457350 Factors Effecting the Simultaneous and Consecutive Reduction and Adsorption of Anionic Cr(VI) and Orange II Dye Onto Chemically Modified Masau Seeds
Ahmad B. Albadarin*, Maurice N. Collins, and Gavin Walker
Bernal Institute, Dept. Chemical & Environmental Science, University of Limerick, Limerick, Ireland *Tel.: +353-(0)-61-237732, E-mail: Ahmad.B.Albadarin@ul.ie
Novel chemically modified masau seeds (MMS) were prepared and used to investigate the solution chemistry factors influencing the reduction of Cr(VI) and adsorption of orange II (OII) dye in single, consecutively (after one another) and multicomponent systems. Epichlorohydrin and diethylenetriamine were employed as etherifying and crosslinking agents, respectively. The effect of reaction time, solution pH, initial concentration, temperature, loading order on reduction/adsorption mechanisms were examined. Additionally, characterisation techniques such as: BET, FT-IR, SEM-EDX and XPS were employed to investigate the physio-chemical properties of the modified masau before and after the adsorption of dye II orange and Cr(VI).
The maximum adsorption capacity of Cr(VI) and OII onto MMS reached approx. 50mg/g (pH = 2, Co = 100mg and dose = 2g/dm3). This is due to the zeta potential changes in the surface charge of the MMS (surface is positive below pH = 6). A higher concentration of positively charged hydrogen ions were achieved at a lower pH resulting in increased levels of protonated amine groups of MMS distributed on its surface.
Park redox and pseudo second-order models were able to adequately predict the kinetics of the reduction of Cr(VI) and adsorption of OII dye, respectively. The experimental data showed that there are no competitive interactions between the dye molecules and Cr(VI) ions. However, Cr(VI) is reduced/adsorbed more easily than the dye molecule and more notably, Cr(VI) diffusivity is about four times higher than the dye diffusivity.
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