Investigation of Acid Treated Lemna minor as Adsorbent for Removal of Cu and Pb from aqueous solution
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Date
2018-06
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Publisher
Addis Ababa University
Abstract
The release of wastewater with heavy metals of Cu, Pb, Zn, Cd etc. Particularly in areas with
expansion of industries can pose a significant threat to human health and environment due to
their toxicity. This paper deals with bio sorption of heavy metals (copper and lead) using acid
treated dried lemna minor powder. The adsorbent after treated with hydrochloric acid was dried
and ground to a particle size range of (820-850) µm. Characterization of the adsorbent such as
proximate analysis, surface charge, FTIR spectroscopy, surface area and XRD was done prior to
bio sorption process. A batch adsorption experiment was carried out using central composite
design expert 6.0.8 and the effect of adsorption parameters: pH, initial metal concentration, and
adsorbent dose was studied. The result indicated that maximum percentage removal of 92.45 %
for Lead (II) was obtained at pH = 11. Similarly, 88.4 % removal was found for Copper (II) at
pH = 9. Temperature effects showed that the adsorption process was endothermic with positive
enthalpy and negative free Gibbs energy values. The Removal efficiency of lemna minor
increased with increase in temperature. Data‘s from the adsorption were analyzed with Temkin,
Langmuir and Freundlich isotherm models. Desorption of Cu
+2
and Pb
+2
were carried out by
using a 100ml of 0.1M HCl in to 250 volumetric flasks with 0.1 g of 43.86 ppm of copper and
42.38 ppm of Lead loaded sun dried lemna minor. The percent desorption increased with time
for both metals and maximum desorption observed at 60-minute contact time with 80% for Lead
and 72.2% for Copper.
Description
Keywords
Heavy metals, Lemna minor, Biosorption, Desorption, Percent removal, adsorption capacity