Removal of turbidity, lead and cadmium ions from wastewaters using products derived from mangifera indica kernel
Loading...
Date
2014-10-30
Authors
Kariuki, John Njuguna
Journal Title
Journal ISSN
Volume Title
Publisher
Kenyatta University
Abstract
Lack of sufficient safe drinking water remains a major challenge world over. Further,
population growth and subsequent growth in agriculture, industry and technology
continues to contribute to increased contamination of the little available clean water
everyday. Major contaminants include, agro-chemical residuals, industrial effluents,
acids, dyes and toxic heavy metals. Heavy metals of concern includes lead and
cadmium because at even very low levels are toxic and have no known metabolism in
the body. Literature findings have established a direct correlation between the level of
turbidity and microbial load. convectional methods fall short because they are
expensive or not readily available. The current work sought to establish a low cost
effective adsorbent by utilizing mango (Mangifera indica L.) kernels agricultural
waste as a resource to prepare adsorbent materials. Biomass, MBM was obtained by
grinding dried kernels, ash, MKA was obtained by burning M.indica kernels in
presence of oxygen in a furnace at 600ºC. Carbon, MKC and activated carbon,
MKAC, were prepared by pyrolysis of dried kernels and activated kernels in a furnace
at 400ºC, respectively. The materials obtained were utilized for the adsorption of lead
and cadmium ions and turbidity from wastewaters. Batch experiments were carried
out to determine the effect of contact time, initial concentration of metal ions, dosage,
temperature and pH on the percentage removal of Pb2+, Cd2+ and turbidity on the four
adsorbents. The adsorption capacity for Pb2+ was 8.73 for MKAC, 5.69 for MKC,
9.69 for MKA and 4.69 for MBM and 12.76, 7.13, 12.71 and 3.8 for MKAC, MKC,
MKA and MBM, respectively for Cd2+. MKAC, MKC and MKA fitted well in
Freundlich adsorption isotherm model for Pb2+ and Cd2+ with R2 values of 0.989 for
MKAC, 0.993 for MKC and 0.978 for MKA with Pb2+ and 0.974, 0.987 and 0.914 for
MKAC, MKC and MKA, respectively for Cd2+. MBM fitted in the Langmuir model
with R2 value of 0.983 and 0.997 for Pb2+ and Cd2+, respectively. Highest percentage
turbidity removal were 54.82, 31.63, 97.37 and 59.97 for MKAC, MKC, MKA and
MBM, respectively. Products derived from M. indica kernel were found to be
effective adsorbents.