title: Coconut coir as biosorbent for Cr(VI) removal from laboratory wastewater.
abstract: A high cost-effective treatment of sulphochromic waste is proposed employing a raw coconut coir as biosorbent for Cr(VI) removal. The ideal pH and sorption kinetic, sorption capacities, and sorption sites were the studied biosorbent parameters. After testing five different isotherm models with standard solutions, Redlich-Peterson and Toth best fitted the experimental data, obtaining a theoretical Cr(VI) sorption capacity (SC) of 6.3 mg g(-1). Acid-base potentiometric titration indicated around of 73% of sorption sites were from phenolic compounds, probably lignin. Differences between sorption sites in the coconut coir before and after Cr adsorption identified from Fourier transform infrared spectra suggested a modification of sorption sites after sulphochromic waste treatment, indicating that the sorption mechanism involves organic matter oxidation and chromium uptake. For sulphocromic waste treatment, the SC was improved to 26.8+/-0.2 mg g(-1), and no adsorbed Cr(VI) was reduced, remaining only Cr(III) in the final solution. The adsorbed material was calcinated to obtain Cr(2)O(3,) with a reduction of more than 60% of the original mass.
authors: Grupo de Análise Instrumental Aplicada, Embrapa Pecuária Sudeste, P.O. Box 339, 13560-970 São Carlos, SP, Brazil.
authors: Mário H
authors: MH
authors: Gonzalez
authors: Geórgia C L
authors: GC
authors: Araújo
authors: Claudia B
authors: CB
authors: Pelizaro
authors: Eveline A
authors: EA
authors: Menezes
authors: Sherlan G
authors: SG
authors: Lemos
authors: Gilberto Batista
authors: GB
authors: de Sousa
authors: Ana Rita A
authors: AR
authors: Nogueira
mesh_terms: D000042:Absorption; D017608:Chromium Compounds / Q000302:isolation & purification*; D003059:Cocos / Q000737:chemistry*; D003362:Cost-Benefit Analysis; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007753:Laboratories; D011199:Potentiometry; D013457:Sulfur Compounds / Q000737:chemistry; D013816:Thermodynamics; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: D017608:Chromium Compounds; D013457:Sulfur Compounds