[Show abstract][Hide abstract] ABSTRACT: Raphanus sativuspeels (RSP) biomass for the adsorptive removal of Cadmium (II) has been
studied. The effect of different experimental parameter like pH, temperature, contact time,
and initial concentration has been reported. The equilibrium adsorption data were subjected
to different adsorption isotherms (Langmuir, Freundlich, Dubinin-Radushkevich, Temkin,
Flory-Huggins isotherm, and Brunauer, Emmet and Teller isotherms), for kinetic studies
pseudo-first-order, pseudo-second-order, Banghams’s model, and intraparticle diffusion
kinetic models were applied. The experimental results indicated that the adsorption of Cd(II)
followed monolayer adsorption model and pseudo-second-order kinetics. The change in ther-modynamic parameters like free energy (DG˚), enthalpy (DH˚), and entropy (DS˚) was also
evaluated. It was found that the RSPexhibits good adsorption capacity for Cadmium (II)
from aqueous solution.
Desalination and water treatment 11/2012; 51(22-24). DOI:10.1080/19443994.2012.752333 · 1.17 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The chemical speciation of heavy metals (arsenic, chromium, copper, lead, zinc and tin) in the sediments of the former tin mining catchment Bestari Jaya, Peninsular Malaysia was determined using the latest version of the Community Bureau of Reference, the BCR 3-step, sequential extraction procedure. A fourth step was introduced for the digestion and analysis of the residue. The analysis of total metal content was carried out using microwave-assisted acid digestion. The percentage of each metal obtained from the four steps extraction (acid-soluble + reducible + oxidisable + residual) is in good agreement with the percentage of total metal content obtained from microwave digestion, which implies that the accuracy of the procedure. The degree of pollution in catchment sediments was assessed using geoaccumulation index Igeo and pollution intensity IPOLL. The results indicates that: (1) the sediments have been polluted with arsenic (8.8%), chromium (12.9%), copper (17.4%), lead (19.5%), zinc (14.9%) and tin (33.8%) and have high anthropogenic influences; (2) the calculation of geo-accumulation index suggests that catchment sediments have background concentrations of all the studied metals (Igeo < 0); (3) high IPOLL showed that all of these heavy metals pose a high environmental risk; and (4) the mobility order of metals in sediments at S1 and S2 was Sn>Pb>Zn>Cr >Cu >As, whereas at S3, S4 and S5 it was Cu>Pb>Zn>Cr>Sn>As. In conclusion, acidic pH, total organic carbon, scavenging ability and co precipitation (inclusion, occlusion and adsorption) of studied metals with nonmetals could account for changes in the geochemistry of the catchment sediments.
Chemical Speciation and Bioavailability 08/2012; 24(3):183-196. DOI:10.3184/095422912X13406425859315 · 0.59 Impact Factor