.1016/S0960-8524(00)00080-8
[4] Crini, G. Non-conventional low-cost adsorbents for dye removal: a review, Bioresource technology, 97, pp. 1061–1085, 2006. doi: http://dx.doi.org/10.1016/j.biortech.2005.05.001
[5] Santos A.B., Cervantes F.J. & van Lier J.B., Review paper on current technologies for deco-lourisation of textile wastewaters: Perspectives for anaerobic biotechnology. Bioresource technology, 98, pp. 2369–2385, 2007. doi: http://dx.doi.org/10.1016/j.biortech.2006.11.013
[6] Ioannidou O. & Zabaniotou A., Agricultural residues as precursors for activated carbon pro-duction – A review, Renewable and Sustainable Energy Review, 11, pp. 1966–2005, 2007. doi: http://dx.doi.org/10.1016/j.rser.2006.03.013
[7] Lázaro D.A., Caldeira C.L, Dantas M.S.S., Franca A.S. & Mansur M.B., Characterization of an absorbent based on Raphanus sativus (L. var.), a solid residue from the biodiesel production, for the removal of methylene blue, In: Proc. of the X Water Pollution, WIT Press, pp. 345–355, 2010.
[8] Ferrero F., Dye removal by low cost adsorbents: Hazelnut shells in comparison with wood saw-dust, Journal of hazardous materials, 142, pp. 144–152, 2007. doi: http://dx.doi.org/10.1016/j. jhazmat.2006.07.072
[9] Karagöz S., Tay T., Ucar S. & Erdem M., Activated carbons from waste biomass by sulfu-ric acid activation and their use on methylene blue adsorption, Bioresource technology, 99, pp. 6214–6222, 2008. doi: http://dx.doi.org/10.1016/j.biortech.2007.12.019
[10] Nunes A.A., Franca A.S. & Oliveira L.S., Activated carbons from waste biomass: An alternative use for biodiesel production solid residues, Bioresource technology, 100, pp. 1786–1792, 2008. doi: http://dx.doi.org/10.1016/j.biortech.2008.09.032
[11] Banat F., Al-Asheh S. & Al-Makhadmeh L., Evaluation of the use of raw and activated date pits as potential adsorbents for dye containing waters, Process Biochemical,, 39, pp. 193–202, 2003. doi: http://dx.doi.org/10.1016/S0032-9592(03)00065-7
[12] Aygun A., Yenisoy-Karakas S. & Duman I., Production of granular activated carbon from fruit stones and nutshells and evaluation of their physical, chemical and adsorption properties, Microporous and Mesoporous Materials, 66, pp. 189–195, 2003. doi: http://dx.doi.
org/10.1016/j.micromeso.2003.08.028
[13] Franca A.S., Oliveira L.S. & Ferreira M.A., Kinetics and equilibrium studies of methylene blue adsorption by spent coffee grounds, Desalination, 249, pp. 267–272, 2008. doi: http://dx.doi. org/10.1016/j.desal.2008.11.017
[14] Xun Y., Shu-Ping Z., Wei X., Hong-You C., Xiao-Dong D., Xin-Mei L. & Zi-Feng, Y. Aqueous dye adsorption on ordered mesoporous carbons, Journal of colloid and interface science, 310, pp. 83–89, 2007. doi: http://dx.doi.org/10.1016/j.jcis.2007.01.069
[15] Haghseresht F., Lu G.Q. & Whittaker A.K., Carbon structure and porosity of carbonaceous adsorbents in relation to their adsorption properties, Carbon, 37, pp. 1491–1497, 1999. doi: http://dx.doi.org/10.1016/S0008-6223(99)00012-3
[16] Rubim J.C., Sousa M.H., Silva J.C.O. & Tourinho F.A., Raman spectroscopy as a powerful technique in the characterization of ferrofl uids, Brazilian Journal of Physics, 31, pp. 402–408,
2001. doi: http://dx.doi.org/10.1590/S0103-97332001000300010
[17] Tafulo P.A.R., Queirós R.B. & González-Aguilar G., On the ‘concentration-driven’ methylene blue dimerization. Spectrochimica Acta Part A, 73, pp. 295–300, 2009. doi: http://dx.doi. org/10.1016/j.saa.2009.02.033
[18] Tognalli G.N., Fainstai A., Vericat C., Vela M.R. & Salvarezza R.C., An exploring three- dimensional nanosystems with Raman spectroscopy: methylene blue adsorbed on thiol and sulfur monolayers on gold, journal of physical chemistry. B, 110, pp. 354–360, 2006.
[19] Naujok R.R., Robert V.D. & Corn R.M., Fluorescence and Fourier transform surface-enhanced raman scattering measurements of methylene blue adsorbed onto a sulfur-modifi ed gold electrode, Langmuir, 9, pp. 1771–1774, 1993. doi: http://dx.doi.org/10.1021/la00031a026
[20] Hutchinson K. & Hester R.E., Raman spectroscopic studies of a thionine-modifi ed electrode, Journal of Chemical Society-Faraday Transactions I, 80, pp. 2053–2071, 1984. doi: http:// dx.doi.org/10.1039/f19848002053
[21] Xun Y., Shu-Ping Z., Wei X., Hong-You C., Xiao-Dong D., Xin-Mei L. & Zi-Feng Y., Aqueous dye adsorption on ordered mesoporous carbons, Journal of colloid and interface science, 310, pp. 83–89, 2007. doi: http://dx.doi.org/10.1016/j.jcis.2007.01.069