TY  - CONF
AU  - Lao, C.
AU  - Sole, M.
AU  - Gamisans, X.
AU  - de las Heras, F.X.C.
T3  - The third international meeting on environmental biotechnology and engineering
PY  - 2008
Y1  - 2008
SP  - 169
AB  - Heavy metals are common pollutants found in many industrial effluents. The use of sorption technologies, based on ionexchange and chemical sorption for the removal of these pollutants from waste water, is especially promising. Low rankcoals contain large amounts of humic acids with carboxylic and phenolic hydroxyl functional groups which can interactwith metal ions. These natural materials, which are available in large quantities, may have potential as inexpensive sor-bents for harmful metal ions encountered in industrial waste waters. In this work, a low-cost sorbent (leonardite) wasinvestigated to remove Cr(III) and Cr(VI) from synthetic aqueous solutions. Batch kinetics and equilibrium experimentswere performed in order to investigate the influence of pH, contact time and initial concentration of sorbate and sor-bent. Adsorption test were conducted using solutions of Cr(NO3)39H2O and K2Cr2O7at concentrations between 1-500ppm of chromium. The adsorbent dose was 1 g/L and the solutions were agitated in a magnetic stirrer. After the adsorp-tion process, solutions were filtered through 0.45 µm Millipore® filters and the remaining concentration of chromiumwere determined by either atomic adsorption spectroscopy (total Cr) or UV- spectroscopy (Cr(VI)). pH influence studiesshowed that at pH<2 there is little or no Cr(III) adsorption The removal efficiency increases at pH 3 and reaches itsmaximum at pH 4-6. For Cr (VI) the maximum removal percentage was obtained a pH <2. This behaviour may be attrib-uted to the combined effect of the nature of the sorbent surface and metal speciation in the aqueous solution. Kineticstudies revealed that for Cr (III), equilibrium was attained in two hours, while contact time to attain equilibrium washigher in the case of Cr(VI) sorption (72 hours). Sorption data were correlated with the Langmuir and Freundlich adsorp-tion models. The maximum sorption capacities obtained from the Langmuir isotherm were 71.4 mg/g and 8.8 mg/g forCr(III) and Cr(VI), respectively. Results also showed that leonardite is able to reduce Cr(VI) to Cr(III).
T2  - The third international meeting on environmental biotechnology and engineering
TI  - Speciation relevance on the removal of chromium from aqueous solutions by a low cost sorbent
ER  -