Peanut Husks Functionalized with Citric Acid and Ethylene -1, 2-Diamine for Removal of Lead (Ii) Ions from Contaminated Water
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Date
2021
Authors
Minda, Stephen
Journal Title
Journal ISSN
Volume Title
Publisher
Kenyatta University
Abstract
Consumption of water contaminated with heavy metals poses a major risk.
Consequently, safe and effective treatment of contaminated water remains a topic of
global concern. Lead is among the most prevalent heavy metal contaminants as it is
widely used in metallic form. It is easily absorbed by the body through water intake.
In body, lead inhibits the enzymes and induces generation of reactive oxygen species
that intensifies oxidative stress. This mechanism makes lead neurotoxic, mutagenic,
teratogenic and carcinogenic. Studies reveal that some parts of Tanzania have higher
levels of lead than the recommended level by World Health Organization and East
African Community of 0.01mg/L in drinking water. Although several water treatment
methods are available, adsorption offers an attractive method for the removal of heavy
metal in terms of cost of adsorbent production, simplicity of design and operation.
Cellulose-carboxylate ion and 6-(2-aminoethylamino)-6-deoxycellulose (or called
celen) are thermally stable and can be easily employed for the adsorption of cations
from aqueous medium. Hence, this study was aimed at modifying the peanut husks
with citric acid and ethylene-1,2-diamine to synthesize cellulose-carboxylate ion and
celen respectively to determine the adsorption capacity and efficiency in the removal
of Pb(II) ion from contaminated water. Peanut husks were collected from Dodoma
region in Tanzania, washed, ground and modified with citric acid and ethylene-1,2-
diamine to prepare adsorbents. FTIR confirmed the peanut husks to contain cellulose
and that the citric acid and ethylene-1,2-diamine are anchored onto the cellulose. XRF
revealed that the peanut husks contained zero percent of Pb metal and XRD proved
the amorphous nature of the cellulose present in peanut husks. Batch experiments
were carried out to determine the effect of pH, contact time, temperature, initial
concentration and adsorbent dose on adsorption process. The experimental data were
fitted in Langmuir and Freundlich isotherms and were found to fit best in Langmuir
isotherm as it had the highest value of correlation coefficient of 0.998, 0.959 and
0.997 for UMP, CMP and EMP respectively. The maximum monolayer adsorption
capacities were 18.8 mg/g for UMP, 11.36mg/g for CMP and 19.23mg/g for EMP.
Based on the adsorption capacities, EMP is a better adsorbent than the rest. These
results indicate that peanut husks tethered with citric acid and ethylene-1,2-diamine
constitute a promising material for the development of an adsorption technology for
the removal of Pb(II) ion from aqueous systems.
Description
A Thesis Submitted in Partial Fulfillment of the Requirements for the Award of the Degree of Master Of Science (Chemistry) in the School of Pure and Applied Science of Kenyatta University, August 2021
Keywords
Peanut Husks Functionalized, Citric Acid, Ethylene -1, 2-Diamine, Removal of Lead (Ii) Ions, Contaminated Water