A Comparative Study of Modified and Unmodified Algae (Pediastrum boryanum) for Removal of Lead, Cadmium and Copper in Contaminated Water
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Date
2017
Authors
Joseph, John Okapes
Mwangi, Isaac W.
Swaleh, Sauda
Wanjau, Ruth N.
Ram, Manohar
Ngila, Jane Catherine
Journal Title
Journal ISSN
Volume Title
Publisher
INTECH
Abstract
The presence of heavy metals in water is of concern due to the risk toxicity. Thus there
is need for their removal for the safety of consumers. Methods applied for removal of
heavy metals include adsorption, membrane filtration and co-precipitation. However,
studies have revealed adsorption is highly effective technique. Most adsorbents are
expensive or require extensive processing before use and hence need to explore for
possible sources of inexpensive adsorbents. This research work investigated the use an
algal biomass (pediastrum boryanum) as an adsorbent for removal of Lead, Cadmium and
Copper in waste water in its raw and modified forms. The samples were characterized
with FTIR and was confirmed a successful modification with tetramethylethlynediamine
(TMEDA). Sorption parameters were optimized and the material was finally
applied on real water samples. It was found that the sorption was best at lower pH
values (4.2-6.8). Sorption kinetics was very high as more that 90% of the metals were
removed from the solution within 30 minutes. The adsorption of copper fitted into the
Langmuir adsorption isotherm indicating a monolayer binding mechanism. Cadmium
and lead fiĴed best the Freundlich adsorption mechanism. Sorption of lead and
cadmium was of pseudo-second order kinetics, confirming a multisite interaction
whereas copper was pseudoȬfirst order indicating a single site adsorption. The
adsorption capacity did not improve upon modification but the stability of the material
was improved and secondary pollution of leaching colour was alleviated. This implies
that the modified material is suitable for application on the removal of metals from
water.
Description
Chapter from the book "Water Quality"
Keywords
Modified algae, Tetramethylethylenediamine, Sorption, Heavy metals, Contaminated water