Abstract:
The increasing population affects the use of fresh water resources thus creating a
need for water purification. Most of the commercial techniques are high cost and
thus a need for a low cost water clarifying and purification method. This research
considered Maerua decumbens root tuber powder as a biosorbent and a natural
coagulant
.The aim was to analyze Maerua decumbens root tuber powder efficiency,
as a primary coagulant, to determine the parameters (physical and chemical)
reduction in clarified water, and optimization of various sorption parameters
by
biosorption of Cu (II), Cr (III), Cd (II), and Pb (II). Maerua decumbens plants was
collected from Baringo County in Kenya, The root tubers were washed cut into small
pieces dried and ground into powder. Water analysis parameters determined
included: alkalinity, conductivity and turbidity. The optimum dosage for the root
tuber was established at 1.25 mg/L. The root tuber used reduced the alkalinity,
conductivity and turbidity to permissible levels. The effect of varying pH on Maerua
decumbens and Alum was also compared and the tuber compared well to Alum. In
biosorption studies, the optimum pH was 5.0 for Cu (II), 5.2 for Cr (III) and Cd (II);
5.5 for Pb (II).Contact time was established after 40 min for Pb (II) and 30 min for
Cr (III), Cd (II), and Cu (II). FTIR analysis for Maerua decumbens root tuber powder
indicated the presence of carbonyl, carboxyl, hydroxyl and amino functional groups,
which were responsible for biosorption of Cr (III), Cd (II), Cu (II), and Pb (II).The
data for biosorption fitted well in pseudo second-order kinetic model than first order.
The isotherms model for the biosorbent fitted well with the Freundlich isotherm
model than with the Langmuir isotherm model. The study showed that this natural
coagulant was a good biosorbent and exhibited good coagulation activity for the
removal of Cr (III), Cd (II), Cu (II), and Pb (II) from aqueous solution.
