**5. Conclusion**

**1 2 3 4**

**Figure 12.** Chromium (VI) Reduction by lactic acid. 1. - Lactic acid standard solution (85%) 2. - Chromium (VI) standard solution (1.0 g /L). pH= 1.0 3.-100 mg Cr (VI)/L with lactic acid (100 mL) 4. - 1000 mg Cr (VI)/L with lactic acid (100 mL)

Furthermore, the researchers examined the ability of different solutions to desorb the metal bioadsorbed (250 mg/L) for the Litchi biomass, obtaining high efficiency with 0.1 N NaOH and 0.5 N (80 and 61% respectively (Figure 13), which are less those reported for desorption of Chromium (VI) with alkaline solutions (100%, pH 9.5), 1.0 N NaOH (95%) and a hot solution of NaOH/Na2CO3 (90%), respectively, [21, 51], and are higher than that reported (14.2%) using 0.2 M NaOH [52]. This indicates that binding of metal to biomass is not as strong and that it can be used up to 6 desorption cycles of removal, which further lowers the metal removal

0 1 2 3 4 5 6 7 8

NaOH 0.1 N NaOH 0.5N H2SO4 H2O Tri

**Time (days)**

**Figure 13.** Desorption of Chromium (VI) (250 mg/L) by different solutions (1 g biomass. 28°C, 100 rpm)

**4.6. Desorption of Cr (VI) by different solutions**

218 Applied Bioremediation - Active and Passive Approaches

process of niches contaminated with it.

**Percentage of Cr (VI) in solution**

The use of biomaterials like natural biomasses has demonstrated to be a promising alternative for removal of Chromium hexavalent from aqueous solution. The screening and selection of the most effective biomaterial (biomasses) with sufficiently high metal binding capacity and selectivity for heavy metal ions, in this case, Chromium (VI), are prerequisite for a full process.

The natural biomasses showed complete capacity of biosorption and reduction concentrations of 1.0 g/L Cr (VI) in solution after different incubation times, and *L. chinensis* Sonn, *C. reticu‐*

*lata*, and *M. americana* shells, were the most efficient, at 28°C, 100 rpm with 1 g of biomass, and after of 10 weeks the natural biomass of *M. americana*, removed 83% of the metal in contami‐ nated soil (100 kg), with 345 mg Cr (VI)/g of soil. These results suggest the potential applica‐ bility of these biomasses for the remediation of Cr (VI) from polluted soils and waters in the fields, and this biomasses are naturals, they can be obtained in big amount, cheaper, and could be removal selectively heavy metals from aquatic mediums.

[7] Sahin, Y. and Öztürk, A. Biosorption of chromium (VI) ions from aqueous solution by the bacterium *Bacillus thuringiensis*. Process Biochemistry 2004; 40 (5), 1895-1901.

Removal of Hexavalent Chromium from Solutions and Contaminated Sites by Different Natural Biomasses

http://dx.doi.org/10.5772/56152

221

[8] Volesky, B. and Holan. Z.R. Biosorption of heavy metals. Biotechnology Progress

[9] Chen, S., Yue, Q., Gao, B., Li, Q. and Xu, X. Removal of Cr (VI) from aqueous solu‐ tion using modified corn stalks: Characteristic, equilibrium, kinetic and thermody‐

[10] Cimino, G., Passerini, A. and Toscano, G. Removal of toxic cations and Cr (VI) from

[11] Perez-Marin, A.B., Meseguer, V., Zapata, J.F., Ortuno, M. and J. Aguilar, J. Removal of cadmium from aqueous solutions by adsorption onto orange waste. Journal of

[12] Acosta, I., López, V., Coronado, E., Cárdenas, J.F. and Martínez, V.M. 2010. Remo‐ ción de Cromo (VI) por la biomasa de la cascara de Tamarindo, (*Tamarindus indica*).

[13] Acosta-Rodríguez, I., Martínez-Pérez, R., Cárdenas-González, J.F., Moctezuma-Zá‐ rate, M.G. and Martínez-Juárez, V.M. Hexavalent Chromium Removal by *Litchi chi‐ nensis* Sonn Peel. American Journal of Biochemistry and Biotechnology 2012; 8(1)

[14] Razmovski, R.N. and Sciban, M.B. Effect of different conditions on Cu (II) and Cr (VI) biosorption by dried waste tea fungal biomass. APTEFF 2007; 38,149-156.

[15] Aldrich, M.V., Torresdey, J.L.G., Videa, J.R.P. and Parsons, J.G. Uptake and reduction of Cr(VI) to Cr(III) by mesquite (*Prosopis* spp.): chromate−plant interaction in hydro‐ ponics and solid media studied using XAS. Environmental Science Technology 2003;

[16] Sarin, V. and Pant, K.K. Removal of chromium from industrial waste by using euca‐

[17] Shafqat, F., Bhatti, H.N., Hanif, M.A. and Zubair, A. kinetic and equilibrium studies of Cr (III) and Cr (VI) sorption from aqueous solution using rosa gruss an teplitz (red

[18] Fiol, N., C. Escudero, C. and Villaescusa, I. Chromium sorption and Cr (VI) reduction to Cr (III) by grape stalks and yohimbe bark. Bioresource Technology 2008; 99,

[19] Clesceri, L.S., A.D. Eaton and A.E. Greenberg. Standard Methods for the Examina‐ tion of Water and Wastewater. 20th Ed., American Public Health Association, Wash‐

rose) waste biomass. Journal of Chile Chemical Society 2008; 53, 1667-1672.

aqueous solution by hazelnut shell. Water Research 2000; 34, 2955-2962.

namic study. Chemical Engineering Journal 2011; 168, 909-917.

Revista de Biotecnología y Bioingeniería 2010; 14, 11-23.

lyptus bark. Bioresource Technology 2006; 97, 15-20.

Hazardous Materials 2007; 139, 122-131.

1995; 11, 235-250.

7-13.

37, 1859-1864.

5030-5036.

ington, D.C.; 1998; pp. 1220.
