Synthesis of Carbon Dioxide and Amine Modified Biomass - Hydrogel for Improved Water Retention in Agricultural Soils
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Date
2024-03
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Kenyatta University
Abstract
Increasingly emission of greenhouse gases especially carbon dioxide that contribute to
global warming is a serious concern worldwide. Attempts to capture carbon dioxide from
the environment from post-combustion industries have been proposed such as use of
alkylamines. This is because amines have a higher affinity of carbon dioxide. However,
they have a challenge of offensive odour that is not comfortable in industrial
environment. Aqueous alkanolamines are also known to be corrosive to material within
the industrial setup. To overcome such challenges this study proposed the use of amines
anchored on solid substrates to serve as an absorbent of carbon dioxide. Its interaction
with carbon dioxide produced a carbamate that futher cross-linked the amine modified
material that was found to have high antibacterial properties. Thus, the material was
capable of being applied in the field for extended duration. Each step of the modification
process which was done using synthetic (Ethyldiamine) and amines from bio-sources
(silver cyprinid -omena) was confirmed using Fourier transform infra-red spectroscopy
FTIR analysis. In this study the main focus was to modify amine from bio sources and
use it as soil modifier in agricultural farms. Amine modified biomass interact with carbon
dioxide from the air to from carbamates that interacts with water and adsorbs it to its
surface increasing its volume and reduces when the water is desorbed and the volume
variation helps to aerate the soil. The modified material was applied in well prepared plot
within the university for the growth of maize (zea may) and arrowroots (Rastrineobola
argentea) during the dry season. The study found that modified material enhanced the
growth of vegetation as 1.0 kg of that material contributed to an average height of maize
of 268.25 cm as well as arrow roots to rapidly bloom providing a plant with a leaf length
of dimension of 68.45 cm within the first month of growth. Also, 0.4g of the modified
material was capable of enabling (one) maize plant to produce 1.055 kg of dry grains
upon maturity. The analysis confirmed significant increase of the height, number of
leaves, leaf length and yields of the plants with the increase in the concentration of
modified biomass. This resulted from the available amount of water in the structure of
modified biomass making the absorbed water available around the plant roots, by
increasing the capability of soil to hold much water. The modified biomass acquired more
than 200% of the swelling capacity compared to the unmodified biomass. Microbial
analysis confirmed that the modification of the material provided sufficient antimicrobial
activity to cover the duration of the plant’s growth. The amount of carbon dioxide
absorbed by the amine modified biomass was directly proportional to the mass used. It
was observed that a sample of 100g of the modified biomass absorbed a maximum of
489.1 cm3
of the total volume of the prepared carbon dioxide gas. The pH of the modified
material remained between 6.60 and 7.40 even after addition of mineral acids such as
hydrochloric acid. This implies that the modified biomass is not significantly affected by
the pH variation and therefore does not affect the acidity or the alkalinity of the soil when
applied. The capability of the modified biomass to retain water in the soil for a longer
period will enhance growth of vegetation in areas with inadequate rainfall and increase
food production in Kenya. Thus, the study found that the modified biomass contributed
positively to the growth and yield of the respective plants by improving soil properties
which enhances root propagation.
Description
A Thesis Submitted in Partial Fulfillment of the Requirements for the Award of the Degree of Master of Science (Analytical Chemistry) in the School of Pure and Applied Sciences of Kenyatta University March, 2024
Supervisors:
1. Isaac W. Mwangi
2. Sauda Swaleh